Food intolerance tests

Many of my clients ask me about food intolerance tests in the hope of identifying the cause of their symptoms. With so many tests available, ranging from holding pieces of metal to blood testing and hair analysis, and with so many plagued by ‘food intolerances’, surely anything is worth a try in the hope of finding a cure to these distressing symptoms?

Are food intolerance tests worth their money? Do they produce reliable results? And long term, can they have a detrimental effect on your health? Want to know what happens when this Dietitian with no symptoms of food intolerances (or allergies) sends off her intolerance test for analysis? Keep reading to find out………

Food reactions

Reactions to food result in a whole range of distressing symptoms, including; skin rashes, swelling, bloating, diarrhoea, constipation, reflux and migraines. Food can cause these reactions by two main ways – by an intolerance or a food allergy. It’s important to identify which one is causing your symptoms, as the reactions need to be uniquely managed. So, what’s the difference between a food allergy and a food intolerance? Simply put

Food allergies involve the immune system, whereas food intolerances don’t.

Food allergies

When we think of food allergies, most of us think of ‘immediate response’ food allergies. These allergies are caused by an antibody called IgE, which recognise the food as ‘foreign’ and dangerous. The IgE antibodies kick off a chain reaction in the immune system which can lead to potentially dangerous and distressing symptoms such as; skin rashes, hives, swelling and anaphlaxis. Tests measuring IgE can be carried out at your local hospital and are scientifically validated, although are rarely ‘black and white’. The results need to be read by a qualified professional, alongside your personal clinical history. I’ll let Dr Collard from Allergy UK explain more…..

Other immune cells can also be involved in food reactions. These reactions are called ‘non IgE allergies’. The antibodies or immune cells involved in these allergies take a longer time to respond to the offending food. This causes diverse symptoms that occur over many hours to days. Many of the symptoms are often gastro (bowel) or skin related, and can produce a confusing picture due to the time delay from consumption of a particular food to the onset of symptoms. These allergies are often referred to as ‘delayed type’  or ‘type 4’ allergies and just to add to the confusion….. some will refer to these allergies as ‘food intolerances’ as although they involve the immune system they are non-IgE allergies.

food intolerance tests

food intolerance tests

A really important difference between a food allergy and a food intolerance is the amount of food that can be tolerated. In allergies, even the tiniest amount of the food or allergen needs to be avoided. Label reading and avoiding potential contamination of the allergen are a major part of life for a person with a food allergy. Food intolerances on the other hand are managed quite differently. The intolerant food can usually be accepted in small amounts and only causes a problem when that amount is exceeded or when combined with other intolerant foods. Food allergies and intolerances are therefore individual to each person and require an individual approach to managing them.

What causes food intolerances?

Food intolerances can be caused by a range of mechanisms, such as a pharmacological response to a chemical (caffeine or salicylates) or an enzyme deficiency in the digestive system preventing digestion and absorption of the food, as is the case with histamine and lactose intolerance. Increasingly research is showing us the role our gut bacteria play in the symptoms and management of food intolerances.

My food intolerance test

I’m very fortunate to not suffer from the distressing symptoms of food reaction that many of my clients describe. I was however, particularly interested in the results of my food intolerance test. Would it confirm that I don’t have any food intolerances/allergies?

One of my clients gave me her previously purchased (but not used) ‘food intolerance’ testing kit. The test can be bought online or from a certain large supermarket chain. At a mere cost of £10, I can see why folk feel there is no harm in taking the test.

The test was from a well marketed company. This particular test measures the level of the IgG antibody in the blood. The theory is that an increase in your IgG levels indicates ‘food intolerances’. Specific IgG levels to specific foods can then be measured to indicate which foods are causing the ‘intolerance’.

My food intolerance test

Food intolerance test

Food intolerance test

The test was really easy to use and simply involved pricking my finger and covering the supplied absorbent wand with my blood, posting it back to the company and await my results of whether I am (or I’m not) suffering from food reactions……….

Very promptly, I received a phone call back. The nice and very convincing man from the well marketed intolerance testing company informed me that I was indeed ‘intolerant’ to a number of foods! Really!?! The nice and very convincing man asked me a number of questions and suggested the next step of identifying my ‘food intolerances’ through a £289 IBS test! I then asked a few questions of my own regarding whether this pricey test would highlight just intolerances or ‘delayed type’ allergies too. The resulting conversation left me utterly infuriated. His scientific knowledge of allergies and intolerances was limited, but delivered with such confidence, I can see how many are convinced. More worryingly, when questioning his dubious scientific understanding over the difference between allergies and intolerances, as “my doctor told me……..”  I was promply told “your doctor is wrong”. Appalled that these companies are undermining their customers confidence in their GP in an attempt to gain their trust and ultimately make money from people who are desperate for answers.

Rant over…

So, needless to say, my journey with ‘food intolerance tests’ ended there.

Are there any scientifically validated food intolerance tests?

food intolerance tests

food intolerance tests

Yes! Validated food intolerance tests, used alongside a detailed clinical history are really useful to add pieces of the jigsaw to your personal clinical picture. It takes the skills and expertise of a medically trained health professional to assess which food intolerance test is best for you. Each test only measures one mechanism which could potentially be causing your symptoms. For example, if your symptoms are caused by a food intolerance due to a lack of a digestive enzyme, your blood allergy test will be negative. Also, it’s not just about food! Other causes of your symptoms need to be considered and ruled out. Going down the route of taking a non scientifically validated food intolerance test could lead to costly and unnecessary food exclusion, which could have a negative effect on your long term health without reducing the symptoms you’re currently suffering from.

I have IBS, which food intolerance test should I do?

There are a number of food intolerance tests that are performed by medical professionals.  Two of the main ones are; stool sample testing and hydrogen breath tests. Stool sample tests can indicate how well you’re digesting and absorbing food and also rule out a number of other potential causes of your symptoms.The hydrogen breath tests measure the hydrogen gas produced by your gut bacteria following the ingestion of certain foods, usually lactose, fructose and sorbitol/mannitol. The results are particularly useful alongside other dietary treatments of food intolerances such as food elimination diets.

Food intolerance tests – Food elimination and reintroduction

As a dietitian, these are the ‘food intolerance tests’ we would most frequently carry out on our clients to see if food reactions are an issue. They would be advised only after taking a detailed assessment and after the ruling out of other medical causes for your symptoms. They can take a long time and require a lot of effort, but the results are individual to the client, with the aim of reducing their symptoms whilst making sure the remaining food contains all the vitamins, minerals and fibre it needs – looking after your health as a whole.

food intolerance test

food intolerance test

Unfortunately there are no quick fixes when it comes to identifying food intolerances and using non validated food intolerance tests (blood IgG testing, cytotoxic food testing, kinesiology, vega testing, electrodermal testing, pulse testing and hair analysis) can often lead to increased confusion, increased costs, missed diagnosis, long term nutritional deficiencies and for many …… continuation of their symptoms.

In summary, my advice would be to steer well clear of any non validated food intolerance test. Discuss any food reactions with your GP and request a referral to a dietitian or an allergy/gastro specialist.

If you enjoyed my food intolerance tests blog post, you might also want to read ‘low FODMAP diet’ blog post.


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Registered Dietitian and owner of The Internet Passionate about family nutrition and the dietary treatment of Irritable Bowel Syndrome (IBS) Busy mum of 3 little uns. Cheshire, UK

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