The New York Times reported in a recent study of peanut allergies in the New England Journal of Medicine that has challenged the conventional wisdom. In a randomized prospective study, the authors divided infants at high risk for peanut allergies into two groups. Those that were fed peanut products (like peanut butter, but not whole peanuts, which can be a choking hazard) were far less likely to develop peanut allergies than those who were not. So in this study, withholding peanut products from infants actually increased the incidence of peanut allergies.

Similarly, children who grow up on farms are less likely to develop asthma than those who don’t because exposure to animals and their fodder “trains” the body to protect against antigens