Nutrition Bites: The Science Behind a Low-FODMAP Diet

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Hi everyone, welcome back to another episode of Nutrition Bites. I’m Sam Kramer your Registered Dietitian at

Today I wanted to talk to you about a low-FODMAP diet. Some of you may have heard of this before, while others may be hearing this for the first time. In all fairness, the low-FODMAP diet is relatively new. Regardless, let’s explore it together!

What is the low-FODMAP diet?

The acronym stands for Fermentable Oligo-, Di-, Mono- And Polyols.

Essentially, these FODMAPs are short-chain sugars found in a variety of foods. Some people have a challenging time digesting these FODMAPs, resulting in poor absorption, digestive discomfort and excessive gas and/or bloating. Now, I’m not saying ALL sugars are bad. Sugar, or carbohydrates, are a vital part of your diet and provide the necessary energy to perform normal daily activities. These particular classes of carbohydrates, however, are hard for some people to digest.

A diet high in FODMAPs may be particularly challenging for people who suffer from gastrointestinal diseases, such as the 1 in 7 who suffer from irritable bowel syndrome (IBS) or those with inflammatory bowel diseases (IBD) like ulcerative colitis or Crohn’s disease. In fact, research has shown people with these diseases who adhere to a diet low in FODMAPs have seen improvement in their symptoms.

Is the low-FODMAP diet hard to follow?

Unlike many lifestyle diets, the low-FODMAP diet does not eliminate just one food group or type of food. As I alluded to before, FODMAPs are found in many different foods, which adds an extra hurdle to finding the exact foods that cause discomfort.

To further compound the situation, while a formal cutoff of what determines a high- versus low-FODMAP food has yet to exist, careful clinical observations have set guidelines. The guidelines say more than 0.5 grams of fructose in excess of glucose per 100 grams puts you at risk of inducing symptoms. The same is true for consuming more than 3 grams of fructose in one average serving, regardless of glucose intake. Lastly, eating more than 0.2 grams of fructans per serving was also considered at-risk of inducing symptoms.

As with anything in nutrition, your individualized needs will dictate modifications. What works for one person may not necessarily be successful for another. My advice is to begin the low-FODMAP diet by performing an elimination of all foods high in FODMAP and then slowly reintroduce one or two items at a time to see which foods you are able to tolerate and which ones trigger symptoms.

You may also want to pair your low-FODMAP diet with a probiotics supplement. Maintaining a healthy gut microflora is critical to your health.*

What are high-FODMAP foods?

Fortunately, there are many resources to help you determine which foods are high-FODMAP and which are low-FODMAP. Many food companies, including the Low FODMAP Food Co., are simplifying the shopping experience by offering foods low in FODMAPs. You can also find help with applications that you download on your phone.

To get you started, follow this list below. Though not a comprehensive list, these foods are high in FODMAPs:

Oligosaccharides, such as fructans and galactans, are in foods like wheat, rye, barley, onions, garlic and some beans.

Disaccharides include lactose; thus, trying to avoid dairy (except for maybe yogurt) would be beneficial.

Monosaccharides are in some fruits like honey watermelon, apples and high-fructose corn syrup.

Polyols – such as xylitol, mannitol and sorbitol – are sugar substitutes in chewing gum and breath mints, among other products.

Note: There are many other high-FODMAP foods not mentioned here. Be sure to talk to your healthcare professional before following a truly low-FODMAP diet.

How do FODMAPs relate to gluten?

The last bit I want to touch on is how FODMAPs relate to gluten. Gluten is the protein in wheat, barley and rye (and sometimes oats) that can cause similar issues in those sensitive to FODMAPs.

Gluten-free diets have become extremely popular over the last several decades, but the majority of research shows that true gluten issues only occur if you have celiac disease – when your body has an immune-mediated inflammatory response to the proteins.

Research has suggested gluten sensitivity may actually be the result of FODMAP sensitivity instead. Over time, the gluten has masked the effect and people think they need to be on a gluten-free diet. In fact, the evidence shows gluten has had no effect on people with reported gluten sensitivity, but their symptoms have improved when FODMAPs were reduced.

However, it is a complex relationship and one must factor in the many variables that can confound one resolution, such as the criteria to diagnose diseases, wheat’s function as a carbohydrate and protein and other nutrients that play a role in gastrointestinal issues.

Interestingly, when you reduce FODMAPs, you subsequently reduce foods also high in gluten. In that respect, you are killing two birds with one stone. It’s difficult to truly ascertain which FODMAP is the true culprit. It may even be both, FODMAPs and gluten! Certainly, more long-term, efficacy trials are warranted.

I hope you enjoyed this edition of Nutrition Bites and how the low-FODMAP diet is making its mark on the nutrition world. It will be interesting to see how the research unfolds.

Until next time, this is Sam Kramer, your registered dietitian, signing off!

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease.