Contribution of Vitamin D Metabolites to Vitamin D Concentrations of Families Residing in Pune City

The objective was to explore the patterns of contribution from vitamin D metabolites (D(2) and D(3)) to total vitamin D concentrations in Indian families. This cross-sectional study was carried out in slum-dwelling families residing in Pune city. Data on demography, socio-economic status, sunlight exposure, anthropometry, and biochemical parameters (serum 25OHD(2), 25OHD(3)) via the liquid chromatography–tandem mass spectrometry method were collected. The results are presented for 437 participants (5 to 80 years). One-third were vitamin-D-deficient. Intake of foods containing vitamin D(2) or D(3) was rarely reported. Irrespective of gender, age, and vitamin D status, the contribution of D(3) to total 25OHD concentrations far exceeded that of D(2) (p < 0.05). The contribution of D(2) ranged from 8% to 33% while that of D(3) to 25OHD concentrations ranged from 67% to 92%. 25OHD(3) is a major contributor to overall vitamin D concentrations, and the contribution of 25OHD(2) was found to be negligible. This implies that sunlight and not diet is currently the major source of vitamin D. Considering that lifestyle and cultural practices may lead to insufficient sunlight exposure for large sections of the society, especially women, dietary contribution to vitamin D concentrations through fortification may play an important role in improving the vitamin D status of Indians.