The Low FODMAP Diet for IBS and IBD

Overview

• A well-researched diet that was founded by Monash University in 2005.
• Proven to be effective in IBS, non-active (remission) IBD and celiac disease already on a gluten-free diet.
• FODMAP stands for Fermentable Oligo-, Di-, Mono-saccharides and Polyols, essentially short-chain carbohydrates.
• The science: osmotic effect draws water into your gut causing distension and discomfort, gut bacteria breaks down FODMAPs into excessive gasses
• Restrictive diet that is intended to be temporary, with a total elimination period of 2 to 6 weeks before rechallenging your gut.
• Optimally done with the help of a dietician.
• Refer to tables below to find out which foods are low FODMAP and high FODMAP.

What is the FODMAP diet?

The low FODMAP diet (colloquially, FODMAPs) is a relatively new diet founded by Monash University. It has been found to be an effective method to successfully reduce the symptoms of IBS and non-active IBD. It is not only useful as a diet for the relief of digestive conditions, but as a system to identify what foods are individually problematic.

What does FODMAP stand for?

The term FODMAP was first used in a 2005 opinion and theory piece about the influence of environmental factors, as opposed to genetic, on the development of Crohn’s disease.¹ Westernization was already thought to be tied to Crohn’s, and food was a natural suspect. It was a perfect example of how the modern lifestyle can cause havoc in our digestive systems through foods that may not be suitable for our body. The article, by Peter Gibson of Monash University, posited that excess short-chain carbohydrates, tiny carbs found in foods, contribute significantly to of all our digestive problems.

He named these short-chain carbohydrates Fermentable Oligo-, Di-, Mono-saccharides and Polyols, FODMAPs.

FODMAPs are short chain carbohydrates. In comparison to long chain carbs such as glucose, they consist or only a few linked sugars. FODMAPs take more effort for our small intestine to digest, and can cause discomfort in certain conditions such as colitis and Crohn’s. FODMAPs include fructose, a simple sugar found in fruits, vegetables, and other sugary foods; lactose, a carbohydrate found in dairy; fructans, found alongside gluten and vegetables such as artichokes and onions; galactans, found in legumes; and polyols, found in some fruits and vegetables as well as artificial sweeteners such as sorbitol and xylitol that are used to lower caloric content.

FODMAPs and the gut

FODMAPs are thought to cause abdominal symptoms through two mechanisms. Firstly, these short chain carbohydrates may have an increased osmotic effect in the small intestine. This means that they draw in more water into your gut. This can then cause your gut to be distended and activate the receptors on the lining of your gut, giving you abdominal symptoms. Secondly, the fermentation of FODMAP carbohydrates  by gut bacteria are thought to release gasses such as carbon dioxide and hydrogen. This stimulation can send messages from your gut to your brain, which can then be felt as bloating or pain.²

It’s not quite a hive of scum and villainy as these bacteria aren’t criminals – they are simply doing their jobs. The culprits here are our diet and our genes. Modern diets cause us to consume far more FODMAPs than the bacteria in the front of our intestine are trained to handle, so the rest must quickly digest the excess and produce unusually high volumes of hydrogen. On top of that, everyone has his or her own unique genetic disposition that causes our bacteria to process foods differently. This can mean that certain foods are ineffectively processed, if at all.

A study done on rats found that a high FODMAP diet increased intestinal permeability and caused inflammation of the gut mucosa. ³ In humans, impaired gut permeability has been associated with conditions such as inflammatory bowel diseases.

The paper suggested that the Western diet and our own personal biology lead to two issues worth researching – which foods and what quantities of them will lead to adverse conditions. The researchers at Monash launched a long-term and exhaustive investigation into testing and retesting exactly how much of which food is too much. The low FODMAP diet is derived from this information and will help you perform your own investigation to solve the mystery of what food is hurting your intestines and worsening your IBS or IBD.

The answer may surprise you. Is it a network of fruits and vegetables forming an unlikely criminal network after decades of feuding? Is it the notorious gluten crime family? Or maybe… it was the beans all along.

How do you carry out this diet?

