Food intolerance tests are increasingly popular, as is the number of people who believe they have a food intolerance or allergy. Only 2-3% of the population suffers from food allergies, but 25% of the population believe they have a food allergy (1).
First of all, it is necessary to understand the difference between food intolerance and food allergy, as these terms are often used as if they mean the same thing.
Food intolerance manifests itself with symptoms a few hours after eating the food, it is not potentiated by the immune system and depends on the amount of food ingested. Some of these symptoms are stomach pains, cramps, diarrhoea, itching and skin rashes. However, these symptoms can also be due to other causes such as irritable bowel syndrome (IBS), stress and anxiety, lactose intolerance, celiac disease and inflammatory bowel disease or food allergy (2).
Food allergy manifests itself immediately after contact with food or traces of that food, and is potentiated by the immune system. In more severe cases, it can lead to anaphylactic shock. Food allergy can also be IgE mediated or non-IgE. IgE-mediated food allergy can be diagnosed using conventional food allergy testing. Non-IgE-mediated food allergy cannot be detected in allergy tests and its symptoms manifest later, after ingestion of the food (3).
Although there are numerous food intolerance tests on the market, none of these are supported by scientific evidence, and different tests can even give different results (1, 2, 3).
The problem with these tests is that they can lead the individual to eliminate food and have a restrictive diet, without it being necessary, which can lead to nutritional deficiencies, in addition to the high economic cost of these tests.
What are the tests that we can trust?
The tests based on scientific evidence, according to the British Dietetic Association (3), are
Skin test - there is an exposure of the individual's skin to the protein of the suspected food. If there is a skin reaction, it means that the individual is allergic to the food in question, and this means that it is an IgE-mediated response.
Blood tests - this test measures the amount of IgE antibodies in the blood. This test is prescribed by the doctor and is called the Radio Allergo Sorbent Test (RAST).
Food challenge tests - the individual ingests a small sample of the suspected food. The amount of food can be increased gradually while the healthcare provider observes the symptoms.
Food exclusion and reintroduction tests - in this test, the individual eliminates the suspected food from their diet for two to six weeks and notes their symptoms. If symptoms improve, the food is then reintroduced. If the symptoms return, then it means that the individual has food intolerance. In this test, only one food should be eliminated and reintroduced at a time.
How to detect foods suspected of causing food intolerance?
The best method of detecting foods suspected of causing food intolerance is by completing a food diary. This diary should record the food and drinks consumed, the times of ingestion, as well as all symptoms. You can download a food diary here.
It is important to consult a Dietitian who will help you interpret your food diary and help you to identify which foods are suspect. This process can be slow, but you can trust the results.
Any other alternative food intolerance tests such as IgG antibody blood test, hair test, pulse test, etc, do not present any scientific evidence (3).
In conclusion, observe carefully your symptoms, and consult a qualified health professional who will help you identify the cause of the problem, which may or may not be related to the ingestion of food.
Do not spend money on food intolerance tests as these have no scientific evidence. If you suspect you may have a food allergy or intolerance, consult a dietitian. Do not eliminate foods from your diet without the recommendation of a dietitian, as this may result in nutritional deficiencies.
If you need help, book a free initial consultation now to know what can a Dietitian do for you.
1 Are Food Intolerance Tests Accurate? – Sigma Nutrition
2 Food intolerance - NHS (www.nhs.uk)
3 Food Allergy Testing Food Fact Sheet | British Dietetic Association (BDA)
Joana Jardim, Registered Dietitian, MSc Clinical Nutrition
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Hi, I'm Joana, a Portuguese registered dietitian in the UK. I am passionate about helping others achieving their health goals.