Did you know that when breast milk is tested, 95% has inadequate levels of vitamin D? This should be no surprise as 80-95% of lactating women are vitamin D deficient. Vitamin D deficiency in children can lead to a condition known as rickets where bones develop poorly and in severe cases can lead to cardiac arrest as seen in a recent case in Switzerland.
Source: Chehade et al. Acute Life-Threatening Presentation of Vitamin D Deficiency Rickets. J Clin Endo and Metab. July 27, 2011 Current Issue.