Increased telomerase activity and vitamin D supplementation in overweight African Americans

Objective: We aimed to investigate whether vitamin D supplementation modulates peripheral blood mononuclear cell (PBMC) telomerase activity in overweight African Americans. Design: A double blind, randomized and placebo-controlled clinical trial (NCT01141192) was recently conducted.Subjects And Methods:African-American adults were randomly assigned to either the placebo, or the vitamin D group (60 000 IU per month (equivalent to ∼ 2000 IU per day) oral vitamin D3 supplementation). Fresh PBMCs were collected from 37 subjects (18 in the placebo group and 19 in the vitamin D group), both at baseline and 16 weeks. PBMC telomerase activity was measured by the telomeric repeat amplification protocol. Results: Serum 25 hydroxyvitamin D levels increased from 40.7±15.7 at baseline to 48.1±17.5 nmol l ^-1 at posttest (P<0.004) in the placebo group, and from 35.411.3 at baseline to 103.731.5 nmol l-1 at posttests (P<0.0001) in the vitamin D group. In the vitamin D group, PBMC telomerase activity increased by 19.2% from baseline (1.560.29 absorbance reading unit (AU)) to posttest (1.860.42 AU, P<0.0001). The significance persisted after controlling for age, sex and body mass index (P<0.039). PBMC telomerase activity in the placebo group did not change from baseline (1.430.26 AU) to posttest (1.460.27 AU, P<0.157). Conclusion: Vitamin D supplementation significantly increased PBMC telomerase activity in overweight African Americans. Our data suggest that vitamin D may improve telomere maintenance and prevent cell senescence and counteract obesity-induced acceleration of cellular aging.