Blog

Allergy or Intolerance?

March 14, 2011
Sherri Meyer, MG Registered Dietitian

The other day I found my son Oliver in the refrigerator dipping his fingers in the peanut butter jar. He has declared peanut butter his new found love and has informed me he doesn’t require a medium other than his fingers to partake. Unfortunately, much of that sticky peanut butter ends up on his clothes (who needs napkins?). So, when his daily snack request for preschool includes peanut butter, I have to gently remind him of the “no peanut butter” rule due to allergies. Oliver doesn’t quite get the food allergy concept and often concludes with “they can have peanut butter when they get big.” Oliver does not yet know this is not the case. Unlike milk, wheat, soy, and egg allergies, which most children outgrow, peanut allergies are usually for life.

All of this got me thinking about the latest information on food allergies vs. food intolerances, and I found a great article by Mary Saucier Choate, M.S., R.D., L.D., which I’ve adapted here. For those of us in the food business, it’s important that we can distinguish the difference.

Food Allergies & Food Intolerances
Often, food intolerance is mistaken for food allergy. Food intolerance is more common than true food allergy. According to the Food Allergy Initiative, a food allergy results when the immune system misreads a harmless food protein (an allergen) as a threat and attacks it. Specifically, if you have a food allergy, the immune system manufactures abnormally high amounts of an antibody called immunoglobulin E (IgE), which fights the “enemy” food allergen by releasing histamine and other chemicals, causing the symptoms of an allergic reaction. If you are very sensitive, eating even a very small amount of a food allergen can cause a serious reaction.

In contrast, a food intolerance, such as celiac disease (gluten intolerance) or lactose (milk sugar) intolerance does not involve immunoglobulin E antibodies. An individualwith food intolerance can generally consume a tiny amount of the offending food without experiencing symptoms. However, the specific amount differs for each individual.

While many foods can trigger a food allergy, the top eight foods that cause allergies are: cow’s milk, eggs, peanuts, wheat, soy, fish, shellfish, and tree nuts.
Symptoms of a food allergy include:

  • A rash, or red, itchy skin
  • Stuffy or itchy nose, sneezing, or itchy and teary eyes
  • Vomiting, stomach cramps or diarrhea
  • Facial swelling


Some can have a serious reaction called anaphylaxis. Anaphylaxis is a severe, potentially fatal allergic reaction. According to the National Institute of Allergy and Infectious Diseases, food allergy is the leading cause of anaphylaxis. Anaphylaxis should always be treated as a medical emergency.

The following food intolerances are often mistakenly called food allergies:
Lactose Intolerance

Lactose intolerance: the inability to properly digest the naturally occurring sugar in milk (lactose). This is caused by missing or low levels of lactase enzymes, which normally break down the lactose sugar during digestion. Because the lactose is not broken down effectively, it is fermented by colon bacteria. This results in gas, and causes symptoms of bloating, abdominal pain, and sometimes diarrhea.

Food Additive Sensitivity
Added preservatives and flavor enhancers such as monosodium glutamate (MSG) and sulfites can cause symptoms that can be mistaken for food allergy symptoms. Sulfites are preservatives that are added to foods and also are naturally occurring in certain foods. Symptoms of sulfite intolerance can occur within 15-30 minutes after consumption. Adverse reactions to sulfites in people without asthma are extremely rare.

Gluten Intolerance
Gluten intolerance, a hereditary disease, is also known as celiac disease, celiac sprue, or gluten-sensitive enteropathy. Gluten is a protein in wheat, barley, and rye. When a person with celiac disease eats a gluten-containing food, the immune system responds by damaging the lining of the nutrient-absorbing small intestine. This damage leads to serious nutrient deficiencies that can remain undetected for a long time. The treatment for celiac disease is a gluten-free diet. Gluten intolerance involves an auto-immune reaction, but the IgE antibody is not involved, so this is not considered to be a true food allergy, rather an intolerance.