Are dietary interventions better than meds for IBS?

Making certain dietary changes may have a larger impact than taking medications in terms of quelling the symptoms of irritable bowel syndrome (IBS) for patients with moderate-to-severe disease.

In a randomized controlled trial conducted in Sweden, the proportion of patients who achieved at least a 50-percent reduction in the overall IBS severity score over 4 weeks was 76 percent with a low FODMAP diet, 71 percent with a low carbohydrate diet, and 58 percent with optimized medical treatment. [Lancet Gastroenterol Hepatol 2024;doi:10.1016/S2468-1253(24)00045-1]

The difference between the dietary intervention groups and the optimized medical treatment group was significant (p=0.023), according to the investigators led by Dr Sanna Nybacka of the University of Gothenburg in Gothenburg, Sweden.

A total of 294 patients (mean age 38 years, 82 percent women) with moderate-to-severe IBS (Rome IV; IBS Severity Scoring System [IBS-SSS] ≥175) and no other serious diseases or food allergies comprised the modified intention-to-treat population (low FODMAP diet n=96, low carbohydrate diet n=97, optimized medical treatment n=101).

The low FODMAP diet group had to stick to a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. This diet was built around foods with easily digestible carbohydrates such as rice, potatoes, some fruits and vegetables, lactose-free dairy, and various proteins. In addition, the group received dietary advice, including eating slowly, having regular and small meals, and limiting consumption of food products that could trigger symptoms.

Meanwhile, the low carbohydrate diet group received a fibre-optimized diet low in total carbohydrates and high in protein and fat. This included plenty of meat, fish, eggs, dairy, vegetables, nuts, and berries.

Finally, the optimized medical treatment group received the best possible drug prescription based on the predominant IBS symptom. For example, patients whose primary symptom was constipation were given the laxative sterculia, while those with diarrhoea were given loperamide.

The interventions lasted 4 weeks. Thereafter, patients were encouraged to persist with their diets or continue taking their medications throughout the 6-month follow-up.

Notably, patients in the diet groups still reported fewer symptoms at 6 months, despite not always strictly adhering to the diets, Nybacka noted. The proportion of patients with clinically significant symptom relief was 68 percent in the low FODMAP diet group and 60 percent in the low carbohydrate diet group.

All patients, regardless of the intervention, had significantly improved quality of life as well as reduced physical, anxiety, and depression symptoms, she pointed out.

There were no cases of serious adverse events or treatment-related deaths recorded across the three groups, Nybacka said. Two patients in each of the diet groups discontinued the intervention due to adverse events, while five patients in the optimized medical treatment group stopped the treatment prematurely due to side effects.

The findings suggest that dietary interventions might be considered as an initial treatment for patients with IBS, according to Nybacka. “With this study, we can show that diet plays a central role in the treatment of IBS but that there are several alternative treatments that are effective.

“We need more knowledge about how to best personalize the treatment of IBS in the future, and we will further investigate whether there are certain factors that can predict whether individuals will respond better to different treatment options,” she concluded.