Novel oligosaccharides in human milk: understanding mechanisms may lead to better prevention of enteric and other infections

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

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 Tgammadelta 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.

The effect of a fructo-oligosaccharide supplemented formula on gut flora of preterm infants

AIM

The intestinal flora of breast-fed infants is generally dominated by bifidobacteria which have beneficial properties. Their presence is due to various components of breast milk, including prebiotic substances. This prospective double-blind study compared the numbers of bifidobacteria in the stool flora of bottle-fed preterm infants randomized to receive for 14 days either a formula with prebiotic fructo-oligosaccharides at a concentration of 0.4 g/dL or the same formula with maltodextrin as a placebo.

METHODS

Within 0-14 days after birth, 56 healthy bottle-fed infants were enrolled to receive either the prebiotic or placebo. Faecal samples were taken at inclusion day and at study day 7. The number of bifidobacteria in the stools, stool characteristics and somatic growth were recorded during the study.

RESULTS

In the group fed fructo-oligosaccharides, both the numbers of bifidobacteria in the stools and the proportion of infants colonized with them were significantly higher as compared to the placebo group (p=0.032 and p=0.030 respectively). There was also a higher number of bacteroids in the fructo-oligosaccharide group as compared to the placebo (p=0.029). At the same time, reduction was noted in the numbers of Escherichia coli and enterococci. (p=0.029, and p=0.025, respectively). Supplementation had also significant influence on stool frequency per day (p=0.0080).

CONCLUSION

An infant formula containing a small quantity of prebiotic oligosaccharides is well accepted and leads to rapid growth of bifidobacteria in the gut of bottle-fed preterm infants while decreasing the numbers of pathogenic microorganisms.

Early consumption of human milk oligosaccharides is inversely related to subsequent risk of respiratory and enteric disease in infants

A pilot study tested the relationship between human milk oligosaccharide consumption, oligosaccharide content of feces, and subsequent disease in breastfed infants. Forty-nine (49) mother-infant pairs provided milk and fecal samples 2 weeks postpartum; infant health was assessed through 2, 6, 12, and 24 weeks. LNF-II (lacto-N-fucopentaose II), a major human milk oligosaccharide, was measured to represent levels of total oligosaccharides consumed in milk and remaining in feces. LNF-II levels in milk at 2 weeks postpartum were associated with fewer infant respiratory problems by 6 weeks (p = 0.010), as were LNF-II levels in infant feces (p = 0.003). LNF-II levels in milk at 2 weeks were also associated with fewer respiratory problems by 12 weeks (p = 0.038), and fewer enteric problems by 6 weeks (p = 0.004) and 12 weeks (p = 0.045). Thus, consumption of human milk oligosaccharides through breastfeeding, represented by LNF-II, was associated with less reported respiratory and gastrointestinal illness in infants.