Issue: August 2024
Fact checked byHeather Biele

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June 25, 2024
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IBS symptom reduction ‘twice as large’ with dietary intervention vs. medical treatment

Issue: August 2024
Fact checked byHeather Biele
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Key takeaways:

  • At 4 weeks, the dietary interventions reduced symptom severity in 76% and 71% of patients vs. 58% on medical treatment.
  • More than half of patients in the diet groups reported improvement in overall health.
Perspective from Kendra Weekley, MS, RD, LD

Although two restrictive diets and medical treatment all reduced the severity of symptoms in irritable bowel syndrome, the effect was greater with diets, suggesting their potential as first-line treatment, according to researchers.

“As IBS is a disorder that can manifest in different ways among patients, we wanted to conduct a large, randomized controlled trial to test three different treatment strategies — two dietary treatments vs. pharmacological treatment — to gain a better understanding of how we can optimize treatment in this patient group,” Sanna Nybacka, PhD, of the department of molecular and clinical medicine at the University of Gothenburg, told Healio.

IBS Symptom Severity Score change from baseline to 4 weeks: Low-FODMAP diet; –149 Low-carb diet; –128 Medical treatment; –76
Data derived from: Nybacka S, et al. Lancet Gastroenterol Hepatol. 2024;doi:10.1016/S2468-1253(24)00045-1.

In a single-blind trial, Nybacka and colleagues enrolled 294 adult patients (mean age, 38 years; 82% women) with moderate to severe IBS at Sahlgrenska University Hospital in Gothenburg, Sweden.

Patients were randomly assigned a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) combined with traditional IBS dietary advice outlined by the U.K. National Institute for Health and Care Excellence (n = 96), a fiber-optimized diet low in total carbohydrates and high in protein and fat (n = 97) or optimized medical treatment based on the patient’s predominant IBS symptom (n = 101) for 4 weeks. Following the intervention period, patients were unmasked to their dietary strategy and encouraged to continue during 6 months of follow-up.

The primary endpoint was the proportion of patients who responded to the 4-week intervention, defined as at least a 50-point reduction in IBS Symptom Severity Score (IBS-SSS) compared with baseline. Researchers noted 5% of patients in both diet groups and 10% of patients in the medical treatment group were lost to follow-up.

According to results published in The Lancet Gastroenterology & Hepatology, 76% of patients in the low-FODMAP diet group achieved the primary endpoint, as did 71% in the low-carbohydrate diet group and 58% in the medical treatment group, with a significant difference between groups (P = .023).

Although total IBS-SSS was reduced at 4 weeks in all groups, patients who adhered to the low-FODMAP diet had a significantly larger mean change in IBS-SSS vs. the other groups (–149 vs. –128 vs. –76). Researchers also reported that the “overall magnitude” of IBS-SSS reduction was greater in the low-FODMAP (–47.1; 95% CI, –69.4 to –24.9) and low-carbohydrate (–36.4; 95% CI, –58.6 to –14.1) diet groups compared with optimized medical treatment.

Further, results of a treatment satisfaction questionnaire at 4 weeks showed 78% of patients on the low-FODMAP diet and 72% on the low-carbohydrate diet reported improvement in IBS symptoms, while 62% and 51%, respectively, reported improvement in overall health. Just 4% of patients on the low-FODMAP diet reported worsening of IBS symptoms vs. 9% on the low-carbohydrate diet, and 3% and 8% reported worsening of overall health.

“What was striking was that all three treatments showed good efficacy, with significant reductions in IBS symptom severity and improved quality of life in all three treatment arms,” Nybacka said. “What also became evident was that the effect size was almost twice as large in the dietary treatment, meaning that the mean symptom reduction was twice as large in the combined low-FODMAP diet with traditional IBS diet compared with medical treatment.”

According to researchers, no serious adverse events or treatment-related deaths occurred.

“These results highlight the importance of dietary treatment in patients with IBS, which should be considered as a first-line treatment option,” Nybacka told Healio. “However, it is also important to remember that there are different strategies that may provide benefit for patients and that treatment strategies need to be individualized.”

Nybacka continued: “This is the first study to show that a low-carbohydrate diet is effective to alleviate symptoms in IBS, but these results need to be confirmed in additional studies before this diet can be implemented in clinical practice. We also need to identify factors that can predict response to the different treatments, in order to better personalize treatments in the future.”