Vitamin D 3 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.
Level 2 - randomized trial
Randomized, double-blind, placebo-controlled trial substudy
PubMed 40409468 · doi:10.1016/j.ajcnut.2025.05.003
What was done
This ancillary study of the randomized, double-blind, placebo-controlled 2x2 factorial VITAL trial evaluated the effects of vitamin D3 (2,000 IU/day) and marine omega-3 fatty acids (1 g/day) over 4 years. The substudy enrolled 1,054 US participants (males ≥50, females ≥55 years). Leukocyte telomere length (LTL) was measured via absolute quantitative PCR at baseline, Year 2, and Year 4 across 2,571 blood samples from 1,031 participants. Changes in LTL were evaluated using mixed-effects linear regression models.
What was found
Compared to placebo, vitamin D3 supplementation significantly attenuated LTL attrition by 0.14 kilobase pairs (kb) (95% CI: 0.007 to 0.27; p = 0.039) over 4 years. In trend analysis, participants receiving vitamin D3 maintained LTLs approximately 0.035 kb higher per year of follow-up compared to placebo (95% CI: 0.002 to 0.07; p = 0.037). Marine omega-3 fatty acid supplementation showed no significant effect on LTL at either Year 2 or Year 4.
Why it matters
This study provides randomized trial evidence that daily vitamin D3 supplementation can modestly reduce leukocyte telomere erosion over 4 years in older adults, while omega-3 supplementation does not appear to affect telomere dynamics.
Limits
The analysis is restricted to an in-person substudy cohort (1,031 participants) of older US adults, which may limit generalizability to younger populations. Leukocyte telomere length is a surrogate biological marker measured in circulating blood cells and may not directly reflect telomere maintenance in other tissues or guarantee changes in clinical aging endpoints.
Cited by
- partial Circulating vitamin D levels between 40 and 60 ng/mL are associated with longer telomeres.