Bacteria exposure limits baby allergy risk

COPENHAGEN, Denmark, Nov. 2 (UPI) -- Infants who encounter a wide range of bacteria are at less risk of developing allergies later in life, researchers in Denmark said.

Professor Hans Bisgaard of Gentofte Hospital and the University of Copenhagen said 25 percent of the population of Denmark suffer from allergies.

"In our study of 411 children we observed a direct link between the number of different bacteria in their rectums and the risk of development of allergic disease later in life," Bisgaard said in a statement. "Reduced diversity of the intestinal microbiota during infancy was associated with increased risk of allergic disease at school age, but if there was considerable diversity, the risk was reduced and the greater the variation, the lower the risk."

In the womb and during the first six months of life, a mother's immune defenses protect an infant, the study said. Bacteria flora in infants are therefore probably affected by any antibiotics mothers have taken and any artificial substances they have been exposed to, Bisgaard said.

"I must emphasize that there is not one single allergy bacteria," Bisgaard said. "What matters is to encounter a large number of different bacteria early in life when the immune system is developing and 'learning.' The window during which the infant is immunologically immature and can be influenced by bacteria is brief, and closes a few months after birth."

The study was published in the Journal of Allergy and Clinical Immunology.