Food sensitivity

Tummy trouble: is it food sensitivity?

In Diet, Nutrition and Recipes, Health and Nutrition by Dr Casey ConroyLeave a Comment

Do you experience nagging digestive issues? You may have Irritable Bowel Syndrome.

Having digestive issues on a near-daily basis isn’t normal. Symptoms such as a sore stomach, bloating that rarely seems to go away, nausea, gas (both burping and flatulence), and uncooperative bowels, may suggest you have Irritable Bowel Syndrome (IBS), which affects around 20% of Australians.

IBS is usually diagnosed by a GP after ruling out other health conditions such as bowel cancer or infection. For many it’s a frustrating condition. Rather than giving you an explanation for your symptoms, IBS suggests a number of possible underlying causes and triggers. And there are many.

Conventional treatment options such as anti-depressants, anti-spasmolytic drugs, and medications to treat diarrhoea or constipation may be trialled. But while these may alleviate symptoms, they don’t usually address the root causes of the problem. 

And so for many people – especially those more inclined towards natural healing – a diagnosis of IBS is akin to opening Pandora’s box and can lead down a winding trail, one with many time and money-consuming sidetracks. Two of these are unsubstantiated food intolerance testing, and questionable elimination diets.

Blame the food?

One of the first conclusions folks with IBS jump to is food sensitivity. And with a plethora of food sensitivity testing options and elimination diets now available, the temptation to ‘take charge of your health’ is understandable, given how frustratingly vague a diagnosis of IBS can be. The two most common ways I’ve seen people do this is by putting themselves on one of thousands of strict elimination diets you can find on the internet, or by ordering a test that gives you a neat and colour-coded list of your problem foods, and eliminating said foods.

The tendency to point the finger at specific foods or food groups as the culprit is an emerging pattern. This is followed by what’s usually a lengthy elimination of those foods, often without the desired level of symptom relief. We end up with a person still suffering from IBS, despite having taken many foods out of their diet.

If you want to get to the bottom (pun unintended) of your digestive maladies, you’ll need to take a more critical, less reactive approach to healing IBS. There are many other possible causes for your upset tummy, some of which have absolutely nothing to do with eliminating multiple foods or entire food groups. 

In our current health-vigilant, food-focused society, we perhaps over-emphasise perfecting our diets and can turn a blind eye to other possible causes of IBS. And given the vilification of so many foods in our current diet culture – sugar, carbs, meat, dairy, gluten, wheat, legumes, and grains being some of the more common so-called ‘toxic’ or ‘fattening’ foods – placing the blame on these foods as the sole cause of our IBS can feel like killing two birds with one stone. But it’s not always the answer.

Possible causes besides food sensitivity

Nagging digestive issues, body aches, fatigue, or unexplained migraines? First, you need to find out if it really is food sensitivity, also sometimes called food intolerance.

Food sensitivity is an inflammatory reaction against a specific food or food component. This is not the same as allergy to a food like peanuts, which may lead to sudden breathing difficulties and require an injection of adrenaline via an epipen. Food sensitivity is less obvious and more complex than food allergy. There can be a wide range of symptoms, and symptoms may kick in only after days, or accumulate over time, making the problem food(s) challenging to identify.

There are some crucial considerations to take before you start eliminating foods from your diet:

1.     Rule out non-IBS possibilities

This should be your first port of call when you begin investigating your digestive issues. Depending on your age and family history, you may need to see your GP to be checked for inflammatory bowel diseases (IBD) such as Crohn’s disease or ulcerative colitis, and bowel cancer.


2.     Coeliac disease

While going gluten free is currently in vogue amongst the remotely health conscious, a small percentage of the population truly cannot consume any gluten without experiencing severe side effects, including extensive gut damage. Although blood and genetic testing can be used to screen for coeliac disease, a diagnosis of coeliac disease should never be made on the basis of these tests alone. A positive blood or gene test always must be followed by a bowel biopsy to confirm diagnosis (1).

3. Gluten sensitivity

Non-coeliac gluten sensitivity is increasingly pinpointed as a potential IBS cause attributed to dietary gluten. This may not show up in coeliac tests, but might be a suspected cause from eliminating gluten and then reintroducing gluten to see if issues such as bloating, stomach pain, or diarrhoea and constipation re-emerge. The cause and treatment of non-coeliac gluten sensitivity is not yet well understood. However, emerging research suggests it may not be gluten that is the culprit but instead the malabsorption of fermentable sugars (FODMAPs)(2).

3. SIBO and parasites

A number of other factors besides food sensitivity may be contributing to your IBS symptoms. These include small intestinal bacterial overgrowth (SIBO), where there is an excess of bacterial growth in the small intestine, and infections by parasites contracted from contaminated food or water.

The optimal diagnosis and treatment of SIBO remains elusive. Bacterial culture and breath tests are being used as diagnostic tools with varying amounts of controversy (3). If you suspect any of these, it is crucial you see a qualified practitioner (such as a naturopath, integrative doctor or dietitian with plenty of experience in this area) for assessment before self-treating with antimicrobial herbs or probiotics, or cutting out foods, in an attempt to kill off bacteria and parasites. Self-treating, as such, may make the problem worse. 

4. Stress

Chronic stress is an often forgotten trigger for IBS. If you have experienced psychological trauma, or are highly anxious or stressed in general, this can trigger digestive disturbances that present like food sensitivity symptoms. Lifestyle modification (e.g., yoga, meditation, ample rest) and seeing a mental health professional can go a long way in helping you manage stress and anxiety.

