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The Low-FODMAP Diet and Its Role in Treating IBS

So far in this series on digestive health, we’ve looked at:

  1. The basics of irritable bowel syndrome (IBS)
  2. Small intestinal bacterial overgrowth (SIBO)

The wonderful thing about medicine is that it is always evolving as we expand our knowledge; the more we know about our bodies, the healthier we can be. The low-FODMAP diet is a perfect example of this. This diet was developed by a research team at Monash University in Melbourne, Australia, after identifying which foods are most likely to exacerbate IBS symptoms. Since its introduction, the low FODMAP diet has helped many IBS sufferers manage their symptoms.

In today’s article, we’ll look at FODMAP foods, and how they can cause digestive problems. I’ll also talk about how to get started on the low-FODMAP diet, as well as which foods you should and should not eat on the diet.

What Does “FODMAP” Mean?

FODMAPs are certain small “short-chain” carbohydrates or starches found in many foods in the modern standard diet. The term FODMAP is an acronym derived from “Fermentable, Oligo-, Di-, Mono-saccharides And Polyols”:

What Do FODMAPs Do?

The body absorbs different carbohydrates at different rates. Those that are poorly absorbed or take a long time to digest can become fermented by bacteria in both the small and large intestines, leading to the production of gases in the gut. FODMAPs are examples of poorly-absorbed carbohydrates; thus, they are likely to ferment and cause gas and bloating in the gut.

In addition to gas production, these small molecules attract water by osmosis. The combination of increased gas and water in the intestines leads to expansion of the colon wall, which irritates the nerves of the digestive system, leading to abdominal pain.

Gas, bloating and pain are the primary symptoms of both SIBO and IBS. Therefore, consuming high-FODMAP foods is likely to increase your IBS symptoms. Conversely, you can try to get control of your symptoms today by starting the low-FODMAP diet.

What Is the Low-FODMAP Diet and How Long Do I Need to Stay On It?

Going on the low-FODMAP diet requires excluding certain foods from your diet completely for an initial period of two to six weeks. To get you started, I have provided a list of the key high-FODMAP foods to avoid (below), as well as a selection of low-FODMAP foods you can eat while on the diet.

After this initial exclusion period, you can begin reintroducing FODMAP foods into your diet. However, it is important to move slowly, gradually increasing your intake of FODMAP foods over time. If you experience digestive symptoms during the reintroduction phase, eliminate the offending food(s) from your diet and try introducing it/them again later.

It’s also important to be patient, as it may take weeks – or even months – to reintroduce the full range of foods into your diet, especially if you’ve suffered with IBS for a long time. If, after many months, you find you still have difficulty increasing the variety of FODMAP foods in your diet, I suggest booking an appointment with a naturopathic physician, who can test you for other possible causes of your IBS (such as food sensitivities).

Do I Need to Be Tested Before I Start the Diet?

No, you do not need to be tested to see if you are reactive to FODMAP foods. If you have stomach pain, chronic gas/bloating and other IBS symptoms, simply eliminate FODMAP foods from your diet and see if your symptoms improve. Following the diet cannot hurt you, as long as you maintain an overall healthy, balanced diet.

You should, however, seek testing if you suspect you have SIBO, as this will enable your practitioner to determine the right course of antibiotics for you.

High-FODMAP Foods – What to Avoid When You’re on the Diet

Rather than specifying which foods contain fructans, oligo-saccharides, etc., I’ve put broken them into food groups, to make the diet easier to understand.

Vegetables to Avoid

Fruits to Avoid

Protein to Avoid

Dairy to Avoid

Breads and Cereals to Avoid

Beans and Pulses to Avoid

Nuts and Seeds to Avoid

Sweeteners to Avoid

Cookies and Snacks to Avoid


Low-FODMAP Foods – Foods You CAN Eat





Breads and Cereals

Beans and Pulses

Nuts and Seeds


Cookies and Snacks


Please note that I have only listed some of the most important foods to avoid while on the low-FODMAP diet. You can find a much more comprehensive list of foods, and a full explanation of how to follow the diet, by downloading the official FODMAP app from Monash University. Also some of the FODMAP foods can be classified even further to contain low, moderate and high amounts of fermentable carbohydrates. This is why you may sometimes see a food listed on both high and low charts. In this case it is the quantity of that food consumed will be important.

Closing Thoughts

I hope this article has helped you understand a bit more about FODMAPs and their role in IBS, as well as how to get started on the diet. Over the years, I have seen many people resolve their digestive problems by learning which foods trigger their IBS symptoms. If you struggle with IBS, SIBO or other chronic digestive symptoms that cause, gas, bloating and pain, I recommend adopting a low-FODMAP diet to see if your symptoms are reduced or eliminated.

If you or someone you know suffers with chronic gut issues, I invite you to drop me a line on the “contact us” page on this site and request a free initial consultation to discuss your needs. I treat patients locally at my practice in Issaquah, Washington, and worldwide via phone or Skype.

Next time, we’ll look in detail at the “gut biome” – what it is, and how it plays a role in IBS and SIBO. I hope you’ll subscribe to this blog, so you can receive that article and all future articles on A Path to Natural Health.


Dr. Maura Scanlan

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