Background: This study aimed to evaluate the effects of inulin supplementation on nutritional intake, anthropometric parameters, and bowel symptoms in individuals diagnosed with IBS-C.

Method: This was a randomised, single-blind, placebo-controlled clinical trial. Participants were randomly allocated into intervention (inulin) and control (placebo) groups for 8 weeks. Assessments included dietary intake, anthropometric measurements, and IBS symptoms.

Irritable Bowel Syndrome (IBS) is a common functional gastrointestinal disorder characterised by chronic abdominal pain, bloating, and altered bowel habits, often without identifiable organic pathology. IBS with predominant constipation (IBS-C) presents management challenges due to its multifactorial aetiology and impact on quality of life.

Inulin, a naturally occurring prebiotic dietary fibre found in many plants, has been studied for its beneficial effects on gut health, bowel function, and body composition. It may increase short-chain fatty acid production, improve intestinal transit, and promote beneficial gut microbiota such as Bifidobacteria. However, evidence on the specific benefits of inulin supplementation in individuals with IBS-C remains limited.

Inclusion criteria were being between the ages of 19-65 years, volunteering to participate in the study, being diagnosed with IBS by a physician according to Rome IV criteria, and having two of the three criteria according to Rome IV criteria: associated with defecation (alleviation), associated with change in defecation frequency, associated with change in stool appearance / symptoms started at least 6 months before the diagnosis was made and recurrent abdominal pain at least 1 day a week for the last 3 months. Exclusion criteria were a history of gastrointestinal surgery (except appendectomy and cholecystectomy), inflammatory bowel disease, lactose malabsorption, gastroenteritis, celiac disease, gastric and duodenal ulcer, metabolic diseases (cardiac, hepatic and renal diseases, diabetes, etc.), malignancy. ), history of malignancy, pregnancy and lactation, use of intestinal motility and antidepressant drugs, involuntary body weight loss of more than 5 kg in the last 3 months, use of dietary fibre supplements in the last 3 months, use of antibiotics in the last 3 months, and use of prebiotic and probiotic supplements in the last 3 months.

In this study, eligible participants were randomly allocated into two groups:

• Intervention group (n=17): received 9.2 g/day of an inulin-oligofructose mixture (50:50), split into two doses daily.
• Control group (n=17): received an isocaloric placebo (maltodextrin, 9.2 g/day) using the same dosing schedule.

The intervention period was 8 weeks, during which participants continued their usual dietary habits. Assessments included dietary intake evaluations, anthropometric measurements (weight, BMI, waist and hip circumference, body composition via bioelectrical impedance), and IBS symptoms (using the IBS-SSS) at baseline and after 8 weeks.

The primary outcome was the change in IBS symptom severity (IBS-SSS scores). Secondary outcomes were changes in anthropometric parameters and dietary intake.

Inclusion Criteria:

• the individuals were between 19-65 years of age
• volunteer to participate in the study
• Individuals diagnosed with IBS by a physician according to Rome IV criteria

Exclusion Criteria:

• a history of gastrointestinal surgery (except appendectomy and cholecystectomy)
• inflammatory bowel disease
• lactose malabsorption
• gastroenteritis
• celiac disease
• gastric
• duodenal ulcer
• metabolic diseases (cardiac, hepatic and renal diseases, diabetes, etc.)
• history of malignancy
• pregnancy and lactation
• use of intestinal motility
• antidepressant drugs
• involuntary body weight loss of more than 5 kg in the last 3 months
• use of dietary fibre supplements in the last 3 months
• use of antibiotics in the last 3 months
• use of prebiotic and probiotic supplements in the last 3 months.

Individual participant data (IPD) will not be shared due to privacy concerns and ethical considerations related to the small sample size, which may increase the risk of participant identification

Participants were blinded to groups