The authors present a case of severe megaloblastic anemia and neurologic damage due to vitamin B12 deficiency in a 6-month-old infant. The cause of the vitamin deficiency was a maternal dietary deficiency because of a strict vegetarian diet and prolonged breast-feeding. The importance of early recognition of significant maternal vitamin B12 deficiency during pregnancy and lactation in vegetarians is emphasized so that appropriate supplementation can be given and irreversible neurologic damage in the infant prevented.
