• Holly Erikitola

What Is a Low FODMAP Diet?

If you're new to all things IBS you may have heard people talking about the benefits of a low FODMAP diet and wondered what on earth it is. In this article, I'm going to explain what FODMAPs are, how they can trigger symptoms and the purpose of a low FODMAP diet.


FODMAPs are types of sugars that are indigestible. Rather than being digested and absorbed like other foods you eat, they are broken down by the bacteria in your gut. This is known as fermentation. During this process, they cause fluid to be drawn into the bowel and gases are released by the bacteria.

The word FODMAP is an acronym for:


Oligosaccharides (fructans & galacto-oligosaccharides)

Disaccharides (lactose)

Monosaccharides (fructose)


Polyols (sugar alcohols – sorbitol, mannitol, maltitol, xylitol, polydextrose, isomalt etc.)

These types of sugars can be found to some extent in most foods except meat, poultry and fish. However, many foods only contain low levels or not enough to cause issues.


As mentioned above, when FODMAPs enter the bowel and are broken down by bacteria, two major things happen. First, fluid is drawn into the bowel. If an excess of fluid builds up this can cause bloating, distension and diarrhea.

Second, the bacteria that consume or break down FODMAPs produce the gases hydrogen, carbon dioxide and methane. If these gases build up, they cause bloating, distension, stomach pain, constipation and diarrhea.


The low FODMAP diet is a way of eating which limits your intake of these fermentable types of sugar. While some foods that are extremely high in FODMAPs are removed, foods with lower amounts can be eaten freely and those with moderate levels can be monitored and eaten in moderation.

By drastically reducing your intake of FODMAPs at any one meal you greatly reduce the chances of triggering your symptoms. This is because less water will be drawn into the bowel and less gas will be produced by the bacteria living there as they have less to feed on.

With less fluid and gas, you’ll experience less distension and bloating, less painful trapped gas, less stomach pain, less diarrhea and less constipation. All of which are primary symptoms of IBS.

The purpose of the diet is not to remove all FODMAPs, but to reduce them enough to get your symptoms under control.


There are three phases to the low FODMAP diet:

  1. The initial FODMAP lowering phase

  2. The FODMAP reintroduction phase

  3. The diet personalization phase

The initial FODMAP lowering phase should last for between two to eight weeks. During this time, you’ll eat purely low FODMAP. You’ll keep a record of what you eat, how you feel, your bowel movements and stress levels to see how you respond.

The reintroduction phase can vary in length depending on how things go but can last around six weeks. During this phase, you’ll keep a detailed record of how you react to each food reintroduction from the different FODMAP types.

The personalization phase is where you decide from all the evidence you have gathered which foods you want to include or need to exclude for the longer term and design a unique tailored diet suitable for you.

Many people have had great success in reducing their symptoms by implementing a low FODMAP diet, especially if their IBS is caused by SIBO, motility issues, gut infections or dysbiosis.

To see the science behind the diet you can check out these studies:

A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology.


Manipulation of dietary short-chain carbohydrates alters the pattern of gas production and genesis of symptoms in irritable bowel syndrome.