ABSTRACT
Objective: To evaluate the seasonal change in serum 25-hydroxyvitamin D (25-OHD) level inhealthy infants and to relate it to common childhood morbidities. Methods: 72 healthybreastfed infants residing in Delhi were enrolled at the end of summer and followed till the endof winter [mean (SD) duration 200 (10) d]. Serum 25-OHD was estimated at baseline andfollow-up. Infants were monitored for common childhood diseases. Results: Mean (SD)serum 25-OHD level was lower at the end of winter (20.7 (8.02) ng/mL) than summer (22.9(8.70) ng/mL) [mean difference (95% CI) –2.14 ng/mL (–3.36, –1.06), P<0.001). Theseasonal distribution of children according to vitamin D status in summer and winter -Deficient(15.3%, 12.5%), Insufficient (19.4%, 30.6%) and Sufficient(65.3%, 56.9%),respectively was comparable P=0.17). The morbidity profile remained unaffected by changein vitamin D status from summer to winter. Conclusions: Seasonal changes in vitamin Dlevels do not have significant clinical effect or effect on overall vitamin D status in apparentlyhealthy infants from North India. This may have implications for results of population surveysfor vitamin D status, irrespective of the season when they are conducted.