This study examined the prevalence of vitamin D deficiency in mothers and infants in Tijuana, Mexico and determined the effect of a single oral dose of 50,000 IU vitamin D3 at birth on 25-hydroxyvitamin D (25[OH]D) levels during infancy. Healthy infants were randomized to receive vitamin D3 or placebo at birth. At birth 23% of infants were vitamin D deficient and 77% had vitamin D insufficiency (mean 25[OH]D level 18.9 ng/ml); 10% of mothers were vitamin D deficient and 61% were insufficient. Infants receiving vitamin D3 had higher 25(OH)D levels at two months (N = 29; 33.9 versus 24.2 ng/ml) and six months (N = 21; 36.5 versus 27.4 ng/ml). Exclusively breastfed infants had lower 25(OH)D levels at two months (14.9 versus 33.4 ng/ml). Vitamin D deficiency is common in infants and mothers in Tijuana, Mexico. A single dose of vitamin D3 at birth was safe and significantly increased 25(OH)D levels during infancy.
Keywords: Host genetics; infant nutrition; vitamin D; vitamin D binding protein; vitamin D deficiency; vitamin D receptor.