More evidence of benefit of dark chocolate
A crossover RCT evaluated 19 hypertensive patients with glucose intolerance, but not overt diabetes, who ate either 100 g of flavonol-rich dark chocolate (50% cocoa) or 100 g of flavonol-free white chocolate for 15 days. Dark chocolate significantly reduced both 24-hour ambulatory systolic blood pressure (–4.52±3.94 mm Hg; P<.0001) and diastolic pressure (–4.17±3.29 mm Hg; P<.0001) compared with white chocolate. It also significantly decreased clinical blood pressure readings (systolic: –3.82±2.40 mm Hg; P<.0001; diastolic: –3.92±1.98 mm Hg; P<.0001).3
Another RCT evaluated blood pressure in 45 healthy adults given a 74-g dark chocolate bar (30% cocoa) or a 74-g placebo bar. Blood pressure decreased significantly 2 hours afterwards: –3.2±5.8 mm Hg systolic (P<.001) and –1.4±3.9 mm Hg diastolic (P<.001).4
Sugarless, but not sugared, cocoa shows effects on blood pressure
One week later, investigators compared 2 cups of cocoa (22 g cocoa powder) with 2 cups of sugarless cocoa and placebo. They found significant blood pressure reduction only with the sugarless drink. This study was the only one that reported sponsorship by a chocolate manufacturer.4
Long-term high-flavonoid consumption linked to lower heart disease mortality
A systematic review evaluated the long-term effects of a high-flavonoid diet over a period of 5 to 26 years. The review didn’t measure chocolate intake specifically, although the authors report that both milk and dark chocolate (percent cocoa not specified) are high in flavonoids, containing about 3 to 5 times as much as a comparable amount of black tea or red wine. Eleven prospective observational studies (N=190,000) met the criteria for this review.
Investigators compared occurrence and mortality rates for coronary heart disease and myocardial infarction among participants in the highest and lowest tertiles of flavonoid consumption. Participants in the highest tertile had significantly lower mortality from coronary heart disease than the lowest tertile, with a relative risk of 0.81 (95% CI, 0.71-0.92; no number needed to treat was available).5
Recommendations
We couldn’t find recommendations from major medical organizations. A Natural Medicines Comprehensive Database monograph states that consuming dark chocolate may modestly reduce blood pressure, but not enough evidence exists to rate chocolate’s effectiveness for cardiovascular disease, hypercholesterolemia, or isolated systolic hypertension.6
The US Food and Drug Administration warned one candy manufacturer against claiming that its chocolate-containing candy bars were “heart healthy,” noting that the candy bars also contained high levels of saturated fats.7