How children’s microbiomes in the West differ from those everywhere else

An unprecedented look at how the gut microbiome of children varies in different parts of the world reveals that babies in the West lack a microbe that is common elsewhere. This could help develop probiotics that are sometimes given to premature babies that are tailored to where the baby lives to maximize the chance that these bacteria will take up residence.

The first 1,000 days of a baby’s life are crucial for establishing their microbiome, which affects everything from their immune function and mental health to their future risk of disease. Our understanding of this has been almost entirely limited to infants in the West, but now the global atlas of children’s microbiomes finally provides the bigger picture.

Yan Shao at the Wellcome Sanger Institute in South Cambridgeshire, Great Britain, and his colleagues sequenced more than 1,900 genomes of the bacterium called Bifidobacteria longumwhich was associated with the development of a stable gut microbiome.

These were taken from stool samples collected in the UK, Sweden, USA and seven countries in South Asia and sub-Saharan Africa: Bangladesh, Pakistan, Kenya, Malawi, Burkina Faso, Uganda and Zimbabwe.

They focused on two subspecies B. longum: B. longum longum and B. longum infantiswhich has been the focus of most previous studies of the infant gut microbiome. By combining their data with genomes sequenced in previous studies, the researchers found that approximately 70 percent of infants from African and South Asian countries had B. longum infantis in the gut at 2 months of age, compared to less than 2 percent of children from the UK, US and Sweden. “Infantis it’s essentially absent in the Western environment,” says Shao.

in contrast B. longum longum settled in the intestines of about a third of infants from these Western countries by 2 months, compared to less than 10 percent of children in African and South Asian countries.

That suggests B. longum longum and B. longum infantis – which help develop the immune system and prevent gut and blood infections — are mostly found in distinct areas, Shao says.

That’s probably because they thrive on different diets, he says. “Bifidobacteria they help digest nutrients from breast milk, and the composition of this varies according to the mother’s diet, so that could be it longum [longum] adapts better to the western diet infantis it benefits diets in other regions,” he says B. longum longum or B. longum infantis probably had other, similar bacteria in their gut microbiome, like Bifidobacterium brevissays Shao.

This study increased the no B. longum about 17 times that of genomes from South Asia that scientists have ever analyzed, and about 11 times that of genomes from Africa. “It’s a huge step forward for underrepresented populations,” he says Lindsay Hall at the University of Birmingham, UK.

Probiotics are generally not recommended for term babies, but they are sometimes given to premature babies. Based on this study, probiotics could be tailored to the region the premature baby comes from, Hall says. For example, B. longum infantis probiotics may benefit people in parts of Africa and Asia, but may not persist as well in the intestines of Western infants. “Only by understanding how bacteria differ in different places can we understand which probiotics will be best for children in specific parts of the world,” he says.

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