Determinants of vitamin D status in Caucasian adults: influence of sun exposure, dietary intake, sociodemographic, lifestyle, anthropometric, and genetic factors.

Very few studies have investigated the determinants of serum vitamin D levels using a set of variables that include simultaneously sun exposure, phototype, dietary intake, sociodemographics, anthropometric, lifestyle data, and genetic polymorphisms. Our objective was to investigate the associations between all these parameters and vitamin D status in a large sample of French adults. This cross-sectional survey was based on 1,828 middle-aged Caucasian adults from the SU.VI.MAX (SUpplementation en VItamines et Mineraux AntioXydants) study. Plasma 25-hydroxyvitamin D (25OHD) concentration was lower among women ( P P =0.04), obese/underweight ( P P P P P P =0.0001). Mutant GC rs4588 and rs7041 single nucleotide polymorphisms were associated with lower and higher 25OHD concentrations, respectively ( P P =0.7). This study provides an overall picture of determinants of vitamin D status. Several modifiable factors were identified, such as daily-life moderate sun exposure, physical activity, and normal-weight maintenance, which should be targeted by public health policies in order to improve vitamin D status in the general population, while avoiding active/intensive sun exposure, in line with recommendations for skin cancer prevention.