BACKGROUND: Cocoa flavanols have potential blood pressure (BP)-lowering effects in shorter-term, smaller-scale randomized clinical trials, but their effect on incident hypertension has not been examined in a large-scale and long-term randomized clinical trial.
METHODS: The COSMOS (Cocoa Supplement and Multivitamin Outcomes Study) is a 2×2 factorial, double-blind, placebo-controlled randomized clinical trial testing cocoa extract (including 500 mg/d cocoa flavanols, with 80 mg/d [-]-epicatechin) and a multivitamin among 21 442 women aged ≥65 years and men aged ≥60 years. Placebos did not include any bioactive compounds. In 8905 COSMOS participants free from baseline hypertension, we investigated the effect of cocoa extract on incident hypertension using Cox proportional hazards models. Incident hypertension was defined as self-reported first-time physician diagnosis, initiation of antihypertensive medications, or elevated BP.
RESULTS: Mean age at baseline was 71.1 years (SD, 6.2), and 59% were women. Over a median follow-up of 3.4 years, cocoa extract supplementation had no significant effect on incident hypertension in an intention-to-treat analysis, with incidence rates of 7.1 and 7.4 per 100 person-years in cocoa and placebo groups, respectively (hazard ratio, 0.96 [95% CI, 0.88-1.05]). In subgroup analyses, cocoa extract supplementation reduced the incidence of hypertension among participants with baseline systolic BP <120 mm Hg (hazard ratio, 0.76 [0.64-0.90]), but not among those with systolic BP of 120 to 139 mm Hg (hazard ratio, 1.05 [0.93-1.18];-interaction=0.002). The effect among baseline systolic BP <120 mm Hg became evident at year 2 after randomization. P
CONCLUSIONS: In older adults, long-term cocoa extract supplementation did not reduce the overall risk of self-reported incident hypertension. However, among those with normal systolic BP at baseline, cocoa extract reduced hypertension risk by 24%.
