Infant Nutrition: Possible Future Developments in Developed Countries

Lactation
The immunophysiology of lactation and breast milk can not be reproduced in an infant formula. The ‘enteromammary axis’ (Figure 1) plays an anti-infective role in the breast-fed baby. Organisms in the mother’s gut initiate an immunological response of lymphocytes and antibodies (sIgA), some of which travel to the breast and then to the baby. While the mother is likely to pass on to her baby the organisms present in her own body through this means, she also passes on the information on how to deal with them. This is in addition to any anti-infective information passed via the placenta as IgG antibodies. Even in developed counties such as Scotland, diarrhoeal episodes are less common in breast-fed babies.

Therefore, methods to support and enhance lactation should be promoted via behavioural changes in mothers and in society generally. In the United Kingdom [1,2], for example, the initial breastfeeding rate (number of babies put to the breast at least once) in 2000 was 69 percent; 42 percent were continuing to breast-feed at 6 weeks, 28 percent at 4 months and 21 percent at 6 months. Two-thirds of mothers were motivated to give at least one feed; why did two-fifths of those give up breastfeeding within six weeks? What role did the health care system, home and work play in this decision? Figures in the Scandinavian countries are much higher. Some suggest the differences between countries are cultural, while others point out that paid maternity leave is much longer in Scandinavia. There is some evidence that mothers have already decided how to feed their baby before they are pregnant: major influences on the decision are their own mothers and their partners. Consequently, the promotional messages must reach women of all ages and men. The antenatal and neonatal  periods are too late to promote breastfeeding. At that point, our appropriate role is to assist a mother in achieving success with her chosen method of feeding her baby.

There is a danger that Ministries of Health promote lactation but pay scant attention to bottle-fed babies. On the other hand, ‘welfare’ or subsidised food schemes may provide benefits to bottle feeding mothers but fewer to those who are breastfeeding. 

The arguments in favor of mothers of small or ill babies providing some breast milk are even stronger and extra persuasion is justified.[3, 4] Nevertheless, many mothers delivering preterm find lactation difficult. Is it possible that, in the future, new pharmacological agents that enhance the neuroendocrine arc of lactation (figure 2) could play a role when consumption of mother’s milk would be lifesaving to infants?

Infant formula 
The 1970’s saw dramatic improvements in infant nutrition in many developed counties of the world. As modern formulas with lower concentrations of protein, phosphorus and electrolytes were introduced, fewer babies had hypocalcaemic convulsions and fewer died from hypernatraemic dehydration. These dramatic events have since been replaced by slow and steady progress, which has resulted in substantial improvements.[5,6] Various themes in this progress have emerged and many stand to be further refined in the future.

An important theme is the appreciation of conditionally essential nutrients. These can be converted in the body from other dietary nutrients and so are not classed as essential. In some conditions, however, such as in the very young or in illness, this conversion is limited so that the nutrient must also be present in the diet to ensure adequate supplies. The dietary supply adds the ‘belt’ to the ‘braces’ of the conversion pathway. Examples of these conditionally essential nutrients are taurine, long chain polyunsaturated fatty acids, and nucleotides, all of which are present in breast milk. Consequently, the composition of breast milk still provides a template for the composition of infant formula and for the effects of the diet on the infant. Many of the references published on this web site refer to these conditionally essential nutrients.

Another biochemical theme is the further reduction of protein in infant formulas to levels near those in breast milk while, at the same time, insuring an adequate supply of all essential and conditionally essential amino acids for building new protein and participating in processes such as neurotransmission and brain function.

One other, rapidly-developing theme is the reproduction of the immunological and microbiological properties of breast milk for which there are three approaches:

1. Modification of protein in a formula to make it less allergenic, for example, by hydrolysis of the cow’s milk protein to constituent peptides and/or amino acids, or use of a non milk protein such as soya.[7] Most paediatricians would reserve these formulas for instances of established allergy or where there is a strong history of atopy in first degree relatives, rather than use them for all bottle-fed babies. 
2. The addition of commensal, ‘friendly’ organisms to a formula (in other words, adding probiotics); or 
3. the inclusion in a formula of various substances, similar to those in breast milk, which encourage the growth of these organisms in the large intestine (in other words, adding prebiotics). Recent contributions to this website have reviewed the possible use of pro- and prebiotics.

Many formulas are now aimed at babies with common symptoms such as regurgitation and digestive upsets. Since these symptoms are usually temporary and of doubtful pathological significance, some paediatricians do not consider these formulas necessary. They suggest that after exclusion of underlying disease, then maternal support and ‘expectant’ management is more appropriate, and say that only when a specific diagnosis has been made should a modified formula be used. However, many paediatricians feel the formulas help mothers and their babies through difficult periods of infancy.

Is it conceivable that, in the future, the modification by molecular genetics of a cow’s lactation system will lead to the production of a bovine, near-copy of human breast milk? Would this development offer any great advantages? Perhaps it would be more effective to promote the choice and practice of human lactation.

