Vitamin D Supplementation and Sunlight Exposure on Serum Vitamin D Concentrations in 2 Parallel, Double-Blind, Randomized, Placebo-Controlled Trials.

Moderate supplementation of 15 ug/d cholecalciferol, in accordance with current recommendations, supports an adequate vitamin D status in adult women, irrespective of latitude, and might concomitantly prevent an increase in parathyroid hormone. The Interaction Between Vitamin D Supplementation and Sunlight Exposure in Women Living in Opposite Latitudes (D-SOL) study was registered at clinicaltrials.gov as NCT03318029.