- A Harvard study found that vitamin D supplements may help slow biological aging by protecting telomeres, the protective caps on DNA.
Over four years, participants who took vitamin D lost fewer DNA base pairs than those on a placebo—equating to nearly three years of aging delay.
Omega-3 supplements showed no effect on telomere length in the study’s findings.
You probably know vitamin D as your go-to for bone health and sunshine. But recent results from a clinical trial called VITAL (VITamin D and OmegA‑3 TriaL) suggest it might do more — specifically, slow down a key sign of aging.
Scientists followed a group of older adults for several years and watched how taking vitamin D affected telomeres — the tiny protective caps on your DNA.
The headline? Vitamin D could help keep those caps healthier, for longer.
“VITAL is the first large-scale and long-term randomized trial to show that vitamin D supplements protect telomeres and preserve telomere length,” co-author JoAnn Manson, said in a news release.
“This is of particular interest because VITAL has also shown benefits of vitamin D in reducing inflammation and lowering risks of selected chronic diseases of aging, such as advanced cancer and autoimmune disease.
The study
The VITAL trial is a randomized, double-blind, placebo-controlled experiment involving older adults – men aged 50+ and women 55+, all in the U.S.
Participants took either 2,000 IU of vitamin D₃, 1 gram of omega‑3 fatty acids, both, or a placebo every day for five years. Out of the total 25,000+, a subset of 1,054 people agreed to have their white blood-cell telomeres checked at the start, after two years, and again after four years.
The results
Here’s a look at some of the primary outcomes from the trial:
Vitamin D matters: People taking 2,000 IU/day lost 140 fewer DNA base pairs from their telomeres over four years—that’s roughly a three-year biological “age credit.”
Omega‑3? Not here: The fish‑oil supplement didn’t make a dent in telomere length.
Big deal, but not done deal: The researchers from Harvard-affiliated hospitals call this “promising,” but they stress that more studies are needed before vitamin D is used as an anti-aging prescription.
The takeaway
Vitamin D at this dose seems to offer a modest but measurable boost in protecting our cellular “clocks”—at least for white blood cells.
It's not a fountain of youth—but it does add a key piece to our understanding of healthy aging.
“Our findings suggest that targeted vitamin D supplementation may be a promising strategy to counter a biological aging process, although further research is warranted,” Haidong Zhu, first author of the report said in the news release.