What Conditions is the Low-FODMAP Diet For?
If you have been diagnosed by your doctor as having Irritable Bowel Syndrome (IBS) or SIBO then we may use a low-FODMAP diet to help manage or alleviate your digestive symptoms such as gas, bloating, belly distension, cramping, diarrhea and/or constipation. The low-FODMAP diet may also be helpful for Inflammatory Bowel Disease (IBD). Many gut-healing diets use low-FODMAP foods. This diet may be modified to your preferences, tolerances and other health conditions. Many will see relief in about two weeks but for some, it may take up to four weeks.
What is the Low-FODMAP Diet?
Researchers at the Monash University in Australia developed the low-FODMAP diet. Several clinical trials have shown that a low-FODMAP diet improves the symptoms of IBS in up to 2/3 of the participants.
FODMAP is an acronym for a group of short-chain carbohydrates that stands for Fermentable Oligo-, Di- and Mono-Saccharides & Polyols. Yes, that’s a mouthful! These carbohydrates are known to rapidly ferment in the gut and/or don’t absorb properly in the small intestine, which can result in gas, bloating, belly distension, diarrhea and/or constipation. Eating foods with these carbohydrates can cause one or more of these symptoms. The symptoms can occur occasionally or they can be ongoing and chronic. One day you could feel great and the next you could be miserable.
FODMAP carbohydrates can be found in a wide range of fruits, vegetables, legumes, beans, nuts, dairy and grains. Examples include:
Oligosachharides, which are found in onions, garlic, wheat, beans, nuts, fruits and vegetables
Lactose, which is found in dairy products such as milk, soft cheese, yogurt
Fructose, which is found in honey, apples, juice, high fructose corn syrup
Polyols, which are found in many fruits, vegetables and artificial sweeteners
The Monash University offers a comprehensive list of high and low FODMAP foods. Their researchers have scientifically tested foods for presence and quantities of the problematic carbohydrates and continue to do so. They update the app regularly. I highly recommend downloading their low-FODMAP smartphone app to have the list ready at your fingertips.
This is the FODMAP "bible". You may find information on FODMAPs elsewhere with conflicting information or it may be outdated. Keep in mind that the Monash University developed the diet and continues to update the list of low/high FODMAP foods with the latest research. This is the only source I trust.
How Does the low-FODMAP Diet Work to Manage Digestive Symptoms?
This fascinating video by Monash University does an excellent job of illustrating how IBS affects the digestive system and how a low-FODMAP diet can help manage symptoms. To summarize:
High-FODMAP foods may be poorly absorbed by the small intestine.
Gut bacteria in the large intestine may ferment the poorly absorbed carbohydrates leading to increased gas pressure. Those with IBS or other gut disorders may have increased visceral sensitivity. This means when the belly distends (from gas or from eating), the brain registers pain.
High-FODMAP foods are also osmotically active, meaning they draw excess water into the large intestines. This extra water causes belly distention (again, which can register as pain). It can also cause diarrhea or constipation.
A Low-FODMAP diet reduces the amount of fermentable carbohydrate intake, which means less fermentation by gut bacteria, less water in the intestines and less opportunity for gas, stomach distension, diarrhea and constipation.
How Long Should I Stay On the Low-FODMAP Diet?
Like other elimination diets, the Low-FODMAP diet is a tool to determine which foods trigger symptoms. After a period of time (3 - 8 weeks), we slowly and systematically reintroduce foods one carbohydrate group at a time. I work with my clients to develop a food reintroduction schedule and a method to track symptoms. We also determine a threshold tolerance of foods. For many clients, it's possible to tolerate small amounts of high-FODMAP foods. It's important to keep in mind...
Elimination diets are not forever diets.
We don't want to limit foods or food groups long term, as that may lead to nutrient deficiencies.
The goal is to liberalize the diet as much as possible while limiting symptoms.
Central Clinical School, Monash University. (2015). IBS symptoms, the low FODMAP diet and the Monash app that can help. Retrieved from https://www.youtube.com/watch?v=Z_1Hzl9o5ic
Cozma-Petrut, A., Loghin, F., Miere, D., & Dumitrascu, D. (2017). Diet in irritable bowel syndrome: What to recommend, not what to forbid to patients! World Journal of Gastroenterology : WJG, 23(21), 3771–3783.