A Fish-to-Nuts Guide on Living with Food Allergies

If you have a food allergy, you’re not alone. The U.S. Centers for Disease Control and Prevention (CDC) estimates that food allergies affect between 4 to 8 percent of children and 2 percent of adults, and these numbers appear to be increasing. On top of this, many people have food intolerances that are often thought to be food allergies.

Michael Mulligan, M.D., and Kristina Philpott, M.D., allergists at the Palo Alto Medical Foundation’s (PAMF) Mountain View and Fremont Centers, answer some of the most common questions about food allergies and intolerances.

Q: What is a food allergy?

A: A food allergy reaction is caused by an immune response to a specific food. When someone eats certain foods – such as peanuts, tree nuts (like walnuts, pecans and almonds), shellfish, dairy and wheat – the body mistakenly treats an ingredient in the food as if it were a harmful pathogen. The body responds to this perceived threat by creating a defense system (antibodies) to fight it. The allergic symptoms occur as a byproduct of the action of the antibodies against the food.

Q: Is a food intolerance different than a food allergy?

A: Most negative food reactions fall into the category of food intolerances — not food allergies. Unlike a food allergy, food intolerances do not trigger responses in your immune system; your body simply does not process the particular food well. For example, lactose intolerance is a type of food intolerance. Some food intolerances are fairly obvious, such as spicy foods causing heartburn. Lesser-known food intolerances involve reactions that occur after you’ve eaten certain foods with “histamine-like” substances, which can cause itching and hives.

Q: What are the most common food allergies?

A: The most common food allergies in the United States are to milk; eggs; peanuts and tree nuts; soybeans; wheat; and fish, particularly shellfish (including shrimp, escargot, squid, crab and clams).

Q: Is it possible to outgrow a food allergy?

A: There is no cure for food allergies, but you may outgrow them. Young children will often lose their sensitivity to foods such as milk, eggs, wheat and soy by the age of 5 to 6. Unfortunately, people with allergies to peanuts, tree nuts, fish and shellfish rarely outgrow their allergies.

Q: How do I know if I have a food allergy?

A: If you are unsure about your sensitivity to a food, keep a food diary for a couple of weeks. List everything you eat, what symptoms you experience and when they occur. Share this information with your doctor, who can confirm your findings with an exam and tests, and help determine what food is causing your symptoms.

Q: If I have food allergies, will my children have them, too?

A: Not necessarily. The tendency to develop allergies is genetically determined, but the specific allergies are not inherited. For example, a child whose parents are both allergic to cats has a good chance of developing allergies, but will not necessarily develop an allergy to cats. It’s the same with food allergies. Breastfeeding your child for at least four months is your best bet for guarding your baby from allergy vulnerability. It also does not appear that delaying the introduction of certain allergenic foods to infants, or avoiding certain foods while pregnant or lactating, has an impact on a child’s chance of developing allergies except for infants with eczema (atopic dermatitis) and possibly other allergic risk factors. As a result, the American Academy of Pediatrics no longer recommends any adjustments in the mother’s diet during lactation unless the infant has a known food allergy or other allergic risk factors.

Q: How are food allergies and food intolerances treated?

A: Food allergies are treated by strictly avoiding the offending food in your diet. People with food allergies also need to know how to treat the reaction if an allergenic food is ingested accidentally. For food intolerances, how much you need to avoid the food depends on the severity of your symptoms. Some people with lactose intolerance, for example, only have mild symptoms that are not uncomfortable enough to eliminate milk and dairy products from the diet, while others prefer to avoid the offending food altogether to avoid symptoms.

Do you have a food allergy, seasonal allergies or asthma? To find a PAMF allergist near you, visit pamf.org/allergy.
Back to top