Breast milk may not be enough

A new study finds a high incidence of vitamin D deficiency in breast-fed babies, mostly during winter. Such a deficiency limits the body’s use of calcium, which is essential for healthy bones and teeth.

As part of a trial of iron supplementation, Ekhard E. Ziegler of the University of Iowa in Iowa City and his colleagues regularly took blood samples over 2 years from 84 newborns who were initially breastfed exclusively.