Nutritional influences on linear growth: a general review.

The first section of this paper reviews what is known about the roles of specific nutrients in the general linear growth faltering that occurs in developing countries. Those reviewed are energy, protein, zinc, iron, copper, iodine and vitamin A. For none of these nutrients was there clear, consistent evidence that supplementation with the nutrient benefited linear growth. Rather, interventions with each specific nutrient had a positive effect on length gain in some studies, while in others these affected only weight gain or had no effect. Reasons for these conflicting results are suggested, including the strong probability that growth is limited by multiple, simultaneous deficiencies in many populations. This point is illustrated with data from the Nutrition Collaborative Research Support Program (CRSP) and other reports. Most interventions with single nutrients have been tested on children older than the age when linear growth faltering is most rapid, that is, within a few months of birth. Possible reasons why growth stunting begins so early in life are presented, but these are mostly hypothetical because of the paucity of information on this topic.