Trust Your Gut: The Low FODMAP Diet

“Highly fermentable short-chain carbohydrates” could be the key to controlling IBS

By Gabriella Salazar

Chances are you have experienced some form of gastric distress within your lifetime. Gastrointestinal (GI) distress and irritable bowel syndrome (IBS) have been studied since the early 1820s. While it is by no means a glamorous topic to discuss, symptoms such as gassiness, cramping, bloating, heartburn, and incontinence have risen starkly within the past decade, so much so that 60 to 70 million individuals within the U.S. are affected by digestive diseases today. Because our microbiome, or gut health, cannot contend with recent shifts in our food production system towards ultra-processing and fortification, individuals are often left with an overall negative and hopeless view on nutrition. This is understandable, considering misleading marketing has made it increasingly difficult for the general public to decipher what is a ‘healthful food’ and what is just as ultra-processed as a candy bar. 

The reasons for the increased prevalence of gastrointestinal disease and inflammation remain unclear, but studies have linked increased gastric distress to highly fermentable short-chain carbohydrates, known as a group as FODMAPS. Therefore, a diet low in FODMAP foods is an eating regime that is low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, all of which are short-chain carbohydrates that our small intestine cannot fully digest. High intake of high-FODMAP foods tends to cause fermentation and supports the production of harmful gut bacteria, in turn causing gastric inflammation and discomfort. As a result, researchers have sought to publicize evidence-based guidelines to eating habits that do not require you to cut out entire food groups, or put yourself on extreme caloric deficits, or pursue a non-sustainable lifestyle. 

In the early 2000s, researchers at Monash University in Australia proposed that a diet controlling the intake of FODMAP foods could be a viable solution for these gut disorders. The university published the findings from their evidence-based dietary approach and saw a 50-86% clinically meaningful decrease in irritable bowel syndrome. 

In 2021, a meta-analysis of studies of a diet low in FODMAP foods found that a low-FODMAP diet not only reduces gastrointestinal symptoms, but it also greatly improves the quality of life in individuals with IBS compared to control diets. PhD candidate Anne-Sophia van Lanen of Wageningen University and Research devised the meta-analysis review to include a total of 722 human subjects with IBS. Individuals partook in short-term studies, ranging from four days up to three months, and the findings were overwhelmingly cohesive. Those who followed a low-FODMAP diet over a controlled diet or a high-FODMAP diet saw improved GI symptoms: specifically, constipation, gassiness, bloating, cramping, and diarrhea. Additionally, there was a statistically significant improvement in self-reported quality of life for those who followed a low-FODMAP diet. Van Lanen’s meta-analysis included twelve papers (nine parallel trials and three crossover studies). Subgroup analyses on variables such as age, adherence, intervention duration, IBS severity, and risk of bias held no significantly different results, and a low-FODMAP diet saw an increased quality of life in IBS patients by approximately 42%. Additionally, a low-FODMAP diet reduced the severity of irritable bowel syndrome by a ‘moderate-to-large extent’ in comparison to a controlled diet.  

On a low-FODMAP diet your body is able to discrete toxic gut bacteria and eliminate the insoluble fibers that block healthy gut bacteria from multiplying. Van Lanen concludes that a low-FODMAP diet has been tested, published, and reviewed sufficiently to be deemed an evidence-based approach for those with IBS to improve their overall gut health and quality of life. Van Lanen says, “It can be incredibly beneficial to eliminate categories of food to help identify the culprit and to help a person not have so much discomfort.”

While a low-FODMAP diet has been proven effective across the nutrition community, there are still safety precautions that should be taken when following any dietary intervention. “Because variety is key to good health, you want to make sure that you’re exposed to everything that your body needs,” says Dan Benardot, a nutrition scholar and professor of practice at Emory University who was not involved in the study. “You can certainly have non-FODMAP foods that can keep a person healthy, but you just have to make sure that you are having a variety of them.”

The authors of the study emphasize that the effects of a low-FODMAP diet are only conclusive in the short-term due to the risk of eating a monotonous diet. The effects of long-term benefits of a low-FODMAP diet are not yet advocated for by nutrition and health professionals, unless under the supervision of a Registered Dietician (RD). More research should be done on how a low-FODMAP diet affects the microbiome after returning to regular eating, the effects of the diet on different age groups, and the use of the diet for anti-inflammatory effects. This is by no means a ‘weight-loss diet’ and should not be treated as such. However, when used responsibly, this diet can improve your gut health exponentially, which in turn has been proven to support a strong immune system, a healthier heart and brain, improved mood, better quality of sleep, and, of course, a more comfortable and effective digestive system. 

Considering that 25 to 45 million people in the United States suffer from IBS, a low-FODMAP diet should be utilized before mere ‘band aid fixes’ that conceal underlying issues with heartburn medication, highly processed probiotics and prebiotic foods, fortified products, and high-dose supplements. 

There are many factors that contribute to how your body uses food and absorbs nutrients, and not all foods are created equal. Low-FODMAP foods and non-FODMAP foods, as listed below, are easier for your body to break down and digest. They also support a healthier overall digestive environment, but there are many factors you should consider when reflecting on your own dietary habits. As Benardot said, there are many components to a healthful diet. “What you eat, when you eat it, how much you eat when you finally do, whether or not you’re eating in a low blood sugar state, I mean, those are the factors that can really create an issue.” So, be cognizant of your eating habits and the behaviors surrounding them, regardless of how you view your own nutritional status and the societal implications of it. If you are someone who suffers from irritable bowel syndrome (IBS), an intermittent low-FODMAP diet may be a tool for you to rid of the bad gut bacteria that could be corroding other areas of your health.