|Activity, Energy Expenditure and Energy Requirements of Infants and Children (International Dietary Energy Consultative Group - IDECG, 1989, 412 pages)|
|The desirable upper limits of energy intake in childhood: Short- and long-term consequences|
Frequently, it is assumed that the breast-fed child provides the basis for specifying the normal needs for children in any society. Thus, the intakes of a breast-fed child are often considered the ideal. The fallacy of this approach is readily understood, however, if it is recognized that the purpose of deriving requirement figures is to specify the amount of food that a bottle-fed child can be expected to consume. Nobody knows how much the normal breast-fed child consumes and there is little concern provided the child is satisfied and grows 'appropriately'. The problem is how to specify the needs of artificially-fed babies. If they do consume more than the breast-fed, then we cannot use the breast-fed as the basis for standards, particularly if it is accepted that there might be metabolic differences in the handling of nutrients in the bottle-fed and breast-fed child. We then have to ask ourselves: what is the optimal intake of the bottle-fed child?
Recent evidence suggests that breast-fed children grow more slowly (i.e., 'less-well') than bottle-fed children from birth to one year of age. The slower rate of growth may not be an intrinsic feature of breast-feeding since classical data show breast-fed children in Europe or Africa growing faster than the NCHS standards. Even if growth is slower on breast feeding, it is often assumed that this slower growth must be satisfactory because, from a teleological point of view, evolutionary pressures will have led to the most appropriate pattern of breast-milk composition and infant response. This view is again unsound because the survival pressures are applied to both mother and child, and the child's ideal needs could be sacrificed in favour of reducing the drain on the mother. Furthermore, we need to ask whether slower or faster infantile growth rates are best for longevity and prolonged good health beyond the reproductive age where evolutionary pressures are not likely to exert much effect.
In the final section of this paper it is argued that evidence suggests that rapid infantile growth is advantageous on a long-term basis, thus casting doubt on the wisdom of automatically accepting the slower growth rates of the breast-fed child as optimal.
These arguments are the basis for the present proposal that we approach the definition of upper desirable intakes by first defining the optimal growth rates of infancy and then working back to see what intakes are required with modern milk formulae to allow babies to grow at this newly-defined rate under the particular climatic and cultural conditions being considered. First, we should address the question of the long-term impact of early growth rates on adult adiposity.