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A Dietitian’s Beginner Guide to IBS

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Here at Ignite Nutrition, we are known internationally for our work specializing in irritable bowel syndrome (IBS). As well as other GI disorders of all kinds. What exactly is IBS? In this helpful guide, hear from Andrea Hardy, registered dietitian and Ignite’s owner about common IBS symptoms. We will also discuss how IBS is diagnosed, some treatment strategies, and how a dietitian can help someone with IBS – plus so much more. Let’s break it all down!

Table of Contents

  1. What is IBS?
  2. How is IBS diagnosed?
  3. Subtypes of IBS
  4. What are the symptoms of IBS?
  5. What causes IBS?
  6. Some potential causes of IBS we’re still learning about
  7. What can I do to manage my IBS?
  8. Is there an IBS diet?
  9. What are FODMAPs?
  10. What foods contain FODMAPs?
  11. Other IBS management strategies
A person wearing a yellow shirt holds a roll of toilet paper in their hands toward the camera. Their head and feet are not visible. There is a text box that reads "A dietitian's beginner guide to IBS"

What is IBS?

Do you feel as if your bowels are taking you on a never-ending roller coaster ride of diarrhea, constipation, or both? Have you ever skipped a meal to avoid your burdening bowel symptoms, like abdominal pain, or nausea? Do you find that your daily activities revolve around the bathroom? If so, you may be experiencing symptoms of irritable bowel syndrome.

You may recognize it in its short form as IBS. IBS is mostly considered a functional gut disorder. This means that your digestive system is not working the way it’s supposed to. But, there isn’t anything structurally wrong in the gut. Structural issues are ruled our before an IBS diagnosis. Common examples of those include celiac disease, or inflammatory bowel disease for example.

Is IBS a brain gut disorder?

IBS is also considered a disorder of the gut-brain axis. Think of it this way; There is a 2-way information highway running between your brain and your gut. In IBS, the brain perceives normal digestion as pain, and can then trigger changes in bowel habits. This disruption is believed to be caused by stretching of the intestines with water and fluid, and most recently, research is underway that has shown a sub-clinical inflammatory response as a contributor to that disruption. Simply put, IBS is not just a “food disorder” and therefore involves a multifactorial approach to adequately manage it.

Canada has one of the highest rates of IBS in the world, estimated to be about 18% of the population.1 This is a significant figure, as IBS can greatly impact a person’s quality of life. IBS is one of those health problems that many people have, but few tend to talk about, so keep in mind that it is not as uncommon as you may think.

How is IBS diagnosed?

IBS is diagnosed when specific criteria are met. A person must have structural disorders and other conditions ruled out, if the doctor suspects them to be a potential issue. This includes celiac, inflammatory bowel disease, colorectal cancer, and hypothyroid to name a few.

Once structural disorders are ruled out, symptoms guide diagnosis.

Does the patient meet the criteria for irritable bowel syndrome?

According to the Rome IV diagnostic criteria for IBS, someone must have recurrent abdominal pain on average at least one day per week in the last three months plus two or more of the following things:

  1. Pain related to defecation
  2. Associated with a change in frequency of stool
  3. Associated with a change in form (appearance) of stool2

Just because those are the only symptoms listed in the diagnostic criteria doesn’t mean there aren’t other symptoms! See our section below on symptoms of IBS.

Subtypes of IBS

Before we get into the symptoms that are involved in IBS, it’s important that we discuss the different classifications of IBS first. As this will determine the type of symptoms someone has. There are 4 different subtypes of IBS – and knowing which one you have can help to ensure you get the type of treatment that will help you best. They are:

  1. IBS with predominant diarrhea (IBS-D)
  2. IBS with predominant constipation (IBS-C)
  3. IBS with mixed bowel habits (IBS-M)
  4. IBS unspecified (IBS-U) – this includes people who don’t fit into the above subtypes

With each constipation and diarrhea, the predominant symptoms must be present greater than 25% of bowel movements. With mixed bowel habits, each are predominant 25% of the time. Some patients do not fit into any of these criteria, but still have IBS symptoms, so they would be classified as unspecified.

What are the symptoms of IBS?

Abdominal pain is the hallmark symptom of IBS. It can get better, or worse with defecation (having a bowel movement.)

Other common symptoms include:

  • bloating
  • gas
  • constipation
  • urgency
  • diarrhea

Any and all of these symptoms can occur in IBS. While nausea isn’t considered a traditional symptom of IBS, studies have found that it’s quite common in IBS, too! If you have symptoms beyond the traditional IBS symptoms, there can often be nutrition, lifestyle, or medication strategies to help manage them, too.

If at any point reading through that list, you were like “Hey, that’s totally me!”, consult your family doctor, or consider speaking with a registered dietitian.

A torso of a man who is holding his stomach in pain. He is wearing a grey waffle knit shirt, blue jeans, and a black belt.

