Is increasing cocoa consumption an effective adjunctive therapy for adults with hypertension?
Consuming 50 g of cocoa daily will lower blood pressure 2 to 3 mm Hg on average in adults with hypertension. Evidence of improved patient-oriented outcomes does not exist. (Strength of Recommendation: C, based on consensus, disease-oriented evidence, usual practice, expert opinion, or case series.)
In 1944, researchers studying the Kuna Indians of the San Blas Islands of Panama found that islanders who drank three to four cups of cocoa daily had lower blood pressure than those who migrated to the mainland and no longer drank cocoa daily.1 Cocoa has high levels of flavonols (e.g., epicatechin, catechin), which can cause antioxidant activity in the endothelium, vasodilation via increased nitrous oxide production, and inhibition of angiotensin-converting enzyme, all of which may lower blood pressure. Hypertension is implicated in 50 percent of cardiovascular disease cases, and clinical practice guidelines suggest lifestyle and dietary interventions in addition to medication to lower blood pressure.
This Cochrane review combined data from 20 trials involving 856 patients. Patients using medications or other interventions to treat hypertension were included. Cocoa was consumed in several forms, including dark and milk chocolate, and cocoa powder. Overall, cocoa had a statistically significant effect of lowering systolic blood pressure by 2.8 mm Hg and diastolic blood pressure by 2.2 mm Hg. Results were more significant in shorter trials, which tended to use flavonol-free control products, and were not dose dependent. In the eight trials in which the control group used a low-flavonol product, blood pressure reduction was similar between the treatment and control groups. However, in the 12 trials in which the control group used a flavonol-free product, those in the treatment group had reductions in systolic blood pressure of 3.7 mm Hg and diastolic blood pressure of 2.7 mm Hg compared with the control group. None of the studies measured health outcomes (e.g., cardiovascular events, mortality).
Treated participants received a mean of 545.5 mg of flavonols or about 50 g of cocoa per day (range = 3.6 to 105 g of cocoa per day). One serving of typical cocoa powder for drinking contains 5 to 10 g of cocoa. The blood pressure–lowering effect was greater in persons younger than 45 years, in those who consumed less than 10 g of sugar per serving of cocoa product, and in those with an initial systolic blood pressure of 140 mm Hg or higher. Five percent of treated patients had adverse effects; the most common were gastrointestinal irritation and laxative effects.
Another Cochrane review found that lowering dietary sodium intake by 2 g per day could lower systolic blood pressure by 5 mm Hg and diastolic blood pressure by 2.7 mm Hg in persons with hypertension,2 yet a third review concluded that advice to lower sodium intake has no impact on cardiovascular outcomes, including mortality.3 Because it is not known if cocoa's effects on blood pressure improve patient-oriented outcomes, and because many cocoa products are high in sugar and saturated fat, family physicians should refrain from recommending cocoa to lower blood pressure in patients with hypertension.