What is the low-FODMAP diet and how does it help IBS?

Reader question

"I'm trying to figure my 'gut' out and now people have suggested for me to go on the low-FODMAP diet for IBS. I have seen doctors and gone through various tests and everything comes back normal. Some doctors have said I have IBS but offer no help. So just curious if you have run across anything beneficial." - Doug M.

Barbara answers

Hi Doug,

Trying to figure out your "gut" can indeed be challenging. Many things can unsettle our gastrointestinal system, including stress, anxiety, food intolerances and diseases like coeliac or cancer.

Sounds like you've done the right thing with your doctors to see what might be causing your distress. A diagnosis of irritable bowel syndrome (IBS), can still be frustrating, however, since IBS is not a specific disease but a cluster of symptoms such as gas, bloating and diarrhoea.

More than a decade ago, scientists began to test a theory that certain naturally occurring sugars in food may trigger digestive problems for some people. They described these substances as "highly fermentable but poorly absorbed short-chain carbohydrates and polyols". And to keep people's eyes from glazing over when they discussed this topic, someone came up with the acronym FODMAP (fermentable oligosaccharides disaccharides monosaccharides and polyols). Whew.

According to the US Academy of Nutrition and Dietetics, these particular types of carbohydrates may cause excessive gas, bloating and diarrhoea in some susceptible people including those with IBS. Problem is, these carbs reside in many nutrient-rich foods such as fruits, vegetables, legumes, lentils and milk. Avoiding them is difficult and can put you at risk for nutritional deficiencies. To further complicate matters, FODMAPs may be the source of some, all, or none of your distress.

At this point, some medical professionals may suggest you try a low-FODMAP diet - one that eliminates or cuts back on major sources of short-chain carbohydrates that tend to "ferment" in your gut. Registered dietitian nutritionist and FODMAP expert Carol Ireton-Jones recommends a two-week trial in which all FODMAP foods are eliminated. If symptoms are relieved, then she recommends adding back one food at a time to see which specific ones are the source of your symptoms.

As you can see, this can be a long and arduous process to find the foods that might be the culprits and those that are not. And you certainly don't need to become malnourished while trying to figure it all out. That's why a smart doc will refer you to an accredited dietitian with expertise in this area.

Barbara Quinn is a registered dietitian and the author of Quinn-Essential Nutrition.

The Monterey County Herald