It would be nice if plants were made just to be our food. But what they have in mind is, in the first place, their own survival. Part of it is that they often contain what could be broadly called “natural pesticides”: substances that are toxic to mold, insects and, sometimes, animals.
We are not talking just poisonous mushrooms and exotic wild plants. It includes foods that we eat almost daily: carrots (contain carotatoxin and myristicin, nerve poison and hallucinogen, respectively), parsley, parsnip and celery (contain psolarens, increasing skin photosensitivity and vulnerability to cancer), black pepper and nutmeg (carcinogen saffrol), some herbs, like comfrey (contains pyrrolizidine alkaloids, inflicting liver damage), and many others.
Naturally occurring plant toxins, just as manmade pesticides, usually disrupt metabolic processes by blocking certain enzymes. Possible effects range from hallucinogenic to degenerative and mutagenic.
Fortunately, most of natural food pesticides are intended for much smaller predators, and don’t pack enough of a punch to harm humans. However, prolonged use of little known herbal preparations and teas, carries the risk of harming your health.
Three major groups of natural food toxins are alkaloids, bioactive amines, and fungal toxins. Worth mentioning are also purines, salicylates, pyrrolizidine alkaloids and carrageenan.
It’s been known for long time that animals grazing on pastures with abundant nightshades, often develop debilitating arthritis. Its cause has been traced to the potent chemical compounds contained in all nightshades, alkaloids. Veterinarian literature records nightshade alkaloids also causing anything from crippling cardiovascular disease, to bone degeneration and genetic damage.
Unfortunately, we humans are not spared from their toxicity. And plants from nightshade family are rather abundant in our diet. They include potato, tomato, peppers, eggplant, cayenne, chili and paprika. Another well-known member of nightshade family is tobacco.
One of the mechanism through which nightshade glycoalkaloids can affect your health is by interfering with the acetyl cholinesterase enzyme, a vital part of the neuromuscular function. You may get the picture of how important this enzyme is from the fact that some snake venoms, as well as some nerve gases (sarin, VX) work by blocking its function.
Nightshade glycoalkaloids are also capable of damaging cell membranes, from endoplasmic reticulum, needed for cellular detoxication and protein synthesis, to sodium and calcium channels, crucial for proper cardiovascular function. But all this may and may not affect you. The mechanism of action of these glycoalkaloids is determined by their level in the body, and individual mode and level of sensitivity. The rate of body accumulation from their very low food level also varies individually, which only makes more unpredictable when and how they will affect you – if ever.
It is still fairly obscured as to how much nightshade toxicity contributes to the epidemic of degenerative diseases we are witnessing. However, practical research study by Dr. Norman Childers indicates that it is the major factor in
3/4 of those suffering from unexplained chronic pain,
be it arthritis, back pain, bad shoulder, sciatica, tendonitis, muscle pain, fibromyalgia or rheumatoid arthritis. While it is an old injury, or degenerated bone or joint that usually gets the blame for the pain, most often it is caused by the inflammation spurred by nightshade glycoalkaloids injuring vulnerable cells in these compromised body areas.
When caused by nightshade toxicity, arthritic symptoms can be cleared by avoiding consumption of nightshades in any form and amount for up to 3 months. Relief can come much faster, but if it doesn’t it is necessary to stay on course for full three month in order to be able to rule out nightshade toxicity.
Nightshade-free diet has to be meticulously planned and executed, considering how many foods, condiments and supplements contain these widely used plants. Even minute amounts can trigger symptoms that may last for weeks.
Pesticide-like action of bio-active amines (chemical compounds also belonging to the broader group of alkaloids) is based on their chemical structure resembling that of some of our hormones, such as adrenaline.
Bio-active amines affect either blood vessels (vasoactive amines) – causing changes in blood pressure and related symptoms like migraine headaches – or the nervous system, by affecting the level and function of neurotransmitters (psychoactive amines).
For instance, the most widely consumed psychoactive amine, caffeine, causes a number of neurological effects from anxiety states and associated symptoms (including panic attacks), to “restless leg syndrome” and neurologically based migraines. Other pharmacological effects of caffeine include stimulating fluid elimination and dilating the airways.
In the nature, caffeine can be lethal to insects feeding on caffeine-containing herbs (it is chemically similar to strychnine, although not nearly as potent). It is much less of a threat to humans, but not necessarily harmless.
