Daily multivitamins may slow biological aging, but experts are cautious

New research suggests that taking a daily multivitamin for two years slows aging among older adults, with greater benefits for those who began the trial with an accelerated biological age. 

The findings did not establish specific benefits for cancer prevention, heart health, or overall mortality. However, they reignite debate on whether supplements or whole foods are better sources of essential nutrients.

Researchers randomized study participants to take either a daily cocoa extract and multivitamin, a daily cocoa extract and placebo, a placebo and multivitamin, or placebos only. They recorded changes in five epigenetic clocks from the beginning of the trial and at the end of the first and second years.

Compared with the placebo-only group, people in the multivitamin group showed slower aging across all five epigenetic clocks, including statistically significant slowing in two clocks predictive of mortality. The cocoa exhibited no effect on epigenetic clocks.

The beneficial changes were equivalent to about four months of lower biological age over two years. Additionally, people who were biologically older than their actual age at the start of the trial benefited the most.

External experts commenting on the paper praise its robust model. Dr. Laura Sinclair, a healthcare lecturer and postdoctoral researcher in the UK, comments: “This study is a large, randomized-controlled, commercially funded trial. The authors have conclusions backed up by their robust data, adjusted for confounders such as age, sex, diet, and lifestyle, and recognized the limitations of their study.”

However, she flags that blood samples only provide an “epigenetic snapshot” of aging. “Other tissues in the body may have different epigenetic ages — for example, your liver may ‘age’ faster than your blood. If we want to really know if supplements can slow biological aging, we need to look at the full picture.”

Experts argue it may be sufficient to consume a balanced diet, instead of relying on multivitamins for essential nutrition.She also does not interpret the findings as a sign to stock up on supplements. “If a person eats a nutritionally balanced diet, then many dietary supplements would probably be superfluous to their individual requirements.”

“However, most adults in the UK are actually not eating a nutritionally balanced diet and so probably would benefit from a multivitamin or a multimineral.”

Differences between years and bodies

How the human body ages on a cellular level, a person’s “biological age,” can differ from their chronological age. Epigenetic clocks estimate biological aging based on small changes in DNA.

These clocks examine specific DNA sites that regulate gene expression (known as DNA methylation) and change naturally as we get older, helping track mortality and the pace of aging.

The study used data from the well-established Cocoa Supplement Multivitamins Outcomes Study (COSMOS). It analyzed DNA methylation data from blood samples of 958 randomly selected healthy participants with an average chronological age of 70.

The results published in Nature Medicine show that two years of supplementation with the multivitamin complex reduced the biological age of treated individuals by 2.7 to 5.1 months compared with the control group. The cocoa extract showed no significant effects across the five epigenetic clocks.

However, external commenter Luigi Fontana, from the University of Sydney, Australia, warns that any positive results could potentially be a statistical fluke. “Several aging markers were analyzed, and the statistical tests were not adjusted for multiple comparisons.”

“When many outcomes are tested simultaneously, it becomes more likely that some apparently ‘positive’ results will appear simply by chance.”

He also highlights that participants in this study were generally healthy older adults rather than people with clear nutritional deficiencies. “If the effect is real, it may simply reflect correction of mild micronutrient insufficiencies in some individuals rather than a fundamental slowing of the biological aging process.”

Future study directions

Further studies are needed to determine how improvements in biological aging may impact clinical health outcomes, suggest the study authors.

The COSMOS team plans to investigate how the effects of a daily multivitamin on biological aging may extend to different outcomes.The COSMOS team plans to investigate how the effects of a daily multivitamin on biological aging may extend to different outcomes they have seen evidence of benefits for, such as improvements in cognition and reductions in cancer and cataracts.

“We plan to do follow-up research to determine if the slowing of biological aging — observed through these five epigenetic clocks and additional or new ones — persists after the trial ends,” says co-author and collaborator Yanbin Dong, M.D., Ph.D., director of the Georgia Prevention Institute, Medical College of Georgia at Augusta University, US.

An external commenter, Pilar Guallar Castillón, who lectures at the Autonomous University of Madrid, Spain, points out that while the multivitamin had a small effect on aging markers, the broader COSMOS trial showed no improvement in overall mortality, heart attacks, or cancer.

“The clinical relevance of these findings is unknown,” she says. “My personal advice is to stop taking multivitamins, whether in pill or gummy form. Eat a healthy, varied diet rich in fruit and vegetables (the main natural source of vitamins and minerals), and do not waste your money on nutritional supplements. There are huge commercial interests in their consumption and a lack of clinical evidence.”

Previous research on the COSMOS trial indicated that cocoa extract supplements may reduce inflammation and prevent age-related chronic diseases. Meanwhile, a daily cocoa extract and multivitamin combination also indicated improved memory and slowed cognitive aging in older adults.