Breastfeeding may prevent disease by changing gene expression in the gut flora

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Let’s face it: breast milk is pretty amazing. It contains antibodies that help wee ones establish strong immune systems, and some studies suggest the act of breastfeeding even lowers mom’s breast cancer risk. Now researchers at the Universities of Chicago, Maryland, and Illinois have another potential bonus to add to the mix: according to a study they conducted in pigs, breast milk shapes the expression of bacterial genes in the infant gut, potentially boosting antioxidant activity and protecting against at least one rare debilitating disease.

It’s not crazy to think that breastfeeding might affect the gut flora—diet is known to have a big effect on the microbiome. When scientists assessed the gut flora of babies, they found that breastfed tots had different bacteria present in their intestines than formula-fed ones did. But the significance of these findings has been unclear.

The authors of the recent PLoS ONE study dug one step deeper: instead of just looking at the bacteria, they also used RNA-based techniques to identify all the RNA transcripts, or protein precursors, produced by the gut bacteria in four three-week-old baby piglets who had been fed by their mothers their whole lives. They compared this to the bacterial RNA found in four three-week-old baby piglets who had been fed formula since birth.

For one thing, the breastfed pigs had more RNA coding for proteins involved in the regulation of oxidative stress, a finding that gives some credence to the idea that breast milk acts as an antioxidant and might protect against some types of tissue damage. But even more interestingly, the researchers found that the breastfed piglets had more RNA coding for enzymes involved in the metabolism of arginine, an amino acid precursor to nitric oxide, which protects the gastroinestinal tract. Arginine has been linked to a deadly form of intestinal inflammation called neonatal necrotizing enterocolitis (NEC): reports have found abnormally low levels of arginine in babies suffering from NEC, and breastfed infants suffer from the disease less frequently than formula-fed babies do.

Perhaps, as the authors of this study suggest, breastfeeding helps the gut bacteria metabolize arginine in such a way that lowers NEC risk. Granted, the study was conducted in pigs and its findings may not be applicable to humans, and no one yet knows whether these particular enzymes are actually protective against the disease, but it’s an idea that warrants further study. If true, breastfeeding may have more benefits than we realize—and that would be good news not just for breastfeeding moms, but for moms who have to rely on formula, too. Once scientists have teased out all of breast milk’s unique benefits, they may one day be able to devise milk formulas that more closely mimic the real (amazing) deal.

Citations:

De Silva M, Senarath U, Gunatilake M, & Lokuhetty D (2010). Prolonged breastfeeding reduces risk of breast cancer in Sri Lankan women: a case-control study. Cancer epidemiology, 34 (3), 267-73 PMID: 20338838

Poroyko V, White JR, Wang M, Donovan S, Alverdy J, Liu DC, & Morowitz MJ (2010). Gut microbial gene expression in mother-fed and formula-fed piglets. PloS one, 5 (8) PMID: 20805981

Turnbaugh, P., Ridaura, V., Faith, J., Rey, F., Knight, R., & Gordon, J. (2009). The Effect of Diet on the Human Gut Microbiome: A Metagenomic Analysis in Humanized Gnotobiotic Mice Science Translational Medicine, 1 (6), 6-6 DOI: 10.1126/scitranslmed.3000322

Penders, J. (2006). Factors Influencing the Composition of the Intestinal Microbiota in Early Infancy PEDIATRICS, 118 (2), 511-521 DOI: 10.1542/peds.2005-2824

AYCICEK, A., EREL, O., KOCYIGIT, A., SELEK, S., & DEMIRKOL, M. (2006). Breast milk provides better antioxidant power than does formula Nutrition, 22 (6), 616-619 DOI: 10.1016/j.nut.2005.12.011

SHAH, V. (2004). Nitric oxide in gastrointestinal health and disease Gastroenterology, 126 (3), 903-913 DOI: 10.1053/j.gastro.2003.11.046

Shah P, & Shah V (2007). Arginine supplementation for prevention of necrotising enterocolitis in preterm infants. Cochrane database of systematic reviews (Online) (3) PMID: 17636753

LUCAS, A. (1990). Breast milk and neonatal necrotising enterocolitis The Lancet, 336 (8730-8731), 1519-1523 DOI: 10.1016/0140-6736(90)93304-8

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