Effects on hypertension, insulin sensitivity, serum lipids, CHD, CHF, arrhythmias, stroke and mortality….
O’Keefe et al reviewed existing data regarding the effects of long-term coffee consumption, with a focus on cardiovascular (CV) health.
Hypertension is a strong independent risk factor for stroke and CHD. Coffee consumption has been associated with acute increases in blood pressure (BP) in caffeine-naive people but exerts negligible effects on the long-term levels of BP in habitual coffee drinkers. The acute effects of coffee are transient, and, with regular intake, tolerance develops to the hemodynamic and humoral effects of caffeine. Antioxidants in coffee, such as chlorogenic acid, have been recognized to improve glucose metabolism and insulin sensitivity.
A recently published randomized study found that consumption of 5 cups of coffee per day increased adiponectin levels and decreased insulin resistance. A prospective study of more than 88,000 women 26 to 46 years of age established a linear relationship of coffee consumption with the reduction in T2DM, whereby even small amounts of coffee on a daily basis conferred benefit. Associations were similar for noncaffeinated and caffeinated coffee.
Coffee contains cholesterol-increasing compounds classified as diterpenes, including cafestol and kahweol. Importantly, the concentration of these compounds depends on how coffee is prepared. Boiled coffee has higher concentrations because diterpenes are extracted from the coffee beans by prolonged contact with hot water.
Many epidemiological studies have evaluated the potential effects of coffee on CHD, and these individual studies have generally shown neutral effects. Several studies have suggested that it is safe for patients with established CHD to continue their habitual coffee consumption. A recent large meta-analysis reported a U-shaped relationship between coffee consumption and the incidence of CHF. Increased CHF risks were noted for both higher than and lower than 4 servings of coffee a day. Data linking coffee consumption to increased risk of arrhythmias are inconsistent. Early animal studies indicated that coffee appeared to cause arrhythmias in a canine model. Yet, more recent studies have suggested that coffee appears not to increase arrhythmias; to the contrary, long-term coffee drinking might actually reduce the risk of abnormal cardiac rhythms.
Coffee may reduce the risk of ischemic stroke. An analysis of a prospective group of >83,000 women from the Nurses’ Health Study who were free of CV disease and cancer at baseline found that coffee consumption was associated with a modest but statistically significant reduction in the risk of stroke during the 24-year follow-up period. Exactly how coffee lowers the risk of stroke is unknown, but postulated mechanisms include coffee’s anti-inflammatory and insulin-sensitizing effects. In the National Health and Nutrition Examination Survey I, 6,594 participants 32 to 86 years of age with no history of CV disease at baseline were prospectively followed for 8.8 years. Coffee intake of participants who were 65 years of age or older exhibited a dose-response protective effect whereby increasing habitual consumption of coffee was associated with lower RRs of adverse CV events and heart disease mortality. Based on these findings, the authors conclude that currently available evidence on CV effects related to habitual coffee consumption is largely reassuring. Coffee can be included as part of a healthy diet for the general public and also for those with increased CV risk or CV disease.
- Coffee contains cholesterol-increasing compounds classified as diterpenes, including cafestol and kahweol.
- Coffee may reduce the risk of ischemic stroke.
- Antioxidants in coffee, such as chlorogenic acid, have been recognized to improve glucose metabolism and insulin sensitivity.
Journal of the American College of Cardiology, September 2013