As other diets have taught us all, not everyone reacts the same to everything. One of the most useful things about FODMAPs, is that it’s a restrictive diet. It is important to note that this diet is intended to be temporary.

For the first 2 to 6 weeks, aim to substitute high FODMAP foods with low FODMAP alternatives. Once you have eliminated every FODMAP for that short period of time, you can enter what is called the challenge phase, and gradually start reintroducing eliminated food for a few days to see if your gut symptoms begin reappear. In order to keep track, introduce one FODMAP at a time, one food at a time and over a period of 3 days. You can determine if a specific food is causing you problems and then decide if it should be removed permanently or partially.

The diagram below from the Monash University Fodmap website illustrates this clearly.

Due to the highly restrictive nature of this diet, it is most effective if done under the guidance of a dietician. While you can attempt restricting different FODMAPs on your own, it may save you some time if you consult with a doctor or dietician, who can test to confirm whole groups of foods or FODMAPs to avoid, such as fructose and lactose, and help you manage your diet.

A low FODMAP diet is the a promising non-medical therapy for IBS and IBD and has no direct side effects, although caution should be taken to sure your diet remains nutritionally balanced. Even though the early FODMAP research was for treating Crohn’s disease, it is more successful in treating IBS than IBD. The diet is supported by over ten years of research at Monash University, who constantly research new findings and retest old ones.

If you do not have an IBS or IBD, or a related condition, the low FODMAP diet will probably be a complete waste of your time and energy. If you have IBS or IBD, no other conflicting factors, and a lifestyle that will not interfere with the diet or your adherence to it, you may want to give the low FODMAP diet a try.

High FODMAP foods

While researching this list, we discovered a lot of contradictory, out of date, and sometimes incorrect information. We strive to keep our information to the highest standards, and found that one significant reason for this misinformation was that many foods have certain thresholds of daily consumption, that will lead to problems. When interpreting this data, many sites choose to classify only as low or high FODMAP foods, which can lead to contradiction. In our list, we are defining both low and high FODMAP foods, but foods marked by an asterisk* can be consumed in significant amounts, and will be listed with an appropriate volume in the Moderate FODMAP Foods section.

FODMAP categories

If you find that you react to one FODMAP more than others, this list will help intuitively understand what foods and FODMAPs you should personally avoid.

Moderate FODMAP Foods

Low FODMAP foods

Research findings

A 2016 meta-analysis of 22 studies investigating the effects of a low FODMAP diet on IBS found it to be an effective method to reduce abdominal symptoms.⁴ Various other individual studies have also found positive results in IBS patients⁵,especially if the IBS is diarrhoea predominant.

Going beyond IBS, the low FODMAP diet has also been shown to be effective in patients with non-active IBD, such as Crohn’s disease or ulcerative colitis that is in remission phase^{6 7} With regards to celiac disease, this diet has shown improvements in abdominal symptoms for patients who are already on gluten free diet.⁸

Treatment of SIBO

A low-FODMAP diet is also one of the crucial intervention steps in the treatment of Small Intestinal Bacterial Overgrowth (SIBO). Read more on that here.

1. Gibson, P. R. and Shepherd, S. J. (2005), Personal view: food for thought – western lifestyle and susceptibility to Crohn’s disease. The FODMAP hypothesis. Alimentary Pharmacology & Therapeutics, 21: 1399-1409. doi:10.1111/j.1365-2036.2005.02506.x
2. Hill, P., Muir, J. G., & Gibson, P. R. (2017). Controversies and Recent Developments of the Low-FODMAP Diet. Gastroenterology & hepatology, 13(1), 36-45.
3. See our excellent article about the carnivore diet for more information about intestinal permeability
4. https://www.ncbi.nlm.nih.gov/pubmed/29328869
5. https://www.ncbi.nlm.nih.gov/pubmed/24076059 https://www.ncbi.nlm.nih.gov/pubmed/29159993
6. https://www.ncbi.nlm.nih.gov/pubmed/30483557
7. https://www.ncbi.nlm.nih.gov/pubmed/28587774
8. https://www.ncbi.nlm.nih.gov/pubmed/29763907