Food allergy and food intolerance are two terms that are often used interchangeably, but they actually refer to different conditions. Both involve adverse reactions to certain foods, but the causes, symptoms, and treatment approaches are distinct.

Food Allergy

A food allergy is an immune system reaction to a particular food protein that is recognised as foreign and harmful. When someone with a food allergy eats even a tiny amount of the allergen, the immune system produces IgE antibodies that trigger the release of histamine and other chemicals, which can lead to symptoms such as hives, swelling, itching, abdominal pain, nausea, vomiting, and in severe cases, anaphylaxis. Common allergens include peanuts, tree nuts, shellfish, fish, eggs, milk, soy, and wheat.

Food allergies can be life-threatening, so it is essential to identify the trigger foods and take precautions to avoid them.

IgE Testing for Food Allergies

Diagnosis of a food allergy may involve skin prick tests, blood tests, and oral food challenges. IgE testing is typically used to diagnose food allergies - IgE antibodies are associated with an immediate immune response to allergenic proteins in food. Blood tests can measure the level of IgE antibodies in the blood in response to specific allergens. High levels of IgE antibodies in response to a particular food protein may indicate a high likelihood of a food allergy.

Typically the only effective treatment for food allergy is avoidance of the trigger foods, which often requires careful scrutinising of ingredient labels and restaurant menus.

Food Intolerance

A food intolerance on the other hand (also known as a delayed food hypersensitivity or non-allergic food hypersensitivity), is a type of immune response to specific foods that may occur several hours to days after eating the food. Unlike IgE-mediated food allergies, food intolerances typically do not involve an immediate immune response and typically do not cause life-threatening symptoms.

Symptoms of food intolerance may include bloating, gas, cramps, diarrhoea, constipation, nausea, headaches, and fatigue. Common intolerances include lactose intolerance (inability to digest the sugar in milk), gluten intolerance (sensitivity to the protein in wheat and related grains), and histamine intolerance (inability to break down histamine, a compound found in certain foods).

The exact mechanisms behind food intolerances are not well understood and the scientific evidence supporting their existence and diagnosis is limited. However, some healthcare providers use IgG testing to identify food intolerances and recommend elimination diets based on the test results.

__IgG Testing for Food Intolerances

IgG testing involves measuring the levels of IgG antibodies in response to specific food proteins in the blood. Elevated levels of IgG antibodies in response to a particular food may indicate exposure or tolerance to the food, rather than intolerance. In some cases, IgG testing can produce false positives and lead to unnecessary dietary restrictions, nutritional deficiencies, and potential harm to gut microbiota.

If you suspect you have a food intolerance, it is important to consult with a healthcare provider for proper diagnosis and treatment. They may recommend elimination diets or other diagnostic methods based on your specific symptoms and medical history.

Diagnosis of food intolerance can be challenging, as there is no definitive test. Elimination diets, in which suspected trigger foods are removed from the diet and reintroduced one at a time, may help identify the culprit.

Summary

In summary, food allergy and food intolerance are distinct conditions with different causes, symptoms, and treatment approaches. While food allergies can be life-threatening and require strict avoidance of trigger foods, food intolerances are typically less severe but can still cause discomfort and may require dietary changes. If you suspect you have a food allergy or intolerance, it is important to consult a healthcare provider for proper diagnosis and treatment.