Food intolerance testing: an interview with Dr Gill Hart

insights from industryDr. Gill HartBSc (Hons), PhD, Cert Mgmt (Open), FIBMS
Scientific Director
YorkTest Laboratories

What are food intolerances and how many people are thought to be affected by them?

Food intolerances are caused by adverse reactions to food or drink ingredients in your body. These are very different to food allergies. It is estimated that up to forty-five percent of the population suffers from food intolerances.

Young woman choosing fresh milk produces at shopping in dairy supermarket store

What’s the difference between food intolerance and food allergy?

Food allergies are potentially life-threatening reactions to foods such as peanuts, tree nuts, shellfish, milk, or eggs. Symptoms come on very, quickly, within minutes of eating the food.

Around two percent of the adult population suffer from food allergies, and it is a life-long condition.

Food intolerances tend to be delayed reactions. They are not life-threatening, but they can make life very difficult for sufferers.

Food intolerances usually occur to a number of foods. At YorkTest, people who come to us with symptoms and have positive reactions, on average react to about four to six different foods. It's far too difficult to actually determine what those foods are without a test.

Also, food intolerances aren’t necessarily for life and once you try to break away from eating the culprit foods, you can sometimes tolerate them again. One exception is coeliac disease. Coeliac disease is a life-long reaction to gluten.

What are the main symptoms of food intolerances and how long after eating the specific food can these occur?

The main symptoms of food intolerances are, to start with, digestive problems such as IBS, bloating, diarrhea, constipation and abdominal cramps. Other symptoms include migraines and headaches, weight gain, low energy and low mood.

In addition, skin problems such as eczema, psoriasis and skin rashes; joint pains; and respiratory symptoms such as rhinitis, sinusitis and glue ear.

Food intolerances usually occur between 2 hours and up to 3 days after eating the culprit food, so it can be quite a long time before the actual symptoms manifest themselves.

Human digestive system

Why can the symptoms take so long to occur and what challenges does this pose for identifying food intolerances?

The time relationship between eating the food and getting the symptoms depends on many factors. It links to the digestive process but also the inflammatory response that happens next.

If you eat a particular trigger food only occasionally, then you may be able to relate the eating of the food with symptoms coming on, whether it's a few hours or a few days later.

In a lot of cases, people are eating their trigger foods routinely or regularly, in which case each reaction will sort of run into the next one. Then, they might get almost continuous symptoms; for example they may get bloating nearly every day, IBS or more frequent migraines.

This delay in the process means that it's very difficult to identify the culprit food or foods without doing a test because you're eating a lot of different foods and the symptoms might be ongoing.

What does food intolerance testing involve?

At YorkTest, we provide a simple finger-prick blood test. The blood collection can be done at home.

You prick your finger with the blood collection kit that's provided. You use a very simple device to collect a couple of drops of blood which you then easily package up and send back to our laboratory.

Once your blood sample arrives in our laboratory, we measure levels of food-specific IgG antibodies present in the blood. This is carried out in our accredited laboratory using a hospital standard test, which is performed by qualified laboratory professionals.

We test for up to 158 different food and drink ingredients. We measure the IgG antibodies to these food and drink ingredients. The results are presented really clearly, so you get a list of the different foods tested, and whether you have a positive reaction, no reaction or a borderline reaction (a very low level of reaction).

Is the testing method based on published research?

Yes it is. The testing methods used for measuring the food-specific IgG antibodies are based on published research.

YorkTest has published its own studies on the effectiveness of food-specific IgG antibody-guided elimination diet. In addition, there are many studies that have been published worldwide and the numbers of studies published are growing.

digital illustration antibodies

What support is given once people receive their results?

At YorkTest we think that it is imperative that people receive help and support in changing their diet. It's absolutely paramount that they receive support in removing foods from their diet, but more importantly replacing those foods with things that would be equally nutritious.

Our Customer Care team at YorkTest expertly guide people through the process. Part of the program includes a food diary and a guidebook with supporting literature, but more importantly, consultations with a BANT-registered Nutritional Therapist. These are carried out over the phone at a time that suits the individual.

The Nutritional Therapist, of course, talks through removing foods from the diet and also what you can replace them with to ensure that you still maintain a balanced diet, which is the most important part of our service.

Is there an additional cost for those consultations or are they included?

No. It's all part of the full test program.

How does YorkTest differ from competitor tests?

YorkTest has been going since 1982 and has been offering food-specific IgG tests since 1998. We have published studies to support the services we offer. We provide robust, validated, scientific, hospital-standard tests.

There are many food intolerance tests on the market that have absolutely no basis in science at all. There are hair tests for food intolerance, for example, which have no scientific basis. You can't measure food intolerance from a hair sample.

YorkTest has years of experience in offering this test and a wealth of very positive customer feedback to support what we do. Ninety-one percent of our customers would recommend the services that we offer.

Who is food intolerance testing intended for?

People may identify with some of the symptoms that I've talked about. The first thing we would advise is for them to go and get checked out by their doctor.

If you've got bloating, digestive problems or any of the symptoms I mentioned, the first thing to do is get examined by your doctor.

If you've been given the all-clear and you still think that food could be contributing to your symptoms, then a food intolerance test is something to consider.

