ABSTRACT
Serum levels of 25-hydroxy-vitamin D [25-OHD], calcium [Ca], phosphorus [P] and albumin were measured cross-sectionally in 3 seasons in infants aged 6 - 22 months: 37 infants were studied in late summer [July and August], 36 infants were studied in early winter [November and December] and 57 infants were studied in spring [March and April] in a village nearby Cairo. All infants came from low socioeconomic background. The aim of this work is to study the relative influence of sunlight exposure, dietary intake and age on serum levels of 25-OHD, calcium and phosphorus serum levels. 25- OHD mean levels showed significant difference between the 3 seasons being highest in summer [31.7 +/- 20 ng/ml] vs. 18.1 +/- 14 ng/ml and 14.8 +/- 9 ng/ml in winter and spring, respectively. Serum calcium did not show significant difference, while serum phosphorus was highest in spring and serum albumin was highest in summer. None of the nutritional elements intake correlated with serum 25-OHD Ca, P or albumin. Age positively correlated with 25-OHD serum levels, but not Ca, P and albumin. Infants above one-year old showed 25-OHD mean level significantly higher than in infants under one year of age