what to do if you think you have a food allergy or intolerance
If you think you have a food allergy or food intolerance you should seek advice from a qualified healthcare professional.
There are many types of ‘allergy tests’ available on the high street, over the internet or through magazines. However, there is no evidence that many of these ‘allergy tests’ are reliable. In fact, the results of these ‘allergy tests’ often encourage individuals to cut certain foods from their diet without any professional medical or nutritional advice.
This can lead to an unbalanced diet and long-term health complications. If you think you may have a food allergy or food intolerance, the best thing to do is to make an appointment with your GP who then may refer you to a medical specialist or a registered dietitian.
The healthcare professional who tests you for allergies will ask for a full medical history. There are also a number of conventional allergy tests which may be undertaken to identify and diagnose food allergy or food intolerance. These are listed below and should only be undertaken with medical or dietetic supervision.
Skin prick test - a minute amount of the diluted allergen is placed on the skin. The skin is then pricked. A small lump may appear, and in conjunction with the medical history taken, a particular type of food allergy may be diagnosed.
Blood tests (RAST-Radio Allergo Sorbent Test) - this allergy test measures the amount of a particular antibody in the blood. The results are again used in conjuction with a medical history. It is possible for a GP or medical specialist to organise this blood test.
Patch Tests - food allergens are applied to a patch of ‘healthy’ skin and the effects are observed after 48-72 hours. This allergy test is used in the diagnosis of hypersensitivity with a more delayed reaction. A patch test may also be used for food-related eczema as well as a skin prick test. This must be undertaken by a specialist healthcare professional who is able to interpret the results accurately.
Food challenges - this is only performed under medical supervision. Very small amounts of the suspect food are given orally (in the mouth) and the presence or absence of symptoms is observed. The individual undergoing the allergy test may or may not be aware of which food is being tested.
Food exclusion and reintroduction - the suspected food is excluded for a period of time and symptoms are observed and recorded. If there is an improvement or resolution of symptoms the suspect food is then reintroduced. If the symptoms then reappear this would indicate that there is a problem with the food. It is best if this is undertaken under the supervision of a registered dietitian, particularly in the case of children, to ensure that the diet remains well balanced during the test period and in the ongoing diet where foods are excluded. There are two main ways in which this can be done:
Single exclusion diet
This excludes all sources of a single food, for example wheat or milk, because dietary investigation has revealed symptoms linked to the particular food.
Multiple exclusion diet
A multiple exclusion diet excludes a number of foods at the same time. This is often used if there is thought to be a dietary link but it cannot be identified.
If an improvement in symptoms is experienced then foods need to be appropriately reintroduced. This helps to identify which foods have caused the symptoms and to establish which need to be excluded from the diet.
If no improvement is seen then a dietitian may need to investigate further as to whether further foods need to be excluded or whether food hypersensitivity is likely to exist.
Elimination diets can be very demanding and will only work if undertaken properly. However, if you have been experiencing symptoms for a long period of time you may be encouraged to follow a elimination diet to see if any improvement is observed.