Abstract

A 7-month-old male presented with lethargy and failure to thrive. The child was exclusively breast-fed from birth by a mother who was a strict vegetarian. Laboratory data revealed macrocytic anemia and methylmalonic acid in the urine, consistent with vitamin B 12 deficient anemia. The patient responded well to supplementation with B 12 alone and was developmentally normal by 11 months of age. This study emphasizes the need for assuring maternal dietary adequacy during pregnancy and after birth.