Should You Do A Food Intolerance Test?

Food intolerances are extremely common with up to 20% of the population experiencing food related symptoms. These include but are not limited to; gastrointestinal symptoms such as bloating, cramping and flatulence as well as extra-intestinal symptoms like brain fogs, headaches and itching (Tuck et al, 2019).

There are many high street retailers selling food intolerance testing kits claiming that their kits can diagnose food intolerances and all you’ll have to do is remove the culprit food and lo and behold, your symptoms will get better.

Sound familiar?

If you’re currently facing food related symptoms and debating whether or not to perform a test on yourself, you must firstly understand what it is that you are coughing up money for.

This article will examine what these kits are testing for, the differences between food intolerances and food allergies plus whether you would benefit from taking one for yourself.

Firstly, a little bit of an immune system recap.

IgE & food allergies

The immune system is a vast network of cells that secrete proteins called antibodies (or also known as immunoglobulins) in response to a foreign invader (also called antigens).

There are several different immunoglobulins that have different functions within the body. 

Immunoglobulins A, D and M make up about 20-30% and are not largely involved in food mediated immune reactions however, immunoglobulins G and E (IgG & IgE) are involved and will be the focal point of this discussion.

What happens during an allergic reaction?

When a true food allergy is present, typically with things like peanuts, shellfish, wheat - an IgE response will occur upon consumption (Valenta et al, 2015). These responses can vary between milder skin rashes to more serious life threatening anaphylaxis.

IgE mediated responses from the immune system are programmed to happen against a specific food, no matter what the circumstances and conditions are when it was ingested. Some allergies are incredibly strong and even the smallest of quantities/trace amounts can set off a reaction - think about how strict aircrafts are with this sort of stuff! (Yu et al, 2016).

Ultimately, these are genetically predisposed allergies where the response is reproducible and sometimes fatal.

What about intolerances?

Outside of true IgE mediated food allergies, there is a lot of grey area when it comes to food intolerances. Let’s explore this further…

During normal digestion of food, proteins will be broken down into smaller amino acids by the enzymes and acids in our stomach which will be then moved onto the small/large intestines where absorption takes place.

However it is not uncommon for about 15% of proteins and certain food allergens to be incompletely digested which allows them the opportunity to break through the lining of the digestive tract - making contact with the residing immune system (Brzozowski et al, 2011).

On the other side of the lining of our digestive epithelial tract (which is only one cell thick), the vigilant immune cells stay alert for any potential pathogens. Breaching of this thin barrier can become more and more present when there are high levels of inflammation present.

In the event that an undigested food particle makes it’s way through the lining of the digestive tract and becomes in contact with the immune system, an IgG immune response ensues (Gocki et al, 2016).

According to the European Union of Allergology and Clinical Immunology (EACCI), the presence of IgG antibodies is not indicative of an allergy or food sensitivity, but indicates a repeated exposure to food/nutrients which are being treated by the body as foreign. They go on to state that using IgG based testing should not be used as a diagnostic tool for food intolerance (Stapel et al, 2008). 

So what do food intolerance tests show us?

It is likely that IgG based testing is merely a picture of our immune system’s normal physiological response to commonly eaten foods which have made its way through the digestive epithelial lining and have interacted with the immune system.

A study carried out on 12 healthy volunteers confirmed this when they were asked to have 9 commonly consumed foods to which they tested their immune responses for. All participants had increased levels of IgG4 however nobody reported any adverse symptoms (Tay et al, 2007).

Again, this indicates that an IgG response to food is normal and does not necessarily equate to symptoms being present - nor does it mean that these foods should be excluded from the diet.

In addition, further inflammation caused by the immune reaction to antigen creates further permeability to an already weakened gastrointestinal lining making it easier for subsequent antigens to penetrate.

As far as diagnosing food intolerances go, there aren’t many clear cut ways in doing this at present. Even diagnosing a wheat/gluten intolerance (not coeliac disease) is done by the long-winded way of removing it from the diet for a period of time to see if symptoms get better followed by a reintroduction/challenge phase to see if symptoms return. 

Common food intolerances like high FODMAP foods (fermentable oligo-di-mono saccharides and polyols like onions, garlic, apples) all follow the same removal/reintroduction process to confirm intolerance. There are breath tests that can be performed to establish an abnormal increase of gas production which is used to confirm a condition called SIBO (small intestinal bacteria overgrowth) which is usually associated with intolerances to high FODMAP foods but the aftercare still remains the same, removal followed by reintroduce.

What else could be contributing to my symptoms?

With food intolerances so rife in today’s world, the search for a single/multiple food/s to blame it on becomes the easy game to play. Optimal digestion is not only complex but also becoming rarer to find as modern day living has become increasingly stressful which has a knock-on effect on digestion.

In my clinical practice, getting a full picture of the individual’s wider health and overall lifestyle is crucial as we know that the human body works as one whole operating system. Increased stress levels is almost always the first place to explore as this can greatly impact one’s ability to optimally digest and absorb the foods that we eat.

How does it do this?

Well the brain in our head is connected to the brain in our guts (enteric nervous system) by a bi-directional pathway served by the vagus nerve, the longest nerve in our bodies. Kind of like the M1 motorway which travels north and south, relaying information both upwards and downwards. This connection is also known as the gut-brain axis (Bhatia & Tandon 2005). The communication between the brain and our gut is happening constantly throughout the day and we can see examples of this in quite simple but astonishing effect in two scenarios. 

Picture scenario 1 where you are about to give a public speech, your legs become a bit wobbly, your palms start to sweat a little and your mouth goes dry. It’s this drying of the mouth and the attenuation of saliva production that tells the body that this is no time to be thinking about digestion. This is your classic ‘fight or flight’ mode and no saliva = no salivary enzymes to break food down. This is likely to be happening throughout the digestive tract where both stomach acid and pancreatic enzyme production will be low - both are essential for optimal digestion (Collins, 2001). Constantly eating on the go or whilst working in front of a computer might not be as stressful as giving a public speech but it definitely isn’t where the nervous system needs to be for optimal digestion.

