Gut bacterium linked to decreased food allergy risk

Bacteria found in the digestive tract of pregnant women may have an effect in reducing the risk of food allergy development in their infants, according to a recent report.

The study, published in Nature Communications by Australian researchers, reveals that Prevotella copri—a microbe found in the gut of people in most hunter-gatherer cultures—may be protective against food allergies during gestation.¹

Researchers used data from more than 1000 mothers and babies between 2010 and 2013, taking fecal samples from women at 36 weeks pregnant, and from their infants after they were born. Samples were taken from babies at 1, 6, and 12-months of age. DNA analysis performed on the samples revealed that women who carried the bacteria had babies who were significantly less likely to develop food allergies.

The research team found that the P copri bacteria may help prevent food allergy development by crossing the placenta and stimulating the developing baby’s immune system.

Lead author Peter J. Vuillermin, MBBS, BMedSci FRAC, PhD, a pediatrician and associate professor at Deakin University in Melbourne, Australia, says the study findings could possibly be used to help develop a supplement for pregnant women that may prevent food allergy development in their offspring.

“Maternal carriage of the bacterium P copri during pregnancy is strongly associated with protection against allergic disease in the offspring,” Vuillermin says. “Prevotella carriage is virtually ubiquitous in pre-industrial, traditional communities and has become increasingly uncommon in Westernized environments.”

One of the reasons some cultures may lack this bacterium is difference in fiber sources. Vuillermin says diets in plant-derived fiber are thought to promote P copri, but this was not demonstrated in the current study.

“The big factors we identified were that P. copri was less common in smaller households and when women had been recently treated with antibiotics,” he says.

According to the report, the larger household size was first linked to food allergy prevalence more than 30 years ago. In the decades since, the “hygiene hypothesis” that guided initial theories developed into a deeper understanding of how lower microbial exposure in early years is a risk factor for allergy development, and that changes in the human microbiome may be to blame.

“It has been proposed that losses of specific bacterial species from out ancestral microbiota may be relevant to the increase in immune-related diseases, and that depletion in the compositional and functional diversity of the gut microbiome during pregnancy plays an important role in stimulating fetal immune development,” the report states.

Skin prick tests were used to evaluate allergies in infants compared with the DNA analysis from fecal samples. The research team found that 7%—18 out of 254—of the infants developed food allergies. In contrast, about 10% of Australians develop food allergies­—one of the highest rates in the world.

More research is needed to determine any potential adverse effects of the bacteria, such as possible colitis and insulin resistance in animal models. However, Vuillermin says the goal is to develop a novel probiotic that creates the same effect as P copri. Additional studies are already being planned.

Reference

1. Vuillermin P, O’Hely M, Collier F, et al. Maternal carriage of Prevotella during pregnancy associates with protection against food allergy in the offspring. Nat Commun. 2020:11(1). doi:10.1038/s41467-020-14552-1