My scientist friend asked how to detox or clean his body from toxins

Over the years, I have experienced family and friends dying of cancer. I observed their lifestyle and toxins they are exposed to. So to answer my friend’s question on how to detox and the mechanism of cleaning our body or getting rid of toxins, I listed some items for Dos and Donts.

Our lymphatic system which travels opposite our blood is responsible for cleaning our blood.  Search for lymphatic, massage and detox in this site

When we clean the many bad foods or toxins that entered our body, we must clean our liver first, our laboratory.  It is closely linked to our heart that during our last breath, our liver is the first and last signal that our heart gets to shut down.

Detox or cleaning our cells from toxins is the key to living longer, the anti-aging process we all are seeking for. In my 50s, I could have died long time ago if I was born centuries ago with no clean water, fresh produce and raising a dozen children. Each child is minus 5 years of a woman’s age.

Detox is like cleaning the toilet. The following are detox tips and anti-aging tips to clean your cells:

Dos in cleansing your body from toxin, also detoxes your liver

  • Massage
  • Adequate sleep
  • Filtered water
  • Lemon
  • Baking soda (pinch in your drinking water)
  • Activated charcoal
  • Digestive enzymes from pineapple and papaya
  • Apple cider vinegar
  • Wash produce with salt or diluted vinegar
  • No over ripe fruits and left over foods or 3-day old rice ( aflatoxin , mycotoxin )
  • No charred BBQ
  • Whole foods ; sulfur rich as they are anti-inflammatory (ginger, garlic, turmeric, coconut, walnuts)
  • Deep breathing thru nose and blow out thru mouth
  • Prayer: May God’s light energy be with you and say Amen to accept it.
  • Resveratrol from Berries, kiwi, citrus fruit
  • Fasting
  • Activated charcoal
  • Clean air

Donts are ways that when practiced or consumed can kills our nerve cells and produce toxins in our cells.

  • Avoidance of too much caffeine, iron and sugar, these are food for cancer
  • Other metal toxins
  • TRANS fat
  • Processed
  • Plastics in food
  • Stress
  • Shift work: not sleeping from 10pm to 4 am
  • Radiation
  • Over medications, chemo, other carcinogens
  • Avoid exposure to fumes, chemicals (formaldehydes,carcinogens,toxins)



Hi Connnie,

And what is your recipe for liver detox and the mechanism by which it works to accomplish that?

From: Male friend in his late 50s whose brother died of pancreatic cancer

Diabetes, meat, iron and A1c

Bacteria and inflammation thrives in the presence of heme, iron. Diabetes starts with inflammation. A1c in the blood shows the 3-month average plasma glucose concentration. CVD, cardiovascular disease, is an inflammation of the vascular system.

Deaths from CVD: 17.9 million / 32% (2015)

Researchers analyzed 14 exercise studies involving 915 adults with type 2 diabetes. Aerobic exercise (such as walking and bike riding) was better at lowering A1C levels—a measure of blood glucose control for the past two to three months—than was resistance training (such as lifting weights).

Email for the Homocysteine with CBC Chemistry Profile blood test from Life Extension for $119. Use paypal account . Free health coaching is included.

From wiki:

Glycated hemoglobin (hemoglobin A1cHbA1cA1C, or Hb1c; sometimes also referred to as being Hb1c or HGBA1C) is a form of hemoglobin that is measured primarily to identify the three-month average plasma glucose concentration. The test is limited to a three-month average because the lifespan of a red blood cell is four months (120 days). However, since RBCs do not all undergo lysis at the same time, HbA1C is taken as a limited measure of 3 months. It is formed in a non-enzymatic glycation pathway by hemoglobin’s exposure to plasma glucose. HbA1c is a measure of the beta-N-1-deoxy fructosyl component of hemoglobin.[1]

The origin of the naming derives from Hemoglobin type A being separated on cation exchange chromatography. The first fraction to separate, probably considered to be pure Hemoglobin A, was designated HbA0 , the following fractions were designated HbA1a, HbA1b, and HbA1c, respective of their order of elution. There have subsequently been many more sub fractions as separation techniques have improved.[2] Normal levels of glucose produce a normal amount of glycated hemoglobin. As the average amount of plasma glucose increases, the fraction of glycated hemoglobin increases in a predictable way. This serves as a marker for average blood glucose levels over the previous three months before the measurement as this is the lifespan of red blood cells.

In diabetes mellitus, higher amounts of glycated hemoglobin, indicating poorer control of blood glucose levels, have been associated with cardiovascular diseasenephropathyneuropathy, and retinopathy. A trial on a group of patients with Type 1 diabetes found that monitoring by caregivers of HbA1c led to changes in diabetes treatment and improvement of metabolic control compared to monitoring only of blood or urine glucose.[3] However, a trial designed specifically to determine whether reducing HbA1c below the normal 6%, using primarily insulin and sulfonylureas (both known to easily drive blood sugar too low), would reduce the rate of cardiovascular events in Type 2 Diabetes found higher mortality—the trial was terminated early.[4] The negative outcomes may well have been a result of the treatment approach, primarily insulin and sulfonylureas, utilized in the “intensive” treatment group instead of LCHFGlP-1 analogues & SGLT-2 inhibitors, none of which have these problems & lower cardiovascular mortality.

A1c p0A1c p1

Bacterial Heme Toxicity and DNA damaging process

Virtually all bacterial pathogens require iron to infect vertebrates. The most abundant source of iron within vertebrates is in the form of heme as a cofactor of hemoproteins. Many bacterial pathogens have elegant systems dedicated to the acquisition of heme from host hemoproteins. Once internalized, heme is either degraded to release free iron or used intact as a cofactor in catalases, cytochromes, and other bacterial hemoproteins. Paradoxically, the high redox potential of heme makes it a liability, as heme is toxic at high concentrations. Although a variety of mechanisms have been proposed to explain heme toxicity, the mechanisms by which heme kills bacteria are not well understood. Nonetheless, bacteria employ various strategies to protect against and eliminate heme toxicity. Factors involved in heme acquisition and detoxification have been found to contribute to virulence, underscoring the physiological relevance of heme stress during pathogenesis. Herein we describe the current understanding of the mechanisms of heme toxicity and how bacterial pathogens overcome the heme paradox during infection.

Iron is an essential cofactor for many enzymes found within all kingdoms of life.

Bacterial pathogens are no exception to this rule, and therefore, they must acquire iron from their hosts in order to cause disease. Iron is a transition metal that can cycle between redox states, making it a valuable cofactor for biological processes. Ferric iron is water insoluble, and as such, it requires specialized proteins to facilitate its mobilization and to maintain intracellular reservoirs. In mammalian species, lactoferrin and transferrin transport iron, while ferritin stores iron. The most abundant form of iron in vertebrates, however, is bound within a porphyrin ring as ferriprotoporphyrin IX (heme). Heme solubilizes iron and enhances its catalytic ability by 5 to 10 orders of magnitude (14111). This catalytic activity is harnessed by hemoproteins involved in oxygenation reactions, oxidative stress responses, electron transport, oxygen transport, oxygen sensing, and oxygen storage. While heme is a necessary prosthetic group for many proteins, it also has the potential to cause toxicity at high concentrations. This property of heme requires that the intracellular pool of heme be tightly regulated.

Intracellular heme concentrations within vertebrates are tightly controlled by balancing the rates of heme biosynthesis and catabolism (87). Free heme released into the plasma by the dissolution of hemoproteins from lysed erythrocytes is quickly scavenged by albumin, hemopexin, and the serum lipocalin α1-microglobulin (13234475). Any hemoglobin released into the serum is tightly bound by haptoglobin and subsequently cleared by tissue macrophages (51). It is evident that the vital yet reactive nature of heme requires that its production, degradation, and availability be carefully controlled in metazoans. Meeting these demands reduces heme-mediated toxicity and minimizes surplus free heme.

Most bacterial pathogens that infect vertebrate tissues have systems dedicated to the acquisition of heme for use as a nutrient iron source. However, the toxicity of heme presents a paradox for microorganisms that satisfy their nutrient iron requirement through heme acquisition. This heme paradox is resolved through tightly regulated systems dedicated to balancing the acquisition of heme with the prevention of heme-mediated toxicity.


Heme acquisition systems.

Bacterial pathogens can circumvent nearly every vertebrate form of heme sequestration. Bacterial heme acquisition systems that extract heme from hemopexin, heme-albumin, hemoglobin, and hemoglobin-haptoglobin have been identified in both Gram-negative and Gram-positive species (116) (Fig. (Fig.1).1). In Gram-negative bacteria there are three known classes of heme transport systems: direct heme uptake systems, bipartite heme receptors, and hemophore-mediated heme uptake systems (116).

FIG. 1.

Mechanisms of bacterial heme acquisition. Bacteria can utilize multiple heme sources found within the vertebrate host. Three types of heme acquisition systems have been identified for Gram-negative bacteria (left). These systems include direct heme uptake 

Direct heme uptake systems bind heme-containing proteins at the outer membrane (OM) of Gram-negative bacteria and transport heme into the periplasm in a TonB-dependent manner (116) (Fig. (Fig.1A).1A). TonB is part of a cytoplasmic membrane complex that couples the proton motive force of the inner membrane to the outer membrane for the energy-dependent uptake of specific substrates, such as heme, into the periplasm (50100104). Once in the periplasm, heme is bound by a heme transport protein (HTP) (116). The heme-HTP complex shuttles heme to an ABC transporter in the inner membrane, through which heme is transported into the cytoplasm in an ATP-dependent process (116). A cytoplasmic protein is typically encoded within direct heme uptake operons, although the exact function of this family of proteins remains unclear. A specific example of a direct heme-binding uptake system is Pseudomonas aeruginosa phuR-phuSTUVW, where PhuR is the outer membrane receptor, PhuT is the HTP, PhuUVW is the ABC transporter, and PhuS is the cytoplasmic protein (5379117). Other pathogens encoding similar direct heme uptake systems include Bordetella pertussisYersinia pestisYersinia enterocoliticaShigella dysenteriaeVibrio choleraeCampylobacter jejuniBartonella quintana, and Escherichia coli O157:H7 (69708495112115118121).

Bipartite heme receptors have been identified only for Neisseria spp. These heme acquisition systems consist of a TonB-dependent outer membrane receptor, HpuB, and an outer membrane lipoprotein, HpuA (60) (Fig. (Fig.1B).1B). The bipartite nature of HpuAB distinguishes it from the direct heme uptake systems, which have only a single-component TonB-dependent receptor (121). HpuA and HpuB form a functional complex, and both are required for the utilization of hemoglobin and hemoglobin-haptoglobin as nutrient iron sources (5961). Coincidentally, a spontaneous point mutation in Neisseria gonorrhoeae pilQ (pilQ1) suppresses the mutant hpuAB phenotype (16). PilQ forms a channel in the outer membrane and is required for pilus biogenesis, but its mutant form allows the entry of heme and various antimicrobial compounds with a TonB-independent, PilT-dependent mechanism (16). This suggests that PilQ or the pilus apparatus may regulate the free diffusion of heme into N. gonorrhoeae and highlights the concept that bacteria carefully regulate their intracellular pool of heme.

