Vitamin D status in Andhra Pradesh : a population based study

Abstract

Background & objective: Data on the vitamin D status of the population in a tropical country like India have seldom been documented. Vitamin D deficiency is presumed to be rare. We carried out this study to document the dietary habits, serum calcium, 25(OH)vitamin D [25(OH)D], and parathyroid hormone levels of urban and rural population in a State in south India.

Methods: A total of 943 healthy urban and 205 rural adult subjects and 76 urban and 70 rural healthy children were studied for their dietary pattern, serum calcium, phosphorus, alkaline phosphatase, 25(OH)D, and N-tact parathyroid hormone levels (N-tact PTH).

Results: The daily dietary calcium intake of both the urban and rural population was low compared to that of recommended daily/dietary allowances (RDA) issued by Indian Council of Medical Research (ICMR). Dietary calcium and phosphorus were significantly lower(P<0.0001) in both the rural adult and children compared to that of the urban adult and children. The dietary phytate to calcium ratio was significantly (P<0.0001) higher in rural adult and children compared to that of urban adult and children. N-tact PTH levels negatively correlated with 25(OH)D in rural (r=-0.24; P<0.002), in urban adult subjects (r=-0.12; P<0.0001) and in rural and urban children (r=-0.2; P<0.05). The 25(OH)D levels of rural adult subjects were significantly higher (P<0.001) than that of urban adult subjects in both males and female groups. The 25(OH)D levels of both the urban and rural children were low.

Interpretation & conclusion: Low dietary calcium intake and 25(OH)D levels were associated with deleterious effect on bone mineral homeostasis. Prospective longitudinal studies are required to assess the effect on bone mineral density, a surrogate marker for fracture risk and fracture rates.