23/08/2025
New trial shows vitamin D supplements *literally slow* telomere shortening — delaying aging for years.
A major clinical trial has revealed that vitamin D supplementation may slow the biological aging process by preserving telomeres—the protective DNA caps at the ends of chromosomes that naturally shorten with age.
Researchers from Mass General Brigham and the Medical College of Georgia conducted a sub-study within the VITAL trial, involving over 1,000 adults tracked for four years. Participants who took 2,000 IU of vitamin D3 daily showed significantly less telomere shortening compared to those on a placebo—effectively slowing aging by nearly three years at the cellular level.
Telomeres play a crucial role in preventing chromosome damage and are linked to age-related diseases such as cancer and autoimmune conditions. This is the first large, long-term randomized trial to show vitamin D’s protective effects on telomeres, building on earlier findings from the VITAL study that linked vitamin D to reduced inflammation and chronic disease risk. While omega-3 supplementation showed no effect, the vitamin D results suggest a simple, widely available intervention may help slow key mechanisms of aging—though researchers caution that more studies are needed to confirm long-term benefits.
Source: Haidong Zhu et al. 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. The American Journal of Clinical Nutrition, 2025.
