Comparison of Microbiome Changes in Healthy Adults Following Ketone Ester Consumption (BREAK)

January 22, 2026 updated by: University of California, San Francisco

Bacterial Responses to Enteric Alterations After Ketones

The goal of this observational study is to learn if a ketone ester can improve the content of the gut microbiome. The main questions it aims to answer are:

  • Does a ketone ester reduce age-related signatures in the gut microbiome?
  • What changes occur in the gut microbiome after consuming a ketone ester?

Participants will:

  • Take a ketone ester every day for seven (7) days
  • Collect and ship stool samples within seven (7) days before, during, and within seven (7) days after the study period
  • Measure their ketone levels with a urine strip every day after having the drink
  • Answer questions about their typical diet on a normal day
  • Record their symptoms, if any arise

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

  • Name: John C Newman, MD, PhD
  • Phone Number: 415-502-5134
  • Email: Newman@ucsf.edu

Study Locations

  • United States
    • California
      • San Francisco, California, United States, 94158
        • Recruiting
        • UCSF Wayne and Gladys Valley Center for Vision
        • Contact:
        • Principal Investigator:
          • John C Newman, MD, PhD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Subject is male or female, 18 to 40 years of age, inclusive, at Virtual Visit 1.
  • Subject has a self-reported BMI of 18.5 to 39.9 kg/m2 (inclusive) at Virtual Visit 1.
  • Subject is willing and able to comply with all study procedures including maintenance of habitual dietary intake, consumption of study product at specified intervals, written questionnaires including study log and beverage tolerability questionnaire (KETQ), habitual exercise and medication and supplement use.
  • Subject has an email address and internet access via computer, phone, or other device, and is willing and able to maintain internet access throughout the trial to complete virtual visits via video conference.
  • Subject has no health conditions that would prevent them from fulfilling the study requirements as judged by the Study Clinician on the basis of medical history.
  • Subject understands the study procedures and signs forms providing informed consent to participate in the study.

Exclusion Criteria:

  • Subject is unable to converse in English or Spanish
  • Subject is unable to provide informed consent due to cognitive impairment or insufficient English or Spanish language comprehension
  • Subject has been hospitalized within 30 days of Virtual Visit 1.
  • Subject has a history or presence of uncontrolled and/or clinically active pulmonary, cardiac (e.g. >= New York Heart Association class III), hepatic, renal, endocrine (including type 1 diabetes), hematologic, immunologic, neurologic (e.g., Alzheimer's or Parkinson's diseases), psychiatric (including unstable depression and/or anxiety disorders) or biliary disorders. Stable chronic disease is not an exclusion criterion unless specified.
  • Subject has a clinically important gastrointestinal condition that would potentially interfere with the evaluation of the study beverage [e.g., inflammatory bowel disease, irritable bowel syndrome, chronic constipation, severe constipation (in the opinion of the Study Clinician), history of frequent diarrhea, history of surgery for weight loss, gastroparesis, systemic disease that might affect gut motility according to the Study Clinician, reflux requiring daily medication, history of gastrointestinal ulcers or bleeding, celiac disease, and/or clinically important lactose intolerance].
  • Subject has a known allergy, intolerance, or sensitivity to any of the ingredients in the study product, including milk protein.
  • Subject is undergoing treatment or active surveillance for cancer, or has been diagnosed with cancer in the prior two years, except for non-melanoma skin cancer.
  • Subject has recently used antibiotics within 60 days of Virtual Visit 1.
  • Subject has extreme dietary habits (e.g., intermittent fasting or time restricted eating, Atkins diet, vegan, very high protein/low carbohydrate or has used weight-loss medications (including over-the-counter medications and/or supplements) or programs within 30 days of Virtual Visit 1.
  • Subject has used medications (over-the-counter or prescription) known to influence gastrointestinal function including, but not limited to, opioids, weight loss medications, antidiarrheals, and antispasmodics) within 30 days of Virtual Visit 1.
  • Subject has used ketone supplements (ketone salts or esters, and medium chain triglycerides [MCT]) within 30 days of Virtual Visit 1.
  • Subject is a female who is pregnant, planning to be pregnant during the study period, lactating, or is of childbearing potential and is unwilling to commit to the use of a medically approved form of contraception throughout the study period. The method of contraception must be recorded.
  • Subject has a condition the Study Clinician believes would interfere with their ability to provide informed consent, comply with the study protocol, which might confound the interpretation of the study results, or put the subject at undue risk.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: 25g Bis-octanoyl-(R)-1,3-butanediol (C8)
Participants will receive 25g of the ketone ester bis-octanoyl-(R)-1,3-butanediol (C8) daily.
Dietary supplement: Exogenous ketone ester
25g Bis-octanoyl-(R)-1,3-butanediol (C8)

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Longitudinal Change in Microbiome Composition
Time Frame: From baseline sampling to final sampling, including intervention period, at 21 days
Microbiome composition will be defined as the following components: 1) alpha-diversity as calculated by Shannon Index; 2) beta-diversity; and 3) microbial community taxa and gene number.
From baseline sampling to final sampling, including intervention period, at 21 days

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Acute Tolerability Symptoms related to Product Ingestion
Time Frame: From start to end of intervention at 7 days
Symptoms will be assessed daily using a standardized Beverage Tolerability Questionnaire (Stubbs et al. J Nutr Health Aging 2024). Symptoms are rated on a scale of mild, moderate, and severe with the following symptoms: 1) gas/flatulence; 2) nausea; 3) vomiting; 4) abdominal cramping; 5) stomach rumbling; 6) burping; 7) reflux/heartburn; 8) diarrhea; 9) headache; and 10) dizziness.
From start to end of intervention at 7 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of California, San Francisco

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: John C Newman, MD, PhD, University of California, San Francisco

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 21, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 30, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 30, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 11, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 24, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
May 1, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
January 26, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 22, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
January 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 25-43835

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

This is a pilot study that will only be used to inform future trial design, no IPD will be shared externally.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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