Daily allowance of Vitamin D for the breastfeeding woman is still an issue and a matter of disagreement among experts. Vitamin D is hardly found in common food and mostly synthesized by skin under sunlight stimulus. Low concentration in breast milk is thought to be due to deficient levels in the serum of mothers. As high as 6.400 IU daily doses of Vitamin D given to the mother have been required to normalize the infant serum content of 25-OH Vitamin D. Moderate exposure of mothers to sunlight, avoiding any burning, is probably the most cost-effective measure to fight Vitamin D deficiency in the infant. 1 mg = 40.000 IU.