Dietary interventions such as low FODMAP should be considered a potential first-line treatment for patients with IBS, outperforming symptom-targeted medication in reducing symptom severity, a study suggests.

However, all interventions in the single centre study resulted in significant and clinically meaningful efficacy at improving gastrointestinal, psychological and non-gastrointestinal somatic symptoms, and quality of life, the researchers said.

Some 300 patients (mean age 38, 82% women) with moderate-to-severe IBS and no other serious diseases or food allergies were randomly assigned to receive one of three treatment options: a low FODMAP diet plus traditional IBS dietary advice, a low-carbohydrate fibre-optimised diet or symptom-targeted medical treatment.

Participants in the dietary groups were blinded over four weeks, however asked to continue with the intervention after unmasking for six months of follow-up. The low FODMAP diet group received guidance on how to reintroduce certain foods, while the medical treatment group were offered dietary counselling.

Findings showed that 76% of the low FODMAP diet group, 71% of the low carbohydrate diet group and 58% of the medical treatment group had a reduction of 50 or more in IBS Severity Scoring System (SSS) at four weeks compared with baseline, with a significant difference between the groups.

There were also reductions recorded across all domains, including pain severity, pain frequency, bloating severity and interference.

The mean change in IBS­-SSS was significantly larger for low FODMAP diet (–149) and low ­carbohydrate diet (–128) than for optimised medical treatment (–76).

At group level, stool consistency improved significantly from baseline to four weeks with both diets, but not with medical treatment, the researchers noted.

Other findings showed that quality of life significantly improved across all groups, as did anxiety and depression scores and non-­gastrointestinal somatic symptoms.

The low FODMAP diet also showed other benefits such as significantly reduced fasting blood concentrations of total cholesterol, HDL, LDL, and triglycerides from baseline to four weeks. Whereas the low carbohydrate diet resulted in reduced glycated haemoglobin and triglycerides but increased total cholesterol and LDL levels.

Long term benefit

Writing in the Lancet Gastroenterology & Hepatology [link here], the Swedish researchers said the positive effects of the interventions, including on symptoms and quality of life, largely persisted during follow-up, providing evidence for long-term benefit.

“Although we found evidence that dietary treatments were more efficacious than medical treatment after four weeks, all three treatment options showed significant and clinically meaningful efficacy,” they said.

“The sustained positive effects of dietary interventions suggest their potential as first-line treatments for IBS, although patient preference, compliance, cost-effectiveness, and effects on nutritional status and the gut microbiota would need to be accounted for.

“Considering the different treatment options in IBS, of which several show good effectiveness, future research is needed to identify possible predictors of treatment outcomes to enable personalised treatment strategies in the future.”

Writing in an accompanying comment [link here], Indian gastroenterologists said a dietitian should first assess patients’ primary diet to avoid unnecessarily restrictive diets, while candidates suitable for pharmacotherapy should also be identified.

“It is imperative not to put patients on indefinite dietary restrictions, but to educate them about the duration of restriction and persistently support them throughout the reintroduction and personalisation phases,” said the gastroenterologists from Apollo Multispeciality Hospitals, Kolkata.

“Moreover, a multifactorial disorder such as IBS might benefit more from a multimodality therapy, including combinations of drugs and dietary treatments.”

IBS and eating disorders

Meanwhile, new Australian research [link here] has shown that a third of patients with IBS may experience symptoms of disordered eating and orthorexia, which was double the rate of those without IBS.

Concerningly, IBS participants scored similarly for disordered eating and orthorexia symptom severity compared to those with a known eating disorder, the researchers said.

The Swinburne University-led study of more than 300 participants also suggested that those with IBS and disordered eating were likely to have higher gastrointestinal symptom severity, higher stress and anxiety, and worse food-related quality of life.

Writing in Neurogastroenterology and Motility, the researchers hypothesised that the restrictive nature of diets such as low FODMAP, while improving symptoms, had the potential of resulting in disordered eating behaviours. Alternatively, eating disorders might lead to IBS in the long term.

The researchers are urging clinicians to consider these characteristics in patients when prescribing dietary therapies.