Hemophore-mediated heme uptake systems involve a secreted heme-binding protein called a hemophore (Fig. (Fig.1C).1C). Holo-hemophores are recognized by an outer membrane receptor that mediates the import of heme. Two types of hemophore-mediated heme uptake systems have been described for Gram-negative bacteria: one uses the HasA hemophore, and the other uses the HxuA hemophore (116). The HasA hemophore-mediated heme uptake system has been identified in Serratia marcescensP. aeruginosaPseudomonas fluorescens, and Y. pestis (445565896). The HasA system encodes an export complex (HasDEF), a hemophore receptor (HasR), and regulatory proteins (HasI and HasS) (7153397116). Either TonB or the TonB homolog HasB provides the energy necessary for transporting heme from the surface-exposed HasR-HasA-heme complex into the periplasm (83). HasR can also bind free heme and hemoglobin-bound heme, but these processes are less efficient than HasA-mediated heme acquisition (3357). The HxuA system has been described only for Haemophilus influenzae type b (Hib) and consists of the hxuCBA gene cluster (19). HxuB is thought to export HxuA into the environment where HxuA binds the heme-hemopexin complex (19). The receptor for the heme-HxuA complex has not yet been determined, although HxuC is a likely candidate (19). While the HxuA system increases the diversity of utilizable heme substrates, the HasA system increases the efficiency of heme uptake (20).

Less diversity has been discovered for the heme uptake systems of Gram-positive bacteria. In general, Gram-positive heme uptake systems consist of surface-exposed receptors that shuttle heme through the cell wall to an ABC transporter for delivery into the cytoplasm (123) (Fig. (Fig.1D).1D). The paradigm for Gram-positive heme uptake is represented by the Staphylococcus aureus iron-regulated surface determinant system (Isd). The Isd import machinery is encoded by 10 genes, including four cell wall-anchored proteins (IsdABCH), a transpeptidase (SrtB), a membrane transport system (IsdDEF), and two cytoplasmic heme oxygenases (IsdG and IsdI) (94). IsdB and IsdH are responsible for binding hemoglobin and hemoglobin-haptoglobin, respectively (24). IsdA extracts heme from IsdB or IsdH for passage to IsdC (647394131). This efficient heme-scavenging system brings heme across the membrane into the cytoplasm through the IsdDEF ABC transporter, where it can either be degraded by the heme oxygenases IsdG and IsdI to release free iron or be trafficked intact to the cell membrane (6894). The function of exogenously acquired nondegraded heme in S. aureus remains to be elucidated. The Isd locus is present in numerous other Gram-positive pathogens, including Listeria monocytogenesBacillus anthracis, and Clostridium tetani (103116).

Other Gram-positive heme acquisition systems distinct from the Isd system have been identified for Corynebacterium spp. and Streptococcus spp. The Corynebacterium diphtheriae heme uptake system is encoded at a genomic locus containing htaC-htaA hmuTUV-htaB. HtaA and HtaB are membrane-associated and surface-exposed proteins thought to be heme receptors, while HmuUV is an ATP transporter that receives heme from HmuT and delivers it into the cytoplasm (3). The exact transport order of heme between HtaAB and HmuTUV has yet to be defined. In a manner similar to that of Corynebacterium diphtheriae Hta/Hmu, Streptococcus spp. encode surface-exposed heme-binding proteins (Shp and Shr) and an ABC transporter (HtaABC) (130). These systems are reminiscent of the Gram-negative direct heme transporters, except that the receptors and heme transport proteins are able to traffic heme through the thick cell wall of Gram-positive bacteria.

Only one hemophore-mediated heme uptake system has been described for Gram-positive bacteria (Fig. (Fig.1E).1E). B. anthracis encodes an Isd heme uptake system that is both similar to and distinct from that of S. aureus(3267). Two proteins unique to B. anthracis are the secreted hemophores IsdX1 and IsdX2 (2667). IsdX1 is capable of removing heme from hemoglobin and passing heme to IsdC or IsdX2 (26). From IsdC, heme is transported into the cytoplasm through the Isd system. IsdX2 is both extracellular and associated with the cell surface, but the exact physiological role that IsdX2 serves in heme acquisition has yet to be defined (26).

Heme biosynthesis.

Most Gram-positive and Gram-negative pathogens have developed mechanisms for acquiring heme from their hosts, yet many of these organisms are also capable of synthesizing heme endogenously. Bacteria such as Streptococcus spp., Mycoplasma spp., H. influenzaeEnterococcus faecalisLactococcus lactisBartonella henselaeBorrelia burgdorferi, and Treponema pallidum do not have the complete machinery to make their own heme, and as such, they either do not require heme-iron or rely on heme acquired from the environment (12828898). In comparison, the majority of bacteria with sequenced genomes contain the machinery for making heme, including bacteria from the AlphaproteobacteriaBetaproteobacteriaGammaproteobacteriaEpsilonproteobacteriaBacillalesLactobacillalesSpirochaetales, and cyanobacteria (3543116).

The physiological relevance of both synthesizing and acquiring heme has remained elusive. Since the final step of heme biosynthesis requires iron to be inserted into the protoporphyrin IX (PPIX) ring, it is likely that bacteria synthesize heme only in environments where iron is available, as has been observed for Bradyrhizobium japonicum (90). In turn, when bacteria capable of both heme biosynthesis and acquisition are in environments that are iron poor, they may switch to utilizing exogenous heme as an iron source. In some bacteria such a response is controlled by the ferric uptake regulator Fur. Under iron-replete conditions, Fur represses the expression of heme uptake machinery in many species, including S. aureusY. pestis, and P. aeruginosa (6879115116). An alternative way of understanding the duality of heme acquisition and biosynthesis may lie in the energetic repercussions of heme biosynthesis compared to those of acquisition. Simply put, it may be less energetically expensive to acquire heme rather than synthesize it. While understandings of bacterial heme biosynthesis and acquisition processes individually have grown significantly, much has yet to be discovered about the interplay between the regulation and physiological uses of endogenous and exogenous heme.

For those bacteria capable of heme biosynthesis, the process is fairly conserved. The first universal heme precursor is δ-aminolevulinic acid (ALA). ALA can be synthesized either from succinyl coenzyme A (CoA) and glycine by ALA synthase (hemA) (Fig. (Fig.2A)2A) or from glutamyl-tRNAGlu by the C5 pathway using GtrA and HemL (Fig. (Fig.2B).2B). Currently, no bacteria are known to use both routes to synthesize ALA, and hemA has been identified only in the Alphaproteobacteria (82). GtrA is the more ubiquitous enzyme used by bacteria to synthesize ALA. In some cases, the gtrA gene has been annotated as hemA, although this enzyme is not the same as ALA synthase and should be identified as gtrA to highlight its distinct function from that of HemA.

FIG. 2.

Schematic of heme biosynthesis in bacteria. The first universal heme precursor is δ-aminolevulinic acid (ALA). ALA can be synthesized by one of two routes, although no bacteria are known to use both ALA synthesis pathways. (A) Succinyl-CoA and 

Once ALA has been synthesized, a series of seven reactions convert eight molecules of ALA into protoheme. This protoheme can be used directly or modified further before being employed as a prosthetic group in hemoproteins. The heme biosynthesis pathway is fully diagrammed in Fig. Fig.2C.2C. Two specific steps in heme biosynthesis of particular note are those that convert coproporphyrinogen III to protoporphyrinogen IX and then transform protoporphyrinogen IX into protoporphyrin IX. Each of these steps can be performed by two enzymes that are functionally redundant, but the distinguishing feature between each pair of enzymes is that one is oxygen dependent and the other is oxygen independent (82). The oxygen-dependent enzymes are found in eukaryotes and are less prevalent in prokaryotes (82). This may allow bacteria to be metabolically flexible and use alternative electron donors to synthesize heme in the absence of oxygen.


Whether through heme biosynthesis or through heme acquisition systems, most bacteria dedicate significant efforts to ensuring an adequate supply of heme. However, the utility of heme is inseparable from its toxic effects, and the degree of sensitivity to heme toxicity varies among bacteria. In general, Gram-positive bacteria are more sensitive to heme toxicity than are Gram-negative bacteria (78). Notable exceptions to this trend are the anaerobic Gram-positive Clostridium spp. and Gram-negative Porphyromonas spp., of which about 40% and 94% of tested strains are sensitive to heme toxicity, respectively (78). The variation in heme sensitivity observed across bacteria suggests one of two possibilities. First, bacteria less sensitive to heme may have more-robust mechanisms of heme tolerance. Alternatively, distinct bacterial genera may produce differing levels of toxic by-products upon heme exposure. Despite bacterial heme sensitivity being recognized for over 60 years, the mechanisms by which heme kills bacteria remain undefined.

One possible mechanism of heme toxicity may be mediated by free iron released during heme degradation by bacterial heme oxygenases (77102). Free iron causes intracellular damage mediated through the production of hydroxyl radicals via Fenton chemistry or through lipid peroxidation (25). The question remains, however, whether heme oxygenases release enough iron to exceed available iron-binding sites within the cell and cause cellular toxicity. The lack of in vivo data demonstrating that iron-mediated lipid peroxidation and Fenton chemistry are the causes of cellular damage after heme exposure support the idea that iron released from heme may not be the cause of heme toxicity. In addition, noniron metalloporphyrins are toxic to S. aureus, although they are not degraded by the staphylococcal heme oxygenases IsdG and IsdI (55113). This suggests that free metals, including iron, are not likely to be the main cause of metalloporphyrin toxicity. In this regard, it is likely that the offending agent is the heme itself (25).

Due to the lack of data regarding mechanisms of heme toxicity in bacteria, models of bacterial toxicity may be extrapolated from eukaryotes. In erythrocytes, free heme disrupts the cell membrane, resulting in hemolysis by a colloid-osmotic mechanism: the cell no longer maintains ion gradients, potassium leaks out, and water enters due to the osmotic gradient (184999). Other eukaryotic cells do not undergo lysis in the presence of heme, although in vitro, endothelial cells are susceptible to heme toxicity by either the peroxidase-like or monooxygenase-like activities of heme (63). The monooxygenase-like reactivity of heme is the cause of heme-mediated DNA and protein damage in vitro and is most likely the mechanism of heme toxicity in metazoans (1263).

