FODMAP Diets, Explained
FODMAP is an acronym of the scientific names of a class of carbohydrates (namely, certain sugars and fiber) that are difficult for the human gut to absorb. Specifically, FODMAP stands for “fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.”
“So far, there has been no evidence that any diet can cause or prevent inflammation of the bowel,” says Bo Shen, MD, a gastroenterologist and the medical director of the Inflammatory Bowel Disease Center at Columbia University/NewYork-Presbyterian Hospital. “But, a low-FODMAP diet, which is essentially a low-carb and low-fiber diet, has been the most scientifically studied diet to date.”
What’s more, he says, a low-FODMAP diet can help control some of the symptoms of Crohn’s or UC, which together affect around 2.3 million people in the United States, according to data from the U.S. National Health and Nutrition Examination Survey.
The exact causes of IBD are unknown, according to the Crohn’s & Colitis Foundation, but genetics have been shown to play a role. Researchers are also starting to study the gut microbiome — the unique composition of microorganisms, such as bacteria, in the human gut — in hopes of learning how it’s related to chronic inflammatory diseases.
What we eat can have a large impact on those bacteria, says Dr. Shen. For example, fiber and simple carbohydrates, such as sugar — like FODMAPs — are the primary food sources of bacteria, so eating a diet heavy in those nutrients can often exacerbate gastrointestinal symptoms, such as bloating, gas, and lower abdominal pain, particularly in people with IBD. “Excess fiber in the diet can make those symptoms worse,” he says.
How a Low-FODMAP Diet May Help Ease IBD Symptoms
In research published in Gastroenterology, scientists tracked 52 people with IBD, measuring their persistent gut symptoms, markers of inflammation, and their fecal microbiome. At the end of the 4-week study, 52 percent of people who followed the low-FODMAP diet reported relief of gut symptoms after the trial, compared with just 16 percent of people who followed a control diet. Plus, those who stuck to the low-FODMAP diet scored higher on quality-of-life assessments.
While the researchers concluded that a low-FODMAP diet is safe and can help control symptoms of Crohn’s and UC, one of the difficulties of studying the microbiome is that everyone’s gut bacteria is distinct, says Shen.
“Each of us has at least 5,000 different kinds of bacteria in our gut,” he says. That makes drawing valid conclusions from comparisons among people difficult. Further research could focus on comparing the microbiome of the same patient before and after a low-FODMAP diet.
What to Eat — and Avoid — on a Low-FODMAP Diet
Until more research emerges, current evidence suggests that following a low-FODMAP diet and limiting certain high-fiber, high-carb foods can help people with IBD feel better.
On a typical low-FODMAP diet, carbohydrates to avoid include:
But, there is also a lengthy list of carboyhydrates that are acceptable on the diet, such as:
- Almond milk (plain, unsweetened)
- Citrus fruits
- Green beans
- Hard cheeses
“This diet is not very restrictive, since there is a wide spectrum of foods to choose from, and is fairly easy to follow,” says Shen, who likes to tell people, “It’s not no FODMAP, just low FODMAP.” Certain foods, such as apples, can be made diet friendly by peeling them.
“Even a low-FODMAP diet still has some fiber,” Shen says.
There’s also little risk in trying the diet in the short-term, though it’s a good idea to work with a registered dietitian to make sure you’re getting all the nutrients you need in your diet. You are still able to get all the nutrients your body needs, including fiber.
Overall, following this diet can be another option to help you manage your UC symptoms and take back some control over your health and life.