You Are What You Eat

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Science  10 Dec 2010:
Vol. 330, Issue 6010, pp. 1457
DOI: 10.1126/science.330.6010.1457-c

Oligosaccharides modified by the addition of a sialic acid to lactose are a major component of milk. These sialylated sugars may act to shape the composition of the gut microflora in neonatal mammals, because they can act as a food source for colonizing bacteria. By comparing mice nursed by wild-type mothers to mice nursed by mothers deficient in sialyl(α2,3)lactose, Fuhrer et al. found that the absence of just this one milk sugar reduced the sensitivity of the mice to acute colitis induced several weeks after weaning. Mice fed sialyl(α2,3)lactose-deficient milk had an altered composition of their intestinal microflora as compared to mice fed normal milk, suggesting that differences in bacterial colonization may have shaped the later susceptibility to gut injury. These results suggest that besides providing passive immunity to the newborn, milk components may act to shape gut colonization by commensal microflora and thereby affect subsequent immune responses, for better or for worse.

J. Exp. Med. 10.1084/jem.20101098 (2010).

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