Weaning
Until recently, the weaning guideline was that very few babies would need solid foods before the age of 4 months and almost all 6-month-olds would benefit from them. In the UK in 2000, 24 percent of 3-month-olds were receiving sold foods, 85 percent by 4 months and virtually all by 6 months. More recent guidelines from WHO, endorsed by many national authorities, say that exclusive breastfeeding (in other words, no solids) till 6 months of age is preferable. These guidelines offer no guidance on the bottle-fed child. Some consider the guidelines of doubtful scientific merit and, in any case, they are impractical in many developed countries.

Large epidemiological studies will be necessary to resolve this issue. Are there any practical and feasible goals in the meantime? These will vary from country to country. For example, in the UK, would it be possible to move the 24 percent of babies who receive weaning foods before the age of 3 months to 4 months, with a more steady increase after that to reach the new recommendation of ‘virtually all’ at 6 months? There is some evidence to recommend a move in this direction. In the1970’s, a move to 6 weeks later in the average age of weaning was followed by a marked reduction in the presentation of coeliac disease in infancy,[8] and weaning at 3 months or earlier has been associated with more wheezing and more body fat later in childhood. [9] It may be that the vast scientific contribution toward making an infant formula similar in composition and physiological effect to breast milk will be matched by a similar scientific contribution toward the development of weaning and complementary foods.

Primary nutritional disorders
Iron deficiency anaemia and rickets still occur frequently in many countries of the world. These have been described in many articles and references on this website. The methods to prevent them are well known: witholding unmodified cow’s milk before 12 months of age or even later, including meat and fortified, manufactured weaning foods in the weanling’s diet, and supplementing with vitamin D for breast fed infants and for any infant consuming less than 500ml/day of an infant or follow-on formula. Unfortunately, the methods are applied with variable success. [10-12]

The future of the infant
The effects of a nutritional influence will depend on the genes of the individual, the stage of development he has reached, and the environment in which he lives. The Barker hypothesis relates the size of the infant (and placenta) to later disease, in other words, a lower birthweight and lower weight at 1 year are contributory factors to the development of later cardiovascular and related diseases. There is considerable discussion about the details, in particular, whether the rate of weight gain in infancy is a contributory factor, and expert statisticians debate the interpretation of the findings.[13,14] The interplay of genes and nutritional influences as causes of disease are becoming clearer, for examples, vitamin D, calcium and their role in osteoporosis; and sodium and its role in hypertension. A deeper understanding of this interplay may improve the future for individual infants.

Developing countries
This article has been concerned mainly with possible developments in developed countries but many of the points made are applicable world-wide. The other important considerations in developing counties, which are not considered here, are the control of HIV infection in mothers during pregnancy and lactation, the safe use of infant formula if and when its use is necessary and appropriate and it can be afforded without financial stress for other members of the family, and the safe preparation and use of weaning [complementary] foods made in the home, by central government agencies or by the food industry. 

References

1. Wharton BA Nutrition in infancy ISSN number 1350 6854. British Nutrition Foundation, 1999: 1-43.
2. Hamlyn B, Brooker S, Oleinikova K , Wands S. Infant Feeding 2000. ISBN 0113225709. The Stationery Office, 2002: 1-232.
3. Smith MM et al Initiation of breast feeding among mothers of very low birth weight infants   Pediatrics 2003 111:1337-42.
4. Mcguire W, Anthony MV, Donor human milk versus formula for preventing necrotising entercolitis in preterm infants: systematic review Arch Dis Child (Fetal and neonatal edition) 2003: 88:F11-F14.
5. Lonnerdal B, ed Breast milk and breast feeding infants: implications for improving infant formula.  Am J Clin Nutr  2003; 77(suppl)1533-58S.
6. Carver JD Advances in nutritional modifications of infant formula Am J Clin Nutr  2003; 77(suppl)1550S-1554S.
7. Zeiger RS. Food allergen avoidance in the prevention of food allergy in infants and   children. Pediatrics 2003; 111:1662-71.
8. Wharton BA  Patterns of complementary feeding (weaning) in countries of the European Union: topics for research. Pediatrics 2000, 105 Suppl: 1273-4.
9. Wilson AC, Forsyth JS, Green SA, Irvine I, Han C, Howie PW. Relation of infant diet to childhood health: seven year follow up of a cohort of children in the Dundee infant feeding study BMJ 1998; 316: 21-5.
10. Wharton BA. Low plasma vitamin D in Asian toddlers in Britain: if in doubt give vitamins, consider iron too, and remember other vulnerable groups BMJ 1999; 318:2-3.
11. Gartner LM, Greer FR; Section on Breastfeeding and Committee on Nutrition. American Academy of Pediatrics. Prevention of rickets and vitamin D deficiency: new guidelines for vitamin D intake. Pediatrics 2003 ;111:908-10. 
12. Wharton BA Iron deficiency in children: detection and prevention. Brit J    Haematol 1999, 106: 270-80. 
13. Eriksson JG, Forsen T, Tuomilehto J, Osmond C, Barker DJ. Early growth and coronary heart disease in later life: longitudinal study.BMJ. 2001;322:949-53.
14. Cole TJ, Fewtrell M, Lucas A. Early growth and coronary heart disease in later life. Analysis was flawed. BMJ. 2001 Sep 8;323(7312):572-3.

This material has been prepared by B. Wharton on behalf of and reviewed by other members of the IFM's Advisory Committee on Child Health and Nutrition, October 2005.