The outer layers of the bacterial cell are notably different from eukaryotic membranes in lipid composition, cell wall, and structure. These outer layers act as an armament that protects the bacterial cell from a multitude of environmental insults. Therefore, it is possible that these eukaryotic mechanisms of heme toxicity do not translate to bacteria, as no reports of heme-induced bacterial lysis have been identified. Gram-negative species such as Y. pestisAeromonas salmonicidaShigella flexneriPrevotella spp., and Porphyromonas spp. accumulate heme in their outer surface (21344262105). Rather than a source of toxicity, this accumulation of heme is thought to contribute to bacterial pathogenesis by increasing bacterial heme storage, utilization, or host invasion (21313441105). Moreover, iron-replete S. aureuspreferentially traffics exogenously acquired heme to the cell membrane, although the function of this process is still unknown (94). Of the species that accumulate heme in their membranes, S. aureus and Porphyromonas spp. are highly susceptible to heme toxicity, while Y. pestis and many Prevotella spp. are highly resistant to heme toxicity (485160). This brief survey suggests that the accumulation of heme on the bacterial surface does not correlate with toxicity. Bacterial heme toxicity appears to depend more on species-specific properties. One piece of evidence to support this notion is that Gram-positive and not Gram-negative bacteria accumulate DNA damage when exposed to heme in vivo (76).

The mechanism of heme-mediated toxicity is multifaceted. While much is known about eukaryotic heme toxicity, the relevance of these findings to bacteria remains unclear. The main cause of bacterial heme toxicity is not due to the release of free iron by cellular monooxygenases or by the peroxidase-like activity of heme (5563111). Some heme toxicity may be due to its monooxygenase-like reactivity, but this has not been directly tested for bacteria (76). Based on what has been reported, a likely cause of bacterial heme toxicity is its ability to damage DNA; however, the two have not been directly correlated (63). Taking these facts into consideration, it is likely that many mechanisms of heme toxicity have yet to be discovered.


While the mechanism of bacterial heme toxicity is not well defined, several means by which bacteria avoid heme toxicity have been characterized. The regulation of biosynthesis and the regulation of uptake are two ways by which bacteria control intracellular levels of heme. When the regulation of heme uptake and biosynthesis is not sufficient to prevent heme toxicity, other mechanisms that are utilized by bacteria include export, sequestration, and degradation. These are discussed in greater detail below and are summarized in Table Table11.


Mechanisms of heme tolerance


S. aureus, one of the pathogens most sensitive to heme, has a heme-regulated transporter (HrtAB) that alleviates toxicity (119). A mutation of the hrtAB transporter genes results in a further increase in heme sensitivity (106). The mechanism by which HrtAB alleviates heme toxicity has yet to be elucidated; however, HrtAB is thought to pump out either heme directly or a toxic metabolite of heme accumulation. Orthologous HrtAB systems have been characterized for Streptococcus agalactiaeB. anthracis, and L. lactis (2785107). Mutations in either the B. anthracis or L. lactis Hrt systems also result in increased sensitivity to heme toxicity (85107). The S. agalactiae hrtAB mutant has not been generated, so the contribution of HrtAB to resisting heme toxicity in this organism has yet to be determined. Other Gram-positive pathogens and saprotrophs that encode putative Hrt systems include L. monocytogenes and Listeria inocua of the listeriae, Bacillus thuringiensis and Bacillus cereus of the bacilli, and Staphylococcus epidermidis of the staphylococci (22108). Notably absent from this list are the nonpathogenic, nonsaprotrophic bacilli B. subtilis and B. licheniformis. This observation suggests that the Hrt system may have evolved in bacteria that come into contact with vertebrate blood to protect them from heme toxicity. This point is underscored by the upregulation of B. anthracis hrtAB in an animal model of anthrax (107).

A dual-operon efflux system has recently been identified for S. agalactiae, comprised of pefAB and pefRCD (27). PefAB and PefCD are two putative heme and protoporphyrin IX (PPIX) efflux pumps, although the role of PefB may be as an accessory protein rather than an actual pump (27). When the pefoperons are disrupted, the intracellular levels of heme and PPIX increase, causing enhanced sensitivity to heme toxicity (27). In addition to pefAB and pefRCDS. agalactiae also encodes orthologs of hrtAB, which are transcribed at higher levels than pefAB and pefCD at high heme concentrations (27). This suggests that the pef transporters are utilized to fine-tune intracellular heme levels, while hrtAB is employed to protect S. agalactiae from heme toxicity in heme-rich environments (27). The differential activity of two heme-regulated transport systems highlights the delicate balance that S. agalactiae maintains to cope with the heme paradox.

Other transporters with broader substrate specificity also provide some protection from heme toxicity. The multiple-transferable-resistance (Mtr) efflux system provides resistance to hydrophobic agents in N. gonorrhoeae (37). The inactivation of mtrCDE causes increased susceptibility to heme, while the overexpression of this efflux pump results in increased tolerance to heme toxicity (9). It is possible that the ability of general efflux systems to provide some resistance to heme is a conserved detoxification strategy used by many bacteria.


The best example of heme sequestration to avoid heme toxicity is in the eukaryotic parasite Plasmodium spp., the causative agents of malaria. During Plasmodium infection of erythrocytes, hemoglobin is digested into amino acids and heme (80). The amino acids are used as a nutrient, but the accumulation of heme is toxic. Plasmodium sequesters heme into a nontoxic, highly insoluble, dark brown substance called hemozoin (28). Hemozoin formation has been reported to be catalyzed by the heme detoxification protein (HDP) (47). Many bacteria utilize ferritin-like proteins to sequester free cellular iron, but heme sequestration tactics have not been well characterized for bacteria.

Some of the cytoplasmic heme-binding proteins associated with the direct heme uptake systems of Gram-negative bacteria have been proposed to function in heme sequestration and utilization. Proteins in this family include Y. enterocolitica HemS, E. coli O157:H7 ChuS, P. aeruginosa PhuS, S. dysenteriae ShuS, and Y. pestis HmuS. Since they were first described for Y. enterocolitica, we will refer to these proteins as the HemS family of proteins. Each of these cytoplasmic proteins is able to bind heme, but there is not a consensus on the function of this family of proteins. The deletion of Y. enterocolitica HemS is lethal, but hemS expression in E. coli prevents heme toxicity (112). It has been proposed that HemS degrades heme, but no biochemical data have been published to support this hypothesis. ChuS, the HemS homolog in E. coli O157:H7, however, has been shown to have heme oxygenase activity in the presence of ascorbate or an NADPH-dependent reductase (114). Whether ChuS degrades heme by an enzymatic or nonenzymatic process remains undefined. Another HemS family member, P. aeruginosa PhuS, degrades heme through a nonenzymatic process that occurs via free H2O2 oxidation of ferric PhuS (53). Rather than acting as a heme oxygenase itself, the most likely function of PhuS is to store intracellular heme and traffic heme to a distinct heme monooxygenase, PigA (53). S. dysenteriae ShuS is necessary for efficient heme utilization and protection from heme toxicity in S. dysenteriae, but data suggest that it is not likely to be a heme oxygenase (128). A potential mechanism by which ShuS could provide resistance to heme toxicity is through the DNA-binding properties of apo-ShuS (48). Y. pestis HmuS is also thought to function in heme utilization, but its mechanism remains ill defined (115). Members of the HemS family of cytoplasmic heme-binding proteins have been assigned diverse functions as heme monooxygenases, heme-trafficking proteins, heme-sequestering proteins, and DNA-binding proteins. Although the functions of these proteins may be diverse, it is clear that they are important for heme utilization and tolerance to heme toxicity.

Another heme-binding protein that contributes to resistance to heme toxicity is the Haemophilus ducreyiCu,Zn superoxide dismutase sodC (74). SodC is unique in its ability to bind a heme molecule at its dimer interface (81). The mutation of sodC results in an increased sensitivity of H. ducreyi to heme toxicity (74). Intriguingly, the mechanism for its protection against heme toxicity seems twofold, as both its antioxidant function and heme-binding function were individually able to rescue the heme sensitivity of the sodCmutant (74). Other cytoplasmic proteins such as AhpC in S. agalactiae and HutZ in V. cholerae also bind heme (54127). AhpC is a 2-Cys peroxiredoxin family protein, but its peroxidase activity does not depend on its heme-binding status (54). The mutation of either of these proteins, however, does not result in increased heme sensitivity (54127). It is thought that instead, these proteins function to store heme and promote its utilization (54127). Whereas many cytoplasmic proteins may bind heme, the specific function that such binding serves may be diverse. Identification of the exact function of heme-binding proteins has proven to be difficult, and much has yet to be learned about the regulation of heme trafficking within the bacterial cytoplasm.


Reducing heme toxicity can also be accomplished by the heme oxygenase-mediated degradation of heme. Although these proteins bind heme, they are not considered hemoproteins, as their heme-binding capacity is for the purpose of catalytically degrading heme. The HO family of heme monooxygenases was first identified for mammals, where they function primarily to protect cells from heme toxicity (116). In bacterial pathogens most heme oxygenases are implicated primarily in iron acquisition, although some have been identified to protect against heme toxicity.

In the presence of an electron donor, the canonical HO proteins degrade heme to free iron, CO, and α-biliverdin (120). HO family heme monooxygenases have been characterized for many bacterial species, a list of which can be found in Table Table1.1. The P. aeruginosa PigA (also referred to as pa-HO) is an exception in the HO family of heme monooxygenases, as it produces a mixture of all four biliverdin isomers (92). Other bacteria predicted to encode an HO family heme monooxygenase include Deinococcus radioduransAgrobacterium tumefaciens, and cyanobacteria, including Anabaena sp. PCC7120, Thermosynechococcus elongatusProchlorococcus marinus, and Nostoc punctiforme (30).

The IsdG family of heme oxygenases, first described for S. aureus, degrades heme to release free iron and form staphylobilin in the presence of a reducing agent (94). IsdG family heme oxygenases have been characterized for S. aureusB. anthracisB. japonicumMycobacterium tuberculosis, and Brucella melitensis and are predicted to be encoded in the AlphaproteobacteriaStreptomycesDeinococcus-Thermus, and Chloroflexi groups (1789101102). S. aureus encodes two IsdG family heme oxygenases (102). While functionally redundant, in that they both degrade heme to staphylobilin, they are differentially regulated by heme (93). IsdG degradation is inhibited in the presence of heme, while IsdI abundance is not affected by heme concentrations (93). In this way, S. aureus increases the rate of heme degradation as intracellular heme levels rise. This is yet another example of how bacteria refine intracellular levels of heme.

The functions of the heme oxygenase products (biliverdin and staphylobilin) in bacteria remain unclear. In cyanobacteria, algae, and plants, biliverdin is a precursor for light-harvesting phytobilin pigments (30). A reaction specific to mammals is the conversion of biliverdin to the potent antioxidant bilirubin (66110). It is possible that bacterial biliverdin and staphylobilin are excreted as waste products or further metabolized to be used as carbon and nitrogen sources. The energetically economical nature of bacteria, however, suggests that it is unlikely that biliverdin and staphylobilin are simply refuse. In the context of iron and heme homeostasis, it is possible that biliverdin and staphylobilin might function as signaling molecules or somehow provide protection from heme toxicity.

