Supplementation with cocoa extract appears to be protective against the development of hypertension among older adults with normal systolic blood pressure (SBP) levels, but not among those with elevated SBP, as shown by the results of COSMOS* presented at EPI Lifestyle 2025.

“In older adults, years-long supplementation of cocoa extract may reduce the risk of incident hypertension among those with normal BP levels,” said lead author Dr Rikuta Hamaya, Brigham and Women’s Hospital, Boston, Massachusetts, US. 

A total of 21,442 older adults (mean age 71.1 years) were included in COSMOS, of whom the majority (58.8 percent) were women. In addition, less than half of the participants (48.6 percent) had SBP <120 mm Hg (normal range) at baseline. Baseline characteristics did not significantly differ between the cocoa extract and placebo groups. [EPI Lifestyle 2025, abstract 3069]

In intention-to-treat analyses, cocoa extract supplementation showed no marked impact on incident hypertension over a median follow-up of 3.4 years (cocoa group: incidence rate [IR], 71.2 per 1,000 person-years; placebo group: IR, 73.8 per 1,000 person-years; hazard ratio [HR], 0.96, 95 percent confidence interval [CI], 0.88?1.05).

However, “a significant interaction was observed between treatment assignment and baseline SBP (p=0.002),” Hamaya said.

Among participants with baseline SBP <120 mm Hg, supplementation with cocoa extract resulted in a lower incidence of hypertension (IR, 38.2 vs 50.3 per 1,000 person-years; HR, 0.76, 95 percent CI, 0.64?0.90). This effect, however, was not observed among those with SBP 120?139 mm Hg (IR, 101.4 vs 96.8 per 1,000 person-years; HR, 1.05, 95 percent CI, 0.93?1.18).

These findings persisted in sensitivity analyses, which used different definitions of hypertension, namely physician diagnosis, initiation of antihypertensive medications, or elevated BP alone. In per-protocol analysis using inverse probability weighting to account for nonadherence, cocoa extract supplementation also proved beneficial among participants with SBP <120 mm Hg.

Preventive effect 

“Among older US adults, we did not find an overall effect of cocoa extract in reducing incident hypertension over 3.4 years,” Hamaya said. “However, the preventive effect was pronounced among participants with SBP <120 mm Hg.”

The present results suggested that a targeted approach could be beneficial for older adults in preventing hypertension by means of cocoa extract supplementation, according to the investigators.

One possible explanation for the beneficial effects in participants with normal BP was that “long-term supplementation of cocoa extract may prevent an increasing natural trajectory of SBP but does not apparently reduce SBP,” Hamaya said.

COSMOS was a two-by-two factorial, randomized, double-blind, placebo-controlled trial that examined the effects of cocoa extract (including 500-mg/day cocoa flavanols, with 80-mg/day epicatechin) and a multivitamin in older adults.

Using Cox proportional hazards models, Hamaya and colleagues examined the effect of cocoa extract on incident hypertension in 8,905 participants free from baseline self-reported hypertension. Incident hypertension was defined as follows: self-reported first-time physician diagnosis, initiation of antihypertensive drugs, or self-reported elevated SBP (≥ 140 mm Hg) or diastolic BP (≥90 mm Hg).

*Cocoa Supplement and Multivitamin Outcomes Study