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What I found was amazing! Foods that I thought were upsetting me were actually fine and other foods that I thought were okay were not. Also, I was relieved to discover that I was not as sensitive to as many foods as I had thought. In fact, after doing the elimination diet I was able to eat MORE things...
— Amazon reader review of IBS—Free at Last! January 12, 2014

What are FODMAPs?

If you’ve never heard of FODMAPs before you are not alone! Luckily you don't have to know much about FODMAPs, or what all the million-dollar words mean, to try the approach. But if you're the curious type, or a medical professional, you might like to know more of the science behind the diet and how a FODMAP elimination diet is meant to work.

The term was coined by Australian researchers Susan J. Shepherd and Peter R. Gibson. In studies at Monash University, they and their colleagues Jane Muir and Jacqueline Barrett found that a low-FODMAP diet helped 75-85% of their IBS patients experience significant, sustainable relief of their IBS symptoms. A low-FODMAP diet avoids foods containing certain sugars and certain fibers capable of causing diarrhea, constipation, gas, bloating and abdominal pain in people with IBS. Examples of FODMAPs include:

  • Lactose (also known as milk sugar; found in milk, yogurt and ice cream)
  • Fructose (also known as fruit sugar; found in fruit, high-fructose corn syrup, honey and agave syrup)
  • Sorbitol, mannitol, and other “-ol” sweeteners (also known as sugar alcohols; found in certain fruits and vegetables as well as some types of sugar-free gums and candies)
  • Fructans (a type of fiber found in wheat, onions, garlic and chicory root)
  • GOS (a type of fiber found in beans, hummus and soy milk)

These five types of FODMAPs have several things in common: They can be poorly absorbed during the digestive process. They are rapidly fermented by the bacteria that live in your gut. They are capable of pulling fluid into the gut in a process called osmosis. The increased fluid load, along with the type and amount of gas produced, cause distension and motility changes, leading to bouts of IBS symptoms. Symptoms are often delayed until hours after eating a high FODMAP meal or snack, because it takes time for FODMAPs to make their way through the stomach and into the intestines, where the effects occur. By reducing the overall dietary load of these carbohydrates, troublesome GI symptoms can be minimized or eliminated.

What is a FODMAP elimination diet?

An elimination diet is a “learning diet” with a strategy and a plan; close monitoring of your symptoms will help you learn how the food you eat affects you. A FODMAP elimination diet may be recommended by your doctor or dietitian. At the beginning, and if you are a good candidate for the diet, you might be advised to limit all of the FODMAPs in your diet. Soon, it will be time to reintroduce FODMAPs, one type at a time. You may find that only one or two FODMAPs are responsible for most of your symptoms. In the end, most people find they can still have their favorite high-FODMAP foods in moderation. For example, if you discover high-FODMAP fruits are a problem area but apples are your favorite food, your new knowledge can help you to decide how to handle it: choose smaller apples, eat just a few slices, eat them less often or go for the gusto and endure the resulting belly ache. The ultimate goal is for each person to eat the most varied diet that he or she can tolerate, not to restrict the diet with one-size-fits-all rules.

How are FODMAPs measured?

Now that the FODMAP concept has been around for a while, there are a number of high- and low- FODMAP food lists circulating on the internet and in various books and apps. Click here to see mine. Where does that information come from?

This machine performs high performance liquid chromatography. I took this photo during my visit to Monash University in 2013. Sales of the Monash University iphone/droid app support their research program.

This machine performs high performance liquid chromatography. I took this photo during my visit to Monash University in 2013. Sales of the Monash University iphone/droid app support their research program.

Lactose and fructose have been fields in the USDA Nutrient Database for Standard Reference for many years. However, only a very small number of the foods in the database actually have any "numbers" in those slots; the rest are missing values.

The vast majority of FODMAP nutrient data is only now being produced at Monash University in Australia. A small team of researchers has analyzed hundreds of foods for their FODMAP content using the machine pictured here. Unfortunately, there is no publicly accessible FODMAP database. We must use what we can patch together from a series of peer-reviewed, published papers by Monash researchers, each one with a slightly different focus. (2007, 2009, 2011, 2013, 2016, 2017). As each new paper comes out, we adjust our teaching tools and edit our food lists accordingly. Working with FODMAPs requires flexibility; corrections and apparent contradictions are a regular thing and we often have to make decisions about food choices in the face of uncertainty.

In any case, you need more than a list of high- and low-FODMAP foods to get the most out of your FODMAP-elimination diet. You need a plan. That's where The IBS Elimination Diet and Cookbook and your registered dietitian nutritionist come in.

[T]horoughly researched and well-thought out and executed resource for patients and practitioners alike. I know I’ll reference the book the next time I work with a client needing FODMAP restriction.
— Today's Dietitian, 2017