This summary has not been mean to be a final drfintive statement: on the contrary the purpose is to emphasize we do not know
FIG 4. Body weight (mean +- SEM) of two cohorts of Cambrige breast-fed boys and girks for the first two years of life in relation to the NCH standards.
FIG 5. Length (mean+-SEM) of two cohorts of Cambrige breast-fed boys and girls for the first two years of life in relation to the NCHS standsrds.
FIG 6. Total energy intake/kg body weight in exclusively brast-fed infants compared to WHO/ FAO 1973 estimated requirements.
All there is to be known about infant dietary requirements and ideal hrowth rates. In the meantime it is perhaps not unreasonable to postulate tgat existing targest might be unrealistic and even physiologically undesirable if one believes that breast-feeding provides, for the healthy mother and child, the best start in life. We have to be certain, h0wever and I recommend much more objective reasearch in this area.
The mother
I have also been asked by the organizers to say a few words about the materal component of the mother-child diad and I must be even more brief than I have been for the child. Once again, however, my overall message is that we cannot afford to be complacent about our current state of knowledge and that we may have to contemplate a quite major revision of our ideas.
When healthy, wealthy women did not in general breast-feed for any appreciable period of time it was unde standable that scientists recommending dietary allowances for lactation should need to compute these on an incremental basis, essentially by adding to the customary energy and nutrient intake of the non-lactaing mothers the nutrotional cost of the milk secreted each day. A similar apporach was used during pregnancy in which the calculated increment covered the cost of producing the baby, the increased subcutaneous fat stores. In both phase of the reproductive cycle it was assumed that nothing happened either to the activity patterns of the mother or to her intrinsic metabolism. That the latter was unaffected would have been surprising cinsidering the profound shifts in individual hormanal activity and more importantly the balance between the different hormones during pregnancy and lactction.
Nutritional needs during pregnancy abd lactation are other important areas for study because it is quite obvious that women are not voluntarily following the dietary pattern which, on theoretical groups, nutritional scientists think they should. For example the energy cost of pregnancy is usually assumed to be in the order of 80,000 kcal and to cover this we customarily advise an extra 350 kcal/d energy intake during the second and third trimesters. In practice neither women in the developing world nor in the industrialized countries are anywhere near approaching this level. Likewise to lactate for 6 months involves the secretion of around 136,000 kcal : even if all the fat laid down in pregnancy is used to augment this maternal energy loss, the mother still gas to find 100,000kcal which conventionally we assume comes from the consumption of an extra 5-600 kcal/d. Once again in practice an increment of such a magnitude is rarely observed. The enigma is particularly marked in the developing for periods of up to two years on incredibly low food intakes.