Low Fodmap Diet IBS Guide

Low FODMAP Diet for IBS Guide [2024]


What is Irritable bowel syndrome IBS?

Irritable bowel syndrome (IBS) is a condition that affects approximately 20% of the population.

It affects males and females of all ages.

If you have ever had irritable bowel syndrome, you know exactly how disruptive and chaotic it can be for your life. There are few words that can describe the stress, both physical and mental, that it typically causes in most sufferers’ lives.

However, there are a few simple tweaks that you can make in your life that can have a huge effect on the severity of your IBS. Changing what you eat to match a well-researched IBS diet is one of the most effective and lowest cost treatments you can use in your battle against irritable bowel syndrome.


IBS Diagnosis

There is no diagnostic test for IBS. Diagnosis is made on symptoms.

There are many conditions that have symptoms like IBS. It is important to try not to self-diagnose IBS, or any other condition, as they can all have different causes and different treatments.

It is therefore important to work with medical professionals to exclude other serious GI conditions (e.g., inflammatory bowel disease, coeliac disease, and bowel cancer) and some gynecological conditions

To make sure you are on the correct path for your symptom management, a proper diagnosis via a medical doctor is recommended. If you suspect you have IBS or an adverse reaction to foods, you should seek the advice of a medical practitioner, such as your general practitioner, a gastroenterologist, an immunologist, or a registered dietitian, and discuss your symptoms.

IBS Symptoms

Symptoms commonly associated with IBS are listed below.

Please note, all of us can experience some of these symptoms from time to time; that is normal. However, when the symptoms are occurring frequently over a significant period (e.g., a few months), it is recommended you speak to your doctor about them, and request some investigations as to the cause start.

The following IBS Symptoms can fluctuate in their severity from day to day and week to week.

  • Changes in bowel habits (diarrhea or constipation or a combination of both)
  • Abdominal pain or discomfort
  • Excessive flatulence
  • Abdominal bloating (feeling of fullness)
  • Abdominal distension (abdomen increases in size, a look of being pregnant)
  • Reflux/heartburn
  • Nausea
  • Vomiting (less common)
  • Fatigue, weakness, lethargy

[message type=”success”]Irritable bowel syndrome (IBS) affects about 20 percent of adults in the United States, and recent research shows that enjoying a
low-FODMAP diet can help drastically reduce your IBS symptoms.[/message]

Research from Monash University in Melbourne, Australia, shows that avoiding FODMAPs can greatly improve symptoms in up to 76 percent of IBS patients.

What is FODMAP?

FODMAP stands for Fermentable Oligo-, Di- and Mono-saccharides, And Polyols, which might not be very helpful unless you are a dietician. Essentially the items listed are all short-chain carbohydrates and sugar alcohols which the small intestine finds it difficult to absorb. The result if this is that bacterial action in the digestive system tends to make them ferment, causing increased liquid and gas production in the gut. A recent theory from Melbourne, Australia says that reducing intake of foods which are high in FODMAPs can help IBS sufferers to relieve symptoms of bloating, gut pain, intestinal gas and motility problems like diarrhoea and constipation.

Low FODMAP IBS Introduction

The low-FODMAP diet is a simple treatment for irritable bowel syndrome (IBS), a condition that affects one in seven people worldwide

[message type=”success”]The low-FODMAP diet has been shown to help at least 75% people with IBS, a condition that has been difficult to manage in the past.[/message]

A diet low in FODMAPs is now recommended internationally as the most effective dietary therapy for IBS and other nasty disorders. A Low FODMAP Diet has also been proven, with solid scientific research, to reduce symptoms of fatigue, lethargy and poor concentration.

The principle of a Low FODMAP Diet for IBS is to restrict the foods high in FODMAPs causing chaos in the gut, before working out an individual’s own personal tolerance thresholds. This means it can be tailored to you specifically and as a result improve the gut symptoms associated with IBS.

What you have to remember is that it’s not about being the incredibly restrictive long term. The ultimate goal is to eat and live as freely as possible with the least restrictions you can get away with – the more FODMAPs you can return to your diet without triggering symptoms, the healthier your gut is likely to be.

Many people who experience IBS have already recognized a strong association between what they eat and the severity of their symptoms.

Many IBS sufferers find changing their diet much more appealing than taking medication. It means they are taking action themselves to relieve their symptoms, and that feeling of empowerment regarding their own health is important

What foods are included or excluded by FODMAP diet?

This is the million dollar question, of course, but not an easy one to answer, especially in the space allowed here. In very broad terms, a variety of fruits, vegetables, grains, legumes, sweeteners, dairy foods and lactose-containing foods are high in FODMAPS. Other foods in the same groups are low in FODMAPS.

There are lists and recipes on line (of course), also books and even apps to help you identify low FODMAP foods. But some more reliable than others, but many high FODMAP ingredients are hidden in processed or pre-packaged foods so cutting them all out can be quite a challenge. Added to which your client may have specific food triggers for their IBS which are unrelated to FODMAPs, but still need to be taken into account.

