Summary: Neatniks, take note. Infants exposed to some dirt, dander and germs at home may be less likely to develop allergies and asthma, reports a new study.
Good news: The cleaning really can wait until tomorrow. Newborns who are exposed to pet dander and household bacteria in the first year of life may be less likely to suffer from allergies and asthma, says new research published in the Journal of Allergy and Clinical Immunology
The study tracked the health of 467 inner-city newborns at high risk for asthma living in Baltimore, Boston, New York and St. Louis. Researchers measured the infants' homes for levels of cat, mouse and cockroach allergens and monitored child allergy rates through blood and skin prick tests, physical exams and parent surveys. Researchers also analyzed bacterial dust samples in 104 of the homes.
The dirtier the surroundings, the healthier the children appeared to be. Seventeen percent of babies exposed to cat, mouse and cockroach dander during the first year of life experience recurrent wheeze, compared to 51 percent of babies with no allergen exposure. Similarly, having a wide variety of bacteria in the home decreased a baby's risk for developing environmental allergies. In all, 41 percent of the allergy- and wheeze-free children had grown up in the dander- and bacteria-rich homes. But among the children with both allergies and wheeze, only 8 percent had grown up in homes high in dander and bacteria.
Timing, however, was key: Only infants who were exposed to dander- and bacteria-rich dust during the first year of life were protected. Children who had the exposure after their first birthdays were more likely to have allergies and wheezing. "The influence [of dander and bacteria exposure] is greatest early in life and determines a lot of the direction that the immune system takes," says study author Robert Wood, M.D., chief of the Division of Allergy and Immunology at the Johns Hopkins Children's Center.
The benefits of early exposure seem to hold true for other types of allergies, too. Doctors used to recommend that parents hold off on introducing highly allergenic foods, like nuts, until age 3 — but it turns out that delayed introduction can actually raise allergy risk. Now, the American Academy of Pediatrics recommend that babies should be introduced to nuts between age 4 and 6 months, once a few other complementary foods (like fruits, vegetables and cereal) have been introduced and tolerated. "The only exception is if a child is born into a family with a strong history of food allergies. Then parents should discuss introducing allergenic foods with the doctor," says allergist Neeta Ogden, M.D., a spokesperson for the American College of Allergy, Asthma and Immunology.
Still, letting germs take over your home won't guarantee your child never gets asthma or allergies, though striving to keep things too squeaky clean could increase her risk. For now, experts can't yet make recommendations for how clean — or unclean — a family's home should be. But they can say this: "The general idea that squeaky clean isn't always best, and that having pets and dirt could be helpful, that isn't a bad message to get out," Wood says. So don't stress about vacuuming the dog fur off the couch this very minute. Instead, use that time to snuggle with your sweet baby.
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