How to Relieve IBS with a Low FODMAP Diet

People with irritable bowel syndrome(IBS) frequently suffer severe abdominal pain, bloating and flatulence. They often report diarrhea or constipation, or occasionally alternating bouts of both. Often, doctors can find nothing wrong with them; they have a “functional” gastrointestinal disorder. There is hope for easing the symptoms, however. Increasingly, research shows that a low FODMAP diet can be helpful.

What Is a Low FODMAP Diet?

FODMAP stands for fermentable oligo-, di- monosaccharides and polyols. These include compounds such as lactose (milk sugar), fructose, fructans, galactans and “polyols,” also known as sugar alcohols even though you could not get tipsy on them. When gut microbes digest these compounds, they create gas. This may well produce the uncomfortable symptoms associated with IBS.

Controlled Trial of a Low FODMAP Diet:

A study shows that when people avoid foods that can be readily fermented by gut bacteria, they feel better (Digestive Disease Week, May 24, 2016). More than 90 IBS patients followed either a low FODMAP diet or a “sensible diet” that reduced caffeine and alcohol for six weeks. (Researchers assigned them randomly.) The ones who reduced FODMAP consumption consulted with registered dietitians. These experts help people discover which foods they should avoid. They could help ensure the volunteers’ diets did not produce serious nutritional deficiencies. (A severely restricted diet might provide too few nutrients.)

More than 50 percent of those on the low FODMAP regimen reported major improvement in their abdominal pain, compared to 20 percent of those eating sensibly.

The Story on Corn Syrup:

Lists of FODMAP-containing foods don’t always mention corn syrup. It is rich in fructose, however. One reader found that getting corn syrup out of the diet made a big difference for IBS symptoms.

Q. Your readers often request information on IBS. I would like to offer a suggestion that may help. Many years ago, I read that adding 1/4 teaspoon of corn syrup to the baby’s formula might offer relief from constipation. It worked like magic.

Fast-forward a few decades, I was bothered with frequent bouts of diarrhea from IBS. Remembering what had worked for my daughter, I wondered if removing corn syrup from my diet would make a difference. I could not believe how many items in my pantry not only contained some form of corn syrup, but often listed it as the first ingredient. Getting rid of it has made a huge difference for me.

A. A surprising variety of processed foods contain corn syrup. A small scientific study concluded, “Fructose, in amounts commonly consumed, may result in mild gastrointestinal distress in normal people.” (Journal of the American Dietetic Association, October 2005) Gas, rumbles, loose stools and stomachache are the most common symptoms associated with too much fructose.

Other Studies of IBS Symptoms and Low FODMAP Diet:

Over the past few years, a number of studies have shown that a low FODMAP diet is associate with less bloating, gas or discomfort. The first was an Australian pilot study in 2007 (Inflammatory Bowel Diseases, Dec. 2007).

By 2010, Australian gastroenterologists concluded

“The low FODMAP diet provides an effective approach to the management of patients with functional gut symptoms. The evidence base is now sufficiently strong to recommend its widespread application.” (Journal of Gastroenterology and Hepatology, Feb. 2010).

American doctors did not immediately adopt this approach, however. On the other hand, in Europe and the UK, doctors now recommend a low FODMAP diet  for people with irritable bowel symptoms (F1000Research, April 29, 2016; World Journal of Gastroenterology, April 21, 2016). Canadian researchers, among others, have reported that changing the FODMAP content of the diet can alter the ecological balance of the microbes in the digestive tract (Gut, July 2017). They found that metabolic profiles and immune system reactivity (measured by histamine release) were altered by the low FODMAP diet.

The Take-Away:

A qualified dietitian can help people with IBS map out a low FODMAP diet that is nutritionally balanced for long-term control of symptoms. Some of the restricted foods are those that are generally recommended as healthful, such as legumes, garlic, onions, leeks, mushrooms and many fruits and vegetables. That’s why it is important not to undertake such a restriction long term without guidance. Moreover, many people find it difficult to stick with the low FODMAP diet for months or years (Journal of Human Nutrition and Dietetics, April 2020). Practical considerations can complicate adherence, even though people who follow the diet report less severe symptoms. According to a recent meta-analysis of ten studies, a low FODMAP diet can improve overall IBS symptoms for most people (Frontiers in Nutrition, Aug. 19, 2021).

Learn More:

We spoke with experts about how to alter gut bacteria to reduce reflux and improve digestion (Show 1023). The diet described by Norman Robillard, PhD, has much in common with a low FODMAP diet.