Most of caffeine’s neurological effects are due to it acting as antagonist to neurotransmitter adenosine, hence affecting brain function. Apart from that, inside the cell, it inhibits conversion of cAMP (cyclic 3′,5′-adenosine monophosphate) into its noncyclic form, thus lowering intracellular levels of this vary basic cellular metabolite. Specific consequences, again, depend on the intake level and individual biochemistry. In addition, caffeine affects hormonal function, effectively elevating important hormones, like adrenaline, noradrenalin and catecholamine (“fight-or-flight” hormone).
The three primary metabolites of caffeine, paraxanthine, theobromine and theophylline, also have their specific, relatively minor effects.
The overall effect on health and wellbeing ranges from beneficial to harmful, mainly determined by the level of consumption and metabolic efficiency. Caffeine is absorbed from intestine within 45 minutes from ingestion; its half-life in an average healthy adult is 4.9 hours, but can vary significantly – especially toward slower metabolizing – from one individual to another.
Obviously, the worst possible combination is high caffeine consumption by a slow metabolizer; such individual is most exposed to the caffeine build-up and its toxic effects. Following table summarizes possible adverse effects of acute caffeine overdose (usually in excess of 300mg, or so, but can be significantly less for sensitive individuals).
CAFFEINE TOXICITY (main symptoms)
Central nervous system
irritability, anxiety, restlessness, insomnia, confusion, headache, delirium
nausea, abdominal pain, vomiting
trembling, twitching, overextension, seizures
rapid and/or irregular heartbeat
visual flashes, ear ringing, rapid breathing, skin oversensitivity to touch/pain
Chronic overuse of caffeine also may – and often does – cause adverse health effects. These are recognized as disorders: caffeine intoxication, as well as caffeine-induced sleep and/or anxiety disorder. Symptoms of the former are similar to those of caffeine overdose. For the latter, the symptoms can range from anxiety to panic attacks; they can mimic mental anxiety/panic disorders, including bipolar (manic depression), often leading into misdiagnosis and unnecessary long-term treatment with medications.
Separately from the overuse symptoms, but likely as frequent, are caffeine withdrawal symptoms, which may take place whenever a habitual caffeine intake is interrupted for more than 12 hours, or so. They vary individually, but typically are the result of the withdrawal of stimulatory effects of caffeine, combined with the increased sensitivity to adenosine (due to the increase in number of adenosine receptors, compensating for the caffeine obstructing their intended use). The symptoms persists for as long as it takes to the body to re-adjust, usually 1-5 days. They include headache, irritability, difficulty to concentrate, drowsiness, insomnia, stomachache, upper body and joint pain.
In all, habitual overuse of caffeine can take your health and wellbeing to a slippery slope. The main culprit of the overuse is usually coffee, in all forms, but some other dietary habits can also contribute. For comparison, 1 tablespoon (6g) of regular ground coffee (Folgers) contains 90mg of caffeine and 1 teaspoon (2.2g) of Folgers’ instant coffee powder 75mg8. A standard 6 fl oz serving of brewed (percolated) coffee averages about 100mg (same as 2 fl oz of espresso, and some 20% less than 6 fl oz of drip coffee), most 12 fl oz regular sodas about half as much, and 6 fl oz of black tea about one third. Most chocolates have low caffeine content, but some chocolate products can have it comparable, per unit weight, to that in black tea and sodas.
Majority of people feel stimulating effect – increase in alertness and/or lowered fatigue – with caffeine intake of 25-50mg. Significantly higher doses – 5 to 10mg per kg of body weight – have been reported to increase endurance in competitive cycling by up to 50%. This dose is still safely bellow caffeine’s LD50 (median lethal dose, a dose that kills half of subjects exposed), estimated for humans at 150-200mg per kg of body weight (equivalent of nearly 100 cups of regular coffee); obviously, regular consumption of caffeine at this level cannot be recommended.
Beside caffeine, the other two significant bio-active amines, histamine and tyramine, can be found in high amounts mostly in fermented foods: cheeses, yeast extracts, tuna, pickled herring, sausage, and others. Tyramine raises blood pressure by constricting blood vessels. Other possible symptoms include migraines, stomach pains and breathing difficulties.
Histamine, has the opposite effect – it dilates blood vessels, lowering blood pressure. Hence, in foods containing comparable levels of both, tyramine and histamine, one will likely tend to neutralize the effect of the other one (actual effect, as always, depends on individual biochemistry/sensitivities).
