Clinical Pearls & Morning Reports
Published July 22, 2020
Coffee and tea are among the most popular beverages worldwide and contain substantial amounts of caffeine, making caffeine the most widely consumed psychoactive agent. A key issue in research on caffeine and coffee is that coffee contains hundreds of other biologically active phytochemicals. Thus, research findings for coffee and other dietary sources of caffeine should be interpreted cautiously, since effects may not be due to caffeine itself. Read the NEJM Review Article here.
Q: Should coffee drinkers worry about an increased risk of cancer related to caffeine consumption?
A: The results of many prospective cohort studies provide strong evidence that consumption of coffee and caffeine is not associated with an increased incidence of cancer or an increased rate of death from cancer. Coffee consumption is associated with a slightly reduced risk of melanoma, nonmelanoma skin cancer, breast cancer, and prostate cancer. Stronger inverse associations have been observed between coffee consumption and the risk of endometrial cancer and hepatocellular carcinoma. For endometrial cancer, the associations are similar with caffeinated and decaffeinated coffee, whereas for hepatocellular carcinoma, the association appears to be stronger with caffeinated coffee.
Q: Does coffee consumption affect one’s risk of gallstones or kidney stones?
A: Coffee consumption has been associated with a reduced risk of gallstones and of gallbladder cancer, with a stronger association for caffeinated coffee than for decaffeinated coffee, suggesting that caffeine may play a protective role. In U.S. cohorts, consumption of both caffeinated and decaffeinated coffee was associated with a reduced risk of kidney stones.
A: Meta-analyses indicate that isolated caffeine intake (i.e., pure caffeine, not in the form of coffee or other beverages) results in a modest increase in systolic and diastolic blood pressure. However, no substantial effect on blood pressure was found in trials of caffeinated coffee, even among persons with hypertension, possibly because other components of coffee, such as chlorogenic acid, counteract the blood-pressure–raising effect of caffeine. Similarly, in prospective cohort studies, coffee consumption was not associated with an increased risk of hypertension. The concentration of the cholesterol-raising compound cafestol is high in unfiltered coffee. Thus, limiting consumption of unfiltered coffee and moderate consumption of espresso-based coffee may help control serum cholesterol levels. Many prospective studies have examined coffee and caffeine consumption in relation to the risks of coronary artery disease and stroke. Findings consistently indicate that consumption of up to 6 standard cups of filtered, caffeinated coffee per day, as compared with no coffee consumption, is not associated with an increased risk of these cardiovascular outcomes in the general population or among persons with a history of hypertension, diabetes, or cardiovascular diseases. Experimental studies in humans and cohort studies do not show an association between caffeine intake and atrial fibrillation.
A: Prospective cohort studies in the United States, Europe, and Asia have shown a strong inverse association between caffeine intake and the risk of Parkinson’s disease. Coffee and caffeine consumption have also been associated with reduced risks of depression and suicide in several cohorts in the United States and Europe, although these findings may not hold in persons who have very high intakes (≥8 cups per day). Coffee consumption has not been consistently associated with the risk of dementia or Alzheimer’s disease.