Prevalence of vitamin D deficiency and its predictors in the Portuguese population: a nationwide population-based study.

Vitamin D deficiency/insufficiency [25(OH)D < 20 ng/ml] is highly prevalent in Portugal, affecting > 60% of all Portuguese adults, with strong geographical and seasonal variation. This study highlights the need to critically assess the relevance of vitamin D deficiency as a public health problem and the urgent need for a wide and scientifically robust debate about the most appropriate interventions at the individual and societal levels.