Table bellow lists some common foods with potentially high levels of tyramine and/or histamine4.
Many foods – cereals, oilseeds, spices and three nuts, moldy fruits and vegetables – can be contaminated with mycotoxins (aflatoxin, ochratoxin A, patulin, fusarium) produced by fungi. Not only potent toxins, able to cause serious damage to the liver, kidneys and nervous system, they are often carcinogenic and mutagenic.
For the most part, mycotoxins are not biodegradable, and can penetrate the food chain (meat, dairy) through infected feed crops. They are not destroyed by cooking or freezing. While children and pets are more vulnerable than adults, no one is safe. One of the most potent mycotoxins – aflatoxin – can be a hidden toxic contaminant in some foods of tropical origin, especially peanuts.
Beside plant foods, mycotoxins can also contaminate foods of animal origin, including meats, either directly, or as a result of mold-contaminated animal feed. Regulations are in place – especially in Europe – establishing permissible mycotoxins level in foods and animal feed. They significantly reduce the exposure; however, nothing can guarantee protection.
The only way to reduce your exposure to mycotoxins is to avoid foods that are not, or don’t appear fresh.
When the body metabolizes purines – an aromatic organic compound whose derivatives are naturally occurring in foods as DNA/RNA constituents (nucleobases adenine and guanine) – inefficient enzyme action can result in the build up of their end metabolite, uric acid. It then crystallizes in joints, causing gout. Foods highest in purines are meats (including fish and chicken), and particularly organ meats.
Table bellow lists high-purine foods, in descending order. Those producing over 400mg/100g of uric acid are very high; foods between 100-400mg/100g are moderately high, and those bellow 100mg/100g are considered low in purines.
PURINES – FOOD CONTENT (uric acid mg/100g)
Chicken breast (w/skin)
Rabbit meat w/bone
Cep mushrooms, dried
Poppy seed, dry
White bean, dry
Sardines in oil
Pork belly, smoked
Beef chuck/fore rib
Pig’s lungs (lights)
Ox lungs (lights)
Chicken for roasting
Pork, hind leg
Chicken leg w/skin
Tuna in oil
Veal knuckle/leg/neck w/bone
Garbanzo beans, dry
Raisins, dried (sultana)
Pork chop w/bone
Sunflower seed, dry
Mungo bean, dry
Barley w/o husk, dry
Some plant foods – like soybean and some beans/legumes – have high nominal levels of purines, although generally lower than in meats.
Quite a few of fruits and vegetables have high salicylates content. Salicylic acid is phenolic compound (which include aspirin and aspirin-based pharmacological agents) to which some people – particularly children – can be sensitive. It can cause urticaria (hives) and/or angioedema, as well as mouth ulcers, irritability and hyperactivity in susceptible individuals.
There may also be some beneficial health effects of salicylates, resulting from their chemical similarity to aspirin. These are still being investigated and, obviously, have to be measured against their possible adverse effects.
Plant foods with highest salicylates level include raisins, canned prunes, raspberries, strawberries, honey (variable), most condiments, pickles, mint, licorice, sweet green pepper, endive, chicory, tomato sauce and pasta, zucchini, almonds and peanuts. Table bellow presents more detailed information on salicylates food content.
SALICYLATES, food content (mg/100g)
fruit: raisins, raspberries, canned plum herbs: licorice, mustard powder (over 10mg/100g) other: pickles, honey
Pyrrolizidine alkaloids are found in quite a few herbs, some of them used occasionally for herbal preparations and teas. It includes Indian herb Heliotropium eichwaldii, with documented cases of toxicity when used internally, and some commonly used Chinese herbal preparations (zicao, kuandonghua, qianliguang and peilan).
The risk factor includes unknowingly substituted harmless herbs with those containing PAs. For instance, popular Mexican herbal tea, gordolobo yerba, usually obtained from Gnaphalium, has documented cases of liver poisoning when made of the similar in appearance Senecio longilobus.
Algae often contain toxic substances. Carrageenan (undegraded, or natural type) is a substance extracted from seaweed, widely used as food additive (thickener and stabilizer). It has been found to cause ulcerative colon disease in laboratory animals.
While ulceration risk in humans is officially limited to the degraded (processed) version of carrageenan, it is prudent to make sure it is not on your menu on a regular basis in neither of the two forms.