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NCT Number: NCT04633369

The Role of the Microbiome in the Response to Dietary Fibers Intake During Intermediate Fasting

Dietary fibers are generally not degraded by the endogenous digestive enzymes, but rather by the complex ensemble of microorganisms that reside in the human gut [1]. This ensemble, collectively known as the human gut microbiome, plays a key role in breaking down, fermenting, and ultimately converting such dietary fibers into a variety of beneficial metabolites, including most notably, short chain fatty acids (SCFA). These end products of fibers' fermentation affect host metabolism, immunity, and physiology, and have been implicated in multiple diseases including obesity, metabolic syndrome, diabetes, and cardiovascular diseases.

Intermediate fasting, and in particular circadian intermediate fasting (i.e. 16 hours of fasting followed by 8 hours of allowed eating), has been shown to have positive associations with multiple health conditions as obesity, diabetes mellitus, cardiovascular disease, cancers, and neurologic disorders In this study, we will try to answer open questions utilizing the long fasting period during the day to investigate the isolated effect of dietary fiber consumption, uncovering the degradation effect, but not the bulking effect, on the microbiome and the host physiology, and in particular its glucose response.

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Key information

Conditions

Dietary Fibers Intermediate Fasting

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Weizmann institute of science

Rehovot, Israel

About this study

During the 22 days of the study, participants will wear a continuous glucose monitor, fill a daily food diary, and collect stool and oral samples which will be used for microbiota profiling. Participants will be asked to carry out an intermediate fasting regime, which will include: 16 straight hours of fasting followed by 8 hours which the participants will be allowed to eat. Drinking water is allowed throughout the fasting hours.

The groups will consume 4, 12, 20 grams of the dietary fiber per day, according to the group they were assigned to, while not exceeding the total fiber consumption of 50 grams per day, which is considered a high-fiber diet.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Male and Female BMI<28 Age - 18-70

Exclusion criteria

Consumption of antibiotics 3 months prior to the first day of the experiment. Consumption of probiotic or dietary fibers supplements 1 month prior to the first day of the experiment.

Practiced in intermediate fasting 1 month prior to the first day of the experiment.

Diagnosis with type 1 or type 2 diabetes. Pregnancy, breastfeeding, or fertility treatments in the last 6 months. Chronic disease (e.g. AIDS, Cushing syndrome, CKD, acromegaly, hyperthyroidism hepatitis, fibromyalgia, etc.).

Cancer and recent anticancer treatment. Psychiatric disorders. Coagulation disorders. IBD (inflammatory bowel diseases). IBS (Irritable bowel syndrome). Alcohol abuse, more than 2 drinks per day for males, and more than one drink for females.

Substance abuse. BMI>28. Daily dietary intake higher than 25 grams per day. History of abdominal surgeries (including Bariatric surgery). Mentally incompetent or lack of judgment

Treatment and study plan

dietary fibers

Dietary Supplement

during days 13-22 the participants will consume the dietary fiber according to their randomization and continue fasting. Participants will be asked to collect stool and oral samples 4 times during this period.

Primary outcomes

  1. microbiome

    Time frame: 1 year

    stool and oral samples

  2. glycemic response of different dietary fibers

    Time frame: 1 year

    Continuous glucose monitoring (CGM)

Sponsors and collaborators

Lead sponsor

Weizmann Institute of Science

Other

Collaborators

  • Hadassah Medical Organization

Registry information

Official study title

The Role of the Microbiome and Host Physiology in Personalized Human Response to Dietary Fibers Intake During Intermediate Fasting

Important dates

Study start
2021
Primary completion
2026
Study completion
2027
First posted
Nov 18, 2020
Registry last updated
Mar 19, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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