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.
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.