A report in the July 4 issue of the Journal of the American Medical Association (JAMA) showed that eating polyphenol-rich dark chocolate as part of a usual diet reduced blood pressure and improved the formation of vasodilative nitric oxide in otherwise healthy people with above-optimal blood pressure.
Twenty-four women and 20 men with untreated upper-range prehypertension or stage 1 hypertension without concomitant risk factors took part in the 18-week study. Subjects were randomly assigned to receive either 6.3 grams of dark chocolate containing 30 milligrams of polyphenols on a daily basis or matching polyphenol-free white chocolate. The primary outcome measure was the change in blood pressure. Secondary outcome measures included changes in plasma markers of vasodilative nitric oxide and oxidative stress, and the bioavailability of cocoa polyphenols.
Dark chocolate intake significantly reduced systolic and diastolic blood pressure, while hypertension prevalence declined from 86 percent to 68 percent.
White chocolate intake caused no changes in blood pressure.