Dietary Fibers Effect on the Gut Microbiota Composition

The randomized double-blinded placebo-controlled multicenter study will be held in parallel groups. During 5 weeks the efficacy of different endpoints as a measure of response to the daily intake of dietary fibers (8 g of either inulin, pectin, beta-glucan or galactooligosaccharides) will be evaluated. Gut microbiota composition, lipids levels, inflammation markers, microbiome metabolites, changes in quality of life and stool parameters will be assessed in order to predict individual response in participants without serious chronic diseases

A randomized double-blinded study will include 270 volunteers without clinical manifestations of chronic diseases. Participants will be randomized into one of five arms daily consuming one of the following: placebo (maltodextrin, 8 g), inulin (8 g), pectin (8 g), beta-glucan (8 g) or oligosaccharides (8 g).

The study will include a 5-day screening period and a 5-weeks intervention period.

During screening stage, a volunteer will complete a questionnaire, and the following measurements will be performed: blood levels of glycated hemoglobin, creatinine, lipids, C-reactive protein, anthropometric measurements, as well as cardiovascular risk will be assessed.

Before and after the intervention blood and stool samples will be collected to conduct the following analyses: an extended lipid spectrum analysis, high-sensitivity C-reactive protein, 16S rRNA gut microbiome sequencing, laboratory stool testing, stool fecal short-chain fatty acids analysis. Anthropometric measures, physical examination will be performed for each volunteer. The following questionnaires will be completed: dietary recall questionnaire, SF-36, the Rome Criteria for the Functional gastrointestinal disorders (functional constipation). The assessed scales will include Bristol stool scale, Hospital Anxiety and Depression Scale (HADS), Hamilton Rating Scale for Depression (HRSD).

Eligibility Criteria:
Inclusion Criteria:

* Subject doesn't have any active complaints
* Subject doesn't have any active or acute diseases at the time of enrollment
* Subject signed informed consent

Exclusion Criteria:

* High or very high cardiovascular risk
* Levels of total cholesterol and/or low-density lipoproteins requiring immediate assignment of drug treatment (according to ESC Guidelines for the management of dyslipidaemias, 2019)
* Diabetes mellitus of any type
* HbA1с of 5,7% or higher
* Obesity requiring medical therapy or surgery (according to European Guidelines for Adult Obesity Management, 2019)
* Gastrointestinal diseases in history including ulcerative colitis, Crohn's disease, celiac disease, gallbladder disease (calculous cholecystitis, cholangitis, etc.) not related to functional disorders; liver or pancreas diseases
* Irritable bowel syndrome, abdominal pain of any location and etiology
* Pain syndrome of any localization
* Flatulence
* Oncology diseases
* Mental disorders
* Rheumatoid arthritis or other autoimmune diseases
* Acute infectious diseases or exacerbation of any diseases
* Recent (\<3 months) administration of proton pump inhibitors, antimicrobial therapy or surgical intervention
* Recent (\<3 weeks) use of probiotics, antacids, nonsteroidal anti-inflammatory drugs, laxatives
* Pregnancy, planning to be pregnant or breast feeding at any point during the study or study enrollment
* Current alcohol/drug abuse (more than 3 points for women and 4 for men according to AUDIT-C questionnaire and/or more than 7 points on the AUDIT questionnaire) or addiction therapy within 12 months prior to screening
* Allergies to any prebiotic or placebo ingredients
* Planned relocation from the home region during the study