The Truth About Food Intolerance Testing
Have you been experiencing uncomfortable digestive symptoms like bloating, excessive wind, loose stools or tummy pain? Are you thinking that maybe your symptoms are caused by a food intolerance?
What better way to figure out what foods are causing these symptoms than to do a food intolerance test right? .. wrong …
Read on to explore why food intolerance tests sadly aren’t worth your time.. or your money.
Food intolerance vs food allergy
Food allergy:
Let’s start by exploring the differences between a food intolerance vs a food allergy, because these are actually two different things.
A food allergy is when your body’s immune system reacts to certain foods. Symptoms are often mild but can be very serious and life threatening for some people. Common symptoms may include feeling dizzy or lightheaded, itchy skin or rash (hives), swelling of the lips face and eyes, coughing, wheezing, itchy runny nose, and feeling sick or vomiting.
There are two main groups of food allergies:
Rapid onset: (minutes to 1-2 hours), known as ‘IgE-mediated’ food allergies, which can be life-threatening
Delayed onset: (several hours to 48 hours), known as ‘non-IgE-mediated’ food allergies, which are not life-threatening, but can be debilitating for some.
Food allergies affect about 6% of adults in the UK and should only be diagnosed by a GP or specialist. The most common triggers are peanuts, tree nuts and shellfish. In adults the most common form of food allergy is pollen food syndrome.
Rapid onset/IgE mediated allergy testing involves testing for the presence of IgE antibodies to the suspected food allergen through a blood or skin prick test. For example, if peanuts were highlighted as a suspected food allergen then the test would be for peanut specific IgE.
The testing process for delayed onset or non-IgE mediated food allergy can be a little for tricky. There are no clinical tests for the diagnosis of Non IgE mediated allergies. These are diagnosed using ‘a trial of elimination and re-introduction’ diet to see if the symptoms improve when the suspected food is removed from the diet. This is safe to do at home under the guidance of your Healthcare professional. The food should be removed for 2-4 weeks and then re-introduced to see if the symptoms return.
Food intolerance:
So how are food intolerances diagnosed if it’s not a food allergy? Sadly, scientists are yet to create a legitimate test to detect food intolerances. We only have validated tests for IgE mediated food allergies like we talked about above.
You may have seen companies marketing expensive online food intolerance tests and at first glance this may get your hopes up of finally being able to figure out the culprit of your symptoms. Sadly though, they should really be avoided because of their dodgy testing methods (more on this below) and misleading results – often causing people to cut out lots of their favourite foods completely unnecessarily. Trust me, I’ve seen it in clinic time and time again!
So how do these companies test for food intolerances?
Most companies use a method of IgG antibody testing. Note IgG NOT IgE like in food allergy testing – which IS legit.
IgG antibodies are the most common type of antibody (a type of protein that your immune cells make) in your blood and usually protect you against infection by “remembering” harmful substances you’ve previously been exposed to.
These tests measure the levels of food specific IgG antibodies in the blood, which these companies claim are a marker of ‘intolerance’. The trick here is that most of us will actually develop IgG antibodies to food during our lifetime without getting symptoms at all. This is because IgG is an indicator of repeated exposure, not clinical symptoms.
So does the test work? Sadly no. There is actually no research out there that shows IgG antibody testing is an accurate way to diagnose food intolerances. In fact – there is no proven relationship between IgG antibodies and food intolerance AT ALL!
So how do we test for food intolerances?
Dietitians use the ‘3 R’ process (Record, Restrict, Re-introduce). This involves tracking foods eaten and symptoms, eliminating suspected trigger foods and finally, re-introducing them one by one to see if symptoms re-occur. If they do, it may be a food intolerance. A registered dietitian such as myself, can help you through this process.
Interested in more information?
Food Allergy and Food Intolerance Testing - BDA
Food Allergy Testing and Diagnosing | Allergy UK | National Charity