Although the role of biliverdin or staphylobilin in heme homeostasis or metabolism remains undefined, some heme oxygenases have been directly implicated in alleviating heme toxicity. The inactivation of N. gonorrhoeae hemO causes a growth defect when the mutant is grown in liquid culture in which heme is the only iron source (133). It is unclear whether this means that the N. gonorrhoeae hemO mutant is simply unable to utilize heme or if it is also more sensitive to heme toxicity. The disruption of B. anthracis isdGcauses growth inhibition across all concentrations of heme, when heme is the sole iron source (101). This suggests that IsdG is needed both for the utilization of iron from heme and for the prevention of heme toxicity. As discussed above, PhuS delivers heme to PigA in P. aeruginosa (53). Whereas the sensitivity of the phuS and pigA mutants to heme toxicity has not been tested, the PhuS homologs HemS and ShuS do provide protection against heme toxicity (112128). It is possible that the HemS family of proteins shuttle heme to a heme monooxygenase and that the controlled degradation of heme by a heme monooxygenase provides protection against heme toxicity (53). Taken together, the regulated degradation of heme by heme oxygenases is a prime example of how bacteria solve the heme paradox by reaping nutritional benefits from heme while simultaneously eliminating the associated toxicity of heme.

Alternative strategies for heme detoxification.

Besides exportation, sequestration, and degradation systems, other mechanisms of heme resistance are employed by bacteria. One example of this is the N. meningitidis gene of hydrophobic agent tolerance, ght. The mutation of ght causes increased susceptibility to heme and other hydrophobic agents (91). A broad spectrum of Gram-negative bacteria have ghthomologs, including the pathogens E. coli O157:H7, V. choleraeB. pertussisPasteurella multocidaH. influenzaeSalmonella enterica serovar Typhimurium, and Coxiella burnetii (91). The mechanism for the increased sensitivity of the ght mutant to heme and other hydrophobic agents has yet to be elucidated; nonetheless, it is separate from the Mtr efflux system and PilQ (91).


Many of the systems involved in resistance to heme toxicity are not constitutively expressed. Rather, bacteria regulate their expression in response to heme toxicity signals. In S. aureus and B. anthracis, the heme sensor system (HssRS) activates the transcription of the hrtAB ABC transporter (107119). HssRS is a two-component system (TCS) composed of HssS as a membrane-bound sensor kinase and HssR as a cytoplasmic response regulator. The mutation of hssRS results in increased heme sensitivity. L. lactisencodes a heme-regulated hrtAB ortholog, ygfBA, but no hssRS ortholog (85119). Instead, the regulator of ygfBA is thought to be the neighboring ygfC gene, but this has yet to be confirmed.

The putative heme and PPIX efflux pumps PefAB and PefCD in S. agalactiae are regulated by the MarR superfamily repressor PefR. The PefR-dependent inhibition of the two operons is alleviated when it binds heme or PPIX (27). PefR relieves its inhibition in the presence of >0.3 μM heme and plateaus at between 1 and 10 μM heme (27). S. agalactiae also encodes putative HssRS and HrtAB systems. In comparison to the regulation of the pef operons, S. agalactiae hrtAB is activated in 1 μM heme and continues to be highly activated in 10 μM heme. The activation of these two distinct efflux systems at different concentrations of heme further highlights the intricate regulatory mechanisms that bacteria employ to control intracellular concentrations of heme.

Another heme-responsive TCS distinct from HssRS is ChrAS from Corynebacterium diphtheriae (46). ChrAS activates the transcription of the heme monooxygenase hmuO and inhibits the transcription of the heme biosynthesis gene hemA (gtrA) in the presence of heme (56). The counterregulation of heme degradation and synthesis by ChrAS is subtly elegant. The disruption of hmuO does not cause heme sensitivity, but the mutation of either chrA or chrS results in growth inhibition and a loss of viability in the presence of high concentrations of heme (5). This indicates that ChrAS has other transcriptional targets and that these targets are involved in protecting C. diphtheriae from heme toxicity. The ChrAS-regulated factors that protect C. diphtheriae from heme toxicity have not yet been identified.

Like hmuO, the hemO heme monooxygenase in Clostridium perfringens is regulated to maintain a certain level of iron and heme in the cell. In the presence of heme, hemO is upregulated, but it is downregulated in the presence of iron (39). The factors responsible for the iron-dependent downregulation of hemO have not been identified. The VirSR TCS and the VirR-regulated RNA (VR-RNA) contribute to the positive regulation of hemO and other C. perfringens virulence genes; however, the stimulus of VirSR is still unknown (3965). It is likely that virulence factors are regulated in the presence of host factors, and it is possible that host heme might be such an environmental signal.


Most bacteria require iron and heme for full virulence, as measured by bacterial growth in animal models of infection. For bacteria that do not synthesize heme, heme acquisition allows them to aerobically respire or activate catalases, which protect against the oxidative burst of host phagocytes (29129). In this way, heme acquisition provides an advantage during infection. This is exemplified by the inactivation of the S. agalactiae cytochrome bd quinol oxidase cydA, which prevents acquired heme from activating aerobic respiration reducing bacterial fitness in a murine model (129). The competitive advantage provided by heme is also likely a factor for bacteria that synthesize heme, as S. aureus heme auxotrophs manifest as slow-growing small-colony variants (122). Most important, however, is the observation that many heme uptake mutants are attenuated for virulence. The inactivation of genes involved in heme acquisition in B. pertussisV. choleraeHaemophilus spp., and S. aureus all result in reduced virulence in animal models (10407186109). While heme provides a distinct advantage for bacteria during infection, the heme paradox requires that bacteria must carefully balance intracellular concentrations of this valuable nutrient source, as it can also be toxic at high concentrations.

The virulence contributions of some mechanisms that respond to and prevent heme toxicity have been assessed in animal models. The deletion of pefR in S. agalactiae results in decreased intracellular levels of heme and reduced virulence in a mouse model of infection (27). Conversely, the deletion of staphylococcal hssR results in an accumulation of heme toxicity and hypervirulence in the mouse liver (119). These data are consistent with the idea that reducing intracellular heme levels might starve pathogens, while increasing intracellular heme triggers hypervirulence. The N. gonorrhoeae MtrCDE efflux pump provides protection from heme and other hydrophobic agents (937). Clinically relevant mutations that result in the overexpression of the MtrCDE efflux pump generally result in increased resistance to hydrophobic agents and, correspondingly, increased bacterial burden in vaginal lavage fluids of infected mice (124). Those authors proposed that the direct relationship between virulence and MtrCDE expression levels is due to increased resistance to innate immune effectors. An alternative possibility is that these mutants are also more resistant to heme toxicity and that this may provide an advantage in vivo. Taken together, these results demonstrate the variable impact that disrupting heme homeostasis can have on a bacterial pathogen. Moreover, this further highlights the importance of resolving the heme paradox in pathogenesis.

Bacteria may synthesize their own heme and/or acquire it from the host environment

Heme is a required cofactor and a useful source of nutrient iron for most bacterial pathogens (Fig. (Fig.3).3). Bacteria may synthesize their own heme and/or acquire it from the host environment (Fig. (Fig.3).3). While we have discovered much about each of these processes independently, the interplay between heme biosynthesis and acquisition is an understudied area of infectious disease biology. For example, it is not known if heme is differentially segregated depending on whether it is acquired exogenously or synthesized endogenously. Moreover, the impact of heme acquisition on heme synthesis has not been evaluated. While it is known that the utility of heme as a redox cycling cofactor poses the risk of heme toxicity; how heme toxicity contributes to the outcome of host-pathogen interactions remains to be determined.

FIG. 3.

Overview of the heme paradox in bacteria. Most Gram-negative and Gram-positive bacteria are capable of acquiring or synthesizing heme. Heme can then be used for cellular processes (blue boxes). However, an accumulation of intracellular heme can cause 

Bacterial heme toxicity is multifactorial, and although it is possible that the DNA-damaging activity of heme impacts its toxicity, other factors are likely to contribute to this process (Fig. (Fig.3).3). Despite our incomplete understanding of how heme is toxic to bacteria, we have made much progress in identifying the methods that bacteria employ to solve the heme paradox. These mechanisms include export, sequestration, and degradation strategies (Fig. (Fig.3).3). These heme tolerance mechanisms are often carefully regulated by TCSs and transcription factors that respond to changes in environmental and intracellular heme. Now that many of the heme-sensing systems have been identified, future work will focus on determining how these systems sense heme as a component of vertebrate blood. An understanding of the exact mechanisms of bacterial heme toxicity not only will provide basic scientific knowledge about how heme causes toxicity but also will provide novel targets for therapeutic intervention.

Know Your A1C: What This Blood Test Can Tell You About Your Risk for Diabetes and Cardiovascular Disease

Know Your A1C: What This Blood Test Can Tell You About Your Risk for Diabetes and Cardiovascular Disease

The higher the A1C level, the greater the risk of developing diabetes-related complications.

By Martin Tibuakuu, M.D., M.P.H. and Erin Michos, M.D., M.H.S. | Aug. 24, 2016, at 6:00 a.m.

Know Your A1C: What This Blood Test Can Tell You About Your Risk for Diabetes and Cardiovascular Disease
Man performing blood test on himself.

After a diabetes diagnosis, A1C is also used for gauging how well treatment controls blood sugar levels. MIKE WATSON IMAGES

A simple blood test can diagnose diabetes, but it also can tell you so much more, including your risk for heart attack and stroke.

Type 2 Diabetes: Who Is at Risk?

Diabetes, which causes chronically high blood sugar levels, is the seventh leading cause of death in the United States, according to the Centers for Disease Control and Prevention. It can also result in serious health complications, including heart disease, blindness, kidney failure and lower-extremity amputations. The CDC reports that close to 29.1 million people are currently living with diabetes in America, meaning about 1 of every 11 people has it. There are different types of diabetes, but Type 2 diabetes accounts for about 90 to 95 percent of all diagnosed diabetes cases.

Risk factors for Type 2 diabetes include older age, obesity, a family history of diabetes, prior history of gestational (pregnancy) diabetes, impaired glucose tolerance, physical inactivity and race/ethnicity. African-Americans, Latinos, American Indians and some Asian-Americans and Pacific Islanders are at particularly high risk for Type 2 diabetes.

What Is Prediabetes?

People with prediabetes have glucose (i.e., blood sugar) levels that do not meet the criteria for diabetes but are too high to be considered normal. These individuals have an increased risk for the development of diabetes and other serious health problems, including heart disease and stroke. According to the CDC, 86 million American adults, or more than 1 of 3 people, have prediabetes. Without lifestyle changes, such as eating healthy foods, getting regular physical activity and maintaining a healthy weight, 15 to 30 percent of these individuals will develop Type 2 diabetes within five years.

What Is the A1C Blood Test?

