Infants with fewer types of intestinal bacteria are at increased risk for developing asthma, a small new study suggests.
Researchers assessed the varieties of gut bacteria in 47 infants and then followed them until they were 7 years old. At that age, 17 percent had chronic asthma, 28 percent had hay fever, 26 percent had the skin condition eczema, and 34 percent reacted to the allergens in a skin prick test.
However, only the cases of asthma could be connected to low diversity of intestinal bacteria when the children were 1 week and 1 month old, according to the study recently published in the journal Clinical & Experimental Allergy.
The findings may provide further evidence that bacteria in the intestines can affect the airways, which has previously been shown in animal studies, the researchers say.
"A high diversity of gut [microbes] during the first months of life seems to be important for the maturation of the immune system," study author Thomas Abrahamsson, a pediatrician and researcher at Linkoping University in Sweden, said in a university news release.
It's believed that for the immune system to function effectively, it needs to be "trained" by large numbers of different microorganisms. If a child's immune system has not been exposed to and stimulated by large numbers of different bacteria, it may overreact to harmless substances, Abrahamsson explained.
