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  • Marianne Trevorrow ND

Irritable bowel syndrome; it's not just about food elimination!

Updated: Feb 27

As a naturopathic doctor, I frequently see patients with irritable bowel syndrome or IBS. Many of these patients have tried various types of diets; dairy free, grain free/keto, elimination or various others, and have had a variety of diagnostic tests, often with no clear answer. These patients then end up wondering what they can do to fix the problem, and frustrated with all the time, energy and money they may have spent with little to no result.


In reality, most food adverse reactions that underpin IBS are not allergies, even though we might think of them that way. To explain, classic food allergy has very distinct symptoms—an immediate, severe type of response that can include hives, shortness of breath and/or fainting. Without immediate treatment, it can be very dangerous, even fatal. Thankfully, however, true food allergies are not that common—recent guidelines have placed the incidence at only 2% of adults and 8% of children in the developed world.


On the other hand, food sensitivities or intolerances are much less severe, but also much more frequent. They also show up an many different ways; for example, they might appear within 30 minutes to an hour after eating, or may take several hours or even days to appear. Some of these food-related symptoms may mimic conditions more commonly associated with environmental allergies; sinus congestion, headaches, eczema or asthma. Or they might be purely digestive: patients may complain of bloating, abdominal cramps, constipation or diarrhea--classic IBS symptoms. A common characteristic of food sensitivities is that symptoms may be triggered by a food at one occasion, but not on another.


Research tells us that most adverse reactions to food are of mixed antibody type, or a combination of sensitivity and intolerance, but usually somewhere along a spectrum of both. Usually food triggers are a commonly consumed part of the diet; one or a combination of gluten, egg, dairy, soy, corn or pea protein.. The initial triggering event may occur following a gastrointestinal (GI) or other infection, a course of antibiotics, or by processes we don’t yet understand. Microscopically, what is happening is that the digestive immune system begins to recognize these foods as 'foreign' bodies, so the system loses tolerance to that food as something to be digested and assimilated into the bloodstream. Once this process begins in the gut immune system, constituent amino acids (the smallest breakdown products of proteins) are then ‘tagged’ with IgG antibodies, creating antibody/antigen complexes. In small quantities, these complexes have no health effects but when deposited into small blood vessels in the gut, lungs, nasal passages or other areas of the body, can potentially cause or increase the symptoms listed above.


With food intolerances, the problem is different; in this case, the person lacks an enzyme in their digestive tract border that can break down the larger food particles into molecules that can be absorbed into the body. This occurs before the food can even be absorbed. The result is that on all or almost all occasions that food is eaten, the patient will experience gas, bloating, reflux, GI pain or similar symptoms. Lactose or gluten intolerance classically fall into this category.


When I first see patients for IBS, we always discuss if they've tried one of the commonly prescribed diets such as FODMAP or dairy/gluten free, and what the result was. Often, if these diets haven't succeeded, patients will ask about IgG Food Sensitivity (FST) testing to help pinpoint food triggers. My response if that while helpful, FST results often finds some foods that may not be triggering symptoms as well as the ones that do--it tends to cast a wide net. However, if the FODMAP or a targeted elimination diet has failed, doing FST can help us decide where to focus our attention, which many patients find helpful. Depending on which foods show up as positive, and how many foods show up as positive, it also gives us a better idea of how well the gut immune system recognizes food proteins as harmless, and not ‘tag’ commonly eaten foods as invaders.


If there is a known trigger food that doesn’t show up on testing, however, we learn that this could likely be an enzyme problem or intolerance. However, one caveat is that false negative results can also occur if the food hasn't been consumed in a three week period prior to testing. To avoid this, we discuss if there is a food the patient has been avoiding and whether it makes sense to reintroduce it prior to having an IgG FST blood sample taken. Of course, we do not do this if these is an established food allergy or gluten intolerance, as these are special exceptions, and I explain this as well.


However we arrive at deciding on an elimination diet, the procedure is the same; a few weeks of total elimination of those foods and then a controlled re-introduction of each food over a few days, watching for a reappearance of symptoms. This will almost always clarify the picture about sensitivity or intolerance, and let us know how many foods are still an issue for a longer elimination.


Please note again, however, that reintroduction is not appropriate for known food allergies; for those cases, I recommend patients work with an Allergist (MD/DO specialty) if they want to evaluate whether reintroduction is possible for them due to the possibility of severe, life threatening reactions.


With more benign adverse food reactions, however, an important point to remember is that eliminating foods by itself rarely solves problems like IBS. The reason for this is that many food reactions are in fact a messenger for the breakdown of proper immune balance and tolerance, and of the orderly digestion of food and elimination of food waste. As research is increasingly telling us, the real problem is a combination of inflammation, loss of tolerance, but also loss of microbial diversity to prime the gut mucosal immune barrier and enable good digestion.


At this point, many people might be thinking—‘what do microbes have to do with digestion and IBS’? To explain, as far back as infancy, we learn to tolerate foods as our digestive and immune systems develop and mature. This process is supported by gradually increasing numbers and varieties of friendly bacteria that line our digestive tract from top to bottom—what is known collectively as our gut microbiota. We inherit most of these microbes from mom: during pregnancy and childbirth, via breastfeeding, and from touch. Others we gain from coming into contact with these friendly bacteria in food, water and people in our surroundings. Collectively, our immune system and digestive enzyme system develop along with this ecosystem of microbes, what we often refer to as 'friendly' bacteria.


What has been happening since antibiotic medicines appeared in the mid 20th century, however, is that with repeated courses of antibiotics, we are losing microbial diversity in our gut ecosystem. Another problem is that our exposure is increasing: antibiotics are increasingly being used in our meat, dairy and poultry industries and in 'antimicrobial' soaps and hand sanitizers that we use.. As a result, while we have far less infectious disease burden in the modern developed world, we now have increasing incidence of conditions such as IBS.. Scientists and many doctors are starting to make the connection between this loss of microbial diversity, food adverse reactions, and the incidence of allergic-type illnesses such as IBS, suggesting that there is a link between healthy gut microbiota, orderly digestion of our food, and a balanced immune system.


As I guide patients along the journey to managing and healing IBS, we discuss the importance of supporting hormonal and microbial health in addition to what should be done with nutrition. To truly solve the problem, we need to decipher why the gut is treating harmless foods like bacteria or viruses, at the point at which the immune system begins to overreact. We certainly explore whether the loss of microbial diversity or physical stressors are contributing to this process. However, we are also learning that simply adding probiotics to the GI tract via supplements only partially solves the problem, similar to what often happens when patients follow one particular type of diet (e.g. FODMAP). To replete microbial diversity, diet therapy with prebiotic and probiotic foods is emerging as a more sustainable and effective strategy than simply eliminating foods long term. Additionally, figuring out where lifestyle factors such as stress, sleep and exercise are making things better or worse with IBS is crucial to the healing process. IBS can be a condition of improvements and relapses. Still, there is hope for healing IBS with a multi-pronged strategy and good, long term naturopathic medical support.


A previous version of this article appeared in Life As A Human E-Magazine: August 2014.


For more information:


1. Blaser, M. Missing Microbes: how the overuse of antibiotics is fueling our modern plagues. Harper Collins, 2014.


2. Waltner-Toews D. Food, Sex and Salmonella: Why Our Food Is Making Us Sick. Greystone Books, 2008.


3. Zutavern A et al. Timing of Solid Food Introduction in Relation to Eczema, Asthma, Allergic Rhinitis, and Food and Inhalant Sensitization at the Age of 6 Years: Results From the Prospective Birth Cohort Study LISA Pediatrics Vol 121, no1, Jan 2008.

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