Babies who are exposed to both bacteria and allergens in the first year of life are less likely to develop asthma and allergies, a study finds.
It's the latest wrinkle in the hygiene hypothesis — the notion that exposure to bacteria trains the infant immune system to attack bad bugs and ignore harmless things like pollen and cat dander.
But what's interesting about this study is that it gets specific; not just any old germs or allergens will do.
Inner-city children who were exposed to cockroach, mouse and cat allergens in the first year of life had less wheezing at age 3. And children exposed to a wider variety of bacteria, especially those in the Bacteriodes and Firmicutes groups, were less likely to develop allergies or asthma. Children exposed to both did best of all.