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Randomized Controlled Trial
. 2025 Oct;82(10):1653-1662.
doi: 10.1161/HYPERTENSIONAHA.125.25209. Epub 2025 Aug 20.

Long-Term Effect of Cocoa Extract Supplementation on Incident Hypertension

Rikuta Hamaya  1   2 , Sidong Li  1   3 , Jessica Lau  1 , Matthew Allison  4 , Bernhard Haring  5 , Aladdin H Shadyab  6 , Nudy Matthew  7 , Lisa Warsinger Martin  8 , Pamela M Rist  1   2 , JoAnn E Manson  1   2   9 , Howard D Sesso  1   2 ; COSMOS Research Group
Affiliations
Randomized Controlled Trial

Long-Term Effect of Cocoa Extract Supplementation on Incident Hypertension

Rikuta Hamaya et al. Hypertension. 2025 Oct.

Abstract

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]; P-interaction=0.002). The effect among baseline systolic BP <120 mm Hg became evident at year 2 after randomization.

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%.

Keywords: cocoa powder; hypertension; incidence; primary prevention; randomized controlled trial.

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Conflict of interest statement

H.D. Sesso and Manson received investigator-initiated grants from Mars Edge, a segment of Mars Incorporated dedicated to nutrition research and products, for infrastructure support and donation of Cocoa Supplement and Multivitamin Outcomes Study (COSMOS) pills and packaging, and Pfizer Consumer Healthcare (now Haleon) for donation of COSMOS study pills and packaging during the conduct of the study. H.D. Sesso additionally reported receiving investigator-initiated grants from Pure Encapsulations and honoraria and travel for lectures from the Council for Responsible Nutrition, BASF, and National Institute of Health (NIH) during the conduct of the study. The other authors report no conflicts.

Figures

Figure 1.
Figure 1.. Screening, randomization, and selection of the participants of COSMOS study who were free from hypertension at baseline
The present study included 8,905 COSMOS participants who were free from hypertension at baseline. Cocoa extract (Cocoa) and multivitamin-multimineral (MVM) supplementations were randomized via a 2*2 factorial fashion.
Figure 2.
Figure 2.. Effects of cocoa extract on incident hypertension and the effect measure modifications based on Cox proportional hazard models in 8,905 COSMOS participants
Analyses were from Cox regression models for incident hypertension by cocoa extract supplementation compared with placebo, controlled for age, sex, study site, and randomization group in the multivitamin-multimineral (MVM) portion of the trial (intention-to-treat analyses). Analyses were not adjusted for multiple comparisons. Race and ethnic group were self-reported. Urinary 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone metabolites (gVLM) and alternative healthy eating index-2010 (AHEI) was dichotomized by median.
Figure 3.
Figure 3.. Proportion free from hypertension according to cocoa extract intervention groups
Kaplan-Meier curves showing the effect of randomized cocoa extract supplementation in participants stratified by baseline systolic blood pressure (normal blood pressure [BP]: <120 mmHg, elevated BP: 120–139 mmHg). Numbers indicate the number at risk of each group.
See this image and copyright information in PMC

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