Can at-home food intolerance tests really diagnose poor gut health?

With a plethora of online companies offering food sensitivity testing, can a simple test tell us what’s bothering our gut or is it all too good to be true? Writer Lisa Bowman investigates. 

We humans have an innate need to blame something for our problems. Spots? Gotta be hormones. Bad mood? It’s a full moon. Bloated? Must be the cheese we just ate. It’s estimated that 10% of the UK’s population has a food hypersensitivity, ranging from serious allergies to mild intolerance.

When companies are flogging DIY food intolerance kits to all and sundry, just how seriously should we take their diagnoses?

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Firstly, it’s important to note the difference between food allergies and intolerance.

“The term ‘allergy’ is often misused as an overarching term for any reaction,” advises NHS consultant immunologist Dr Dinusha Chandratilleke.

“Having an allergy means there’s immune system involvement. For example, with a peanut allergy, the immune system incorrectly detects that peanut is a dangerous protein and produces immunoglobulin E (IgE) antibodies, which cause part of the immune reaction – this could be hives, swelling episodes, breathing difficulties, feeling light-headed or collapse.Allergic reactions happen very quickly after exposure – within half an hour to an hour, but often within minutes.

“Food intolerance reactions are more localised, eg nausea, abdominal pain, feeling tired or bloated. Non-allergic reactions happen hours or days later, so if the timing is quite delayed after eating a suspected food, it’s unlikely to be an allergic reaction.”

Are any intolerance tests credible?

The British Dietary Association (BDA) only recommends four types of testing when it comes to food hypersensitivity:

  1. Skin prick tests (a small amount of diluted allergen is placed on your skin, which is then pricked)
  2. Allergen-specific IgE blood tests (blood is tested for increased levels of IgE antibodies)
  3. Food challenges (consuming small amounts of suspected food culprits) 
  4. Food exclusion (cutting food out then slowly re-introducing it).

The BDA does not recommend any other type of testing, simply because they’re not scientifically proven. These include hair sample tests and commercially available MAST (multi-allergen screening test) blood tests, which are inconsistent and often present patients with a long list of “bad” foods, severely restricting their diet. 

Prue Butterworth went to her GP after suffering from recurring facial swelling, where she was referred for skin prick and blood tests, which revealed no allergies or intolerances. “Desperate for answers, I purchased a hair sample test online,” she tells Stylist. “The results showed numerous intolerances, which I found overwhelming, so I ignored the results. I later found out that the swelling was a reaction to medication I was taking.”

This is why it’s important to seek advice from your GP in the first instance, so they can assess your full medical history and work out if there are any other potential causes for your symptoms.

“People often say, ‘I’ve had a reaction to something and I’m not sure what it is,’ expecting to be tested for many things to identify what the cause was,’ says Dr Chandratilleke. 

“Realistically that’s not what happens. We want to know the sequence of events leading up to the particular reaction – what they ate and when – and how long the symptoms took to develop and settle down. Then we work out whether the reaction was suggestive of an allergic reaction or intolerance. It’s a bit like a police investigation – we need as much information from the patient as possible to lead us to a list of potential culprits.

“With this information, we can then select tests that are relevant to the patient. This often includes keeping a food diary, which is usually overseen by a dietitian. That way, if you suspect you have an issue with, for example, egg and you have problems on some days when you eat egg and some when you don’t, it can help us to rule that food out.”

She says that hospitals or allergy departments are only going to be doing testing that’s reliable and scientifically justified: “If some of these private intolerance tests had good evidence behind them, we’d be doing them.

“I can definitely understand the appeal, as it sounds nice to be able to do a blood test and get a list of what you can and can’t eat, but in general, these tests aren’t reliable.” 

Andrea Maylor suffered with stomach issues for three years before turning to a private food intolerance test.

“I ended up in hospital because of my issues, but the NHS wasn’t very helpful and I wasn’t offered any food intolerance testing, so I decided to take matters into my own hands,” Maylor explains.

“I ordered a hair sample and blood test online, which left me with a huge list of foods I couldn’t eat, including dairy, most meat and some fruit/vegetables. I cut out everything on the list except red wine, and my issues went away. I’ve tried reintroducing some of the foods, and without fail, the pain always comes back. The dietary restrictions have had a huge impact on my life, but it’s been worth it.” 


Nutritionist Yalda Alaoui spent thousands of pounds on food intolerance tests during years of suffering with IBS, receiving inconsistent results.

“After years of research and retraining as a nutritional therapist, it became clear that reactions after eating can be a sign of leaky gut syndrome rather than a problem digesting certain foods,” explains Alaoui.

“When gut bacteria aren’t diverse enough, we can lose the mucus layer covering our gut lining, which leads to the gut being permeable and small particles of food entering the bloodstream. The immune system subsequently produces antibodies against those food particles, which may show up in intolerance tests. However, that doesn’t mean you should avoid those foods – the solution is to improve microbiome diversity via your diet.” 

Studies show that stress can also mimic food intolerance reactions. Cortisol is released in times of stress, which can affect bowel function, as well as cause hives.

Wellness business mentor Vicky Shilling was struggling with IBS when she purchased a food intolerance blood test. The results motivated her to cut yeast, sugar and fermented foods out of her diet.

“The changes I made to my diet did coincide with an improvement in my IBS symptoms,” Shilling says.

“However, I was also doing stuff like meditation, exercising more and blogging about my experience, which helped me de-stress. The dietitians I met via my blog made me realise the test I took wasn’t worth the paper it was written on.”

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So, if you suspect you may be intolerant to certain foods, rather than potentially wasting money on costly testing, you’re better off keeping a food diary in the first instance – also noting down any potential emotional triggers – before discussing that info with your GP.

Of course, if you suspect a serious allergy, head straight to your GP. 

For more health and nutrition information, visit the Strong Women Training Club.

Images: Getty

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