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IBS and the Low-FODMAP Diet

There’s all kinds of popular advice about what to do when living with IBS, but one particular intervention, the low-FODMAP diet, stands out above the rest. Over the years, more and more evidence has emerged in support of the low-FODMAP diet for improving IBS symptoms. “Unlike most dietary manipulations tried in the past to alleviate gastrointestinal symptoms of IBS, all studies on low FODMAP diet have consistently shown symptomatic benefits in the majority of patients with IBS.” [1]

But what exactly is the low-FODMAP diet, and how can you use it to help alleviate IBS? Read on to find out.


FODMAP is an acronym referring to a list of food compounds that the small intestine does not absorb very well. This malabsorption can trigger unpleasant symptoms, especially in people with IBS. It stands for


These fermentable short-chain carbohydrates cause more fluid and gas to build up in the bowels, ultimately leading to bloating, pain, and diarrhea—in other words, classic IBS symptoms [2]


The idea behind the low-FODMAP diet is to minimize consumption of FODMAP foods to decrease IBS symptoms. It’s important to note that FODMAP foods are not inherently bad or unhealthy, and indeed can be nutritious components of a well-balanced diet. However, because the gastrointestinal system in those with IBS tends to be more sensitive than usual, it may be helpful to minimize FODMAP foods if you have IBS. Keep in mind that, since everyone is different, you may not necessarily need to exclude all FODMAP foods. One way to determine if a certain food is triggering IBS symptoms is the trial by elimination method. 


Because many FODMAP foods are quite nutritious, it would be well worth it to consult with your doctor or a registered dietician to determine if you do in fact need to exclude FODMAP foods (and if so, which ones), as well as what you can eat instead. This is important to ensure your diet remains well-balanced and that you are still meeting your daily nutritional requirements.


At this point, you may be wondering how to identify FODMAPs in your food, as the technical terminology is a little cryptic. Here’s a more normal-speak breakdown, including common food sources [4]:


These consist of fructo-oligo-saccharides (known as FOS or fructans), & galacto-oligo-saccharides (GOS). Some common sources of FOS & GOS are legumes, wheat, rye, artichokes, garlic, and onions.

A common disaccharide is lactose, the sugar found in cow’s milk. Dairy foods such as milk, yogurt, pudding, ice cream, and cheese typically contain lactose, although some dairy products and aged cheeses contain lower levels of lactose than others. 

These are glucose and fructose, commonly found in honey, table sugar, and fruits. You can still eat fruits, but may want to limit or avoid especially high-fructose fruits such as apples, pears, mango, watermelon, cherries, and peaches. Also avoid products with high-fructose corn syrup.

This category includes artificial sweeteners such as xylitol, sorbitol, and mannitol, so you may want to avoid most sugar-free mints and gums, especially if they contain an artificial sweetener ending in -ol. Polyols are also found in some vegetables, mushrooms and stone fruits.


For a more exhaustive resource on high-FODMAP foods you may want to avoid, as well as some low-FODMAP alternatives, check out this resource by Monash University, the institution that originated FODMAP research.

Implementing the Low-FODMAP Diet

From the Monash University researchers who created the original low-FODMAP diet,

“The Monash University Low FODMAP DietTM is best followed under the supervision of a qualified dietitian or healthcare professional who is experienced in this specialized area. The diet begins with a 2-6 week period of high restriction and then transitions to a more relaxed diet where certain foods are gradually re-introduced.” [6]


In other words, implementing the low-FODMAP diet works in much the same way as the trial by elimination diet, although it covers a wider range of food categories, which is why it’s best implemented alongside qualified medical guidance. The basic steps are as follows:


1. Elimination
The first step of the low-FODMAP diet is to eliminate all FODMAPs for 2-6 weeks, or up to 12 weeks in some cases. This is the period of time used to determine if a low-FODMAP diet may be right for you. If your symptoms do not improve during this phase, then there is no reason to continue, as FODMAP foods are not contributing to your IBS symptoms.

Dr. Sue Shepherd, one of the pioneering FODMAP researchers, confirms this, saying that “for some people a change in the food they eat may help their IBS, whilst for others it will make no difference.” [8]


2. Gradual Reintroduction
The second step is to gradually reintroduce the FODMAP foods one at a time up to a tolerable level. This is to determine whether some FODMAP foods might not have to be entirely avoided, and if they may instead be consumed up to a certain level without worsening IBS symptoms.


Want to learn more about FODMAPs from the institution that started it all? Head to Monash University’s FODMAP website, which has many resources available, including free recipes, blog articles, and an app.


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