An estimated 10 to 15 percent of adults in the U.S. suffer from Irritable Bowel Syndrome (IBS), according to the American College of Gastroenterology (1). That equates to between 25 million and 45 million people. And if you’re one of them, you know just how painful and uncomfortable the chronic symptoms can be.
People with IBS suffer from abdominal cramping, diarrhea, bloating, constipation and urgent bowel movements. And while IBS is considered a functional gastrointestinal disease (in the sense that it’s not life-threatening), it remains important for people suffering from IBS to find relief for the triggers and symptoms.
One way of potentially alleviating IBS symptoms is to consider a low-FODMAP diet. “Studies have now been conducted worldwide showing that a low-FODMAP diet is effective in managing IBS symptoms,” says Dr. Marina Iacovou, senior research dietitian and project manager at Monash University in Melbourne Australia—a leading research university for FODMAP studies. “The diet has been shown to be effective in 3 out of 4 people, or approximately 75 percent.”
So is a low-FODMAP diet something that you should try? It gets a bit complicated, so let’s break it down.
What are FODMAPs?
FODMAP is an acronym for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. These are a group of fermentable short chain carbohydrates and sugar alcohols that are indigestible or poorly absorbed by some people.
“As FODMAPs travel through the gastrointestinal tract, they draw excess fluid into the small intestine and generate gas when they are fermented by bacteria in the large intestine,” says Dédé Wilson, co-founder of FODMAP Everyday and author of The Low-FODMAP Diet Step by Step. “This fluid and gas build-up can lead to symptoms of IBS, such as abdominal bloating and distension, pain, flatulence and nausea, as well as diarrhea and constipation.”
Understanding the Different Types of FODMAPs
A key part of being on a low-FODMAP diet is understanding the types of FODMAPs and what foods they are commonly found in.
This term encompasses fructans and galacto-oligosaccharides, says Wilson. Common foods that are high in these FODMAPs include wheat, onions, garlic, beans and cashews.
Wilson explains that when it comes to FODMAPS, disaccharides usually refer to the lactose found in dairy products, such as milk, ice cream, custard, puddings and certain types of cheese. Lactose intolerance is not uncommon. According to The National Institute of Diabetes and Digestive and Kidney Diseases, it’s estimated that nearly 30 million to 50 million American adults have sensitivities to lactose.
“This references the simple sugar called fructose,” says Wilson. “Fructose is a problem when it is present in greater amounts than glucose in foods.” Some examples of foods containing monosaccharides include apples, mangoes, pears, asparagus, agave and honey.
Polyols such as sorbitol and mannitol occur naturally in many fruits and vegetables, including apples, blackberries and peaches. But Wilson says commercially manufactured polyols such as xylitol, maltitol and isomalt are also found in sugar-free gum, candy and other processed foods, as well as some dietary supplements and medications.
Stages of a Low-FODMAP Diet
There are multiple stages of a low-FODMAP diet. The first two phases refer to an elimination phase and what’s called the “challenge” or reintroduction stage. These stages take place before settling on a long-term dietary plan.
“The elimination phase is a brief two- to six-week phase where FODMAPs are eliminated from the diet to calm the digestive system,” says Wilson. “Its brevity is important because this phase eliminates certain sources of fiber and prebiotics, and following any very restrictive diet can lead to nutritional deficiencies.”
Because of this, Wilson explains that it’s very important to work under the supervision and guidance of a registered dietician or gastroenterologist before starting on a low-FODMAP diet.
Iacovou agrees. “It is very important for people to reach a state where their symptoms are well-controlled and not troublesome,” she says. “It is equally as important that they eventually identify which foods are key triggers for their symptoms.”
Once the elimination phase is complete, individuals can start to reintroduce FODMAP foods back into their diets. The “challenge” or “reintroduction” phase may take several months and is meant to identify the specific types of FODMAPs and foods that trigger IBS symptoms. “Eventually foods can be reintroduced into the diet at a dose that is well-tolerated,” says Iacovou. “Every individual will be different, as symptoms and tolerance levels vary between people.”
Following the elimination and reintroduction phases, it’s important to work with a registered dietician or gastroenterologist to figure out how a lower-FODMAP diet can work long term. “The goal is to always eat as broadly as possible without triggering symptoms, and this can mean constant vigilance,” says Wilson.
Foods to Avoid on a Low-FODMAP Diet
During all stages of a low-FODMAP diet, no entire food group is off limits. While not a complete and comprehensive list, Wilson and Iacovou say that the following are common high-FODMAP foods that should be avoided during the elimination phase and may be troublesome for people with IBS:
But it’s important to keep in mind that the amount of FODMAPS in certain foods are related to portion size. “The same food can become high-FODMAP if too much is eaten,” says Wilson. “Almonds are a perfect example. Ten whole almonds are fine, but 20 are not.”
Working with a registered dietician or your gastroenterologist is imperative to incorporating the right recipes and portion sizes that work for you.
The list of low-FODMAP foods is extensive, and individuals on this diet have plenty of options. “People can still eat a complete, nutritionally-balanced diet that is based on their habitual diet,” says Iacovou.
But according to Wilson, some of the most common no- or low-FODMAP foods include:
Low-FODMAP Diet: Risks and Things to Consider
One of the biggest risk factors of a low-FODMAP diet, says Wilson, is when people self-diagnose and attempt to embark on this type of eating without working with a medical professional. “Risks come in applying the diet incorrectly,” she says. “This can happen if you use disreputable or incorrect sources. People download apps because they are free, make recipes because they are called low-FODMAP, and believe what they read on blogs. Unfortunately, there are many sources presenting information that is not accurate.”
Iacovou also says that the elimination phase of the low-FODMAP diet should not be followed long-term. “Eventually people will reach a point where their diet is personalized to a tolerance level that controls their symptoms,” she explains. In addition to potentially altering gut bacteria composition, she says, unnecessary long-term restriction can compromise social activities and initiate food fears. Because of this, the low-FODMAP diet is not recommended for individuals at risk of or who have eating disorders.
Because of its complexity, the low-FODMAP diet isn’t meant to be the next diet trend. “It is not the next ‘fad’ diet or for anyone seeking the next best ‘healthy’ diet,” says Iacovou. “The low-FODMAP diet is a way of eating for people diagnosed with IBS to reduce their symptoms that would otherwise be problematic on a daily basis.”
In fact, says Wilson, people shouldn’t start on a low-FODMAP diet until they have a formal IBS diagnosis from a gastroenterologist and the diet is explicitly suggested by a doctor.
If a low-FODMAP diet is recommended, individuals should keep track of their symptoms and how they feel during each stage of the diet. Wilson says that personal feedback is imperative to success. “This is a learning diet and while it is always best to work with a registered dietitian, ultimately you are going to be able to give yourself the best and most specific feedback,” she says. “You are in charge, and after years of feeling like food has been charge, it’s an incredibly empowering position to be in.”