Abstract
INTRODUCTION: An understanding of the influence of family relationship on vitamin D concentrations could be useful in designing community-based strategies to improve vitamin D status. Hence, the aim of this study was to explore if family relationship had an impact on total serum 25-hydroxyvitamin D (25OHD) concentrations of individuals living in Pune, India. METHODS: This cross-sectional study included 104 families. Data collected included anthropometry (height and weight), body composition (bioelectric impedance), sunlight exposure (validated questionnaire), and blood samples for estimation of serum 25OHD(2) and 25OHD(3) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Total serum 25OHD was computed as the sum of the serum 25OHD(2) and 25OHD(3) concentrations. Linear mixed model analysis was employed to assess the impact of family on serum 25OHD(2) and total 25OHD concentrations. The strength of the family-level component was assessed by calculating the intra-family correlation for each model separately for children and adults. RESULTS: More than half (63%) of the participants of the participants (235 adults, 118 children) had poor daily sunlight exposure (< 30 minutes). Around one-third, both adults and children, were found to be vitamin D deficient. Intra-family correlation was found to be higher in children than in adults for serum 25OHD(2) (0.6 vs 0.4) and total serum 25OHD (0.5 vs 0.1) concentrations. CONCLUSIONS: Our findings indicate that the likelihood of having similar vitamin D concentrations is higher among children as compared to adults in a family. This suggests a role played by genetic factors or possibly shared habits among children in a family, thus resulting in stronger correlations. This can facilitate the adoption of early preventive measures for treatment or prevention of vitamin D deficiency, even if one child among siblings is vitamin D insufficient.