Patient organisations, including Allergy New Zealand and clinical bodies, strongly recommend people not use tests promoted online for allergy testing.
Food allergy is a serious condition and requires qualified health professionals with advanced training in allergy to diagnose and then monitor patients. There is no cure, and management requires strict avoidance of the food concerned. Most food allergies commence in early childhood, and it is rare for an adult to develop an allergy to a food, particularly one they have eaten before without problems.
An allergy is caused by the immune system over-reacting to a food which it has identified as a threat to that person. The majority of food allergy reactions are IgE-mediated, happen within minutes of eating even a small amount of the food, and usually cause skin symptoms, although anaphylaxis (a severe, life-threatening reaction affecting the breathing or circulation) can occur. The risk of anaphylaxis is one reason why food allergy needs to be properly diagnosed. Another is to ensure children get the right dietary advice to manage their condition safely while maintaining nutrition for normal growth and development.
The only tests used for IgE-mediated food allergy are skin prick or blood to measure the level of specific IgE in the immune system. However, the main consideration in making a diagnosis is the patient’s clinical history. Without this history, the allergy tests on their own are very difficult to interpret.
There are also many causes of adverse food reactions, most of which don’t involve the immune system or an associated risk of anaphylaxis. This chart sets out the difference between food allergy (which involves the immune system) and food intolerances.
Food intolerance can cause people a lot of problems. Some may have a metabolic condition, such as lactose intolerance, caused by a lack of the lactase enzyme in their body to digest lactose, the sugar in milk. Others may have an inflammatory condition in the digestive system, such as irritable bowel syndrome, which lots of different foods can inflame; or they could be caused by other health problems or be age-related.
For most of these conditions, there is no test. Sorting out what food causes the problem usually requires an elimination diet for a few weeks, then reintroducing the food. It is recommended people see a dietitian who can help sort out the elimination diet while ensuring the person maintains good nutrition.
The risk of using tests that have not been scientifically proven to work, and are not done in conjunction with the person’s history of food reactions and health conditions, is an unnecessarily restricted diet, and/or possibly a delay in diagnosis and treatment leading to poorer outcomes. In children, this has been seen to cause malnutrition and/or poor growth and development.
For more information, see the FAQ from the Australasian Society of Clinical Immunology and Allergy on: https://www.allergy.org.au/about-ascia/info-updates/online-allergy-testing