The purpose of this study is to assess the efficacy and safety of a food supplement with standardized menthol, limonene, and gingerol content in patients with irritable bowel syndrome (IBS) or IBS/functional dyspepsia (FD).

Using a random number generator, 56 patients meeting inclusion criteria with IBS or IBS/FD were randomly assigned to either the intervention group (28 individuals) or the control group (28 individuals) (Table 2). Non-functional causes for the symptoms were excluded by a detailed evaluation of the medical history, physical examination, extensive panel of blood tests, stool analysis, and colonoscopy with biopsies.

Diarrhoea-predominant IBS patients (IBS-D) and mixed bowel habits IBS patients (IBS-M) were treated with smooth muscle antispasmodics. The constipation-predominant IBS patients (IBS-C) were treated with smooth muscle antispasmodics and laxatives. IBS/FD patients were treated with smooth muscle antispasmodics and proton pump inhibitors.

At Visit 1, all patients were randomly assigned into two groups. In the intervention group (Group 1), the supplement "Standart Zdorovya GASTRO" (1 capsule, 730 mg, once a day) was added to the standard treatment regimen for 30 days. In the control group (Group 2), placebo (1 capsule, 730 mg, once a day) was added to the standard treatment regimen for 30 days (Table 1). Researchers and patients were not informed who received a supplement or placebo. During the 30 days of the study, three outpatient visits were conducted (Visit 1 - Day 1, Visit 2 - Day 15 + 2 days, and Visit 3 - Day 30 + 2 days).

Symptom severity was assessed on each visit using "7x7" questionnaire [Ivashkin, V., Sheptulin, A., Shifrin, O., Poluektova, E., Pavlov, C., Ivashkin, K., Drozdova, A., Lyashenko, O., Korolev, A., 2019. Clinical validation of the "7 × 7" questionnaire for patients with functional gastrointestinal disorders. J. Gastroenterol. Hepatol. 34, 1042-1048. https://doi.org/10.1111/jgh.14546\], on 1 and 3 visits stool samples were collected for the qualitative and quantitative composition of the intestinal microbiota based on 16S rRNA gene sequencing.

The study protocol was approved by the Ethics Committee of the Mental Health Research Center, Moscow, Russian Federation (No. 418 dated 01/31/2018) and written informed consent was obtained from all participants.

Inclusion Criteria:

• irritable bowel syndrome (IBS)
• diarrhea-predominant IBS
• constipation-predominant IBS
• mixed-type IBS
• IBS/functional dyspepsia symptoms
• Must be able to swallow tablets

Exclusion Criteria:

• organic bowel disease
• renal disease
• hepatic insufficiency,
• schizophrenia
• bipolar disorder
• epilepsy

Using a random number generator, 56 patients with IBS or IBS/FD were randomly assigned to either the intervention group (28 individuals) or control group (28 individuals).

Researchers and patients were not informed who received a supplement or placebo.