Vitamin D status: Multifactorial contribution of environment, genes and other factors in healthy Australian adults across a latitude gradient

▸ Ambient ultraviolet radiation six weeks prior to blood sampling best predicted vitamin D status. ▸ Time in the sun predicts serum 25-hydroxyvitamin D concentration in a logarithmic association. ▸ Environmental, phenotypic and genetic factors explained over 50% of the variation in vitamin D. ▸ The most important environmental predictor was ambient ultraviolet radiation. ▸ Gene epistasis in vitamin D pathway genes has a significant influence on vitamin D status.