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Human Milk and Nutrition Battle Long-term Effects of a Dangerous Intestinal Disease in Preterm Infants

    Written by: Marina Wang | Issue # 111 | 2022

    • Previous research has shown that breast milk can help mitigate the deleterious effects of necrotizing enterocolitis (NEC), a life-threatening disease of the gut that can result in the death of intestinal tissue.
    • A long-term prospective study assessed whether factors such as nutritional content (preterm- versus term-infant formula), as well as being fed breast milk affected risk of gut infection and intelligence in a cohort of preterm infants.
    • Human milk was associated with a lowered risk of infection and NEC in infants.
    • Neonatal infection or NEC was associated with subsequent lower IQ at 7 and 30 years.
    • Nutritional content of milk fed to infants also had a positive effect on intelligence, whether the nutrients were provided in human milk, preterm- or term-infant formula.

    Preterm infant birth can be a stressful ordeal for new parents. Tiny babies can suffer from breathing and cardiovascular failure [1] and in some cases, two to three weeks after acute conditions appear to be improving [2]; healthcare professionals must watch for infection and necrotizing enterocolitis (NEC). NEC is a disease in which infection causes the tissue of the intestinal tract to become inflamed and die. Dying tissues are known to release free radicals, and exogenous and endogenous insults, such as ischaemia, inflammation, excitotoxicity, and free-radical insults can damage vulnerable tissues during brain maturation [3]. Previous studies have shown NEC is associated with long-term changes to brain microstructure and a decreased IQ [4]. However, infants fed human milk were six to ten times less likely to develop NEC than those fed cow milk. Still, the roles that nutrition and human milk play in preventing NEC and improving intelligence are unclear.

    In a newly published long-term cohort study, scientists at UCL Great Ormond Street Institute of Child Health in London, England, reported their efforts to tease apart the mechanisms behind how infection, nutrition, human milk, and intelligence are interrelated [5].

    “There’s a lot of talk about how breast milk is better for the child and better for brain development,” says Winok Lapidaire, the lead author of the new paper. “But it’s always difficult to tease out why it’s better and the sort of mechanistic pathways behind that—particularly because you can’t really experiment with nutrition.”

    Preterm infants miss out on the rapid growth over the third trimester, that is made possible by the nutrients they receive in the womb and without needing to expend calories for temperature regulation or gas exchange. As such, after birth they have higher nutritional requirement than infants born full-term. Human milk contains many important factors such as anti-inflammatory agents, growth factors, and immune cells, but over the first few weeks after preterm delivery, protein levels decrease [6]. This was unknown in the 1980s when Lapidaire’s study began, but what makes this study so interesting is that the infants have now been followed for 30 years.

    The study began with 926 preterm infants born in the 1980s across five hospitals in London. Researchers at the time were interested in testing the effects of preterm versus term formulas, so some of the infants were fed the more nutritious preterm formulas, while others were fed term formula. Additionally, some of the infants received banked donor breast milk from the hospital and/or human milk from their mothers. Whether or not the infants developed infections was noted, and the controls were given IQ tests at ages 7, 15, 20, and 30 [5].

    Lapidaire and her colleagues found that a 10 percent increase in milk intake—from either banked or maternal milk—was associated with an 8–12 percent lower chance of developing NEC. Additionally, at ages 7 and 30, subjects who had suffered NEC in infancy had lower Full Scale IQ and Performance IQ scores. Having the less nutritious term formula was associated with increased risk of NEC [5].

    Overall, the researchers found that both human milk and adequate nutrition were important in combatting the maleffects of NEC. Human milk reduced the risk of infection, which subsequently can affect Performance IQ and Full Scale IQ. Nutrient content also had a positive association with higher Verbal IQ scores, regardless of whether the infants were fed human milk [5].

    A long-term randomized control study coming from the same cohort is one of the things that made this study unique, Lapidaire says. “You wouldn’t be able to do this before because there weren’t enough surviving infants,” she explains.

    Lapidaire isn’t certain what particular elements of human milk may reduce the risk of infection and subsequently help with brain development, but there are many components in milk that are anti-inflammatory or immunity-boosting and can stave off infection or brain damage.

    Lapidaire looks forward to potentially following this cohort as they enter their 40s, and notes that MRI scans on subjects’ brains could also add a level of detail to the present study. In addition, she’s interested in looking at other health outcomes such as cardiovascular health.

     

    References

    1. Premature Birth – Symptoms and Causes. Mayo Clinic. [Internet]. Available from: https://www.mayoclinic.org/diseases-conditions/premature-birth/symptoms-causes/syc-20376730.
    2. Necrotizing Enterocolitis (NEC). National Institute of Health. [Internet]. Available from: https://www.nichd.nih.gov/health/topics/nec#:~:text=Necrotizing%20enterocolitis%2C%20or%20NEC%2C%20is,The%20condition%20typically%20affects%20infants.
    3. Volpe JJ. Brain injury in premature infants: a complex amalgam of destructive and developmental disturbances. Lancet Neurol. 2009; 8: 110–124.
    4. Rand KM, Austin NC, Inder TE, Bora S, Woodward LJ. Neonatal infection and later neurodevelopmental risk in the very preterm infant. J. Pediatr. 2015; 170: 97–104.
    5. Lapidaire W, Lucas A, Clayden JD, Clark C, Fewtrell MS. Human milk feeding and cognitive outcome in preterm infants: the role of infection and NEC reduction. Pediatr Res. 2022;91: 1207–1214.
    6. Underwood MA. Human milk for the premature infant. Pediatr Clin North Am. 2013; 60(1): 189-207.