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Food allergy vs. Food intolerance

Many people often confuse the terms “food allergy” with “food intolerance.” While both situations have similar symptoms, they are entirely different reactions.

Food allergies and intolerance are “non-toxic” adverse reactions after ingestion or contact with specific foods. The mechanism by which these adverse reactions are generated is different for each term.

What are they?

Food allergy is an exaggerated immunological response of the organism, mediated by immunoglobulin E (IgE) and other cells, to a food or food compound (proteins) known as “allergen” that the body perceives as harmful when it is not, and attacks producing a series of symptoms. It can be potentially dangerous.

IgE antibodies result from an immediate-hypersensitivity reaction to a substance, in this case, a food. IgE-mediated food allergy usually occurs within minutes of ingestion, making it relatively easier for patients and physicians to identify what food is causing an immediate response.

It is essential to highlight how dangerous food allergies can be. One in four people living with allergies has had an anaphylactic shock, which can be fatal if not treated in time. It is a generalized allergic reaction that occurs suddenly and within minutes of contact with the allergen. It produces difficulty breathing, hypotension, weak and sped-up pulse, and bronchospasm, the latter being life-threatening if untreated. As for food intolerance, individuals may eat small amounts of bothersome foods with little to no reaction. But, when they have too much, their body reacts.

Food intolerance happens when the immune system produces immunoglobulin G (IgG) antibodies to neutralize these food molecules that it interprets as intruders. This process often results in inflammation, stomach pain, and bloating, among other symptoms that may be discomforting and affect a person’s lifestyle but are not usually dangerous.

When circulating IgG antibodies to foods are present in the bloodstream, this may suggest increased intestinal permeability, otherwise known as “leaky gut syndrome.” When the tight connections forming the barrier in the gut don’t work as they should, larger substances such as food proteins can pass through, causing an immune response. This immune response then results in the production of IgG antibodies to foods.

In other words, when a person is unaware of what foods they cannot tolerate and keep on ingesting them, the metabolism enters a vicious circle where the more food proteins enter the bloodstream, the more inflammation occurs, and vice versa. The only way to stop this vicious circle from happening is by identifying which foods are triggering an IgG reaction and then eliminating them completely from the diet for a period of time. The idea is to then re-introduce the foods at a later stage to identify which are the problematic foods in the longer-term.

How to act in each case?

In both cases, the food that produces the reaction should be avoided. However, food allergies should be eliminated from the diet and avoided at all costs. With intolerances, the body can assimilate it in small quantities without presenting such severe or generalized symptoms. The ideal will always be to consult a doctor and make an early diagnosis.

Finally, as a summary, the following table is presented:

Food Allergy

Immunological reaction through IgE

Affects skin, respiratory and digestive system

Symptoms in less than 2 hours

No matter the amount

Food Intolerance

Immunological reaction through IgG

It affects the digestive system and skin

Symptoms in less than 72 hours

It depends on the amount

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