I have five grandchildren, one as much fun and as charming as the next. Two of them are allergic to foods: One has allergies to tree nuts, peanuts, sesame seeds and melons; the other is allergic to milk, soy and eggs. When I was a kid—in what my children refer to as ‘the olden days’—I can’t remember any of my friends having food allergies. And when I began practicing pediatrics in 1980, food allergies were quite rare. In recent years, food allergies seem to be more common. I asked my colleague and Mercy Clinic pediatric allergist Dr. Laura Esswein, who cares for both of my allergic grandchildren, about this. Here are some of her thoughts:

Food allergies affect approximately 6 to 8 percent of children younger than 5, and about 3 to 4 percent of adults. It is possible that new research may soon allow a treatment that might help the allergy go away.

Only some food reactions truly can be called ‘allergies.’ Many people have intolerances to food. For example, lactose intolerance causes tummy pain in some people after drinking milk. Although intolerances may cause discomfort or annoying symptoms, they are not dangerous. A true food allergy is caused by the body’s own immune system reacting to a food protein. Food allergies often cause an itchy skin rash, but symptoms can include vomiting, wheezing, difficulty breathing, throat-swelling and even death. Even a tiny amount of the problem food can cause severe symptoms in sensitive patients.

Allergy to peanuts and nuts is one of the more common, and often more severe, food allergies. It also is an allergy that is usually not outgrown, unlike milk and egg allergies that usually resolve before a child starts school. In a child who has had symptoms from peanuts or nuts in the past, there is no way to predict how severe a future reaction may be. In fact, many patients who have fatal or near-fatal reactions to nuts  never had severe symptoms before.

Because peanut and tree nut (almond, pecan, walnut, etc.) allergies are so common and can be so severe, many preschools have a no-nut policy. Preschool children can be messy eaters, and even a trace of peanut butter left on the table could be very dangerous to another child. It may seem frustrating to have to check labels if your child is not allergic, but keeping the environment safe for all children is critical.

So when should you allow your baby to have peanuts or tree nuts? That answer is not very clear. Peanuts and tree nuts can be a choking hazard, so many pediatricians recommend avoiding them until age 3, anyway. From an allergy standpoint, avoidance used to be recommended until age 3, but recent research has not proven that this helps avoid the allergy. Factors such as family history, presence or absence of asthma and eczema also need to be considered. It is best to discuss all these factors with your pediatrician before introducing nuts or peanuts to your young child.

Dr. Joseph Kahn is president of Mercy Children’s Hospital Services, mercy.net.