Low FODMAP diet more effective than medication

By Staff 10 Min Read

  • Irritable bowel syndrome (IBS) is a prevalent gastrointestinal condition, estimated to affect about one in 10 people globally.
  • A new study suggests that dietary interventions may be more effective in reducing IBS symptoms than medical treatments.
  • All options showed meaningful symptom improvements, but experts agree that sustained dietary changes are key to managing IBS.

A new study suggests that dietary interventions may be more effective than medication for managing symptoms of irritable bowel syndrome (IBS).

IBS is a chronic gastrointestinal condition affecting an estimated 10% of the global population, making it one of the most common disorders related to gut-brain interactions.

In a first-of-its-kind study, researchers at Sahlgrenska University Hospital in Gothenburg, Sweden, compared the effectiveness of two diet-based treatments and one pharmaceutical treatment in adults with moderate to severe IBS symptoms.

After 4 weeks, both diets and medical intervention significantly reduced symptom severity, with diets outperforming the medical option, and a low FODMAP diet combined with traditional IBS dietary advice being most effective.

A low FODMAP diet contains foods that are low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, hence its name. This type of diet is often associated with better gastrointestinal health.

In the current study, 6 months after the diet groups had partially resumed normal eating patterns, the majority still reported clinically meaningful symptom improvement.

These findings appeared in The Lancet Gastroenterology & Hepatology.

This single-center, single-blind, randomized controlled trial was conducted in a specialized outpatient clinic for disorders of gut-brain interactions.

The study’s 294 participants were predominantly women (82%) with an average age of 38 and moderate-to-severe IBS.

Included participants scored 175 or higher using the IBS Severity Scoring System (IBS-SSS)—measuring abdominal pain frequency and intensity, bloating, satisfaction with bowel habits, and quality of life related to IBS—and had no other serious diseases or food allergies.

They were randomly assigned into three groups:

  • a low FODMAP diet coupled with traditional IBS dietary advice from the United Kingdom’s National Institute for Health and Care Excellence (NICE)
  • a high-fiber, low-carbohydrate diet with an average carbohydrate intake of 50 grams (g) per day
  • pharmaceutical treatment tailored to their specific IBS symptoms.

Participants were unaware of their diet types, but those in the medication group knew their treatment.

A study dietitian informed the diet groups about their diets without revealing diet names or labeling foods as low in FODMAPs or carbohydrates.

After the initial 4-week intervention, the diet groups were advised on how to proceed for six months, including reintroducing FODMAPs for some, while medication group members were offered nutritional guidance alongside their ongoing treatment.

A reduction in IBS-SSS scores was the primary measure of the interventions’ success.

Within the study, high completion rates were observed, with 90% or more of participants finishing the 4-week interventions across all groups.

Following the 4-week intervention, each group recorded a significant decrease in IBS symptoms, as indicated by a drop of 50 points or more in IBS-SSS scores.

The most notable improvement was in the group following a low FODMAP diet and traditional dietary advice (76%), followed by the low-carbohydrate group (71%) and the medication group, which showed the least but still significant improvement (58%).

All groups experienced substantial improvements in quality of life, with fewer physical, anxiety, and depressive symptoms reported.

Despite partially returning to their normal diets during the 6-month follow-up, 68% in the low FODMAP and traditional advice group and 60% in the low-carbohydrate group continued experiencing significant symptom relief, indicating potential long-term benefits.

The traditional dietary recommendations that were given in the study included consuming regular meals and snacks, sitting during meals, chewing foods thoroughly, and limiting common IBS symptom triggers like coffee, carbonated drinks, alcohol, fatty foods, and spicy foods.

These recommendations were integrated with low-FODMAP food consumption, including foods like rice, potatoes, quinoa, gluten-free bread, vegetables, and fruits, along with low-fat, lactose-free dairy products, fish and seafood, and plant-based proteins.

This combined diet intervention resulted in superior IBS outcomes in the present study.

Alyssa Simpson RDN, CGN, CLT, a registered dietitian and certified gastrointestinal nutritionist, who was not involved in the study, explained why the low FODMAP diet, in particular, is so helpful for those with IBS:

“The low FODMAP diet reduces fermentable carbohydrates that cause gas, bloating, and discomfort in IBS, while also decreasing foods that draw water into the intestines, improving stool consistency. Reducing fermentable carbohydrates in [the] diet may shift the balance of bacteria towards those that thrive on non-fermentable substrates, potentially improving symptoms of IBS.”

She also described how the second best option in the study, a fiber-rich, low-carb diet, could benefit IBS.

Unlike diets high in refined carbs and added sugars, a high-fiber, low-carb diet “may help promote a healthier balance of gut bacteria, which could positively impact IBS symptoms,” she said.

Similar to a low FODMAP diet, “a low-carbohydrate diet may alter the gut microbiota by reducing the availability of carbohydrates for fermentation, favoring the growth of bacteria that metabolize proteins and fats.”

Simpson noted that medications for IBS can indirectly affect the gut microbiome by positively impacting gastrointestinal function and symptoms.

However, certain medications, like antibiotics, can disrupt the balance of gut bacteria, leading to potentially harmful effects, she cautioned.

The present study is the first to test a combined low FODMAP and traditional IBS diet, assess a low-carb diet’s effectiveness for IBS, and compare these dietary approaches to standard medical treatments.

Kiran Campbell, a registered dietitian not involved in the study, highlighted that “all three interventions in the study showed improvements in quality of life, anxiety and depression symptoms, and non-gastrointestinal somatic symptoms — like weakness, fatigue, dizziness, etc.”

While all participants in this study experienced benefits, this study had a limited duration, and they were under observation while receiving treatments, so it is possible participants reported improvements in part due to their awareness of being studied.

Still, recent research supports this study’s findings, indicating that low FODMAP and traditional IBS diets outperform other dietary interventions in easing IBS symptoms.

Campbell suggested that in addition to the better outcomes, there are potential long-term benefits of using dietary interventions over medications as a first-line treatment for IBS.

She said these include “improving a patient’s understanding of nutrition and helping them remove barriers to lifelong healthy eating,” as well as potentially helping patients pinpoint specific foods that are causing GI distress.

“In some patients, resolving [gastrointestinal] issues may be as simple as avoiding certain types of sugars (FODMAPS). If pharmacological approaches are used as a first-line of defense these patients would otherwise never know where the issue is originating from. Dietary approaches to managing IBS are a great way to rule out food causes [of] abdominal issues.”

— Kiran Campbell, RDN

To optimize the management of IBS symptoms through dietary interventions, Simpson and Campbell agreed the ultimate goal is to minimize unnecessary restrictions and focus only on eliminating specific trigger foods.

Simpson and Campbell noted that by identifying and avoiding only the foods that aggravate symptoms, patients can achieve a balanced diet, reduce the risk of nutritional deficiencies, and maintain a healthier gut microbiome, contributing to overall quality of life.

They highly recommend working with a registered dietitian for a tailored approach to ensure a diet that is nutritionally adequate, varied, and as unrestricted as possible, facilitating long-term maintenance and well-being.

Ultimately, the experts both emphasized the need for more research into the effects of interventions on nutritional status and the gut microbiome to improve IBS management strategies.

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