A Pilot Study to Examine the Effects of Vitamin D Supplementation on Mitochondrial Bioenergetics in Older Adults

This pilot study is a 4-month open label trial in 15 older (65-89 yrs) men and women with initial 25(OH)D concentrations of 12-\<18 ng/mL to explore the effect of increasing 25(OH)D concentrations to ≥30 ng/mL through vitamin D3 supplementation on changes in mitochondrial bioenergetics. We will assess the bioenergetic profile of blood cells isolated mitochondria, and muscle fibers as well as the expression of mitochondrial proteins and regulators of mitochondria biogenesis before and after supplementation. All participants will be given vitamin D3 (4,000 IU/d) for 4 months.