Study details and key findings

The current study was part of COcoa Supplement and Multivitamin Outcomes Study (COSMOS), a large-scale trial from Brigham and Women's Hospital examining the effect of cocoa extract and multivitamins on cancer risk and heart disease. COSMOS focused on older adults, including men ages 60 and older and women ages 65 and older, and had 21,442 participants overall.

For the study, researchers analyzed blood samples from 958 healthy participants to see how a daily multivitamin-multimineral supplement or cocoa extract affected biological aging. The mean chronological age of the participants was 70 years, and most (89.1%) were white. Participants were randomly assigned to take either cocoa extract and a multivitamin, a multivitamin only, cocoa extract only, or placebos.

After a two-year period, researchers used five epigenetic clocks to estimate how much participants had biologically aged. Epigenetic clocks, which are also called biomarkers, can identify small changes in DNA over time.

Overall, the researchers found that participants who took a daily multivitamin aged more slowly on two epigenetic clocks called PCPhenoAge and PCGrimAge, which were developed to estimate mortality risk. The reduction in the yearly rate of increase was roughly 2.6 months for PCPhenoAge and 1.4 months for PCGrimAge.

The multivitamin also had a greater effect on people who had accelerated biological aging on PCGrimAge at baseline, reducing their biological age by 0.236 years compared to 0.013 years for people who had normal or decelerated biological aging. 

Similarly, Danica Chen, a professor of metabolic biology, nutritional sciences, and toxicology at the University of California, Berkeley, said that the biomarkers used in the study are "cutting-edge" but additional research is needed before scientists can use the biomarkers to recommend intervention for aging, such as multivitamins.

"We do not know yet whether [multivitamins] have an effect in improving tissue function or reducing disease risk," Chen said. She added that the field of aging research "is at the stage that we are really just looking for even proof of concept."

Howard Sesso, the associate director of preventive medicine at Brigham and Women's Hospital and Harvard Medical School and the study's senior author, also noted that the findings, while interesting, are still preliminary and the overall effect on biological age was small.

"This doesn't mean that everyone should go out and start taking a multivitamin," Sesso said. "Rather, this is starting to provide the connecting dots."

Although it's still too early to link the study's findings to real-world clinical outcomes, Sesso said they provide a good starting point for future research. "This study opens the door to learning more about accessible, safe interventions that contribute to healthier, higher-quality aging," he said.