[Infographic] Food Allergy vs. Food Intolerance

Food allergies and food intolerance can look a lot alike. But while both can leave you feeling miserable, only a true allergic reaction can be life-threatening.

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Food Allergy vs. Food Intolerance

Food IntoleranceFood Allergy
SymptomsDigestive problems, nausea, gas, cramps, abdominal pain, diarrhea, irritability, nervousness, headaches

Breathing problems, throat tightness, coughing, vomiting, swelling, abdominal pain, hives, drop in blood pressure

While food intolerance usually affects the organs of the gastrointestinal tract, allergic reactions affect the entire immune system. At first glance, symptoms can be similar, so it’s important to know whether a food allergy is present so that measures can be taken against anaphylaxis.
CausesLack of digestive enzymes; foods irritating the digestive systemFood proteins (allergens)
An intolerance is often caused by enzyme defects, as in the case of lactose intolerance. A food allergy is caused by an adverse reaction to food proteins on the part of the immune system. Common food allergens include peanuts, tree nuts, fish, egg and milk.
MechanismNon-immune-mediated (Enzymatic; Pharmacological) Immune-mediated ( Immunoglobulin, or IgE)

With food intolerance, an enzyme may be missing or diminished.

The mechanism of food allergies involves the immune system. There are two main phases:

1) Sensitization phase: IgE antibodies are produced in reaction to allergenic proteins and attach to the surface of effector cells, known as mast cells. Once attached, they are ready to react to the offending food.

2) Allergic reaction: Allergenic proteins re-enter the body, binding to the IgE. This produces an inflammatory reaction, causing mast cells to release histamine and other inflammatory mediators.

Reaction time
Hours/several daysMinutes/up to 24 hours
A food intolerance can be painful, but an allergy can be lethal. Anaphylactic shock, or anaphylaxis, is a life-threatening condition that can cause a sudden drop in blood pressure and impair breathing. Such reactions are unpredictable and therefore all the more dangerous. As there is no treatment for a food allergy, allergic individuals have only one option: strict avoidance of foods with ingredients to which they are allergic.