factors causing discrepancies in the results of vitamin d assessment in community studies: proper judgement, proper act a note for the policymakers

Vitamin d was identified over one hundred years ago, yet vitamin d deficiency (vdd) is still the most prevalent nutritional problem all around the world. the national food and nutrition surveillance together with other reports have documented alarming rates of vdd and its possible adverse consequences in both children and adults in iran. however, the prevalence rates of vdd reported by various research groups show a wide range. in this short review, we discuss some of the main causes of these discrepancies and propose some strategies to minimize them. finally, some key recommendations for future studies and combating vdd are presented for policymakers.highlights:vitamin d deficiency (vdd) is a global health problem and iran is no exception. nevertheless, the prevalence rates of vdd reported by various research groups show a wide range.to have a better picture of vitamin d status in the community, standardization of definitions of vitamin d status and laboratory methods is necessary.one approach to minimize inter-method variations of 25(oh)d assay is harmonization.using any method to assay circulating 25(oh)d, vdd prevalence rate of 50 percent and above is undoubtedly a major health problem and necessitates prompt intervention.vitamin d fortification of flour is an effective strategy to improve vitamin d status of the community but must be examined in a pilot study.