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Food Allergy vs. Food Sensitivity vs. Food Intolerance

Lindsey Harding, ND

Oct 31, 2023

Understanding the difference between allergies, sensitivities, and intolerances to food

Allergies & Sensitivities are caused by the immune system reacting to foods that it thinks are harmful to the body. The immune system releases antibodies to neutralize the threat. These antibodies are called immunoglobulins, abbreviated “Ig”. There are 4 main types of immunoglobulins - E, M, G, A.

Food Allergy 

The immune system attacks food particles with an antibody called IgE. IgE antibodies have the most aggressive and fastest effect on the body, resulting in severe allergic type reactions, and in many cases, anaphylaxis. Less severe IgE allergies do occur and can cause a range of symptoms from skin rashes to changes in blood pressure. Most IgE reactions happen quickly, within minutes to hours after consuming the insulting food.

Food Sensitivity 

The immune system attacks a food particle with antibodies called IgG or IgA. Both of these reactions can happen within a few hours or may not happen until a day or two or three (up to 72 hours) after the food is consumed. 


·       Often indicates repeated exposure & inflammation - foods that are consumed too often may become IgG sensitivities until the inflammation is healed


·       These immunoglobulins are present in the mucous membranes (nose, mouth, GI tract, urethra, etc). Foods that trigger an IgA reaction tend to have symptoms specific to these areas, such as nasal congestion, such as stomach upset, diarrhea, & UTI-like symptoms.

Food Intolerance

An intolerance is when the body does not produce enough of an enzyme to properly digest a certain food. The most common intolerance is lactose intolerance. In this case, the small intestine does not produce enough lactase - the enzyme needed to break down lactose, the sugar in dairy. 

Fructose intolerance. Fructose is a sugar in fruit, honey, and some vegetables. This intolerance is considered rare, and is known as hereditary fructose intolerance. Fructose malabsorption from lack of a protein that allows the body to absorb the fructose sugar is much more common, and results in nearly all the same symptoms as intolerance (gas, fullness, bloating, cramping, diarrhea).

Gluten intolerance – different than celiac disease, an autoimmune disease – gluten intolerance is also known as non-celiac gluten sensitivity.

Salicylate intolerance. Salicylates are compounds that naturally occur in some fruits, vegetables, herbs, and spices. Salicylates are also used in artificial flavorings and preservatives, including toothpaste, chewing gum, and candies.

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