Certain bacteria in a mother’s microbiome are linked to lower risk of food allergies for her child Tetra Images, LLC / Alamy

The presence of certain bacteria in a mother’s gut is linked to a decreased risk of their baby developing food allergies in the first year of life.

Prevotella copri is a bacterium that ferments fibre from our diet into fatty acids, and it has been linked to reduced allergic reactions in the offspring of mice with a high-fibre diet. Peter Vuillermin at Deakin University in Australia and his colleagues examined whether this association was also found in humans, in whom the fatty acids are thought to help regulate inflammation.

The team analysed data from a study of Australian mothers and infants collected between 2010 and 2013. Faecal samples were gathered from women when they were 36 weeks pregnant, and from infants one, six and 12 months after birth.


DNA from faecal samples of 58 infants with a diagnosed food allergy were compared with those of 236 infants without allergies.

The team found that around 20 per cent of babies without any allergies had P. copri in their faecal samples, compared with 8 per cent of those with allergies to egg, peanut and cow’s milk, among others.

Read more: Food allergies may be on the rise because babies start solids too late

The presence and abundance of P. copri in the mother’s stool was also associated with a decreased risk of allergy. In fact, only one mother with an infant who had allergies had more than 0.03 per cent of the bacterium detected in her stool sample.

Analysis showed that when a woman had twice as much P. copri as another – as indicated by the expression of a specific P. copri gene in their stool – it was associated with an 8 per cent decrease in the risk of food allergy in her child.

P. copri might also be able to protect against non-food allergies such as hay fever, says Vuillermin, especially because childhood food allergies can make subsequent allergies more likely.

He adds that large households were a strong forecaster of P. copri being present in the mother’s microbiome, probably because there are more people to share microbiota with, which boosts microbiome diversity.

P. copri is less prevalent in Western countries due to a range of factors, including generally smaller households and greater use of antibiotics, which the bacterium is sensitive to, says Vuillermin.

Journal reference: Nature Communications, DOI: 10.1038/s41467-020-14552-1

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