Sunlight exposure and development of rickets in Indian toddlers.
To study the role of sunlight exposure in determining the vitamin D status of underprivileged toddlers. Height and weight were measured, clinical examination was performed, Food Frequency Questionnaire was administered and history of sunlight exposure was obtained in all (61) toddlers attending daytime crèche (Group B). Ionised calcium (iCa), inorganic Phosphorous (iP), alkaline phosphatase activity (ALP), serum parathyroid hormone (PTH) and 25 Hydroxy vitamin D (25OHD) were measured. Data were compared with results of a survey measuring similar parameters in 51 (of 251 eligible) toddlers from the same slum (Group A). 111 children (mean age 2.6 yr (0.7), boys 56) were studied. Prevalence of hypovitaminosis D was 77% in group B toddlers (46 of 60) and 16.4% (10 of 61) had rickets, while none of the group A toddlers had 25OHD levels below 30 nmol/L. Four children (7.8%) from Group A as against 24 (42.9%) from Group B, had sunshine exposure of < 30 minutes per day. Underprivileged toddlers who were deprived of sunlight had a much greater incidence of hypovitaminosis D and frank rickets. The study has important public health implications and underscores the necessity for sunlight exposure in young children.