Benefits of Coffee
Humans have been drinking coffee for at least 500 years. It is now one of the most widely consumed beverages in the U.S. and worldwide. Traditionally, high consumption of coffee has been considered to have negative health consequences, often attributed to the stimulant effects of caffeine. However, coffee is also one of the largest sources of antioxidants in the diet and contains various compounds with potential beneficial effects on glucose metabolism, inflammation and blood vessel function. Because smokers tend to drink more coffee than non-smokers, some of the negative consequences attributed to coffee in previous studies may have been due to smoking.
In the HPFS, we have extensively studied the health consequences of coffee, and have generally not found negative consequences. In fact, we have found several potential health benefits of coffee. The clearest benefits include less inflammation, lowered insulin resistance, and decreased diabetes risk. In the HPFS, men who drank four to five cups per day had a 29 percent lower risk of diabetes; those consuming six or more cups had a 54 percent lower risk. This lower risk was observed for decaffeinated coffee as well as caffeinated coffee (Bhupathiraju et al. Am J Clin Nutr. 2012 Nov 14 [Epub ahead of print]).
We also found no evidence of harm for coronary heart disease. As with diabetes, we even saw potential benefits with higher consumption in relation to cardiovascular mortality. For overall mortality, compared to very light coffee drinkers (those who consumed less than one cup per day), participants who drank four to five cups per day had a 7 percent lower risk of death from any cause. Those who drank six or more cups per day had even less risk—a 20 percent reduction. This apparent benefit was mainly due to a reduced risk for cardiovascular mortality. Decaffeinated coffee consumption was associated with a small reduction in overall and cardiovascular mortality (Zhang et al. Diabetes Care. 2009 Jun;32(6):1043-5. Lopez-Garcia et al. Ann Intern Med. 2008 Jun 17;148(12):904-14).
In regards to overall cancer, coffee consumption was neutral—no perceived benefit or harm. However, coffee may have some benefits against specific types of cancer. For example, last year we reported that coffee was associated with a lower risk of developing an advanced or potentially lethal prostate cancer (Wilson et al. J Natl Cancer Inst. Epub 2011 May 17). One to three cups per day was associated with a 29 percent lower risk, and risk was further reduced with higher intakes. Men with at least six cups per day had a 60 percent lower risk. The findings were similar for caffeinated and decaffeinated coffee. Please note that these findings are novel and researchers in our group are now examining this hypothesis in other studies.
In addition to prostate cancer, we have found that consumption of five or more cups of coffee and tea daily was associated with a 40 percent lower risk of brain cancer (glioma), compared with no consumption (Holick et al. Cancer Epidemiol Biomarkers Prev. 2010 Jan;19(1):39-47). The lower risk appeared to be attributed largely to caffeine. Higher caffeine intake was also associated with a 13 percent lower risk of basal cell skin cancer, the most common type of skin cancer.
Our past research highlights other benefits of coffee. Among men, after adjustment for age and smoking, the risk of Parkinson’s disease was 58 percent lower for those with high caffeine intake (the top one-fifth of men) compared to those with low caffeine intake (the bottom one-fifth). This inverse association—the more caffeine consumed, the lower the risk of Parkinson’s disease—was observed with consumption of coffee, caffeine from noncoffee sources, and tea, but not decaffeinated coffee. These results suggest that caffeine is the beneficial component.
Additionally, we have found that men who consistently drank two to three cups of regular coffee per day were at 40 percent lower risk for developing symptomatic gallstone disease. Drinking at least four cups was associated with almost half the risk. As in Parkinson’s disease, decaffeinated coffee was not associated with a decreased risk.
In the past several decades, the HPFS has been at the forefront of research regarding the health consequences of coffee and caffeine. The findings on diabetes, cardiovascular disease, total mortality, Parkinson’s disease and gallstones have been largely confirmed by other studies. The novel findings on prostate and brain cancer require further study.
In the past several decades, the HPFS has been at the forefront of research regarding the health consequences of coffee and caffeine. The findings on diabetes, cardiovascular disease, total mortality, Parkinson’s disease and gallstones have been largely confirmed by other studies. The novel findings on prostate and brain cancer require further study.
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