The term A1C is short for HbA1c, or hemoglobin A1C. It refers to glycated hemoglobin, which develops when hemoglobin – a protein within red blood cells that carries oxygen – becomes coated with glucose or sugar in the blood. The amount of glucose that combines with this protein is directly proportional to the total amount of sugar in a person’s system, and so the higher blood glucose levels are, the higher the A1C level. Red blood cells have a life span of 120 days; by measuring A1C, clinicians are able to determine average blood sugar levels over approximately two to three months. A1C is particularly important in people with diabetes because the higher the A1C level, the greater the risk of developing diabetes-related complications. After a diabetes diagnosis, A1C is also used for gauging how well treatment controls blood sugar levels. In the U.S., A1C results are given as a percentage of hemoglobin that is glycated.

How Does an A1C Test Differ From a Blood Glucose Level?

An A1C measurement is a marker of average blood sugar levels over a period of two to three months, so it is a more stable test assessing longer-term blood sugar control. This means less day-to-day fluctuations to A1C levels due to stress and illness. A1C is often tested using blood samples from the arm, but samples can also be taken from a finger prick. Fasting is not required before A1C testing like it is for the blood glucose test.

On the other hand, the blood glucose level gives us the concentration of glucose in the blood only at the time of the test.

Health care providers measure both A1C and blood glucose to ensure good diabetes control, which informs them of the long-term and day-to-day control of blood sugar levels.

How Do We Diagnose Diabetes and Prediabetes?

Both diabetes and prediabetes may be diagnosed based on either A1C or blood glucose criteria. Blood glucose criteria could either be a blood glucose level measured after an overnight fast or a two-hour blood glucose value after eating 75 grams of sugar.

An international committee of experts from the American Diabetes Association, the European Association for the Study of Diabetes and the International Diabetes Federation recommends that the A1C test be the primary test used to diagnose prediabetes and Type 2 diabetes.

What Are the A1C Criteria for Diabetes and Prediabetes Diagnosis?

A1C can indicate if people have prediabetes or diabetes based on the following:

A1C Percentage
Normal Below 5.7%
Prediabetes 5.7%–6.4%
Diabetes 6.5% or greater

An A1C level of 6.5 percent or more measured on two separate occasions indicates you have diabetes.

If your A1C test returns a reading of 5.7 to 6.4 percent, this indicates you have prediabetes and are at an increased risk of Type 2 diabetes. At this point, you need to talk to your doctor about appropriate lifestyle changes that could reduce your risk of developing full-blown Type 2 diabetes in the future.

It is important to note that normal ranges for A1C levels may vary from one lab to another, so patients who may wish to interpret their own A1C results need to keep this in mind, especially when using a lab that is different from the one used for previous testing.

What Is the Target A1C Level?

For most people with previous diagnoses of diabetes, a target A1C level of 7 percent or less is a common treatment target. However, this is a general target, and health care teams do tailor targets to meet individual goals. A1C values are not indicators of specific diabetes complications, meaning any complications could arise with any A1C value. However, the closer someone’s value is to the normal A1C range, the better. A person’s recommended A1C target should take into account his or her ability to achieve the target without any risk of serious health complications caused by blood sugar levels that are too low (called hypoglycemia).

What Are the Benefits of Lowering A1C?

Studies have shown that reducing A1C by 1 percent in people with diabetes reduces the risk of serious health complications involving small vessels of the eyes and kidneys, as well as nerves by almost 25 percent.

Also, a study published in the journal BMJ revealed that people with Type 2 diabetes who reduce their A1C level by 1 percent are:

  • 19 percent less likely to suffer cataracts
  • 16 percent less likely to suffer heart failure
  • 43 percent less likely to suffer amputation or death due to blood vessel diseases

A lower A1C level in the blood means a lower amount of sugar in the blood on average, which reduces the risk of developing complications caused by high blood sugar levels.

Who Should Get an A1C Test?

  • Everyone with Type 2 diabetes should be offered an A1C test at least once a year.
  • Some may require an A1C test more often. This is especially true for patients who had a recent change in medication(s) or if a health care team wishes to more frequently monitor a patient’s diabetes status to get it under control.
  • For those without diabetes, experts recommend that anyone 45 or older should consider getting tested for A1C, especially if they are overweight. If they are younger than 45 but are overweight and have one or more additional risk factors for diabetes, they should consider getting tested.

What Are the Limitations to A1C Testing for Diabetes?

While A1C tests are usually reliable and widely used, it’s important to acknowledge that the test may not be accurate in people who:

• Have insufficient hemoglobin due excessive bleeding (may have a falsely low A1C reading).

• Have iron-deficiency anemia (may have a falsely high A1C test).

• Have hemoglobin genetic variations or uncommon forms of hemoglobin, commonly found in African-Americans and people of Mediterranean or Southeast Asian heritage.

• Have had a recent blood transfusion or have other forms of hemolytic anemia (may have falsely low A1C results)

• Are pregnant.

What Can You Do to Protect Yourself From Diabetes?

Anyone can benefit from a reduction of long-term diabetes complications, such as heart attack, stroke, kidney failure and diabetic nerve pain, by controlling their A1C levels through adopting healthy lifestyle practices. The benefit of reducing A1C should not be underestimated. To reduce A1C levels, you can:

Eat healthy. By keeping your post-meal blood glucose low, A1C can gradually be reduced in patients with diabetes and prediabetes. Those with diabetes and prediabetes need to eat foods that are high in nutrition and avoid excess calories. A healthy diet is rich in fruits, vegetables, fiber, lean protein and “good” monounsaturated and polyunsaturated fats in moderation. Saturated fats, refined “simple” carbohydrates and processed foods should be limited. For instance, switching white bread and white rice for whole-grain and brown rice will help reduce blood glucose spikes after a meal. Understanding what to eat and what to avoid can be challenging. Talk to a registered dietitian if you need help with food choices and meal planning. Tracking daily food intake using a diet diary or calorie-counter app can help keep things in check.

Be physically active. By keeping physically active, blood glucose is moved from the blood into cells to produce energy for the body, which lowers blood glucose levels. Also, physical activity improves our body’s sensitivity to insulin, a hormone needed to transport glucose into cells. This means that less insulin is needed to transport large amounts of glucose. Everyone should incorporate physical activity into their daily routine. For those without diabetes, being physically active will help to prevent the onset of prediabetes and Type 2 diabetes. For those with diabetes, it will help them maintain good blood sugar levels. The American Diabetes Association recommends aiming for 30 minutes of moderate- to vigorous-intensity aerobic exercise at least five days a week, or a total of 150 minutes per week. Moderate intensity means that you are working hard enough that you can talk but not sing during the activity, while vigorous intensity means you can’t say more than a few words without pausing for a breath during the activity.

Maintain a healthy weight. Losing weight through diet and exercise if you are overweight will significantly improve blood sugar levels, meaning a good A1C measurement.

Monitor your numbers. Carefully monitor both blood sugar and A1C levels if you have diabetes. Your medical team will most likely recommend regular A1C testing to monitor your overall diabetes control over a period of two to three months. However, A1C should never replace blood sugar level monitoring. For instance, people on insulin and other medications that cause hypoglycemia need regular blood glucose monitoring to ensure blood glucose doesn’t get too low.

Hepatitis C Virus Infection in African Americans

By Brian Pearlman

Hepatitis C is more prevalent among African Americans than among persons of any other racial group in the United States. However, comparatively little data are available on the natural history and treatment of hepatitis C in this population. Compared with white persons, African American persons have a lower rate of viral clearance and, consequently, a higher rate of chronic hepatitis C. Nonetheless, African American persons may have a lower rate of fibrosis progression than do white persons. African American persons with hepatitis C–related cirrhosis have higher rates of both hepatocellular carcinoma and liver cancer–related mortality than do white persons with hepatitis C–related cirrhosis. In nearly all treatment trials that enrolled a significant proportion of African American subjects, such patients had inferior treatment responses, compared with those of white subjects. The prevalence of infection with hepatitis C virus genotype 1 is higher among African American patients than white patients, although this difference does not account for a greatly dissimilar response to therapy. Some of the postulated mechanisms for these disparate treatment responses and natural histories of infection are also reviewed.

Hepatitis C virus (HCV) infection is a major public health problem for persons of all races, and it has become the most common cause of death associated with liver disease in the United States [1]. According to population-based studies, HCV infection accounts for >10,000 deaths per year [2]. Furthermore, the number of HCV-related deaths is expected to triple by the year 2020 [3].

African Americans experience complications of some chronic diseases disproportionately, compared with their white American counterparts [4, 5], and they are often underrepresented in clinical trials [6]. These differences also exist with respect to HCV infection; African American subjects represent only 5%–10% of participants in clinical trials involving HCV infection. Moreover, clinical features, such as the natural history of infection, infection prevalence, and therapeutic response, are disparate among minority and majority populations.

The African American population in the United States has a dominant ancestry from sub-Saharan West Africa [7]. However, the term “African American” has been criticized because of its imprecise geographic and cultural meaning. Furthermore, a racial classification does not necessarily convey genetic homogeneity [8]. Despite these limitations, the term “African American” will be used throughout this survey.

The aim of this review is to highlight the discrepancies in HCV infection characteristics and treatment responses between African American and white persons in the United States.

Epidemiology, Genotype, and Natural History

According to the most recent US census data, 12% of the population is African American, whereas 75% is white [9]. HCV infection is more prevalent in the African American population than in any other racial group in the United States (table 1). Although African Americans represent only 12% of the US population, they represent ∼22% of the estimated Americans with chronic HCV infection [3].

Table 1

Rates of hepatitis C seroprevalence among African American and white populations.

The mode of transmission of HCV appears to be similar for white and African American individuals. In a retrospective chart review of 355 patients with chronic HCV infection, injection drug use was the most common means of transmission for both ethnic groups, followed by receipt of a contaminated blood transfusion. In ∼25% of patients, irrespective of race, the mode of transmission was unknown [12]. In a prospective, controlled treatment trial involving >400 patients, injection drug use was also the predominant means of transmission (48%–50% of cases) in subjects of both races [13].

The prevalences of HCV genotypes also differ among racial groups. Although 70% of overall HCV isolates in the United States are of genotype 1 [14], there is a higher prevalence of genotype 1 infection among African Americans than among any other racial group (table 2). The explanation for this disparity is currently unknown.

Table 2

Prevalence of hepatitis C virus (HCV) genotype 1 among HCV-infected patients.

According to the Center for Disease Control and Prevention’ sentinel surveillance data on viral hepatitis [16], there has been a significant decrease in the number of cases of acute HCV infection since 1989. This decrement was seen in all ethnic and racial groups studied [17]. Between 1991 and 1996, African American patients accounted for 10% of patients with acute HCV infection. With respect to acute infection clinical features, African American and white subjects had nearly identical elevations in aminotransferase levels and in rates of jaundice and death [18].