Now picture scenario 2, you’ve just had xmas dinner and you are sitting on the sofa watching your favourite movie, you start dozing off. The blood in your body rushes to the digestive tract to support digestion and your energy levels drop. The ‘rest and digest’ mode of your nervous system supports optimal digestion but requires both you and your external environment to be calm and relaxed.

Mindful eating

Have you ever experienced yourself getting bloated or negatively reacting to certain foods on certain occasions but then was completely fine when you had it again on another occasion? Maybe at a party, or on holiday where you were in a better headspace and calmer?

HOW you eat your food can matter greatly.

A novel yet exciting approach in supporting chronic digestive issues is something called mindful eating. This is where you spend some time moving away from screens, heavy work and shifting your attention to the food in front of you and your mind-body connection. Focussing on breathing and stimulating the vagus nerve has been shown to improve the gut brain association of digestion (Adeniyi, 2015). 

I have come across multiple occasions in clinical practice whereby an individual is convinced that a food intolerance is present and would want to undergo all the different tests to diagnose it and take all the supplements to try and correct it - to then go away on holiday and not experience the same symptom when consuming that very same food.

Typically speaking, when a true food intolerance is present, you would have a strong idea about it. You most likely would have had multiple encounters with it over several years and may have even tried removing it from your diet already. But when symptoms are new or seem to fluctuate from week to week, a stress based reaction may be more likely (Yaribeygi et al, 2017). 

The low-down on food intolerance testing

There are two main responses that we might see when it comes to food allergies and food intolerances. IgE responses occur during ingestion of a food allergy that is likely to have developed during childhood whereas more commonly seen IgG responses arise from repeated exposure to certain foods that have been incompletely digested.

The immune system is an extremely complex subject which food intolerance testing companies may exploit. Especially when marketing to desperate consumers knowing that they are desperate for answers.

There may be other reasons why you might be struggling with certain foods or symptoms, like your specific gut microflora, lack of enzymes, hydrochloric acid, stress etc.

Currently there is no official way of diagnosing food intolerances so the only real way of finding out if you’re sensitive to a certain food is by doing it the long way and going through an elimination phase followed by a reintroduction phase.

Work with a digestive health practitioner 

If you’re currently experiencing food based symptoms and feeling overwhelmed about where to start, set up an initial discovery call to learn about my programs and how I may be able to help you rediscover your gastrointestinal health and improve your overall quality of life.

References

Adeniyi, Morenikeji, O.A. and Emikpe, B.O. (2015) ‘The prevalence of gastro-intestinal parasites of carnivores in university zoological gardens in South West Nigeria’, Journal of Veterinary Medicine and Animal Health, 7(4), pp. 135–139. doi:10.5897/jvmah2014.0336.

Collins SM. Stress and the Gastrointestinal Tract IV. Modulation of intestinal inflammation by stress: basic mechanisms and clinical relevance. Am J Physiol Gastrointest Liver Physiol. 2001 Mar;280(3):G315-8. doi: 10.1152/ajpgi.2001.280.3.G315. PMID: 11171612.

Konturek PC, Brzozowski T, Konturek SJ. Stress and the gut: pathophysiology, clinical consequences, diagnostic approach and treatment options. J Physiol Pharmacol. 2011 Dec;62(6):591-9. PMID: 22314561.

Gocki J, Bartuzi Z. Role of immunoglobulin G antibodies in diagnosis of food allergy. Postepy Dermatol Alergol. 2016 Aug;33(4):253-6. doi: 10.5114/ada.2016.61600. Epub 2016 Aug 16. PMID: 27605894; PMCID: PMC5004213.

Stapel SO, Asero R, Ballmer-Weber BK, Knol EF, Strobel S, Vieths S, Kleine-Tebbe J; EAACI Task Force. Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. 2008 Jul;63(7):793-6. doi: 10.1111/j.1398-9995.2008.01705.x. Epub 2008 May 16. PMID: 18489614.

Tay, S.S. et al. (2007) ‘Patterns of immunoglobulin G responses to egg and peanut allergens are distinct: Ovalbumin-specific immunoglobulin responses are ubiquitous, but peanut-specific immunoglobulin responses are up-regulated in peanut allergy’, Clinical & Experimental Allergy, 0(0). doi:10.1111/j.1365-2222.2007.02802.x.

Tuck CJ, Biesiekierski JR, Schmid-Grendelmeier P, Pohl D. Food Intolerances. Nutrients. 2019 Jul 22;11(7):1684. doi: 10.3390/nu11071684. PMID: 31336652; PMCID: PMC6682924

Valenta R, Hochwallner H, Linhart B, Pahr S. Food allergies: the basics. Gastroenterology. 2015 May;148(6):1120-31.e4. doi: 10.1053/j.gastro.2015.02.006. Epub 2015 Feb 11. PMID: 25680669; PMCID: PMC4414527.

Yaribeygi H, Panahi Y, Sahraei H, Johnston TP, Sahebkar A. The impact of stress on body function: A review. EXCLI J. 2017 Jul 21;16:1057-1072. doi: 10.17179/excli2017-480. PMID: 28900385; PMCID: PMC5579396.

Yu W, Freeland DMH, Nadeau KC. Food allergy: immune mechanisms, diagnosis and immunotherapy. Nat Rev Immunol. 2016 Dec;16(12):751-765. doi: 10.1038/nri.2016.111. Epub 2016 Oct 31. PMID: 27795547; PMCID: PMC5123910.