The Hygiene Hypothesis
It's not only food allergies that are on the rise. "In the past 20 years, we've also seen a significant increase in hay fever, asthma, and eczema," says Dr. Sampson, former president of the American Academy of Allergy, Asthma, and Immunology (AAAAI). Asthma rates in young children have tripled since the 1980s, and the percentage of Americans testing positive to one or more allergens has doubled. Doctors' best explanation is "The Hygiene Hypothesis." Some children's immune systems aren't developing properly because kids are exposed to fewer diseases and less dirt and bacteria these days, scientists theorize. Without as many germs to fight, the immune system mistakenly overreacts to foreign substances (nuts, dust, pollen) that aren't really dangerous.
If you or your partner has any kind of allergy (and more than a third of adults do), your child's risk of developing one is about 40 percent -- double the risk of children without an allergic parent. If you both have allergies, his risk rises to 60 percent. But allergies to specific foods don't run in families. "If you're allergic to shrimp, your child may be allergic to peanuts or eggs, or he may have hay fever instead," says Wesley Burks, MD, chief of pediatric allergy at Duke University Medical Center, in Durham, North Carolina. If your baby has eczema, however, you should be on the lookout for reactions to food; 40 percent of babies with the skin condition develop a food allergy.