Although the incidence of acute HCV infection does not seem to vary between races, the chronic HCV infection rate is higher among African American than among white individuals (table 3). Despite higher rates of chronic infection, HCV-infected African American persons may have a slower rate of fibrosis progression, compared with their white counterparts. In a retrospective chart review of 355 patients who underwent liver biopsy at a university medical center, the authors found significant differences between African American and white patients that could not be explained by age, alcohol use, or duration of infection [12]. The study suggests that histologic progression of HCV infection occurs less rapidly among African American patients than among white patients; however, there are obvious limitations of a retrospective analysis of disease progression. Furthermore, 19% of the non–African American patients were Hispanic, and a subgroup analysis was not separately performed. This factor is especially important, because Latino persons may have a faster rate of liver fibrosis than do either African American or non-Hispanic white persons [21, 22]. Nonetheless, other studies support the notion that African American persons may experience slower histologic progression than do white persons ( table 4).

Table 3

Rates of chronic hepatitis C among African American and white subjects.

Table 4

Rate of hepatitis C–related cirrhosis among African American and white subjects.

Prospective, randomized controlled trials are needed to better clarify the natural history of infection in African American persons. Discrepancies in disease severity may not necessarily correlate with differences in disease progression, as has been seen in cross-sectional and retrospective studies. Furthermore, not all studies have confirmed that natural histories of infection are dissimilar between races; preliminary data from a large multicenter treatment trial of patients with chronic HCV infection show no difference between African American and white patients with regard to the rate of fibrosis [25].

The mechanism for the possible discrepancies in the natural history of hepatitis C is unknown; however, the answer may lie in disparate HCV-specific CD4 T cell responses between African American and white persons. The strength and sustenance of HCV-specific T cell responses have already been identified as critical determinants of viral clearance during acute HCV infection [26,27–28]. In a clinical and immunologic analysis of 99 HCV-infected patients, CD4-proliferative T cell responses were observed in response to HCV-derived antigens in African American and white participants with both viral persistence and spontaneous clearance. Compared with chronically infected patients with a relatively weak HCV-specific T cell response, patients who achieved HCV clearance had a robust T cell response, irrespective of race. However, compared with chronically infected white patients, chronically infected African American patients had a significantly greater T cell proliferative response to HCV [29]. Futhermore, acute HCV infection clearance requires a potent IFN-γ response [30]. In African American patients, HCV-specific CD4 T cell proliferative responses were not accompanied by IFN-γ production, suggesting a dysregulated, virus-specific T cell function in cases of chronic infection in this population. The authors concluded that there are novel ethnicity-related differences in CD4 T cell responsiveness to HCV [29].

Other mechanisms invoked to explain the disparities in the natural history of hepatitis C among different races include the stronger association of certain human leukocyte antigen class II alleles with HCV clearance in African Americans [30] and the lack of immune system recognition of the virus in African Americans [12]. In a recent study, variants of the immunomodulatory IL-10 and IL-19/20 genes seemed to play a role in the spontaneous clearance of HCV in African American patients; no such relationship was found in white patients [31].

Although fibrosis may evolve more slowly in African Americans, the rate of hepatocellular carcinoma is increasing more quickly in this population. Compared with non-Hispanic white men, among whom the incidence of hepatocellular carcinoma increased from 2.3 to 2.8 cases per 100,000 persons (for 1981–1985 vs. 1991–1995), the age-adjusted incidence among African American men increased from 5.3 to 6.1 cases per 100,000 persons in the same time period [32].

Not only is the rate of hepatocellular carcinoma among African American persons 2-fold higher than the rate among white persons [33], but the rate of liver cancer–related mortality is 2–3 times higher among African American patients than among white patients [32]. More recent data confirm that the risk of hepatocellular carcinoma is twice as high among African American men than it is among white men [34].


Although the prevalence of chronic HCV is higher in the African American population than in the white population, African American subjects are usually underrepresented in clinical trials. Moreover, despite improvements in antiviral therapy, rates of sustained response to treatment among African American patients are relatively poor ( figure 1).

Figure 1

Progressive improvement in rates of sustained response to therapy for chronic hepatitis C virus infection in white and African American (AA) subjects. PegIFN, pegylated IFN; R, ribavirin.

Older therapies. Several authors have reported inferior response rates in chronically HCV-infected African American patients who have received standard or consensus IFN therapy, with or without ribavirin ( table 5).

Table 5

Summary of trials that included a significant number of African American patients with chronic hepatitis C virus infection who received older therapies.

Therapy today. In trials of pegylated IFN monotherapy treatment, there were inadequate numbers of African American subjects to make meaningful conclusions about the role of race in treatment outcomes [40, 41]. Likewise, in the registration trials of treatment with pegylated IFN and ribavirin, too few African American subjects were enrolled to make outcome assessments [42, 43].

Fortunately, 2 recent prospective trials have examined the effect of pegylated IFN treatment in a large number of African American subjects. Not only did these studies use pegylated IFN with ribavirin— today’ standard of care— but they also enrolled the largest number of HCV-infected African American patients of any other trial to date. Both of these studies will be analyzed in detail.

The first trial [44] compared a group of 100 African American patients with a control group of 100 non-Hispanic white patients, both of which were treated with pegylated IFN-α -2b (1.5 µ g/kg per week) and ribavirin (1000 mg per day for 3 months, followed by 800 mg per day until week 48). Both groups were treatment naive and were equally matched with regard to infecting genotype, with each group including 98 genotype 1–infected patients. The groups were also well matched with respect to age, duration of infection, viral load, alanine aminotransferase level, education level, and the presence of steatosis, fibrosis, and cirrhosis.

Treatment was well tolerated; 81% of African American and 79% of white patients completed therapy. Rates of adherence to treatment and of adverse events were also similar in both groups, and depression was the most common reason for discontinuation of therapy, regardless of ethnicity. Twenty-four percent of white patients and 22% of African American patients required dose reductions, with similar numbers of patients having the doses reduced because of neutropenia and anemia.

Compared with non-Hispanic white subjects, African American subjects had substantially poorer rates of sustained virologic response (19% vs. 52%; P <.001). The only predictor of sustained virologic response in multivariate analysis was race. Also analyzed was the predictive value of an early virologic response, defined as a ⩾ 2-log10 reduction in HCV RNA level at week 12 of therapy. None of the subjects who did not achieve an early virologic response at week 12 reached a sustained virologic response, irrespective of ethnicity. Thus, the negative predictive value of early virologic response was 100%. However, fewer African American patients than white patients achieved an early virologic response (40% vs. 69%; P <.001). Moreover, there was a discrepant positive predictive value for patients who did achieve early virologic response (48 [83%] of 58 white patients with an early virologic response had a sustained virologic response, compared with only 18 [64%] of 28 such African American patients).

Study limitations included differences in sex, body weight, and diabetes status, some of which may have impacted response rates. Furthermore, alcohol use and abstinence were not documented in the study. Because alcohol affects response to IFN-based therapy [45], discrepancies in the 2 groups’ rates of alcohol consumption may have influenced results. Finally, the ribavirin doses used were less than those customarily used for HCV genotype 1–infected patients. Although this may have impacted rates of sustained virologic response, it would have not engendered any outcome differences between ethnic groups.

The second study [46] was a prospective, multicenter trial that enrolled 78 African American subjects and 28 white subjects who were infected with HCV genotype 1 and were treatment naive. All subjects received pegylated IFN-α -2a (180 µ g per week) and ribavirin (1000–1200 mg per day, dosed on the basis of weight) for 48 weeks. Unlike the study mentioned above, this trial allowed the use of growth factors. Sustained virologic response was the primary end point, but early virologic response was assessed at week 12 of the study. Pre- and posttreatment liver biopsy specimens (for 69 patients) were also evaluated for histologic improvement.

Patient characteristics, including age, viral load (high), alanine aminotransferase level, fibrosis score, and rate of cirrhosis, were similar in the 2 groups. However, there were discrepancies in the percentages of male participants and in mean body weight.

Rates of adverse events, especially injection site reactions, vomiting, alopecia, and xerosis, were higher among white patients. Thirty-nine percent of white subjects discontinued therapy, compared with 23% of African American subjects. Severe neutropenia (neutrophil count, <0.5 × 109 cells/L) occurred more frequently among African American subjects, and more patients in this group had their IFN treatment dose reduced for this reason (37% vs. 18%).

At week 72, in the African American group, the rate of sustained virologic response was 26% (95% CI, 16%–35%), which was significantly lower than the rate for the white group (39%; 95% CI, 21%–57%). The rate of sustained virologic response for white subjects was somewhat lower than that seen in registration trials [42, 43], but the authors attribute this anomaly to the high rate of premature discontinuation of therapy and to the small size of the cohort of patients. Significant predictors of sustained virologic response in multivariate analysis were age of <41 years, low pretreatment viral load, and an alanine aminotransferase level of <3 times the upper limit of normal.

With regard to histologic response, examination of paired biopsy specimens revealed improvement in fibrosis scores in 25% of African American patients. More than 90% of patients whose paired biopsy specimens were examined in both groups showed improvement or at least stabilization of fibrosis. of the 36 African American patients who did not achieve sustained virologic response and who underwent both biopsies, 22% achieved fibrosis improvement. These data may support the concept that some patients may achieve reversal in fibrosis, irrespective of whether they achieved a sustained virologic response [47].

Study limitations included the high rate of treatment discontinuation in the white group, the lower rate of sustained virologic response in the white group, and higher weights in the African American group, which may have contributed to the poor response to IFN. Nonetheless, multivariate analysis failed to show a significant association between body mass index and nonresponse to treatment. Another limitation of the study was that racial disparity in histological outcomes did not reach statistical significance, because too few of the patients underwent paired liver biopsies. Like the previous study, this study did not indicate differences in alcohol use between patient groups.

Despite some limitations of the aforementioned studies, some important conclusions can be drawn from both. African American persons have lower rates of sustained virologic response to pegylated IFN combination therapy than do white persons, even when controlling for genotype 1 infection. Furthermore, the negative predictive value of not achieving an early virologic response at week 12 is reliable for both races. Despite the fact that early virologic response had an inferior positive predictive value for African American patients, patients of both ethnicities should be treated for 48 weeks if early virologic response is achieved.

Preliminary findings from the weight-based dosing of Peg-Intron and Rebetrol (WIN-R) trial demonstrate that weight-based dosing of ribavirin confers a significant advantage in the treatment of African American persons infected with genotype 1, compared with fixed dosing of ribavirin [25]. WIN-R is a prospective trial of 5000 treatment-naive HCV-infected patients from >200 US study centers designed to study weight-based versus fixed-dose ribavirin therapy. Patients were randomized to receive either pegylated IFN-α -2b, 1.5 µ g/kg per week, plus ribavirin, 800 mg per day, or the same amount of pegylated IFN-α -2b plus ribavirin, 800–1400 mg per day, depending on weight. Baseline characteristics in the study’ 2 arms were not significantly different. Three hundred eight-seven genotype 1–infected African American patients were among those treated. Sixty-four percent of the African American patients had high viral loads, and 31% had at least bridging fibrosis (determined by biopsy), which is significantly more advanced disease than has been seen in previous trials. Erythropoietin or ribavirin reduction was permitted.

