In the United States, coffee consumption exceeds 400 million cups per day; it's second only to water as the most widely consumed beverage. "Even potentially small health benefits or risks associated with coffee intake may have important public health implications given its widespread popularity," noted authors of a recent JACC article, but "many misconceptions persist regarding the health-related effects of coffee."

James H. O'Keefe, MD, from Mid America Heart Institute at Saint Luke's Hospital of Kansas City and University of Missouri-Kansas City, and colleague focused on CV effects of coffee, specifically its impact in the following areas: blood pressure, insulin sensitivity, serum lipids, coronary heart disease (CHD), heart failure (HF), arrhythmias, stroke, and mortality. They looked at available data from a variety of studies, including the National Health and Nutrition Examination Survey, Nurses' Health Study, and international registries.

The exact mechanism through which coffee confers health benefits is debated. Caffeine is thought to be a major player, but decaffeinated coffee seems to offer some health benefits—and may be a reasonable option for people who experience uncomfortable effects from caffeine stimulation. Caffeine, although the major acute BP-raising compound found in coffee, was not found to be solely responsible for the CV effects associated with acute and chronic coffee consumption. Of note, O'Keefe et al. found that most of the studies that found the BP-raising effects of coffee were temporary and only found in nonhabitual coffee drinkers.

Other compounds in coffee are thought to play a part in raising cholesterol, but researchers found that the impact of coffee on serum lipid levels depended mainly on the coffee preparation, with filtered coffee being ideal for patients with dyslipidemia.

Coffee may exert helpful CV effects indirectly, Dr. O'Keefe and colleagues note, such as reducing the risk of depression (a risk factor for the development of CV disease), Alzheimer's disease, Parkinson's disease, and other diseases of the central nervous system. Of course, the authors noted, moderation is key, tending towards two or three cups daily or up to four (depending on caffeine tolerance). From the available evidence, the authors concluded, coffee can be included as part of a healthy diet for the general public, as well as those with CV risk or CVD.

Many of the analyses showed generally neutral, with certain studies finding that consumption of >1-2 cups daily may decrease the long-term risk of CHD. The same assumptions can be made about coffee consumption and CHF risk and arrhythmias, even at doses exceeding 6 cups daily. Some studies even suggested that coffee has a protective stroke risk: consuming 3–6 cups of coffee per day showed a significant reduction in stroke risk (RR = 0.79) in one study examined.

"The currently available evidence on CV effects related to habitual coffee consumption is largely reassuring," they concluded. However, they added, it is possible that habitual coffee drinkers may differ in other important dietary and sociologic aspects from the non-consumers. "Therefore, the possibility that coffee consumption may be acting as a surrogate marker of some other dietary or lifestyle risk factor cannot be fully excluded."

O'Keefe JH, Bhatti SK, Patil HR, et al. J Am Coll Cardiol. 2013 July 3. [Epub ahead of print]

Keywords: Depression, Risk, Stroke, Cholesterol, Registries, Public Health, Caffeine, Dyslipidemias, Parkinson Disease, Diet, Coffee, CardioSource WorldNews

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