Cleanliness May Not Be Next to Godliness When it Comes to Allergies, Asthma
"These findings are not surprising. There is a growing body of evidence that things that happen to an infant early in life -- perhaps even in the uterus -- may influence whether or not that baby becomes allergic," says Paul Williams, MD, clinical professor of pediatrics and environmental health at the University of Washington in Seattle. He tells WebMD there is evidence that other environmental factors, such as early exposure to antibiotics, living in the city or on a farm, family size, and even birth order may influence a child's tendency to develop allergies or asthma.
However, Williams, who was not involved in the study, warns that the hygiene hypothesis is far from proven. "There is suggestive evidence that intestinal bacteria [that can be transmitted by mouth] influence the development of allergies, but no firm conclusions can be drawn yet." To minimize the chances of a child developing allergies, he encourages women to breastfeed, as this promotes the establishment of normal bacteria in the baby's intestinal tract, and recommends more judicious administration of antibiotics to babies.
- In the U.S., 40-50 million people suffer from allergies, and more than 17 million have asthma, a disease that claims more than 5,000 lives each year.
- One hypothesis suggests that modern hygiene, vaccines, and sanitation decrease children's exposure to certain microbes, preventing their immune systems from building up natural defenses.
- A new study adds further evidence to this hypothesis, showing that people who do not have antibodies to bacteria, viruses, and parasites transmitted via food, saliva, or feces are more likely to have allergies or asthma.