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Food allergy tests could risk your health

Which? probe finds many tests unreliable


Some food intolerance checking firms are playing on people’s fears to sell them costly and dubious tests, a Which? investigation reveals today.

And the diagnosis could potentially risk your health if you follow advice to exclude foods, as this could lead to nutritional problems.

Our undercover researchers trialled alternative tests that claim to diagnose food intolerances through analysis of blood samples or strands of hair, changes in electric current, or resistance to pressure applied to their legs or arms.  


We found that:

  • the tests diagnosed 183 intolerances – although the researchers actually had just one medically confirmed allergy and one food intolerance between them
  • identical blood and hair samples sent under different names to the same company produced different test results
  • there was little or no overlap between test results from different companies
  • the testers felt the practitioners applied more pressure when measuring resistance for certain foods – which they were then told to avoid
  • the tests recommended excluding up to 39 foods – which could make it difficult to eat a balanced diet and lead to nutritional problems.


The tests cost between £45 and £275 each, but an expert panel of medical specialists and a dietitian that assessed the results felt that none had diagnostic value for genuine allergies or intolerances.

Many people confuse intolerances – which can be caused by an inability to digest a particular food and have symptoms such as nausea, vomiting and headaches – with allergies, which affect the immune system and can cause severe reactions including anaphylactic shock.

Neil Fowler, editor of Which? magazine, said: ‘A severe allergy can be life-threatening, so it’s no surprise that people want to find out if they should avoid certain foods.But some companies are playing on these fears to sell expensive intolerance tests that are not medically proven. 

‘Our tests have shown them to be unreliable – and they could even endanger your health as following their recommendations could lead to nutritional deficiencies.’

Which? advises people who are concerned that they may have an allergy or intolerance to keep a record of symptoms and a food diary, and speak to their GP.

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