Cocoa polyphenols reduce blood pressure
The July 4, 2007 issue of the Journal of the American Medical Association reported the results of a randomized clinical trial which found that consuming small amounts of dark chocolate is associated with a reduction in systolic and diastolic blood pressure (BP). The findings of previous research suggest that polyphenols, a group of plant compounds including flavanols that have been associated with a number of health benefits, may be responsible for a blood pressure-lowering effect associated with eating chocolate.
Dirk Taubert, MD, PhD, of University Hospital in Cologne, Germany, and his associates gave 20 men and 24 women 6.3 grams per day dark chocolate, providing 30 milligrams polyphenols, or an equal amount of white chocolate, which does not contain polyphenols, for 18 weeks. Participants were 56 to 73 years of age with untreated upper-range prehypertension or stage 1 hypertension. Blood pressure, weight, and blood values of cholesterol, triglycerides, glucose, and S-nitrosoglutathione (vasodilative nitric oxide--which increases the dilation of blood vessels resulting in lower blood pressure), were measured at the beginning of the study and at 6, 12 and 18 weeks.
At the trial’s conclusion, those who received dark chocolate experienced an average reduction of 2.9 mm Hg systolic and 1.9 mm Hg diastolic blood pressure. Systolic and diastolic blood pressure remained the same in the white chocolate group throughout the treatment period. A concern regarding increased chocolate intake has been that health benefits could be offset by increased weight gain, serum lipids, or blood glucose, however, these remained essentially unchanged. Hypertension prevalence decreased from 86 percent to 68 percent in the dark chocolate group, and S-nitrosoglutathione was elevated in plasma, while not changing among those who received white chocolate.
“Although the magnitude of the BP reduction was small, the effects are clinically noteworthy,” the authors observe. “On a population basis, it has been estimated that a 3 mm Hg reduction in systolic BP would reduce the relative risk of stroke mortality by 8 percent, of coronary artery disease mortality by 5 percent, and of all-cause mortality by 4 percent.”
“The most intriguing finding of this study is that small amounts of commercial cocoa confectionary convey a similar BP-lowering potential compared with comprehensive dietary modifications that have proven efficacy to reduce cardiovascular event rate,” they note. “Whereas long-term adherence to complex behavioral changes is often low and requires continuous counseling, adoption of small amounts of flavanol-rich cocoa into the habitual diet is a dietary modification that is easy to adhere to and therefore may be a promising behavioral approach to lower blood pressure in individuals with above-optimal blood pressure,” the authors conclude.
Nutrients that may help lower blood pressure include:
Clinical trials show higher mortality in patients taking calcium channel blockers for hypertension compared to patients using other types of drugs such as beta-blockers, diuretics, and angiotensin-converting enzyme (ACE) inhibitors. Because calcium channel blockers are associated with gingival overgrowth, and because other drugs known to cause gingival overgrowth (such as phenytoin) are associated with elevated levels of homocysteine, it follows that patients treated with calcium channel blockers might be at risk for increased homocysteine levels. Such an association might explain the excess mortality risk observed in patients treated with calcium channel blockers relative to those treated with other hypertension medications, since homocysteine may contribute to atherosclerotic heart disease. Strategies to achieve and maintain optimal blood levels of homocysteine—such as ensuring optimal intake of B vitamins—are thus important for individuals using calcium channel blockers such as nifedipine.
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