ABSTRACT Until relative recently, human lactation was the predominant form of infant feeding in traditional areas of the developing world, whilst artificial feeding predominated in western industrialized nations. This situation in rapidly changing, and now an ever increasingly large number of mothers in countries like the United Kingdom are electing to breast-feed. These changes have provided the opportunity for American and European nutritional scientists to take a fresh look at maternal nutritional needs during the reproductive phase, and also to reconsider the nutritional needs of babies to satisfy adequate rates of growth. The results of these investigations in the western world are of direct relevance to nutritional health planing in the lesser developed countries.
There is in creasingly informed speculation that nutritional needs during pregnancy and lactation for dietary energy may not need to rise by anything like the amount originally considered desirable. Furthermore, the energy needs of young babies may also not need to increase so steeply during early infancy.If confirmed, these two sets of hypotheses will mean that health planners will be able to set more practicable dietary targets with respect to these crucially important sectors of the community, targets which should be more easily achieved within the economic constraints of the developing world. The full paper will discuss these new considerations giving particular emphasis to more recent concepts relating to the long term adequacy of exclusive breast feeding, and the introduction of supplementary or complementary feeding.
Introduction
Recommended dietary allowances for energy and for the essential nutrients, together with our standards for healthly growth, are all essentially based on dietary and anthropometric data collected in the industrialized countries of Europe and North America.There has been much adverse comment on this during recent years but it is not my purpose to reiterate these criticism: on the whole I believe that using as guidelines, the physiological and physical characteristics of childern brought up under as ideal circumstances as possible, makes sense and provides developmental targets worth striving for, even if their achievesensible perspective and philosophical about the short-comings we find but it is proper to aim for a worthwhile ideal.
Having made this general statement there are I believe, however, a number of important areas where perhaps a recvaluation may be timely and one of these involves our growth and dietary standards for infancy.
Unit relatively in Europe and North America human lactation was not the predominant form of infant feeding during its first months of life, a fact which contrasted markedly with the more traditional areas of the developing world. This situation is changing rapidly,however, and now an ever increasing number of mothers in countries like the United Kingdom are electing to breast-feed. These changes have forced American and European pediatricians and nutritionists to take a fresh look, not only at growth performance, but also at dietary requirements during this particularly critical phase of life.
We have also had to think again about the spontaneous changed in the mothers own dietary intake during pregnancy and lactation.These studies are particularly important to our understanding of human physiology because unlike in many developing countries food shortage, or food economics, are rarely major limiting factors influencing food intake although I suppose consideration of fashion may still influence some attitudes. Be this as it may, we in the Western world have recently come up with a number of surprising findings which are of importance not only to an understanding of our own health problems but, I firmly believe, to health planning in the developing world as well. Infancy and growth trends in the Western World
Our current growth standards are based of children who were predominantly bottle-fed prior to 1970. Futhermore at this time infant milk formular were quite different from what they are now and, in addition, often incorrectly prepared being made much more concentrated than they should have been. Solids were also introduced at an early age, frequently from 4 weeks and in the great majority from13 weeks. It is perhaps not surprising that investigators at that time found that bottle- fed babies grew more rapidly than breast-fed ones and some so much so that the were frankly obese. Yet these children from the predominant group in our current growth standards.
The situation just deseribed would now appear to be at thing of the past, at least as far as the UK is concerned.Taitz and Lukmanji(1) discussing the current situation have described how bittle-fed babies there has been a swith from inmodified formulae to much modified milks. Whilst rates of growth in breast-fed babies have remained virtually constant over the years those of artificially fed intants have been falling. A contribulary factor to this change, in addition to the use of modified milks, has been the later introduction of solids.
It is perhaps not surprising therefore that anthropometric parameters relating to adiposity, such as skinfold thickness measurements, are those which have shown the greatest change over the past 15 years. Figure 1 shows the Tanner triceps standards (2) derived from data collected between 1966-7 in the UK (3) together with recent cross-sectional data from Australia (4), Germany (5) and the USA (6) and also from our own longitudinal study carried out on intially breastfed Cambridge babies. In the standards 50th centile values between 6 and 10 months are sround 11.5 mm in girla and slightly more in boys. In marked contrast all the newer data cluster in the region of 8-8.5 mm. It would clearly maked difference of one were interpreting data from many developing countries not on the basis of standards such as those of Tanner but as the newly obtained data: the gross lack of subcutaneous fat usually commented upon would not be so starkly apparent.
Limb circumference measurements, understandable popular with many authorities in the developing world with limited facilities, also show similar treads in the western eorld. Figure 2 illustrates the current WHO standard values for mid-upper-arm circumferent by Wolanski (7) together with our values recently recorded in Cambrige. At all times both the boys and girls had considerably lower limb circumferences than the standard; at 12 months for example, the standard value for boys has been assumed in the WHO Manual on the Assessment of Nutritional Status to be 16 cm, whilst our values are nearer 14.5 cm.
Weight difference between breast-fed babies and those fed old fashioned formulae have already been discussed and Figure 3
FIG 1 Triceps skinfold thickness(mean+- SEM) of two of Cambrige breast-fed boys and girls compared to theTAnner Standards, using a logrithmic scale (2) and to mean values from other recently studies of breast-fed plus bottle-fed infants. Symbols indicate country, year of study and referdnce.
FIG 2. Mid-upper-arm circumference(mean +-SEM) of two cohort’s of Cambrige breast-fed boys and girls to the WHO standards complied from data of Wolanki(7).FIG3. Weight growth of boys and girks relative to the NCHS standards (8)shows our weight growth curves growth for predominantly breast-fed babies in the first 6 months of life (8) in comparison with NCHS standards. Figure 4 shows the subsequent weight development of these children and Figure5 the corresponding height growth. Interesting the children initially grew relatively more quickly than the standards. From 4-6 months however the mean growth curve crossed back over the centile lines until the boys who in the first 3 months had been near the 75th centile eaned up, in the second year, around the 25th centile for weight: a similar pattern occurred with height. Similar growth patterns in initially breast-fed babies have been observed by others(9,10).
There is insufficient time to go into detail but our current re-evaluations are revealing that many sets of weight and height data from the developing world appear less extreme when interpreted on the bisis of growth data from European breast-fed rather than from bottle-fed children prior to 1970.