A new clinical trial suggests vitamin D could play a role in slowing biological aging by protecting telomeres—the DNA caps that naturally shorten as we get older. Telomere shortening is strongly tied to chronic diseases, making this discovery a promising step in healthy aging research.

Researchers analyzed data from the large VITAL trial and found that people who took 2,000 IU of vitamin D daily had significantly less telomere shortening over four years compared to those on a placebo. The effect was equal to slowing cellular aging by nearly three years. Omega-3 supplementation, however, did not show the same benefit.

Experts say the findings highlight vitamin D as a low-cost, widely available option to support healthy aging. While more studies are needed to confirm the long-term benefits, scientists see this as an important step toward simple interventions that may help preserve health and reduce age-related decline.