A study published in the journal of the American Gastroenterological Association (April) has found a causal link between caesarean section birth, low intestinal microbiota and peanut allergy in infants. Researchers of the University of Alberta’s Faculty of Medicine & Dentistry analysed the gut bacteria of 1,422 infants of three-four months age and again when they were one year old. They identified four trajectories for bacterial development, including one in which infants had persistently low levels of bacteroides, critical for immune system development. This profile was most common in infants born by caesarean section.

The infants were also given skin prick tests at one and three years of age to assess their reaction to a variety of allergens, including egg, milk and peanut. Infants with low bacteroides levels exhibited a threefold increase in their risk of developing peanut sensitivity by age three with the risk eight times higher for babies born to mothers of Asian descent. “It’s important to know what predicts or increases risk of food sensitivities because they identify which infants will go on to develop asthma and other types of allergies,” says Anita Kozyrskyj, pediatrics professor at Alberta University.

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