In addition the usual method (based on what my clients tell me) is to hugely restrict the person’s diet and then over several weeks gradually re-introduce low FODMAP foods one by one so their effect can be monitored. This can lead to dietary imbalances, at least in the short term, which might have to be addressed with supplements.

I do appreciate that we all know our own bodies. However, due to the complexities of correctly implementing a healthy low FODMAP diet, the best advice you can give to any client wanting to explore it is to ask their GP for a referral to a dietician, who will help them find their way through the maze of conflicting and sometimes confusing advice.

Is FODMAP Diet worth trying for IBS Suffers?

So far it seems around 70-75% of IBS patients are likely to have an improvement in the severity or frequency of IBS gut-related symptoms by following this diet. Research is still ongoing as larger studies need to be carried out to confirm this initial finding.

It doesn’t help with non gut-related symptoms like headaches which are sometimes associated with IBS, but yes it’s worth exploring for many of those with the condition.

Low-FODMAP Diet vs. Standard Dietary on IBS

My primary motivation for launching IBS diet plan was to raise awareness of the low-FODMAP diet. The advice I was given after my diagnosis seemed psuedo-scientific and, frankly, baseless. Most importantly, it didn’t effectively treat my IBS symptoms.

The low-FODMAP diet did. And while the theory is still being tested for efficacy; today it held its own yet again.

A study conducted by H. M. Staudacher, K. Whelan, P. M. Irving, and M. C. E. Lomer aimed to determine whether a low-FODMAP diet is effective for IBS symptom control, and also how it stacked up against the standard dietary guidelines and conventional dietary treatment advice. Patients self-reported symptom severity, and the study concluded that 76% (three-quarters!) experienced great relief on a low-FODMAP diet as compared to 54% on a standard diet. General symptom response was also greatly improved – with the low-FODMAP group scoring 86% as compared to a standard of 49%.

More good news:

  • 82% of IBS patients on the low-FODMAP diet experienced a reduction in bloating
  • 85% of IBS patients on the low-FODMAP diet experienced a reduction in abdominal pain
  • 87% of IBS patients on the low-FODMAP diet experienced a reduction in flatulence.

Keep in mind that patients were simply instructed how to follow the diet – their ability to follow it precisely and accurately was untested. It seems likely that nearly everyone who suffers from IBS could see a reduction in symptoms on a properly executed low-FODMAP diet.

Clearly, a low-FODMAP dietary treatment is much more effective than standard dietary advice for controlling irritable bowel syndrome symptoms.


[message type=”notice”]Once you have a diagnosis of IBS, you should seek specific advice about modifying your diet from a qualified dietitian.[/message]

A dietitian may determine whether you have an intolerance by taking a dietary history. Before your appointment, it’s wise to keep a record of the food you eat in a typical week, and the symptoms you experience during those seven days

Once you have a diagnosis, a registered dietitian will provide expert advice on which foods to limit and what to replace them with.

Other IBS related Diseases

Because the diagnosis of IBS is based on the pattern of the symptoms, it is important to rule out other conditions that have the same symptoms, such as celiac disease and inflammatory bowel disease (IBD), both of which can mimic IBS.

Anyone with symptoms of IBS should be examined for these disorders before going on a low-FODMAP or gluten-free diet, so speak with your doctor about being tested if you haven’t already. However, bear in mind that is possible to have both IBS and another digestive disorder.

Low FodMAP also shows promise for treating persistent symptoms associated:

  • Celiac disease
  • Crohn’s disease
  • Ulcerative colitis.


The short-chain carbs/FODMAPs are in everyday foods and are always poorly absorbed, but it comes down to you and your gut on whether, and how much, you can tolerate them.

People who have IBS have very sensitive intestines, and the stretching of the gut that comes from the poor absorption contributes to a lot of pain. Many can tolerate some FODMAPs, while others may find that all FODMAPs can be symptom triggers. Not everyone has a problem with all the different FODMAP groups, which is why it’s important to work with a nutritionist or dietician to figure out what exactly your specific trigger foods are.

By controlling and managing the consumption of foods that contain the FODMAPs triggering your symptoms you should then be able to significantly reduce or even say goodbye to your IBS type symptoms.

How do FODMAPs cause symptoms of IBS?

FODMAPs all have the same characteristics:

  1. They are poorly absorbed in the small bowel.
    This means that many of these molecules arrive from the stomach into the small bowel but don’t get absorbed, instead of passing right through to the colon. This occurs either because they cannot be broken down or they are slow to be absorbed. We all differ in our ability to digest and absorb some FODMAPs: Fructose absorption is slow in all of us but very slow in some; some people do not make enough lactase (the enzyme needed to break down lactose); and the ability to absorb polyols (which are the wrong shape to pass readily through the lining of the small bowel) also varies from person to person. Since none of us can digest fructans and galacto-oligosaccharides (GOS), they are poorly absorbed in everyone.
  1. They are small molecules, consumed in a concentrated dose.
    When small, concentrated molecules are poorly absorbed, the body tries to “dilute” them by forcing water into the gastrointestinal tract. Extra fluid in the gastrointestinal tract can cause diarrhea and affect the muscular movement of the gut.
  2. They are “fast food” for the bacteria that live naturally in the large bowel.
    The large bowel (and the lower part of the small bowel) naturally contains billions of bacteria. If molecules are not absorbed in the small bowel, they continue the journey to the large bowel. The bacteria that live there see these food molecules as fast food and quickly break them down, which produces hydrogen, carbon dioxide, and methane gases. How quickly the molecules are fermented depends on their chain length: Oligosaccharides and simple sugars are fermented very rapidly compared with fibre, which contains much longer chain molecules, known as polysaccharides.