What causes IBS?

While we don’t know the exact cause of IBS, research is getting closer to understanding what causes it.

Some factors that increase the risk of developing IBS include: 

  • genetics
  • getting a gastrointestinal virus
  • environment
  • psychosocial factors
  • being female

Researchers now have data to show several potential causes of IBS. This is not surprising, IBS is very heterogenous. While it might feel frustrating not knowing the exact cause, as a dietitian, I am excited about this research as it is leading the medical community to consider sub typing IBS even further, by cause, so we can find the best interventions for the patient.

Some potential causes of IBS include:

The Gut Microbiome and IBS

When we talk about the gut microbiome, we’re taking about the trillions of bacteria that live in your intestines. These microbes play an important role in our health. When they are disrupted, this appears to contribute to symptoms of IBS, potentially disrupting how our immune system reacts to food, how we digest food, how our gut and brain communicate, and so much more. Researchers have found that diet plays a key role in modulating these responses. While data is preliminary, it is promising. Diet or therapeutics specifically targeting the gut microbiome may be in the near future to manage IBS.

Our Immune System and IBS

Aside from the gut microbiome and genetic factors, new research is even looking at the ways in which IBS could be related to the immune system. While there aren’t a lot of studies yet, the current research suggests that in a subset of IBS patients, there appears to be an allergic, non-IgE mediated component that plays a role in their IBS symptoms.3 In addition, FODMAPs, or fermentable carbohydrates, also appear to inappropriately activate the immune system in the gut, leading to an inflammatory cascade that triggers symptoms4,5. More research is needed. But, it does appear that the immune system is involved in IBS – a relatively new finding that may lead to more targeted and helpful interventions.

What can I do to manage my IBS?

While there is no cure for IBS, there are many things that can be done to manage and control symptoms. IBS management is multifactorial, meaning it involves several different approaches and not just one direct strategy.

Things like food intake, stress management, exercise, and medications all need to be considered, which is why we take a 4-pillar approach to IBS care with our patients at Ignite Nutrition.

IBS can really put a damper on activities in your daily life, like going to work, travelling, socializing with others, and eating. In fact, more than 70% of those with IBS feel that their symptoms interfere with everyday life and 46% report missing work or school due to IBS.1

Can stress contribute to IBS symptoms?

Stress in particular can definitely be a contributor to the symptoms of IBS. It’s important to identify the possible stress triggers to help with your mental health overall as well as your symptoms. These days, we are always on the go, with demands pulling us in a hundred different directions. As hard as it may be, it is important to make time for ourselves, exercise, do things we enjoy and get a good night’s rest!

When we constantly feel unwell, it is also common for people to seek out alternative therapies for IBS and while there are a lot of BIG claims about the best IBS fixes, we do need to ensure the things we try are safe and sustainable. IBS is not a one-size fits all and therefore requires an individual approach unique to the individual who is experiencing it.

Is there an IBS Diet?

Some people find that there are certain foods that trigger their IBS symptoms. At this time, the most well-researched diet to support IBS is the low FODMAP diet. This elimination-style diet is strongly supported by research. But may not be an appropriate fit for everyone. Particularly if there is a history of disordered eating.

In many cases, a full elimination diet isn’t even necessary. For many IBS patients, pulling in some more basic nutrition principles to support IBS such as adjusting fibre and fluid intake, eating mindfully, and reducing gut irritants like caffeine and alcohol is just as effective. In fact, much research shows, diets like the NICE diet, or the Mediterranean diet, often performs almost as well as the Low FODMAP diet in managing IBS symptoms.

What are FODMAPs?

FODMAPs stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. This acronym refers to a group of carbohydrates which can be poorly digested in our gut, and for some people, cause unpleasant IBS symptoms.

Following the low FODMAP diet reduces the total amount of these fermentable carbohydrates you consume at a time. This diet starts with a period of restriction. Followed by a reintroduction phase. Proper reintroduction and a balanced, healthy diet is KEY to long term gut health. Your registered dietitian will help you through this process!

Think about your FODMAP threshold like a bucket. The size of the bucket differs between individuals – some buckets are smaller and some are larger. For those who have a larger bucket, they can eat foods containing FODMAPs freely and comfortably. For those who have a smaller bucket, their threshold to high FODMAP foods is lower, so if you overfill your bucket, you can experience IBS symptoms.

Metal buckets of different sizes and heights sitting on a white wooden floor

It’s important to know – FODMAPs aren’t bad for your gut, and it’s NOT all or nothing. Rather, they contribute to symptoms when consumed in excess.

What foods contain FODMAPs?

FODMAPs are present in a lot of foods that most of us eat regularly. Therefore, following a low FODMAP diet can be quite restrictive. As mentioned above, FODMAPs are found in foods that have carbohydrates. But, not ALL carbohydrates are considered FODMAPs. The low FODMAP diet certainly isn’t a low carbohydrate diet. You can think of it more like a “swap this for that” when it comes to carbohydrate-containing foods.