Although dose reductions occurred more frequently for patients who received weight-based doses of ribavirin than for those who received standard doses (12% vs. 8%), the rate of discontinuations of treatment for adverse events was not significantly different (18% vs. 17%). Anemia was no more common among patients who received 1400 mg of ribavirin per day than among those who received lesser doses. of the 362 African American subjects who weighed ⩾ 65 kg, those who received weight-based ribavirin dosing had better end-of-treatment and sustained virologic response rates than did those who received flat dosing; in fact, rates of sustained virologic response were more than doubled (sustained virologic response rate, 21% vs. 10%; P =.004). However, even though African American patients achieved higher response rates with weight-based doses of ribavirin, rates of sustained virologic response were still inferior to the rates for white patients.

A summary of the large treatment trials of African American persons who received pegylated IFN and ribavirin is shown in table 6.

Table 6

Findings from large trials of African American patients with chronic hepatitis C virus (HCV) infection who were treated with pegylated IFN-α -2b (Peg-IFN) and ribavirin (R).

Mechanisms for inferior treatment response. A multitude of hypotheses have been promulgated to explain the dissimilar treatment responses among ethnic groups. As discussed previously, dysregulated CD4 function has been described in African Americans [29]. Other possibilities include discrepant viral kinetics, cytokine production, and iron stores.

An initial decrease in the HCV RNA level, referred to as “phase 1,” occurs hours after the administration of IFN; it represents blocking of viral replication. The subsequent, slower decrease in the viral level (phase 2) represents the clearance of HCV-infected hepatocytes and usually occurs days to months after IFN therapy is initiated. The phase 2 decrease is the better predictor of ultimate HCV RNA clearance [48, 49]. Ethnicity may influence these phases. In a kinetics study that compared African American and white subjects who received combination therapy, the former had both small phase 1 and phase 2 decreases in the viral load [50]. A significant difference was found between African American and white subjects with regard to inhibition of viral production on the first day of treatment. The findings for phase 2 decreases in the viral load were also discordant; the rate of loss of infected cells was lower in African American subjects. The authors believed that the inadequate phase 1 decrease among African American patients accounted for the limited phase 2 decrease; thus, their poor response to therapy may be related to an impaired ability to block viral production early in treatment. However, when controlled for treatment effectiveness, differences in the decrease in the viral load were not statistically significant. More studies are clearly needed.

Ethnicity-associated cytokine production may also explain dissimilar treatment responses. A study compared cytokine production in phytohemaglutinin-stimulated PBMCs obtained from infected and control participants, both African American and white. Relative to healthy white control subjects, African American subjects produced higher levels of proinflammatory (TH1) cytokines IL-2 and TNF-α and lower levels of down-regulatory (TH2) cytokine IL-10. Furthermore, HCV-infected white patients who responded to treatment produced less IL-10 and more transforming growth factor–β than did white subjects who did not respond to treatment. Because there were no African American patients who responded to therapy in this study, cytokine profiles could not be correlated with therapeutic outcome in this population. The authors postulated that the “subnormal” cytokine production among white responders may be more “permissive” to IFN-based therapy, as well as that the relatively more robust immune response among African American patients may yield inferior treatment results [51].

Elevated hepatic iron stores have also been invoked to explain resistance to IFN-based therapy in African Americans. Ioannou et al. [52] found that the risk of having increased iron stores, defined as elevated serum ferritin and transferrin saturation, was >5 times greater among HCV RNA–positive African American subjects than among HCV RNA–positive non–African American subjects. After adjustment for age, alcohol intake, sex, body mass index, and education level, HCV-positive African American patients with elevated aminotransferase levels had higher iron stores than did white patients. Because the response to standard IFN monotherapy may be influenced by hepatic iron content [53,54–55], the authors surmised that the discrepant iron stores may mirror discrepant treatment results. Limitations of the study include the assumptions that response rates to combination therapy with pegylated IFN and ribavirin are limited in the face of excess iron and that peripheral iron studies accurately reflect hepatic iron content.

Neutropenia. African American persons have significantly lower mean concentrations of leukocytes and neutrophils than do white persons [56]. Lower neutrophil counts before commencement of treatment may lead to a greater likelihood that the IFN dose will be reduced during treatment or even that the patient will be excluded from participation in clinical trials.

In a multivariate analysis of a National Institutes of Health treatment study of 119 patients with chronic HCV infection who received standard IFN combination therapy, only African American race was associated with baseline neutropenia. Unlike prior treatment trials, neutropenia was not used as an exclusion criterion for therapy. Although African Americans have a >2-fold chance of developing neutropenia during treatment, none of the neutropenic patients developed serious bacterial infections. Furthermore, those with neutropenia had minimal additional cell count decrements during treatment. Thus, the authors recommended that constitutional (benign) neutropenia should not be an exclusion criterion for IFN-based therapy [57]. Similar results were evident in the preliminary analysis of the WIN-R trial [25]. Some authorities have even suggested lowering neutrophil thresholds for dose modifications in African American patients [58].

Finally, in the 2 large treatment trials of African Americans [44, 46], severe neutropenia was not associated with serious infection. However, in one study [46], neutropenia was the most common reason for modification of the IFN dose among African American patients (for 37% in this group). In the second trial [44], both races had similar rates of neutropenia episodes (13%–14%).

HCV-HIV coinfection. Approximately one-third of all HIV-infected persons in the United States are coinfected with HCV. One hundred eighty HCV-HIV–coinfected patients in an inner city area were evaluated for suitability for combination therapy with IFN plus ribavirin. African Americans were more than twice as likely to be ineligible than eligible for HCV treatment. Concomitant medical problems, psychiatric problems, poor adherence to treatment, and/or ongoing substance abuse were factors that led to patients being ineligible for therapy [59].

Of the 3 recent large trials that have focused on HCV treatment in HCV-HIV–coinfected persons, only 2 enrolled a significant percentage of African American subjects. However, race was not predictive for sustained response in either univariate or multivariate analyses in both studies [60, 61].


A summary of key differences between HCV-infected African American patients and white patients is shown in table 7. Despite lower rates of sustained response to contemporary therapy, therapeutic nihilism is not warranted when treating HCV-infected African American patients. With few exceptions, the African American population has been underrepresented in clinical trials of HCV infection, despite having a higher rate of infection; clearly, more clinical studies are needed, particularly those that investigate the mechanisms for disparate treatment responses. Likewise, prospective studies of African American patients are needed to clarify rates of disease progression in cases of chronic HCV infection. Later in 2006, final results are expected from a multicenter study sponsored by the National Institute of Diabetes and Digestive and Kidney Disease. This trial, called the Viral Resistance to Antiviral Therapy for Chronic Hepatitis C (VIRAHEP-C), has enrolled ∼200 African American subjects and ∼200 white subjects who will be treated with pegylated IFN and ribavirin. The purposes of the study are to assess response rates to therapy, as well as to analyze both viral factors and host factors, including genetic and immunologic variables that may influence treatment results.

Hemochromatosis patients should be on a low-iron diet

HEMAHemochromatosis is a common genetic condition and yet there are still a number of misperceptions surrounding the diagnosis and management of this condition. Hemochromatosis affects both men and women. Typical patients do not have alcoholism or viral hepatitis, and often have normal liver enzymes. Clinical expression is highly variable. Genetic testing is widely available and particularly useful in family studies. Hemochromatosis can be readily diagnosed and treated. The purpose of the present review is to address the medical myths and misconceptions of hemochromatosis.

Keywords: Genetic testing, Hemochromatosis, Iron

The medical landscape is vast with an expanding array of information about old and new diseases. Thus, it becomes an insurmountable task for any physician to be up-to-date on all of the recent developments in modern medicine. For most physicians, it is acceptable to inform patients that they may not have all of the current information about their medical condition. This may lead to further study in textbooks or increasingly on the Internet, or they may seek a referral to a specialist with expertise in this area. In the present review, some of the common myths and misconceptions of hemochromatosis are explored.


Hemochromatosis is rare

A large population study (1) has demonstrated that one in 227 Caucasians in North America is homozygous for the C282Y mutation of the hemochromatosis gene. This is the typical genetic pattern seen in over 90% of typical patients; however, there are many C282Y homozygotes who are asymptomatic. Approximately, 20% of male homozygotes and 50% of female homozygotes will have normal serum ferritin levels. If the disease is defined based on symptoms, the prevalence would be much lower, and because the symptoms may be non-specific, it is more difficult to assess the prevalence of symptomatic hemochromatosis. This differs significantly between referred patients and participants in population screening studies. There has also been considerable debate about whether the genotype should be used to define hemochromatosis or whether it should be based on the presence of iron overload, independent of genotype (2). The bottom line is that this condition is extremely common within the Caucasian population and physicians should have a low index of suspicion when ordering screening tests, such as the transferrin saturation test and the serum ferritin test, for iron overload.

Women are not affected by hemochromatosis

As an autosomal recessive condition, hemochromatosis affects men and women equally in regard to the inheritance of the hemochromatosis gene. It has been considered that the effects of menses and pregnancy will significantly offset the lifelong accumulation of iron with tissue injury. A study (3) of 176 female hemochromatosis patients, matched to 176 male patients with respect to birth year, demonstrated similar hepatic iron concentrations in both sexes. However, male patients had a higher prevalence of cirrhosis compared with female patients (26% versus 14%). Cirrhosis in a female hemochromatosis patient has rarely been discovered in a population screening study. It is also important to assess women so that genetic counselling can be provided to their children and siblings.

Most hemochromatosis patients are alcoholics

The misconception that most hemochromatosis patients are alcoholics stems from the fact that most alcoholics have elevations in serum ferritin levels and some patients with alcoholic liver disease have increased iron deposition in the liver (alcoholic siderosis). This latter condition was widely reported from the Boston area in the 1960s (4) and likely ‘contaminated’ the hemochromatosis literature with patients who did not actually have genetic hemochromatosis. Studies (5,6) on the prevalence of alcoholism based on hemochromatosis pedigrees have shown no increased evidence of alcoholism. The genetic test for hemochromatosis remains a powerful diagnostic tool to help separate alcoholic liver disease from hemochromatosis.

Many hemochromatosis patients have chronic viral hepatitis

The prevalence of both hepatitis B virus (HBV) and hepatitis C virus (HCV) is not consistently higher in hemochromatosis patients. A screening study (7) that identified 302 C282Y homozygotes found one case of concomitant HCV and none with HBV. Much like alcoholic liver disease, both chronic HBV and HCV have been associated with elevations in serum ferritin levels and less commonly associated with increases in hepatic iron concentrations with advanced liver disease (8). Genetic testing is useful in this setting to differentiate hemochromatosis from iron abnormalities secondary to chronic viral hepatitis.

