Vitamin D May Help Slow Down Aging: Study Finds

The research team examined data from the long-running VITAL study, a randomized clinical trial involving more than 1,000 participants—women aged 55 and older and men aged 50 and above. Participants were randomly assigned to take either vitamin D3 (2,000 IU/day), omega-3 fatty acids (1 g/day), or a placebo over a span of up to four years. This telomere-focused sub-study specifically aimed to observe whether these supplements could influence the rate of telomere shortening.

The results were promising: individuals who took vitamin D experienced significantly less telomere shortening than those given a placebo. In fact, vitamin D supplementation appeared to slow cellular aging by nearly three years’ worth of telomere decline. Interestingly, omega-3 supplements did not show a similar effect in preserving telomere length.

“VITAL is the first large-scale and long-term randomized trial to show that vitamin D supplements protect telomeres and preserve telomere length,” said co-author JoAnn Manson, principal investigator of VITAL. “This is of particular interest because VITAL had also shown benefits of vitamin D in reducing inflammation and lowering risks of selected chronic diseases of aging.”

Reference: https://news.harvard.edu/gazette/story/2025/05/vitamin-d-supplements-may-slow-biological-aging/