Some High FODMAP foods include:

  • Certain vegetables and fruits like onion, garlic, mushrooms, apples, and watermelon
  • Certain grains; specifically wheat, rye and barley
  • Certain nuts & seeds like pistachios & cashews
  • Pulses like black beans, kidney beans, and large amounts of chickpeas and lentils
  • Lactose-containing dairy (*only if you’re lactose intolerant!)
  • Processed foods that contain high FODMAP ingredients or high FODMAP sweeteners such as honey, sorbitol, or xylitol

All in all, the low FODMAP diet should be thought of as a tool to help manage your IBS symptoms. However, there are other management strategies for IBS aside from just the low FODMAP diet.

Other IBS Management Strategies

IBS management involves a variety of different aspects of health and wellness. While we love our work as gut health dietitians, it’s not just about the food! Some other IBS management strategies to consider include:

  • Mindfulness and stress management strategies including meditation, deep breathing, yoga, gut-directed hypnotherapy, and working with a psychologist or counsellor
  • Medication management such as laxatives, antidiarrheals, pain medications, motility drugs, and neuromodulators to help with the gut-brain connection
  • Supplements such as fibre supplements, enzyme supplements, and herbal supplements that can help with management of IBS symptoms and digestion of specific foods
  • HOW we eat – This involves looking beyond the types of foods we eat and instead focuses on how quickly we eat, how much air we swallow while eating, and our timing and spacing of meals and snacks.
  • Exercise and movement, particularly for helping with stress reduction and bowel motility.
  • Improving sleep quality by improving sleep hygiene, going to bed earlier, and limiting screen time before bed.

IBS does not define you, even though at times you may feel it is controlling your life. With proper management, symptoms can be controlled. Which can improve your quality of life. With the support of your physician and registered dietitian, IBS can be managed—and managed in a way that promotes long term health and nutrition.

A person wearing a yellow shirt holds a roll of toilet paper in their hands toward the camera. Their head and feet are not visible. There is a text box that reads "A dietitian's beginner guide to IBS"

FAQs About IBS

What is IBS?

IBS is a functional gut disorder, meaning that nothing is structurally wrong, but your digestive system is not working the way it’s supposed to. Learn more

Is there an IBS diet?

The most evidence-based diet to support IBS is the low FODMAP diet. This is an elimination diet followed by a reintroduction of foods to identify dietary triggers of IBS symptoms. There are also more basic nutrition guidelines for IBS management if someone is not a good fit for the low FODMAP diet or if they’d like to start with something less restrictive.

What does FODMAPs stand for?

FODMAPs stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. This acronym refers to a group of carbohydrates which can be poorly digested in our gut, and for some people, cause unpleasant IBS symptoms. Learn more about the low FODMAP diet

Is there a test for IBS?

At this point there is no laboratory test or otherwise to diagnose IBS. One test of interest available is called IBSchek, which tests for anti-vinculin antibodies – a marker of post infectious IBS. As research improves, these tests will have more utility in helping determine a treatment path for patients, at this point, they do not inform our intervention rather they’re just a ‘nice to know’.

What does IBS pain feel like?

IBS pain varies for people, but many of our patients say it can feel crampy, or achey. Some patients describe it as a feeling of being inflamed or ready to burst (from the bloating and distension). Some patients experience it in one spot, where others have it more diffuse.

What causes IBS?

While we don’t know the exact cause of IBS, there are some factors that increase the risk of developing IBS including genetics, being female, contracting a gastrointestinal virus, and psychosocial factors. Researchers continue to investigate several potential causes of IBS including the roles the gut microbiome and the immune system plays in developing IBS.

Categorized: Gut Health & IBS

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  1. Retrieved from: https://cdhf.ca/digestive-disorders/irritable-bowel-syndrome-ibs/statistics/ (June 2, 2022)

  2. Retrieved from: https://theromefoundation.org/rome-iv/rome-iv-criteria/ (June 2nd, 2022)

  3. Fritscher-Ravens, et al. (2019). Many patients with irritable bowel syndrome have atypical food allergies not associated with immunoglobulin E. Gastroenterology, 157(1): 109-118. Retrieved from: https://pubmed.ncbi.nlm.nih.gov/31100380/ (June 2022)

  4. 1.Gibson, P. R., Halmos, E. P., & Muir, J. G. (2020). FODMAPS, prebiotics and gut health‐the FODMAP hypothesis revisited. Alimentary Pharmacology & Therapeutics, 52(2), 233-246.

  5. Prospero, L., Riezzo, G., Linsalata, M., Orlando, A., D’attoma, B., & Russo, F. (2021). Psychological and gastrointestinal symptoms of patients with irritable bowel syndrome undergoing a low-FODMAP diet: the role of the intestinal barrier. Nutrients, 13(7), 2469.