Diabetes is a cardinal feature of hemochromatosis

Although hemochromatosis was once called ‘bronze diabetes’, recent population screening studies (1,9) have not demonstrated an increased prevalence of diabetes in C282Y homozygotes compared with a control population. The pathogenesis of diabetes in hemochromatosis is likely multifactorial and can include defects in insulin secretion and insulin resistance (10,11).

Most hemochromatosis patients have elevated liver enzymes

Although liver disease is the most consistent feature of the disease, hemochromatosis is not an inflammatory liver disease and, therefore, many patients will have normal liver enzymes (12). In a review (13) of 351 C282Y homozygotes from our hemochromatosis clinic at the London Health Sciences Centre in London, Ontario, 277 of 351 (79%) patients had an aspartate aminotransferase level of less than 40 U/L and 238 of 351 (68%) patients had an alanine aminotransferase level of less than 40 U/L. It remains prudent to screen patients with unexplained enzyme elevations with transferrin saturation and serum ferritin tests.

Most patients with an elevated serum ferritin level have hemochromatosis

A population screening study (1) has demonstrated that elevation in serum ferritin levels is seen in approximately 10% of primary care patients. When these patients are investigated in a referral clinic, only 33% to 42% have genetic hemochromatosis. More common causes of increased serum ferritin levels include obesity, fatty liver and daily alcohol consumption (14).

An elevated hemoglobin is common in hemochromatosis

Some physicians have told patients that they do not have hemochromatosis because their hemoglobin levels are normal. Perhaps this is based on the concept that if iron deficiency reduces hemoglobin, iron excess could increase hemoglobin. A review of 634 C282Y homozygotes at our clinic at the London Health Sciences Centre (London, Ontario) showed a mean hemoglobin level of 145±13 g/L, which suggests that polycythemia is not a reliable marker for iron overload.

Hemochromatosis is not a cause of significant liver disease

It has been well established that with timely diagnosis and institution of iron depletion therapy, patients with hemochromatosis can be expected to have a prognosis equal to that of controls. However, among patients with severe iron accumulation, the risk of progression to cirrhosis is significant. As in other causes of cirrhosis, morbidity and mortality rates are increased due to the many associated complications of end-stage liver disease including the development of hepatocellular carcinoma. However, in the case of cirrhosis due to hemochromatosis, the incidence of hepatocellular carcinoma is significantly higher than that of many other causes of liver disease. Iron overload in hemochromatosis has also been shown to potentiate alcoholic liver disease and may have a similar effect on the course of HCV and nonalcoholic fatty liver disease (1517). Given that 1.8% of the population in the United States are HCV-positive and that up to 24% have nonalcoholic fatty liver disease, the coexistence of these disorders with hemochromatosis is likely to affect a reasonable proportion of our population.

Carriers of the hemochromatosis gene often have iron overload

It has been common for physicians to tell patients with mild elevations in serum ferritin levels that they may be carriers of the hemochromatosis gene. Mild elevations in serum ferritin levels in the general population are very common and occur in all ethnic groups, so they are unlikely to be explained on the basis of heterozygosity for the hemochromatosis gene. A large population study (1) has now demonstrated that C282Y heterozygotes have iron studies similar to those of the general population. There is an increased prevalence of mild iron overload in compound heterozygotes (C282Y/H63D), and some C282Y heterozygotes may also carry an unidentified second mutation.

Children of hemochromatosis patients are at the highest risk of disease

The misconception that children of hemochromatosis patients are at the highest risk of disease arises because of a misunderstanding by patients and physicians of the concept of autosomal recessive inheritance. Usually a typical C282Y homozygote has heterozygous parents and so there is a higher risk for siblings. The risk is slightly higher than 25% because there is a possibility that one of the parents is a homozygote. Children of homozygotes are at a much lower risk because the partner must also carry the C282Y mutation. Among Caucasian couples, the risk to children is approximately 5% (18). Genetic testing of children younger than 18 years of age is not recommended because of a number of potential concerns about informed consent and genetic discrimination.

Genetic testing for hemochromatosis is a research tool

Genetic testing for hemochromatosis has a number of unique characteristics. Unlike most genetic diseases, in hemochromatosis there is a single genetic mutation (C282Y) that explains most typical cases. The test is widely available and can be performed at a relatively low cost. There have been a number of studies (1921) that have assessed the psychosocial impact of genetic testing for hemochromatosis which have concluded that the test is well accepted by patients and has rarely been associated with insurance discrimination. For these reasons, the genetic test has become one of the most commonly requested tests and is a powerful diagnostic tool that is accessible to most physicians.

Hemochromatosis patients should be on a low-iron diet

Although dietary iron is the source of excess iron in hemochromatosis, a decrease in dietary iron has not been shown to decrease iron stores in hemochromatosis. All food groups contain iron and most humans will absorb only a small fraction of orally ingested iron. Iron absorption includes components from heme and nonheme iron sources (22), and the control or lack of control over these regulatory mechanisms is incompletely understood in hemochromatosis. It has been speculated that a defect in hepcidin, a circulating peptide produced by the liver, is a fundamental defect in hemochromatosis which results in an increase in intestinal iron absorption (23). Iron supplementation of food was introduced in the 1950s as a marketing tool, and the added iron has poor bioavailability. Generally, vegetarians have lower serum ferritin levels than meat-eating patients but this does not translate into a dietary recommendation (24). The description of bacterial infections from Yersinia (25) and other Vibrio species has led to recommendations to avoid raw shellfish which may be appropriate for all patients rather than just hemochromatosis patients. Hemochromatosis patients are advised to avoid iron supplementation and large doses of supplemental oral vitamin C which may adversely affect some patients with iron overload (26).

Hemochromatosis is a progressive disease

Because hemochromatosis patients presumably begin absorbing excess iron at birth, it seems intuitive that progressive iron overload over time would occur. However, it has not been possible to show a correlation between liver iron concentration and age in hemochromatosis (27). It has become apparent through various studies, in which genetic testing was performed after many years of observation such as in the Copenhagen Heart Study (28), that many C282Y homozygotes do not have a progressive rise in serum ferritin levels, even without phlebotomy treatment. This is the most likely explanation for the discordance between the high frequency of the hemochromatosis genotype and the relatively low representation of hemochromatosis in liver transplant registries (29) or in death certificate data (30). There have been patients who have refused phlebotomy therapy and have been observed over many years to not have any changes in their serum ferritin levels. Phlebotomy therapy has never been subjected to a randomized trial. The strongest supporting evidence for a beneficial effect of phlebotomy is the improvement of liver fibrosis that has been demonstrated on serial liver biopsies in hemochromatosis patients (31). Maintenance therapy is even less established following iron depletion, and many patients will not demonstrate any evidence of iron reaccumulation after many years of observation (32). Many patients enjoy the concept of continuous therapy for hemochromatosis and these patients can be encouraged to be voluntary blood donors several times per year (33). If they are ineligible, an annual ferritin determination is a reasonable alternative to guide maintenance therapy.


Hemochromatosis is a common and relatively simple genetic disease to diagnose and treat. It can be diagnosed and treated by family physicians using transferrin saturation, serum ferritin and C282Y genetic testing. Physicians who are not comfortable with interpretation of the genetic test and subsequent family counselling should refer to local specialists and try to avoid any perpetration of misinformation.

Connie’s comments: Calcium and magnesium supplements cancels iron absorption.

Caffeine, drugs, iron, zinc, heart and latest research

Coffee is a complex mixture of chemicals that provides significant amounts of chlorogenic acid and caffeine. Unfiltered coffee is a significant source of cafestol and kahweol, which are diterpenes that have been implicated in the cholesterol-raising
effects of coffee.

The results of epidemiological research suggest that coffee consumption may help prevent several chronic diseases, including type 2 DM,41 Parkinson’s disease69 and liver

Large prospective cohort studies in the Netherlands, US, Finland and Sweden have found coffee consumption to be associated with significant dose-dependent reductions in the risk of developing type 2 DM, although the mechanisms are

Several large prospective cohort studies have found that caffeine consumption from coffee and other beverages is inversely associated with the risk of Parkinson’s disease in men and women who have never used postmenopausal estrogen.3,67,68

The results of animal studies suggest that the ability of caffeine to block adenosine A2A-receptors in the brain may play a role in this protective effect.

Epidemiological studies also suggest that coffee consumption is associated with decreased risk of hepatic injury, cirrhosis and hepatocellular carcinoma, although the
mechanisms are not clear.

Inverse associations between coffee consumption and colorectal cancer risk observed in case-control studies have not generally been confirmed in prospective cohort studies.

Coffee and Health A Review of Recent Human Research

Most prospective cohort studies have not found that coffee consumption is associated with significantly increased risk of CHD or stroke.

However, randomized controlled trials lasting up to 12 weeks have found that coffee consumption is associated with increases in several cardiovascular disease
risk factors, including blood pressure6 and plasma tHct.

At present, there is little evidence that coffee consumption increases the risk of cancer. Although most studies have not found coffee or caffeine consumption to be inversely associated with bone mineral density in women who consume adequate calcium, positive associations between caffeine consumption and hip fracture risk in three prospective cohort studies suggest that limiting coffee consumption to 3 cups/d (300 mg/d
of caffeine) may help prevent osteoporotic fractures in older adults.

Although epidemiological data on the effects of caffeine during pregnancy are conflicting, they raise concern regarding the potential for high intakes of coffee or caffeine to increase the risk of spontaneous abortion and impair fetal growth

Serious adverse effects from caffeine at the levels consumed from coffee are uncommon, but there is a potential for adverse interactions with a number of medications. Regular
consumers of coffee and other caffeinated beverages may experience withdrawal symptoms, particularly if caffeine cessation is abrupt.

Overall, there is little evidence of health risks and some evidence of health benefits for adults consuming moderate amounts of coffee (3–4 cups/d providing 300–400 mg/d
of caffeine). A review of the effects of caffeine on human health commissioned by Health Canada also concluded that moderate caffeine intakes up to 400 mg/d are not associated
with adverse health effects in healthy adults.

However, some groups, including people with hypertension and the elderly, may be more vulnerable to the adverse effects of caffeine. Currently available evidence suggests that it would be prudent for women who are pregnant, lactating, or planning to become pregnant to limit coffee consumption to 3 cups/d providing no more than 300 mg/d of caffeine.

Caffeinated soft drinks are the principal source of caffeine in the diets of children and adolescents in the US, although coffee consumption increases somewhat during adolescence.

Limited data from short-term clinical trials suggest that daily caffeine intakes of 3 mg/kg of body weight or more may have adverse effects in children and adolescents.

men women caffeine 3men women caffeine 2men women caffeine 1men women caffeine