Gut health gimmick: Food intolerance tests

I'd be surprised if you hadn't heard of food intolerance tests by now. Gut health is becoming a new trend, and it's easy to see why: 40% of us in the UK are believed to have gut health issues (1), from the most common ones like irritable bowel syndrome (IBS) to less common ones like coeliac disease.


The gut is a really important part of our overall health (not just our digestion). For instance, 60-70% of our immune cells are in and around the gut, so people with poor gut health tend to find they're ill more often than others. The gut has been linked to almost every other organ in the body, so maintaining a healthy gut is vital for feeling good and staying healthy in the long term.

There are plenty of ways to improve your gut health that look at overall diet and lifestyle, yet many people start with the assumption that the problem is a single food or nutrient, when that is very rarely the case. I have had clients ask whether I provide food intolerance tests because they’ve seen them online - as soon as you search for anything related to the gut, algorithms pick up on this and you’ll start to see personalised ads for everything from these food intolerance tests to kefir chocolate.

With such a variety of potential gut health issues, it would be amazing to diagnose every single one of them with a simple test. The problem is, the science just isn’t there yet. Some issues, for instance, coeliac disease or an allergy to milk or wheat, can usually be tested for free via your GP:

  • IgE testing for allergies (not to be confused with IgG testing, detailed below)
  • coeliac disease testing
  • hydrogen breath test or blood test for lactose intolerance

The ones offered online, however, are usually IgG testing (used in York tests), hair analysis, breath test for anything other than lactose intolerance and even kinesiology or muscle analysis. None of these tests are legitimate ways to diagnose a food allergy or intolerance. An IgG test, which stands for Immunoglobulin G, tests for exposure to something, not intolerance. So it shows you what you’ve eaten recently, not what you’re intolerant to.

Why I don’t offer food intolerance tests

1. At best, they’re absolutely useless. Read that again. They are not able to actually diagnose a food intolerance or allergy. At worst, they’re harmful - when people restrict whole foods or food groups with the belief that they are causing the issue, a) the underlying issue may not be resolved and b) they may not be getting the nutrients they need, for example fibre.

Recently, the Advertising Standards Authority ruled that York Tests, which provide IgG intolerance tests, were not allowed to claim to diagnose food intolerance anymore. This means that it’s now illegal to make these claims. ⁣Read the fine print on these websites (if you can find it), and you’ll see how careful they are with wording.

2. Doing these tests often delays people going to see a professional about their issue - a GP, dietitian or registered nutritionist. That means that many need urgent medical investigation by the time they do see one, which could have been avoided with earlier help.

3. If you need any more reasons, they’re also very expensive!

If you think you have an intolerance to a certain food, before trying a test online or self-diagnosing, have a chat with your GP. They will be able to help you with the appropriate testing and diagnosis.

If you have gut health issues like bloating, diarrhoea, gas or constipation, book in a free discovery call with me to see how I can help, or check out the specialised Gut Health package on my website.



The views expressed in this article are those of the author. All articles published on Nutritionist Resource are reviewed by our editorial team.

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