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Dark Chocolate for Your Blood Pressure?

A small amount of dark chocolate eaten daily for 18 weeks decreased systolic and diastolic blood pressure by a few mm Hg.

Cocoa is rich in plant polyphenols such as flavanols and might have a beneficial effect on endothelial function and blood pressure: In short-term trials, daily intake of at least 100 g of chocolate was associated with reductions in BP. Now, investigators have conducted a randomized, controlled trial to assess whether daily low doses of flavanol-rich dark chocolate could elicit similar BP reductions. Forty-four otherwise healthy adults (age range, 56–73; 24 women) with prehypertension (BP range, 130/85–139/89 mm Hg) or stage I hypertension (BP range, 140/90–160/100 mm Hg) consumed 6.3 g of dark chocolate (30 mg polyphenols) or 5.6 g of white chocolate (no polyphenols) daily. Before study enrollment, the participants had not regularly eaten chocolate. The 6.3-g and 5.6-g doses increased total energy intake by less than 2%, thus precluding the necessity of other dietary adjustments to maintain stable body weight.

In the dark chocolate group, systolic and diastolic BP declined steadily over time: At 18 weeks, the mean change in BP was –2.9/–1.9 mm Hg compared with baseline (P<0.001). By contrast, BP remained unchanged in the white chocolate group. The BP reductions were greater in individuals with higher baseline BP, and results were similar in men and women. Increased plasma S-nitrosoglutathione, a marker for vasodilative endothelial nitric oxide, was inversely correlated with the changes in systolic and diastolic BP in the dark chocolate group; levels did not change with white chocolate intake. Body weight remained constant in both groups.

Comment: On a population basis, a reduction of 3 mm Hg in systolic BP is estimated to reduce the relative risk for stroke, cardiovascular, and all-cause mortality by 8%, 5%, and 4%, respectively. Daily ingestion of a small piece of chocolate improved BP to a degree comparable to that seen with dietary modification such as the Dietary Approaches to Stop Hypertension (DASH) diet. Adhering to the DASH diet often requires multiple dietary changes and calculations, but it’s relatively easy to eat a piece of dark chocolate daily! Additional effects on BP are unknown for those who already consume chocolate regularly; nonetheless, dark chocolate lovers will be happy if the results of this small study are confirmed in larger trials.

— Wendy S. Biggs, MD

Published in Journal Watch Women's Health July 19, 2007

Citation(s):

Taubert D et al. Effects of low habitual cocoa intake on blood pressure and bioactive nitric oxide: A randomized controlled trial. JAMA 2007 Jul 4; 298:49-60.

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