Updated: Apr 26, 2019

The low-FODMAP diet is a diet that restricts specific types of sugars, called Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. These sugars are called “fermentable” because the bacteria in the intestines use them as a fermentation source, producing gas as a side product. These sugars also hold water in the intestines, which can create bloating when eaten in excess.

Because excessive consumption of FODMAPs might contribute to intestinal pain, bloating, and gas, the low-FODMAP diet is more extensively researched than any other diet for patients with irritable bowel syndrome (IBS). Studies show that the low-FODMAP diet is reliable for reducing abdominal pain, bloating, and flatulence, but less effective for improving constipation or diarrhea. Although the low-FODMAP diet is often the first diet recommended for patients with IBS, not all studies show that it is any better than other diets that restrict gas-producing foods (like beans, cabbage, and onions). It is important to note that the low-FODMAP diet restricts a variety of intestinal irritants, including gluten and dairy.  

The biggest concern about following the low-FODMAP diet indefinitely is that it may decrease the number of beneficial intestinal bacteria. The sugars that are restricted in this diet also serve as prebiotics, or fuel to feed the good bacteria in the gut. Studies show that the low-FODMAP diet can decrease the number of intestinal Bifidobacteria—even in patients who feel better on this diet.  

Resources:

1. Gibson PR, Shepherd SJ. Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach. J Gastroenterol Hepatol. 2010;25(2):252-258.

2. Halmos EP, Power VA, Shepherd SJ, Gibson PR, Muir JG. A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology. 2014;146(1):67-75..

3. Böhn L, Störsrud S, Liljebo T, et al. Diet low in FODMAPs reduces symptoms of irritable bowel syndrome as well as traditional dietary advice: a randomized controlled trial. Gastroenterology. 2015;149(6):1399-1407.

4. Staudacher HM, Lomer MC, Anderson JL, et al. Fermentable carbohydrate restriction reduces luminal bifidobacteria and gastrointestinal symptoms in patients with irritable bowel syndrome. J Nutr. 2012;142(8):1510-1518.


About the Author: Dr. Gerard Guillory, MD is Board Certified in Internal Medicine and has published two books on Irritable Bowel Syndrome (IBS). In 1985, he opened The Care Group, PC. Today, his clinic is a Primary Care facility that is a hybrid of functional and traditional medicine treating patients with digestive disorders, autoimmune disease, and other conditions. You can learn more about Dr. Guillory here.