Allergic reactions to certain food or food group are called food allergies. If you have a non-allergic adverse reaction to food, it is usually described as food intolerance. When someone is having an allergic reaction, it is important to determine what is allergy and what is food intolerance.
Food allergies occur when your immune system reacts adversely to a particular food or food additive. Chemically, it is believed that your body is responding to the proteins in the food. This is what is causing an allergic reaction. Unfortunately, even a very small amount of the protein can trigger a reaction. Also, most proteins can cause reactions even after being cooked, though cooking or canning these foods may reduce or eliminate your allergy symptoms.
It is estimated that in the US, up to 8% of children and 2% of adults are affected by food allergies. A small number of foods are believed to cause the majority of food allergies. The top eight food allergens are:
- Cow’s milk
- Fish (including cod, salmon, and tilapia)
- Shellfish (including crab, shrimp, and lobster)
- Tree nuts (including walnuts, almonds, and cashews)
Some interesting information:
An allergy to one food sometimes results in an allergy to all foods of the same family. For example, allergy to one type of shellfish (like crab) puts you at higher risk of being allergic to others (shrimp and lobster). This is called cross-reactivity.
It is possible for people allergic to beef to be able to safely drink cow’s milk, and for patients allergic to chicken to eat eggs. It is also possible to have an allergic reaction to egg yolks but not egg whites (because they contain different proteins). In any of these instances, however, it is always important to exercise caution and consider avoiding the food entirely.
In small children, temporary, non-allergic food reactions are common, especially fruits, egg white, cow’s milk, and wheat. For example, your child may have a temporary rash near the mouth that is simply caused by the natural acids in foods like oranges and tomatoes. Another example is diarrhea caused by the high sugar content in fruit juice or other beverages.
Food Allergy Symptoms
- Hives (itchy, red, swollen areas of skin)
- Swelling and itching in the throat and mouth
- Diarrhea, abdominal cramps, vomiting
In extreme cases, eating or drinking a food that you are allergic to cause anaphylaxis – a life-threatening, whole-body, allergic reaction.
The signs of anaphylaxis include:
- Flushing, tingling, or warmth in the mouth
- An itchy, red rash
- Shortness of breath
- Severe sneezing
- A feeling of unease
- Cramping in the abdomen and/or uterus
- Vomiting and/or diarrhea
Anaphylaxis symptoms are treated with injectable epinephrine and antihistamines. If there is any possibility that you are experiencing the signs of anaphylaxis, you should seek emergency medical treatment.
Food intolerance is a non-allergic reaction to components in a food other than its proteins. One common example is lactose intolerance, which is a reaction to lactose, a type of sugar that is found specifically in milk. It occurs in individuals who lack the enzymes that are needed to properly digest lactose, and causes uncomfortable abdominal symptoms.
Different food intolerance reactions may be triggered by the chemicals found in a specific food. For example, a person may experience nervousness after drinking caffeine in soft drinks or coffee, headaches caused by chemicals in chocolate or cheese, or a variety of adverse reactions to food additives, whether they are artificial colors, preservatives, etc.
An allergist is specially trained to diagnose food allergies and will begin your visit by taking a medical history and performing a physical exam. Your doctor will also likely perform allergy skin tests to determine which foods, if any, are causing your allergic symptoms.
If the diagnosis of food allergy remains in doubt, your allergist may recommend a test called a “food challenge”. This test involves the patient eating small amounts of a suspected allergen under the close supervision of a allergy specialist that is prepared to treat the patient in case of a severe reaction. When properly performed, a food challenge is very effective at confirming that a specific food is truly causing your symptoms.
The first step of treating food allergies is to avoid the food that triggers your allergies. You should always read food labels when you are at the store, and you should always ask what ingredients are in the food you are selecting at a restaurant. It is a great idea to let the restaurant know of your food allergies so that they can recommend safe foods and ensure that your meal does not come into contact with your triggers.