Iron nutrition in childhood: the interplay of genes, development and environment.

The state of a child's iron nutrition depends on his genetic endowment, the stage of development he has reached and the environment in which he lives. Genetic disorders lead more commonly to iron overload than to deficiency. Generally interplay between genes and environment is apparently of little importance when considering iron deficiency; are we missing something? The greatest demands for iron are at the time of most rapid growth, i.e. during infancy and puberty, but during early infancy body stores can meet the demand without a need for dietary iron. Oxygen, diet and microbes are the important environmental factors related to iron nutrition. The relationship of oxygen toxicity to iron nutrition in the newborn has received only fleeting study, the availability of iron from many foods is unclear; the clinical significance of iron overload and deficiency in the evolution of an infection is also unclear despite a wealth of in vitro observation. I am not convinced that the bottle fed baby should receive iron in his diet during the first 4-6 months of life. Thereafter, while the concept of universal unselective supplementation causes some uneasiness there are considerable epidemiological arguments for fortification of food with iron.