Cocoa extract supplements are shown to protect the heart and slow aging

Older adults taking a daily cocoa extract showed a steady drop in a blood marker associated with inflammation. The work points to one way cocoa’s nutrients might connect to heart health as people age.

High-sensitivity C-reactive protein, called hsCRP, rises when the body is inflamed, and higher levels correlate with a greater chance of future heart problems. Doctors evaluate it alongside other risk factors, not on its own.

The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) was led by Dr. Howard Sesso, at Brigham and Women’s Hospital, part of Mass General Brigham (MGB).

The team set out to investigate whether multiyear cocoa extract use could shift a cluster of age-related inflammatory signals, a process often called “inflammaging.”

Studying cocoa extract and heart health

The researchers looked at five blood signals over two years in 598 people from the larger trial.

These included hsCRP, which shows inflammation, plus four proteins that play roles in the immune system: interleukin-6, tumor necrosis factor-alpha, interleukin-10, and interferon-gamma.

COSMOS is a large randomized trial in older adults that tested cocoa extract and a common multivitamin in a placebo-controlled, double-blind design.

Participants assigned to cocoa took capsules that delivered 500 milligrams (mg) of cocoa flavanols per day, including 80 mg of the flavanol epicatechin.

Randomized means people were assigned by chance rather than by preference or health status. Double-blind means neither participants nor study staff knew who took cocoa or placebo during follow-up.

What the results show

Across two years, hsCRP fell by an average of 8.4 percent per year compared with placebo in the cocoa group.

The other markers were mostly stable, although the team reported a small rise in interferon-gamma.

Interferon-gamma is a key immune cytokine that helps coordinate white blood cell responses. The meaning of that increase is not yet clear and will need more follow-up.

Comparing supplement effects

Other large nutrition trials have tested supplements for aging and heart health, with mixed results.

For example, vitamin D and fish oil trials showed little to no effect on inflammation markers, despite being linked to other positive health outcomes.

This contrast makes the cocoa extract findings stand out, though replication will be important.

The researchers note that plant flavanols in foods like tea, berries, and grapes also show anti-inflammatory signals in smaller clinical studies.

That broader pattern points toward flavanols as a shared nutrient class worth watching, rather than cocoa alone.

Cocoa extract and heart health

In the larger COSMOS trial, cocoa extract did not reduce the combined rate of all cardiovascular events, but it was linked to a 27 percent lower risk of cardiovascular death.

That result came from prespecified analyses of clinical outcomes in more than 21,000 participants.

Inflammation can contribute to artery damage over time, so a downward shift in hsCRP offers a possible clue. It connects a nutrient signal in the blood to a pattern seen in cardiovascular outcomes.

“We also appreciate the important overlap between healthy aging and cardiovascular health, where aging-related inflammation can harden arteries and lead to cardiovascular disease,” said Sesso.

What supplements can’t replace

Supplements cannot stand in for balanced meals, regular exercise, good sleep, and not smoking. Those habits lower inflammation and cut heart risk in ways that a single capsule cannot match.

This study focused on blood signals, not on preventing disease events by itself. Changes in one marker are useful to track, yet they do not prove cause on their own.

Tracking long-term cocoa effects

The team plans to keep tracking participants in COSMOS to see whether cocoa flavanols influence other age-related outcomes beyond heart health.

Longer follow-up may reveal whether changes in inflammation markers connect to brain function, vision, or overall survival in older adults.

They also note that differences by sex or age could matter. For example, the slight reduction in interleukin-6 seen in women but not men hints that responses may vary. Future studies will need to confirm whether these trends are consistent in larger groups.

Cocoa in daily life

If future work shows the hsCRP shift lines up with better clinical outcomes, cocoa flavanols could be part of a broader healthy aging plan.

That might look like diet patterns that already include fruits, vegetables, tea, and modest cocoa products.

Quality and dose matter with any supplement. The COSMOS capsules contained defined amounts of flavanols, which is not the same as chocolate bars with unknown content and added sugar.

The study is published in the journal Age and Ageing.

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