Multiple types of FODMAPs are usually present in any one meal. Because they all cause distension in the same way once they reach the lower small bowel and colon, their effects are cumulative. This means that the degree of bowel distension can depend upon the total FODMAPs consumed, not just the amount of any individual FODMAP consumed. If someone who cannot digest lactose well and absorbs fructose poorly eats a meal that contains some lactose, some fructans, some polyols, some GOS, and some fructose, the effect on the bowel will be 1 + 1 + 1 + 1 + 1 = 5 times greater than if they ate the same amount of only one of that FODMAPs. That is why we have to consider all FODMAPs in food when modifying our diet.

[message type=”notice”]And in terms of a low-FODMAP diet, the component we’re most concerned about is carbohydrates.[/message]

Carbohydrates, which consist of sugars, starches, and fibre, are an important component of our diets since they provide our bodies with energy. Here’s how: Our digestive systems break down the carbs we eat until they can be absorbed through the intestinal wall into the bloodstream, where they’re converted into energy. And they’re in a lot of the foods we eat, including fruits, vegetables, bread, and pasta. But
certain carbs—the FODMAPs—can cause issues in people with IBS and other digestive disorders.

After ruling out other health conditions, you can also get a breath test, to identify and pinpoint the offending sugars in your diet. From here, you will have a base as to which sugars are the most malabsorbed, and can begin your low FODMAP journey to improve your symptoms.

Wheat, Barley, Rye, Onions and Garlic – Why They Trigger Symptoms of IBS

Instead of resulting to pharma drugs, this elimination diet uses “food as medicine” to help people discover which foods may be triggering symptoms.  A group of sugars called FODMAPs are poorly absorbed in the small intestine and research suggests they contribute to IBS and FGID symptoms.  Learn more and read on!

Wheat, barley and rye as well as onions and garlic contain fructans which are part of the FODMAPs family.  Fructans are malabsorbed in the small intestine which means they aren’t digested properly and then ferment in the small intestine causing bloating, gas, constipation and diarrhea.  Of all the FODMAPs, fructans are the greatest contributor to IBS as humans were not made to have the enzymes to break down fructans and GOS (galacto-oligosaccharides).

“What are FODMAPs?”

The low-FODMAP diet has been instrumental in helping relieve common symptoms of IBS and Functional Gastrointestinal Disorders.  FODMAPs stand for Fermentable, Oligo-saccarides, Di-saccharides, Mono-saccharides And Polyols. These fructans, galacto-oligosaccharides, lactose, excess fructose and polyols are found in natural and processed foods.

When FODMAPs are malabsorbed they can cause more water to be delivered through the bowel which can contribute to diarrhea in some people.  Sugars from FODMAPs make their way to the large intestine and are then fermented by bacteria, producing gases.  Gas can be produced in the small or large intestine, and which we all know so well, then comes symptoms of bloating, distention, abdominal pain and even back pain.  For some, this gas production can slow movement through the bowel and mean constipation.  Sometimes it can take days or weeks for these symptoms to ease up.  It wasn’t until I found the low-FODMAP diet that I began to notice a difference in how my body began to digest the right foods.  Keep in mind, everyone’s body chemistry, environment and stress level is different, so following the low-FODMAP diet is very individualized.

“Which Foods Should I Avoid?”

Along with wheat, barley, rye, garlic and onions, honey, lactose, sugar alcohols, certain veggies, fruits and certain legumes are avoided.  The low-FODMAP diet is not a gluten-free diet, however you will see us mention gluten-free foods as most are wheat-free.  Not all gluten-free foods are free of FODMAPs so you’ll need to read all the labels of products (example: Udi’s White Sandwich Bread is low-FODMAP but Rudi’s Original sandwich bread has high FODMAPs like inulin and honey).

Take a look at this page to learn more about the foods to avoid and this page to see our grocery list of all the foods you can safely enjoy on the diet.  And finally visit this page to learn How to Start the Low-FODMAP Diet.

If you have already taken hydrogen breath tests and know you can either completely absorb fructose or lactose, you do not have to completely negate either from the diet, but can as an extra precaution during the first and second phase.

There’s a lot to learn, so you’ll want to follow us on social media as we share new content, tips, advice and recipes often.  Plus you’ll meet people who feel your pain and know what it’s like to have painful, uncomfortable and sometimes embarrassing symptoms.  We are here for you!  Comment below with any questions.

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