Food allergy is completely different from food intolerance. A food allergy involves an immune system response, food intolerance does not.
This Medical News Today article provides in-depth and reader-friendly information on the features associated with either a food allergy or intolerance, the difference in symptoms between food allergy and food intolerance, common foods that cause allergies and/or intolerance, and how common food intolerance and food allergies are.
Features associated with food allergy or intolerance
Below are some 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.
- 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.
- In a food allergy, a protein causes an allergic reaction (an immune response). An "allergen" is a protein that causes a food allergy.
Allergens are not harmful substances in themselves, i.e., most people can be exposed to them without any adverse effects. They are called allergens because they affect some people by triggering a response in their immune system.
- 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.
- 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.
What is the difference in symptoms between food allergy and food intolerance?Symptoms of food allergy and intolerance are different
- According to the American Academy of Allergy Asthma & Immunology1 (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 AAAAI1. 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:
- groundnuts (peanuts)
- nuts from trees (Brazil nuts, walnuts, almonds, and hazelnuts)
- The most common foods that cause intolerance are:
- 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.2 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.3
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.4 It added that peanut allergy is becoming more prevalent in the USA.