Butterfat feeding in early infancy in african populations: New hypotheses.

The feeding of butterfat and animal milk to infants during their first 6 months has been documented in a number of pastoralist populations in Africa and elsewhere. In the view of the majority of nutrition scientists and physicians, this practice heightens the risk of malnutrition and infection for the infant. Where these nonbreastmilk foods are used to replace breastmilk, this view certainly is justified. In high-risk populations who use foods such as butterfat as complements to unrestricted breastfeeding, however, the relationship between early supplementation and infant growth and morbidity may be complex. Moreover, it may be mediated by the nutritional status of mothers and the nutritional adequacy of their breastmilk. In this work, the ecological context of butterfat feeding in Turkana, Kenya, is examined. It is argued that butterfat promotes positive infant energy balance prior to the critical period of the transition to active immunity, which occurs during the stressful dry season. Breastmilk alone may be inadequate to sustain growth and fat storage of young infants, since the diet and nutritional status of Turkana mothers suggest that fat content of their milk may be at the low end of the human range. In an environment where selection pressure is assumed to be high, a strategy of complementing the fat in human milk with butterfat may prolong positive energy balance of infants and enhance their resistance to infection and their survival during the critical period. Hence, it is an important component of human adaptation in Turkana. Am. J. Hum. Biol. 10:163-178, 1998. © 1998 Wiley-Liss, Inc.