Babies born by C-section to mothers of Asian descent are eight times more likely to develop peanut allergy by age three
Researchers of the University of Alberta Faculty of Medicine & Dentistry have recently found a causal link between caesarean section birth, low intestinal microbiota and peanut sensitivity in infants, and they report the effect is more pronounced in children of Asian descent than others.
The research team analysed the gut bacteria of 1,422 infants in the CHILD Cohort Study, by examining fecal samples collected at three or four months of age and again at one year. They identified four typical trajectories for bacterial development, including one in which the infants had persistently low levels of Bacteroides, a type of bacteria known to be critical to immune system development.
The infants were 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. The babies with low Bacteroides levels were found to have a threefold increase in their risk of developing a peanut sensitivity by age three—and the risk was eight times higher for babies born to mothers of Asian descent.
The researchers also observed that the infants with low Bacteroides also had lower levels of sphingolipids, proteins which are key to cell development and signalling in many parts of the body, including the immune system.
The overall rate of allergies is increasing in western countries and is likely linked to environmental factors, said Kozyrskyj, who is principal investigator of the SyMBIOTA (Synergy in Microbiota) laboratory, which studies the impact of maternal and infant antibiotic use, birth mode and breastfeeding on the composition of the intestinal microbiota in infants.