Abstracts

Does breastfeeding affect the infant’s immune system responsiveness?

Much information now exists that breastfeeding protects against a whole range of infections and infectious diseases, sepsis, pneumonia, otitis media, urinary tract infection, diarrhoea and necrotizing enterocolitits. However, little is still known about the mechanisms of protection. This paper comments on the differences between bottle fed and breastfed infants in their responsiveness to immune stimulation.

Breastmilk contains a large number of factors which are capable of modulating the infant’s immune system.

• Large amounts of inflammatory and anti-inflammatory cytokines which exert important down-regulating effects on lymphocyte proliferation.
• Similarly prostaglandin E2 produced by breastmilk macrophages exerts these effects
• Colostrum contains a considerable number of macrophages and activated lymphocytes. These are taken up by the infant during the first few days of life.
• Lactoferrin is found in large quantities as well anti-secretory factors which have anti-inflammatory capacity and inhibit fluid and electrolyte secretion from the intestines.
• Large quantities of complex oligosaccharides (which are almost totally missing in cow’s milk) with more than 100 different configurations are present. These are taken up by the breastfed infant, but not available to bottle fed infants. Oligosaccharides may function as bonds for leukocyte adhesion molecules and in turn effect leukocyte integrin activity.
• Epidermal growth actors, which have been postulated to enhance maturation of the gut epithelial barrier, leading to decreased uptake of foreign protein antigens in the breastfed infant and hence to decreased immune stimulation.
• Breastfeeding also effects the microflora of the infant. Bottle fed infants harbour more enterococci, clostridia, Bacteroides, and enterobacteria. Breastfed infants have more staphylococci and a less varied flora. Secretory IgA response to bacterium in the gut prevents colonization of the intestinal tract. This may be the reason for the strong protection against sepsis afforded by breastfeeding.
• Differences in gut flora and their impact on the immune responsiveness between bottle-fed and breastfed infants continue even after complementary feeding commences.

Effect of long-chain polyunsaturated fatty acids in infant formula on problem solving at 10 months of age.

Research funded by Milupa compares the effects of adding long chain polyunsaturated fatty acids to the formulas of term infants. Cognitive behaviour was tested at 10 months by a three-step solution to uncovering and retrieving a hidden toy. (See comment below.)

Comment: Long-chain polyunsaturated fatty acids in infant formula and breastfeeding

P. Willats and colleagues interpret their data as suggesting that ‘term infants may benefit from long-chain polyunsaturated fatty acids (LCPUFA) supplementation and that the effects persist beyond the period of supplementation.’ They might also have argued that term infants would benefit from receiving breastmilk, which is naturally high in LCPUFA, and that the benefits would be expected to persist beyond the period of breastfeeding. Other researchers have found long-term advantages in intellectual and retinocortical development for infants fed breastmilk, and have associated these with breastmilk LCPUFA.

Breastfeeding is the standard against which artificial feeding should be measured. It is therefore surprising that Willats and colleagues included no reference group of breastfed infants in their study.

It may be relevant that the study was supported by Milupa Ltd, UK, a firm with an interest in marketing its LCPUFA-supplemented products but not in the promotion of breastfeeding. Research design and interpretation need to be rigorously protected from the subtle pressures of commercial sponsorship.”