Trial shows protection against telomere shortening, which heightens disease risk

Results from a randomized controlled trial reveal that vitamin D supplementation helps maintain telomeres, protective caps at the ends of chromosomes that shorten during aging and are linked to the development of certain diseases.

The new report, published in The American Journal of Clinical Nutrition, is based on data from the VITAL (VITamin D and OmegA-3 TriaL) sub-study co-led by researchers at Harvard-affiliated Mass General Brigham and the Medical College of Georgia. The findings support a promising role for vitamin D in slowing a pathway of biological 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, the principal investigator of VITAL and chief of the Division of Preventive Medicine at Harvard-affiliated Brigham and Women’s Hospital and the Michael and Lee Bell Professor of Women’s Health at Harvard Medical School.

“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,” said Manson.

What Are Telomeres?

Telomeres are made of repeating sequences of DNA, or base pairs, that prevent chromosome ends from degrading or fusing with other chromosomes. Telomere shortening is a natural part of aging and is associated with an increased risk of various age-related diseases.

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. women aged 55 years and older and men aged 50 years and older for five years.

The VITAL Telomere sub-study included 1,054 participants whose telomere length in white blood cells was assessed at baseline and again at Year 2 and Year 4.

Key Findings

  • Vitamin D3 supplementation significantly reduced telomere shortening over four years.
  • The effect was equivalent to preventing nearly three years of biological aging.
  • Omega-3 fatty acid supplementation showed no significant effect on telomere length.

“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, first author of the report and a molecular geneticist at the Medical College of Georgia, Augusta University.

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