What is the difference between food intolerance and food allergy?

‘Food Intolerance’ and ‘Food Allergy’ are often thought to be variations of the same thing but the biological processes behind them, and how they affect you, are very different.

Food Allergy

Food allergy is quite rare, affecting about 2% of the adult population. During an allergic reaction, the body’s immune system believes it is being ‘invaded’ and produces IgE (Immunoglobulin E) antibodies to fight off the food or drink ingredient it mistakenly considers to be harmful.

The body’s inflammatory response in this circumstance can vary from mild to severe and can affect one or more systems in the body, such as the digestive system, respiratory system or the skin. In extreme cases, the immune system triggers a response throughout the whole body, resulting in a systemic reaction (anaphylaxis) which is potentially fatal.

Food Intolerance

Unlike allergy, food intolerance which is generally more common usually involves a delayed biological reaction which, although often uncomfortable and unpleasant, is not life threatening.

Causes of food intolerance

People react differently to different foods. There is no one definitive test because food intolerance takes on different forms such as:

  • Food Allergy – immediate reaction (IgE)
  • Coeliac Disease – lifelong autoimmune reaction to gluten proteins which damages the gut wall and prevents nutrients being properly absorbed
  • Enzyme deficiencies – lifelong deficiencies such as lactose intolerance
  • Chemical sensitivities – such as reactions to food additives like tartrazine (E102), caffeine  and sunset yellow (E110)
  • Reaction to histamine in foods
  • Delayed onset food intolerance (measurement of food-specific IgG antibodies used by YorkTest as a strategy to determine which foods to eliminate); need not be lifelong

YorkTest Programmes

The NHS acknowledges food intolerance and recommends food diaries and elimination diets as the preferred method of treatment. It can however be difficult to identify problem foods, especially as it is common to experience reactions to several different foods at the same time.

The problem with an elimination diet can be that, without knowing exactly which foods are causing a problem, you might be depriving yourself unnecessarily of nutrients you don’t need to avoid. Also if you try cutting out a combination of suspected ingredients all at once it can make it more difficult to pin point the exact trigger foods.

At YorkTest Laboratories, we have spent the last 35 years, researching and developing our knowledge in the field of diagnostic testing and we are the leading providers of food-specific IgG antibody testing services.

Working alongside trained Nutritional Therapists, YorkTest have developed comprehensive programmes with individually tailored nutritional advice and support to help people balance their diets, optimising their health and wellbeing.


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Important Information

Some people have detectable levels of raised food-specific IgG antibody levels but do not experience any health problems. We recommend that only people showing symptoms should take a test, and we always advise that these symptoms should first be checked out by a GP to rule out anything serious.

YorkTest food intolerance programmes do not provide information about Coeliac Disease, enzyme deficiencies such as lactose intolerance, IgE-mediated allergies, histamine sensitivity or other chemical sensitivities.

YorkTest Nutritional Therapists have chosen to use the YorkTest food-specific IgG antibody test as a strategy for the elimination diets that they recommend. The presence of food specific IgG antibodies indicates that the body has shown a reaction to a particular food(s). Many people have circulating levels of IgG antibodies to foods in their blood, but, in order to support their strategy for dietary elimination, YorkTest and their Nutritional Therapists have defined the cut-off used to determine whether food-specific IgG antibodies are detected or not as 10 AU (arbitrary units) per millilitre (AU/mL) of blood, with a “borderline” result being defined as 6-10 AU/mL.

The YorkTest Food Intolerance Programmes measure food-specific IgG antibodies.