What is the low FODMAP Diet?

By Danielle Capalino, MSPH, RD

If you have done a google search lately looking for a solution to your digestive symptoms, you may have stumbled upon the word “FODMAP” and wondered what it is means. Or, perhaps your doctor recommended the diet for you and gave you a handout, leaving you with more questions than answers. First, let me start by spelling it out- FODMAP is an acronym that stands for (a mouthful!) fermentable oligo- di- mono- saccharides and polyols. I know – that didn’t help at all, and probably made you more confused! Stay with me for a moment. Practically speaking, FODMAPs are difficult to digest carbohydrates that can cause a slew of gastroenterological symptoms like gas, bloating, diarrhea, and constipation. Even though it’s hard to pronounce, this diet really works. Studies show that up to 70% of IBS sufferers find relief when following a low-FODMAP diet.

FODMAP is really an umbrella term for all of these hard to digest carbohydrates. There are five categories of foods that fall under the FODMAP umbrella: lactose, fructose, galactooligosaccharides (GOS), fructans, and polyols. Through undertaking an elimination diet you may find that you have a sensitivity to one/some/all of these categories.

The low-FODMAP diet works in three phases – and it is important to go through all three and not just stop after the first phase. Phase One is an elimination diet in which you remove all high-FODMAP foods from your diet (I will tell you what those foods are shortly). Once you have removed those foods for 2-6 weeks, hopefully you will feel so much better. Phase Two is the testing phase where you systematically reintroduce each category of FODMAPs to determine the foods that were causing you distress. Phase Three is the personalization phase with a diet that is customized to you based on how you reacted to the systematic testing. Because not everyone will react to the same FODMAPs you and someone else on the low-FODMAP diet might actually be able to tolerate very different foods.

It is helpful to have a list of high and low FODMAP foods so that you can remember which foods are in and out on the elimination diet. It’s quite difficult to memorize the list because these foods do not look alike, or taste alike. I will explain each of the FODMAP categories in more detail:

Lactose is a sugar naturally found in milk. Not all dairy products contains lactose and hard aged cheeses and butter have very little lactose. Whereas milk, cottage cheese and yogurt have significantly more lactose.

Fructose is a sugar naturally found in fruits. It only becomes a problem in those who are sensitive when the there is more fructose than glucose in a given food. Some examples of high fructose fruits are: apples, pears, and mangos. Some examples of low fructose fruits are bananas, oranges, and blueberries.

Fructans are a carbohydrate that is found in a variety of foods including (but not limited to) wheat, onions, and garlic. Though wheat is high is fructans, fructans are NOT related to gluten (which is a protein) they just happen to exist in many of the same foods.

Galactooligosaccharides (GOS) are primarily found in beans.

Polyols are sugar alcohols which appear in the diet naturally in certain fruits, as well as in artificial sweeteners that end in the letters -ol. Naturally polyols are in stone fruits, like prunes (which is why prunes help with constipation), snow peas, and mushrooms. Polyols are found in sugar-free candies, gums, and drinks.

Get a list of high and low FODMAP foods here.

Danielle Capalino, MSPH, RD, is a registered dietitian in New York City, providing nutritional counseling on digestive health. She is a graduate of the Massachusetts Institute of Technology and the Johns Hopkins School of Public Health. Learn more: www.daniellecapalino.com. She is also the author of Healthy Gut, Flat Stomach (named one of the top 7 wellness books of 2017 by People Magazine) and The Microbiome Diet Plan.