As a dietitian I get often get enquiries asking me about food allergy or intolerance testing. Often, people are fairly sure that something they are eating is causing them some digestive problems but they just can’t put their finger on the culprit, so it makes logical sense to turn to allergy testing to help. Unfortunately there are many tests commercially available that not only have no scientific basis, but the resulting dietary advice can be extremely detrimental. I have seen many people who have been told to cut out many foods unnecessarily, which has resulted in poor nutrition and a noticeable decline in health and well- being. More often than not, they have no noticeable improvement in the digestive symptoms which led them to having the allergy tests in the first place. This blog attempts to explore some of the allergy or intolerance tests currently available and examine their reliability.
Firstly, we need to distinguish between food allergy and food intolerance. Food allergies are caused by the body’s immune system and food intolerances aren’t. If you have an allergy the body produces antibodies (IgE) to the trigger food which produce the effects which can include rashes, facial swelling and anaphylaxis. Testing for this type of reaction involves blood allergy testing for the specific Antibody (IgE) and can be organised by your GP, this type of test needs to be done by a qualified professional who has full access to your media history and can interpret the results accurately- you should never need to pay a commercial company for this service.
Another type of allergy which produces more delayed symptoms such as digestive symptoms is non IgE medicated allergy and can’t be diagnosed by a blood test.
Food intolerances are not caused by the body’s immune system but may be caused by lack of a digestive enzyme which allows us to process a certain food, or a reaction to food being digested by the bacteria in the gut which causes digestive symptoms such as pain, bloating and diarrhoea.
Non IgE allergy and food intolerances are harder to detect, they can’t be picked up using blood tests or other (less scientific) methods of testing. A skilled medical professional will be able to suggest any likely causes of your food intolerance by taking a detailed medical and symptom history. They can then suggest tests which may be diagnostic such as stool tests or breath tests. Any tests which are performed are usually accompanied by an exclusion diet, where the suspect food (or group of foods) are removed from the diet for a period of time until the symptoms have settled. They are then reintroduced to see if the symptoms reappear. This can be quite a complex and time consuming process and it is essential that it is done under the guidance of a registered dietitian to ensure that the diet remains nutritionally adequate throughout.
So, to summarise, please don’t be tempted to part with your money to companies who offer you allergy or intolerance testing, it is likely to be unhelpful and expensive at best and potentially damaging to your health at worst. If you suspect you have a food allergy, contact your GP in the first instance- allergies can be life threatening.
If you would like to discuss a suspected food allergy or intolerance with Dietitian Mairi Wilcock, contact the clinic today to discuss without obligation.