What is the difference between food allergy and food intolerance?

Date: Jul-25-2013Food allergy is completely different from food intolerance. A food allergy involves an immune system response, food intolerance does not.

If you have food intolerance you cannot properly digest a substance in certain foods, often because you have an enzyme deficiency. Food allergy has nothing to do with enzyme deficiency.

Below is a list of features associated with either a food allergy or intolerance:

Onset of symptoms

Food allergy symptoms appear soon after eating the culprit food.
Food intolerance symptoms appear later.

Amount of problem food eaten

A person with a food allergy cannot tolerate even small amounts of the culprit food, as is the case with peanuts.
With food intolerance, a very small amount of the food can be consumed with no adverse reaction.

An immune response versus an enzyme deficiency

In a food allergy, a protein causes an allergic reaction (an immune response).
In food intolerance, the person usually has an enzyme deficiency, meaning that a substance in the food is not digested properly. Food intolerance may also be caused by certain chemicals in foods, food poisoning (toxins), the natural occurrence of histamine in some foods, salicylates which are present in many foods, and food additives.

Food allergies can be life-threatening

In some cases of food allergy, there can be a severe and life-threatening allergic reaction (anaphylaxis) to certain foods.
Food intolerance adverse reactions can be severe and extremely unpleasant, but are rarely life-threatening.

Symptoms of food allergy and intolerance are different

According to the American Academy of Allergy Asthma & Immunology (AAAAI), "Symptoms of allergic reactions to foods are generally seen on the skin (hives, itchiness, swelling of the skin). Gastrointestinal symptoms may include vomiting and diarrhea. Respiratory symptoms may accompany skin and gastrointestinal symptoms, but don't usually occur alone."
The main symptoms associated with food intolerance are "intestinal gas, abdominal pain or diarrhea", according to the AAAAI. Other symptoms are also possible, but the ones related to problems with the gut are the "core symptoms".

There can be some overlap in food intolerance and allergy symptoms. In such cases, an accurate diagnosis is more difficult.
Common foods that cause allergies and intolerance

The most common foods that cause allergic reactions are:

- eggs

- fish

- groundnuts (peanuts)

- milk

- nuts from trees (Brazil nuts, walnuts, almonds, and hazelnuts)

- shellfish

- wheat

The most common foods that cause intolerance are:

- beans

- cabbage

- citrus fruit

- grains containing gluten

- milk (lactose)

- processed meats

How common are food intolerance and food allergy?

According to The Cleveland Clinic, about 7% of children and 1% of adults have a food allergy. This means that most childhood food allergies eventually go away. It is estimated that approximately 10% of Americans are lactose intolerant.

Researchers at the USDA/ARS Children's Nutrition Research Center at Baylor College of Medicine believe lactose intolerance prevalence may be far lower than previously estimated.

The National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health (NIH) reported in July 2012 that nearly 1 in 20 kids under the age of 5 and almost 1 in 25 adults have a food allergy. It added that peanut allergy is becoming more prevalent in the USA.

Written by Christian Nordqvist

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