A large clinical trial suggests vitamin D may slow biological aging by preserving telomeres.
Findings from the VITAL randomized controlled trial show that vitamin D supplementation can help preserve telomeres, the protective caps at the ends of chromosomes. These structures naturally shorten with age, a process linked to the onset of many health conditions.
The study, published in The American Journal of Clinical Nutrition, draws on data from a VITAL sub-study led jointly by researchers at Mass General Brigham and the Medical College of Georgia. The results highlight vitamin D’s potential to slow one of the biological mechanisms associated with aging.
“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, MD, principal investigator of VITAL and chief of the Division of Preventive Medicine at Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system. “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, such as advanced cancer and autoimmune disease.”
What Are Telomeres?
Telomeres consist of repeating DNA sequences (base pairs) that serve as buffers, preventing chromosome ends from deteriorating or attaching to other chromosomes. Over time, telomeres naturally shorten, and this process has been strongly tied to a greater likelihood of developing age-related illnesses.
A few short-term, small-scale studies have suggested that vitamin D or omega 3 fatty acid supplementation may help support telomeres, but results have been inconsistent. VITAL is a randomized, double-blind, placebo-controlled trial of vitamin D3 (2,000 IU/day) and omega-3 fatty acid (1 g/day) supplementation that tracked U.S. females aged 55 years and older and males aged 50 years and older for five years. The VITAL Telomere sub-study included 1,054 of these participants, whose telomere length in white blood cells was assessed at baseline and at Year 2 and Year 4.
Compared with taking a placebo, taking vitamin D3 supplements significantly reduced telomere shortening over four years, preventing the equivalent of nearly three years of aging compared with placebo. Omega-3 fatty acid supplementation had no significant effect on telomere length throughout follow-up.
“Our findings suggest that targeted vitamin D supplementation may be a promising strategy to counter a biological aging process, although further research is warranted,” said Haidong Zhu, PhD, first author of the report and a molecular geneticist at the Medical College of Georgia, Augusta University.
Reference: “Vitamin D3 and marine ω-3 fatty acids supplementation and leukocyte telomere length: 4-year findings from the VITamin D and OmegA-3 TriaL (VITAL) randomized controlled trial” by Haidong Zhu, JoAnn E Manson, Nancy R Cook, Bayu B Bekele, Li Chen, Kevin J Kane, Ying Huang, Wenjun Li, William Christen, I-Min Lee and Yanbin Dong, 21 May 2025, The American Journal of Clinical Nutrition.
DOI: 10.1016/j.ajcnut.2025.05.003
This work was supported by the National Heart, Lung and Blood Institute (R01 HL131674-01). The parent VITAL trial is supported by R01 AT011729.
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