Proceedings of the Nutrition Society

Research Article

Session 1: Feeding and infant development Breast-feeding and immune function

Symposium on ‘Nutrition in early life: new horizons in a new century’

on 11 – 13 December 2006, The Winter Meeting of the Nutrition Society,, was held at Churchill College, Cambridge, an international conference to mark the 100th anniversary of the birth of Elsie Widdowson, hosted by MRC Human Nutrition Research Cambridge jointly with the Neonatal Society supported by the Royal Society of Medicine.

Lars Å. Hansona1 c1

a1 Department of Clinical Immunology, Göteborg University, Göteborg, Sweden

Abstract

The newborn receives, via the placenta, maternal IgG antibodies against the microbes present in its surroundings, but such antibodies have a pro-inflammatory action, initiating the complement system and phagocytes. Although the host defence mechanisms of the neonate that involve inflammatory reactivity are somewhat inefficient, this defence system can still have catabolic effects. Breast-feeding compensates for this relative inefficiency of host defence in the neonate by providing considerable amounts of secretory IgA antibodies directed particularly against the microbial flora of the mother and her environment. These antibodies bind the microbes that are appearing on the infant's mucosal membranes, preventing activation of the pro-inflammatory defence. The major milk protein lactoferrin can destroy microbes and reduce inflammatory responses. The non-absorbed milk oligosaccharides block attachment of microbes to the infant's mucosae, preventing infections. The milk may contain anti-secretory factor, which is anti-inflammatory, preventing mastitis in mothers and diarrhoea in infants. Numerous additional factors in the milk are of unknown function, although IL-7 is linked to the larger size of the thymus and the enhanced development of intestinal Tγδ lymphocytes in breast-fed compared with non-breast-fed infants. Several additional components in the milk may help to explain why breast-feeding can reduce infant mortality, protecting against neonatal septicaemia and meningitis. It is therefore important to start breast-feeding immediately. Protection is also apparent against diarrhoea, respiratory infections and otitis media. There may be protection against urinary tract infections and necrotizing enterocolitis, and possibly also against allergy and certain other immunological diseases, and tumours. In conclusion, breast-feeding provides a very broad multifactorial anti-inflammatory defence for the infant.

Correspondence:

c1 Corresponding author: Professor Lars Å. Hanson, fax +46 31 342 46 21, email lars.a.hanson@immuno.gu.se