Data on the vitamin D status of the populations in a tropical country like India have seldom been documented. Vitamin D deficiency is presumed to be rare. Population studied by the author and others in the country has proved otherwise. Studies were carried out to document the dietary habits, serum calcium, 25-hydroxyvitamin D [25(OH)D], and parathyroid hormone levels of urban and rural population in a state in south India. The daily dietary calcium intake of both the urban and the rural population was low compared to that of recommended daily/dietary allowances (RDA) issued by Indian Council of Medical Research (ICMR). About 85% of the populations have varying degree of vitamin D status – either hypovitaminosis or vitamin D deficiency. The 25(OH)D levels of rural adult subjects were significantly higher (P < 0.001) than that of urban adult subjects in both male and female groups studied. The 25(OH)D levels of both the urban and the rural children were low.
Low dietary calcium intake and 25(OH)D levels are associated with deleterious effects on bone mineral homeostasis. The quality of diets has to be improved with enrichment/supplementation of calcium and vitamin D to suppress secondary hyperparathyroidism-induced bone loss and risk of fractures. Prospective longitudinal studies are required to assess the effect on bone mineral density, a surrogate marker for fracture risk and fracture rates. In the background of low dietary calcium and low vitamin D status an environmental toxin like fluoride has deleterious effects on the bone. The effect of fluoride and its concomitant renal tubular damage affects the bone mineral metabolism in a deleterious way.