DISTINCTIVE ASPECTS OF METABOLISM AND NUTRITION IN INFANCY

Objectives: The effects of genes, the stage of development, and the en vironment on various metabolic processes in infancy are described. Som e themes discussed cross these three boundaries. Conclusions: Certain substances not normally regarded as essential may become conditionally essential if their precursors are limited in the diet or, alternative ly, if the processes of conversion are reduced in activity because of abnormal gene function, or developmental immaturity. Diet is a clear e nvironmental influence but, because the nature of the diet is closely related to age, it is a developmental influence as well. Certain nutri ents are followed from the diet, via the gut and intermediary metaboli sm through to individual tissues and the whole body. The relationships of diet, metabolism and brain function have attracted considerable in vestigation in recent years. In the right environment, with the correc t genes, the processes of development will be smooth and without undue metabolic disturbance. Considerable variation can be accommodated wit hin the elasticity of the systems, but some changes may lead to tempor ary, or even permanent, malfunction.