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Nutritional influences on linear growth: A general review

1. The role of individual nutrient deficiencies in linear growth faltering
2. Dietary quality and linear growth
3. Nutritional explanations of early linear growth faltering
4. The impact of diarrhea, infections and parasites on growth

L.H. Allen

Department of Nutrition, University of California, Davis, CA 95616-8669, USA

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.

This review of nutritional influences on linear growth begins with a discussion of specific nutrient deficiencies that can cause linear growth retardation. The review reveals that there is a great deal of inconsistency in the reported growth-promoting benefits of supplementation with single nutrients. This may in part be explained by the fact that several nutrient deficiencies probably occur simultaneously in growth-stunted children. Our own data from the Nutrition Collaborative Research Support Program (CRSP) and other studies are used to illustrate this point, and to emphasize the importance of considering overall dietary quality as a predictor of linear growth. Another potential explanation is the fact that growth faltering is most rapid during the first year of life, whereas most supplementation studies have been performed on children older than this. The possible nutritional explanations of this very early growth failure are discussed.

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