Breastfeeding linked to healthy infant gut

The health of individuals can be influenced by the diversity of microbes colonising the gut, and microbial colonisation can be especially important in regulating both intestinal and immune development in infants. However, little is known about the potential interactions between the host’s health at a molecular level, their gut microbes, and diet.

The human intestine is lined by epithelial cells that process nutrients and provide the first line of defence against food antigens and pathogens. Approximately one-sixth of intestinal epithelial cells are shed every day into feces, providing a non-invasive picture of what is going on inside the gut.

In this study, the authors used transcriptome analysis to compare the intestines of three-month old, exclusively breast-fed or formula-fed infants, and relate this to their gut microbes. Transcriptome analysis looks at the small percentage of the genetic code that is transcribed into RNA molecules and is a measure of what genes are actively making proteins. Concurrently, the microbes (microbiome) were identified by genetic analysis.

The results showed that the breast-fed babies had a wider range of microbes in their gut than the formula-fed infants, but that their immune systems had developed to cope.

Robert Chapkin from the Texas A&M University, who led this multi-centre study, explained: “While we found that the microbiome of breast-fed infants is significantly enriched in genes associated with ‘virulence’, including resistance to antibiotics and toxic compounds, we also found a correlation between bacterial pathogenicity and the expression of host genes associated with immune and defence mechanisms.”

He continued: “Our findings suggest that human milk promotes the beneficial crosstalk between the immune system and microbe population in the gut, and maintains intestinal stability.”

Scott Schwartz, Iddo Friedberg, Ivan V Ivanov, Laurie A Davidson, Jennifer S Goldsby, David B Dahl, Damir Herman, Mei Wang, Sharon M Donovan and Robert Chapkin. A Metagenomic Study of Diet-Dependent Interaction Between Gut Microbiota and Host in Infants Reveals Differences in Immune Response. Genome Biology, (in press/April 2012)