The national health program for vitamin D supplementation in a developing country.

Background: Previous studies have reported a high frequency of vitamin D deficiency (VDD) among different age groups in Iran.

Aims: In this study, the current coverage, status of vitamin D supplement taking, and program efficacy have been evaluated by the Office of Nutrition Department Society in Iran since 2014.

Methods: This study was conducted in collaboration with the International UNESCO center for Health-Related Basic Sciences and Human Nutrition and the Office of Nutrition Department Society.