A lot of people now are self-diagnosing, the fad being gluten-free and dairy-free. People are doing that without any support and sometimes without replacing eliminated foods with something equally nutritious. They are doing that on their own and starting an elimination diet with no knowledge at all.

What we provide is a starting point for an elimination diet, with results that reflect the body's needs. The IgG antibodies are there in your blood, we measure them accurately and let you know about the foods your body is fighting.

Are food intolerances becoming more prevalent? What are the likely reasons for this?

Yes, they are. This has been widely researched, not only from an allergy point of view, but from an intolerance point of view.

I think there are quite a few reasons for that. If you think about all the processed foods that we eat now, the additives that are used, the way that animals are farmed, the amount of stress we are under.

All these factors can all influence the way that our gut processes foods. In addition, the gut plays a major role in the immune system. That is really influential.

Also, I think the use of antibiotics has a big part to play. The gut flora is important in protecting your gut and ensuring you digest food properly. The use of antibiotics can actually influence the balance in your gut flora.

What do you think the future holds for food intolerance testing?

I'm really excited about the future for food intolerance testing. I think there has clearly been a huge increase in education and awareness about food intolerance. I think that what we know now and the fact that “free-from” foods are now much more readily available is much better compared with five years ago.

Add to that the regulations that are now in place; cafés and restaurants are required to let you know what's in all the different foods. If you have an allergy or intolerance it is a lot easier to eat out now.

I think people are taking much more time and control over their health. They understand that what they eat impacts their health and they feel more empowered than ever to do something about it. I think that this awareness and empowerment will continue to grow and is really important.

I also think that this increased awareness must force gold standards for food intolerance testing because the water is muddied by those tests that have no scientific basis, which is really doing a big disservice at the moment.

YorkTest is leading the way in testing for food intolerance. We would welcome “gold standards” for food intolerance testing and embrace this, but these need to be “pushed through” and I really hope that happens.

I think it's a very exciting arena that we are working in. The public need correct information about the tests that they are buying.

I'm a biochemist and I have over 30 years' experience in the development and validation of diagnostic tests. I've been at YorkTest for eleven-and-a-half years now and I'm an expert in food intolerance, as well as other areas of biochemistry.

I feel passionately that if people use diagnostic tests or testing services that they understand what they're buying and feel empowered to question the manufacturers in order to ensure they get what they actually need.

Where can readers find more information?

They can visit our website or call us for more information:

Food Intolerance Tests are available to people living in most regions around the world.

About Dr Gill HartGill Hart BIG IMAGE

Dr Gill Hart BSc (Hons), PhD, Cert Mgmt (Open), FIBMS is one of the UK’s leading biochemists, with over thirty years’ experience. An established media talent, Dr Hart has offered her expertise to national media and leading figures within the industry, including addressing the House of Lords and appearing as an interviewee on national television TV.

Dr Hart began her career as Senior Biochemist at the Hammersmith Hospital and subsequently specialized in the development and validation of diagnostic tests and testing services for hospital use. In 1999 she set up her own organization to service the needs of the clinical diagnostics industry.

Considered a key influencer within the field of diagnostic testing, Dr Hart joined YorkTest Laboratories in 2005, and has applied her extensive scientific and regulatory knowledge across its health screening services. She regularly gives talks and lectures and was a featured speaker at the 2015 BioSynergy Conference.

Dr Hart’s work has been published in respected outlets such as The Lancet and British Journal of Anaesthesia. Latest authored whitepapers include:

  • Food-specific IgG guided elimination Diet; a Strategy for Weight Loss?
  • Food-specific IgG guided elimination diet; role in Irritable Bowel Syndrome?
  • Role of food-specific IgG-based elimination diets to improve chronic ill health symptoms
  • Best practice for laboratory diagnostic testing
  • Measurement of homocysteine; a risk factor of cardiovascular disease, stroke, Alzheimer’s, dementia, migraines and infertility
  • The impact of nutrition on mental health
April Cashin-Garbutt

Written by

April Cashin-Garbutt

April graduated with a first-class honours degree in Natural Sciences from Pembroke College, University of Cambridge. During her time as Editor-in-Chief, News-Medical (2012-2017), she kickstarted the content production process and helped to grow the website readership to over 60 million visitors per year. Through interviewing global thought leaders in medicine and life sciences, including Nobel laureates, April developed a passion for neuroscience and now works at the Sainsbury Wellcome Centre for Neural Circuits and Behaviour, located within UCL.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Cashin-Garbutt, April. (2018, August 23). Food intolerance testing: an interview with Dr Gill Hart. News-Medical. Retrieved on July 22, 2024 from

  • MLA

    Cashin-Garbutt, April. "Food intolerance testing: an interview with Dr Gill Hart". News-Medical. 22 July 2024. <>.

  • Chicago

    Cashin-Garbutt, April. "Food intolerance testing: an interview with Dr Gill Hart". News-Medical. (accessed July 22, 2024).

  • Harvard

    Cashin-Garbutt, April. 2018. Food intolerance testing: an interview with Dr Gill Hart. News-Medical, viewed 22 July 2024,


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
Cardiovascular health is intricately linked to the food security status of minoritized groups