Food Allergies: A Case of Mistaken Identity

Nutrition expert Heather Reese breaks down the basics of common food allergies.

A food allergy occurs when the body mistakes a food item for a harmful substance, and the immune system creates antibodies to protect itself. Once this mistaken identity occurs, every time a person eats that food the body will release histamine and other chemicals, triggering an allergic reaction. This response can affect the respiratory, gastrointestinal and cardiovascular systems. It can also cause a skin reaction.

Common Food Allergens

While any food item can cause an allergic reaction, there are eight foods responsible for 90 percent of all food-related allergies. The eight common food allergens are:

• Eggs

• Fish and shellfish

• Milk

• Peanuts

• Soy

• Tree nuts

• Wheat

I will discuss each one in further detail below.


Experts estimate that about 12 million Americans have legitimate food allergies. And anyone can experience an allergic reaction to a food that had never been a problem before. These reactions can range from uncomfortable to life threatening and they usually develop about an hour after the food is ingested. Common symptoms include:

• Rash, hives and itching

• Swelling of the lips, face, tongue, throat and other body parts

• Wheezing, nasal congestion or dry throat

• Difficulty breathing

• Nausea, vomiting or diarrhea

• Dizziness, lightheadedness or fainting

The most severe allergic reaction is anaphylaxis, which can present as a constriction of the airway from a swelling in the throat or a lump that makes it difficult to breath. It can also result in shock or a severe drop in blood pressure, a rapid pulse rate or a loss of consciousness.

Risk Factors

While anyone can suffer from food allergies, there are factors that put you at an increased risk of developing them. A family history of even seasonal allergies can increase your risk of food allergies. Age is also a factor. Food allergies are most common in children and toddlers because as you age your body is less likely to absorb food allergens. While allergies to nuts and shellfish are usually lifelong afflictions, most other childhood allergies are outgrown.

Food Allergy vs. Food Intolerance

Not all food reactions are allergic. You can have a food intolerance, which results in many of the same symptoms, such as nausea, vomiting and diarrhea. Many people confuse these food intolerances for allergies; however a reaction to a food intolerance does not involve the immune system. It is not a histamine reaction. Many people with food intolerances can ingest small amounts of the food item without a problem, whereas even a very small amount of a food one is allergic to will result in an allergic reaction. An example of food intolerance is lactose.

Food Allergy Considerations

If you do suffer from a food allergy, you can't assume that simply avoiding the actual food that you are allergic to is enough. You must also read food labels and ask questions when dining out to ensure that you do not inadvertently ingest a food allergen that you have a reaction to. Below I summarize some additional considerations you should take in avoiding food allergens, but it is still important to be your own advocate and to always be aware of what you are eating.

Egg allergy

Eggs come in more forms than scrambled or over easy. They are also used to make foams and toppings for coffee and bar drinks, and can be found in a lot of commercially produced pastas. Egg whites can even be found in some egg substitutes. Since flu vaccines are grown on egg embryos they can contain a little egg protein, so it's important to tell your doctor if your child is allergic to eggs before he receives the flu shot.

Fish and shellfish allergy

Fish and shellfish allergies are commonly reported in both adults and children. If you've had an allergic reaction to one type of fish it is recommended that you avoid all types, and the same is recommended for seafood. If you do suffer from this allergy you should avoid seafood restaurants due to a high probability of cross contamination of food preparation surfaces. Some people who suffer from fish and seafood allergies can have a reaction just from walking through a fish market or being around fish while it is cooking.

Milk allergy

Casein and whey are the two main protein allergens in milk. While two percent of infants are allergic to milk, 60 percent of those children outgrow the allergy by the age of four. Fortunately, while milk is used in a lot of baked goods it can be easily substituted. Common substitutes include water, juice, rice milk and soy. Because goat's milk contains similar proteins to cow's milk, it is not considered a good substitute for people who suffer from this allergy.

Peanut allergy

A peanut allergy is the most common cause of death from food and it can be a life-long allergy, though recent research indicates that about 20 percent of children with a peanut allergy outgrow it. Reactions to just a small exposure to peanuts can be life threatening. People suffering from this allergy must be diligent in reading food labels. Many processed snacks and candies contain peanuts or are manufactured on machines that are also used for peanut products, which can result in cross contamination. Most doctors recommend that people with peanut allergies also avoid tree nuts as a precaution.

Soy allergy

Since soy has become a common addition to processed foods, it can be difficult to avoid. Soy can be found in baked goods, cereals, crackers, infant formulas, sauces and soups. It can even be found in peanut butter and canned tuna fish.

Tree nut allergy

Tree nuts include almonds, brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts. These nuts are sometimes used as a filling for bean bags, kick sacks, and draftdodgers, those long bean bag type things that you put at the base of your door to keep the cold air out.

Wheat allergy

A wheat allergy is often confused with Celiac Sprue, an entirely different condition. People with Celiac Sprue must avoid gluten, which can be found in many different grains. While those with a wheat allergy only need to avoid wheat. This grain flour is used in most baked products and as filler in crab cakes, but can be easily substituted with rice or corn flour. Wheat is also used as a decoration on some country style home décor items.

Diagnosis and Treatment

You should see a doctor if you experience the symptoms of a food allergy after ingesting one of these common food allergens. You doctor may ask you to keep a food diary and record when symptoms occur to determine which foods you are having a reaction to. The next step may be an elimination diet, in which you eliminate food items from you diet and then add them back one by one to determine which foods are causing an allergic reaction.

There are also tests that your doctor can perform to determine if you are suffering from a food allergy. A skin prick test, in which small amounts of suspected substances are injected underneath your skin, is a common allergy test. If you are allergic you will develop a raised bump. Blood tests can also be used to diagnose food allergies by measuring the amount of antibodies your body creates in response to different food items.

Unfortunately, the only way to treat a food allergy is to completely avoid the foods that cause symptoms. For some food allergens this can be difficult because while keeping them out of the house is easy, many can be well hidden in processed and restaurant foods. If you have a food allergy you can take certain precautions to prevent a reaction, such as reading food labels and asking questions when dining outside your own home.