Vitamin D

backgroundLimited studies suggest that vitamin D or omega 3 fatty acids (n-3 FAs) supplementation may be beneficial for telomere maintenance, however, evidence from large randomized clinical trial is lacking.

objectiveWe aimed to determine whether vitamin D or n-3 FAs supplementation reduce leukocyte telomere length (LTL) attrition over time by leveraging the VITamin D and OmegA-3 TriaL (VITAL) trial.

methodsVITAL is a large, randomized, double-blind, placebo-controlled tr ial with a 2 x 2 factorial design of vitamin D3 (2,000 IU/day) and marine n-3 FAs (1 g/day) supplements for 5 years among a representative sample of 25,871 US females ≥55 and males ≥50 years of age. The VITAL Telomere study (NCT04386577) included 1054 participants who were evaluated in person at the Harvard Clinical and Translational Science Center. LTL was determined by the Absolute Human Telomere Length Quantification quantitative Polymerase Chain Reaction (PCR) method at baseline, Year 2, and Year 4. The pre-specified primary outcome measures were changes in LTL between baseline, Year 2 and Year 4. Analyses of intervention effect used mixed-effects linear regression models.

resultsLTL was measured in a total of 2,571 samples from the 1031 participants at baseline, year 2, and year 4. Compared to placebo, vitamin D3 supplementation significantly decreased LTL attrition by 0.14 kilo base pairs (kb) (95%CI: 0.007, 0.27) over 4 years (p = 0.039). Overall trend analysis showed that the vitamin D3 supplementation group had LTLs that were about 0.035 kb higher per year of follow-up compared to placebo group (95%CI: 0.002, 0.07, p=0.037). Marine n-3 FAs supplementation had no significant effect on LTL at either year 2 or year 4.

conclusion4-years of supplementation with 2000 IU/day vitamin D