5. Disordered eating

If your pattern of eating is chaotic, you restrict, under-eat or binge (these two often go hand in hand), skip meals, or you feel emotional distress around food, then this can be a trigger for digestive symptoms independent of food sensitivity. The mind-body connection is real and impactful. The number of times I’ve seen patients suffer severe symptoms after eating a food they believed contained gluten, only to later find out it was gluten free, is astounding.

Sorting out issues concerning your relationship with food first may mean food is no longer, or much less of, a symptom trigger. Reaching out for help and seeing an eating disorder specialist is crucial if you think you may have issues concerning your eating behaviours.

Low FODMAP and food chemical elimination diets

So you’ve ruled out all of those possibilities, now what? Here’s what to do if you’re fairly certain the problem is food sensitivity.

Food sensitivity investigation must be centred on a carefully selected elimination diet, regardless of the results of any testing you get. Such investigation is the gold standard and involves relatively short periods of eliminating various foods, followed by food challenges in order to determine symptom triggers. The longest anyone should be on an elimination diet is three to eight weeks. The exception to this is coeliac disease, where gluten needs to be avoided lifelong.

But which elimination diet? Depending on your symptoms and history, the two most evidence-based elimination diets for IBS are low FODMAPs and food chemical elimination. An accredited practising dietitian experienced in treating food sensitivity is your best bet here.

Elimination diets should not be undertaken lightly. They can be very restrictive and lead to other health problems if undergone unsupervised for too long. 

Paleo, blood group, GAPS and other elimination diets

Several authors and experts now recommend different elimination diets as the miracle plan to cure ailments. These often help you shed a few kilos too. 

Try not to fall into the trap of searching Google for an elimination diet to follow. This can result in symptoms worsening or, at the very least, delaying proper treatment and prolonging suffering.

Some sources of information advise a blanket diet to try to control what looks like food intolerance symptoms. These diets include, but aren’t restricted to: wheat free, dairy free, anti-candida, liver cleansing, blood group diet, or paleo. None of these diets are evidence-based for the purpose of diagnosis and treatment of genuine food sensitivity.

These diets often help, even if the underlying rationale (blood group, candida, liver cleansing, etc.) was unsubstantiated. Wheat- and dairy-free diets may assist with coeliac disease or lactose intolerance, for instance.

The problem is that often people are told they must diet forever. However, when suspect foods are not re-challenged, a definitive answer is never found, and problems like nutritional deficiency can result. Also when multiple foods are cut out long term, enjoyment of food may suffer. In susceptible people, food obsession and disordered eating may arise.

Food sensitivity testing

Here’s a common scenario: an individual complains of nagging digestive issues and fatigue. A practitioner suggests a blood test to help them discern which foods are causing the problem. Not knowing any better and desperate to feel well, our sore tummy sufferer hands over their money. They get the results back and dutifully eliminate those foods (all 87 of them!)… but nothing much happens.

Over time they resume eating anything they want and are the same as before, minus a couple hundred bucks. So what gives?

When considering testing and treatment for food sensitivities, tread carefully as much of what is available is both costly and unhelpful. Remember that the gold standard for food sensitivity testing is a correctly prescribed and monitored elimination diet. So the value of testing in the first place is questionable.

Nowadays, several tests are used to ‘diagnose’ food sensitivity. These tests include IgG antibody testing and IgE testing (e.g. RAST), which are suitable tests in specific situations but are inappropriate and inaccurate when testing for food sensitivity (4). 

Don’t waste money on expensive food sensitivity testing that yields questionable results. Unfortunately some practitioners see it as an easy way to show or prove to their patients on paper that they need to change their diet.

Regardless of test results (you don’t actually need to undergo testing) you should trial the right elimination diet in the right way.

In ending…

Hopefully this gives you more clarity when navigating the tricky world of food sensitivity. Remember, an elimination diet must always be individualised. It should also be conducted under close dietetic and medical supervision to minimise the risk of malnutrition. It should never be adhered to for longer than a few weeks. And it should always be followed by challenges to identify avoidable triggers.  

When foods are reintroduced, the symptoms they provoke are typically obvious and more severe than previously experienced. This makes it much easier to pinpoint the culprit foods.

The ultimate goal is to find a diet that manages symptoms with the least amount of restriction. People then have the choice to include trigger foods if they wish, knowing that symptoms may be provoked, but that they can go back to a ‘safer’ diet to help symptoms subside if they become intolerable.



  2. Biesiekierski, Jessica R. et al. (2013). No Effects of Gluten in Patients With Self-Reported Non-Celiac Gluten Sensitivity After Dietary Reduction of Fermentable, Poorly Absorbed, Short-Chain Carbohydrates. Gastroenterology, 145(2), 320-328.
  3. Dukowicz, A. C., Lacy, B. E., & Levine, G. M. (2007). Small Intestinal Bacterial Overgrowth: A Comprehensive Review. Gastroenterology & Hepatology3(2), 112–122.


About the author

Dr Casey Conroy

Dr Casey Conroy, MNutrDiet, BVSc, is a holistic dietitian and nutritionist, naturopath in training and yoga teacher who specialises in women's health, hormones, and the Health At Every Size approach to weight and body concern. She is the founder of Funky Forest Health & Wellbeing on the Gold Coast, and she loves chocolate and any yoga involving an eye pillow..

Share this post

Leave a Comment