COMMENTARY

Fill 'er Up! Health Effects of Coffee

Charles P. Vega, MD

Disclosures

October 03, 2013

In This Article

Discussion

This is not the first study performed on the health effects of coffee, and the subject remains controversial. It is interesting that the results of this study buck the trend of recent, high-quality research that suggests that coffee improves health outcomes.

Coffee can raise blood pressure acutely, but the consensus appears to be that it has a negligible role in promoting hypertension. In one systematic review of observational studies, only mild coffee consumption of 1-3 cups per day was associated with a higher risk for hypertension compared with no coffee consumption.[3] A more recent review found that the cumulative effect of coffee consumption on blood pressure was less than 1 mm Hg, and coffee did not promote hypertension.[4]

Coffee has more mixed effects on other important cardiovascular risk factors. A meta-analysis of 12 studies found that coffee increased serum levels of total cholesterol, low-density lipoprotein cholesterol, and triglycerides, with a dose-response effect.[5] In contrast, a meta-analysis of 18 studies with over 400,000 participants in total found that each additional cup of coffee consumed daily was associated with a 7% reduction in the risk for incident type 2 diabetes.[6]

Given these variable effects on cardiovascular disease risk factors, how does coffee consumption affect the rates of actual cardiovascular events? Previous research found a positive association between coffee intake and the risk for either myocardial infarction or cardiovascular death.[7] However, a recent review found that moderate coffee consumption reduced the risk for heart failure, with a peak protective effect at 4 servings per day.[8] This same review also found that high levels of coffee consumption might increase heart failure risk. A review of 9 cohort studies found that at least 4 cups of coffee per day reduced the risk for stroke by 17% compared with abstinence from coffee.[9]

What about mortality outcomes among coffee drinkers vs nondrinkers? Research is mixed in this area as well. In an observational study of 37,742 Japanese women, coffee consumption had no significant effect on the overall risk for mortality, but there was a clear reduction in the risk for death due to coronary heart disease among coffee drinkers.[10] Another study examined mortality outcomes associated with coffee among 3837 patients with diabetes.[11] Like the current study by Liu and colleagues, it featured a broad age range among its subjects. However, in contrast to the current research, coffee consumption was associated with a lower risk for mortality, even at levels of greater than 6 cups per day. Finally, data from the Health Professionals Follow-Up Study and Nurses' Health Study, which featured similar largely white and well-educated populations in comparison with the current study, demonstrated no effect of coffee consumption on the risk for mortality among men and a lower risk for mortality among women who drank coffee.[12] Again, the benefit among women was principally for cardiovascular mortality.

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