Food Allergies and Intolerances

What are food allergies?

The term "food allergy" often defines a variety of adverse physical reactions to foods. A true food allergy is an abnormal response of the body's immune system to certain foods or food ingredients. For some people, eating even a little of the offending food can cause a life-threatening reaction. Less sensitive people may be able to tolerate small amounts of the food to which they are allergic. One of three people believes he or she has a food allergy, yet only about 1% of adults suffer from true food allergies.

What is the difference between a "food allergy" and a "food intolerance?"

Unlike a food allergy, a food intolerance does not involve the immune system. However, the physical symptoms of a food intolerance, such as intestinal discomfort, can resemble those of a true food allergy. For this reason, a food intolerance reaction may be easily confused with an allergic reaction. It is important that the symptoms be evaluated and diagnosed by a board-certified allergist.

What are common symptoms of food allergies and intolerances?

Physical responses to allergic food substances include:

Skin reactions: swelling, hives, rashes.

Nose/lung reactions: nasal congestion, asthma.

Stomach/intestinal reactions: nausea, diarrhea, gas.

Symptoms can develop immediately, within two hours, or may appear one to two days after eating a food. Persons who believe they have experienced an adverse reaction should seek medical evaluation. Many typical symptoms could be caused by other illnesses such as the flu or food poisoning.

The most severe type of food allergy reaction is called anaphylaxis (an-a-fi-LAK-sis). This reaction can occur within moments after eating the offending food, and typically involves several parts of the body. Symptoms may include hives, difficulty breathing, and loss of consciousness. Without immediate medical attention, death may occur. Common foods that cause anaphylaxis are peanuts, nuts, eggs, and shellfish.

What foods commonly cause food allergies?

In adults, common allergic reactions are caused by fish and shellfish, peanuts and nuts such as walnuts or pecans, and eggs. In children, common food allergy culprits are milk, egg, peanuts, wheat, and soy.

Diagnosing a food allergy requires a physical examination by an allergist who may recommend you consult with a registered dietitian to help you manage your diet.

What might cause a food intolerance?

People may react adversely to foods for a number of reasons, including:

Digestive and other physical conditions can mimic food allergy symptoms.

An enzyme deficiency, such as when the body cannot digest lactose (a milk sugar) often produces symptoms of gas, cramps, and bloating. This is known as lactose intolerance, and is not a milk allergy.

Sometimes natural substances in foods such as wine, fish, and cheese may cause allergy-like symptoms.

Food additives are rarely linked with food intolerance reactions. Sulfites, a preservative, are safe for most people, but can be dangerous for a small number of severe asthmatics.

According to the Food and Drug Administration (FDA), the flavor enhancer monosodium glutamate (MSG) is safe for the vast majority of people. Some people have reported mild, short-term symptoms after consuming MSG, but under clinical testing, people were no more likely to respond to MSG than to a placebo.

What can I do to help manage my food allergies?

Once a true food allergy has been diagnosed, strict avoidance of the offending food is the only treatment. To do this, read food labels carefully and consistently. For additional information, contact the food company. When eating out, ask about ingredients and how the dish was prepared.

Ingredient substitution is a useful skill for the food allergy sufferer. A registered dietitian can guide you toward appropriate food substitutions. Specialty food product suppliers can provide product suggestions.

For more information
The American Dietetic Association/National Center for Nutrition and Dietetics Consumer Nutrition Hotline.
For food and nutrition information or for a referral to a registered dietitian in your area, call 800/366-1655. For customized answers to your food and nutrition questions by a registered dietitian, call 900/CALL-AN-RD (900/225-5267). The cost of the call will be $1.95 for the first minute and $.95 for each additional minute.

American Academy of Allergy and Immunology
24-hour Physicians' Referral and Information Line, 800/822-2762. This organization will provide you with a list of allergists in your area, as well as general information on food allergies, other allergies, and asthma.

The Food Allergy Network
4744 Holly Avenue
Fairfax, VA 22030
703/691-3179
This consumer-based group produces a newsletter and several publications related to food allergies.

American Allergy Association
P.O. Box 640
Menlo Park, CA 94026
Send information on your allergy, along with a self-addressed envelope and two stamps and you'll receive information tailored for you.

This fact sheet is supported by a grant from Ajinomoto U.S.A., Inc.