Effects of Kefir Consumption on Health Outcomes: Gastrointestinal System, Immunity, Biochemical Parameters, Body Composition, Sleep Quality and Mental Well Being in Healthy Adults (KefirCons)

September 23, 2024 updated by: Merve Pehlivan, Medipol University

The goal of this clinical trial is to evaluate the effects of the administration of kefir on gastrointestinal system, mental health, biochemical parameters, immunity and inflammation processes as well as the sleep quality, elucidating the possible health effects of kefir consumption in healthy adults. The main questions it aims to answer are:

  1. Will be better the gastrointestinal system symptoms severity of volunteers in the intervention group will be better compared to the control group?
  2. Will be better the mental health status of volunteers in the intervention group will be better compared to the control group?
  3. Will be better the biochemical parameters of volunteers in the intervention group will be better compared to the control group?
  4. Will be better the immunity and inflammation processes of volunteers in the intervention group will be better compared to the control group?

The participants were asked to consume 250 mL of plain lactose-free kefir daily for 6 weeks. Any particular time was not specified for kefir consumption. Kefir consumption routine of participants was followed up by regular phone calls every week and evaluated by examining their consumption records. Those who consumed less than 85.0% (skipping kefir consumption maximum once a week) of the planned kefir consumption during the study period were excluded from the study.

Study Overview

Status

Status

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

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.

Detailed Description

In order to evaluate the general characteristics, history of diseases and nutritional behaviors, a face-to-face questionnaire was conducted on all participants by the researchers. The questionnaire form contained information about the demographic information (age, gender, educational status, marital status, etc.), history of diseases (diagnosed diseases, drugs used etc.), basic nutritional habits (number of major meals/snacks consumed in a day, water consumption, etc.) and anthropometric measurements (body weight, height, body mass index, waist circumference, neck circumference). In the intial (pre-intervention) and final (post-intervention) stages of the study, anthropometric measurements of the participants were taken, and body composition analysis was done. In addition, biochemical findings and 3-day food consumption records were taken in the intial (pre-intervention) and final (post-intervention) stages of the study. Effects of kefir consumption on gastrointestinal system, biochemical findings, mental health, immunity and inflammation, sleep quality, was evaluated by assessment of the relevant status of participants before and after kefir intervention and comparison with the control group. Short Physical Activity Assessment Tool was used for evaluating physical activity levels of the participants, mental health status by The Warwick-Edinburgh Mental Well-Being Scale (WEMWBS). Gastrointestinal system symptoms were evaluated by using the Gastrointestinal Symptom Rating Scale (GSRS), sleep quality by the Pittsburg Sleep Quality Index (PSQI) and diet quality by the Healthy Eating Index-2015 (HEI-2015). Measurements were recorded prior to kefir intervention (initial measurement) and post kefir intervention (final measurement) for kefir and control groups.

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 (Actual)

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.
65

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 Locations

  • Turkey
    • Beykoz
      • Istanbul, Beykoz, Turkey, 34815
        • Istanbul Medipol University

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:

  • Volunteer to consume 250 mL of plain lactose-free kefir once a day,
  • Being healthy
  • Being 18-35 years of age.

Exclusion Criteria:

  • Follow a special diet for health reasons,
  • Have an allergy to any food, have hepatic, renal and biliary diseases, have immunodeficiency, autoimmune and chronic gastrointestinal diseases, have a history of cancer, diabetes or cardiovascular diseases,
  • Being pregnant/breastfeeding,
  • Using vitamin-mineral and probiotic supplements,
  • Using antibiotics in last one month and throughout the study period,
  • Consuming probiotic foods or kefir on a regular basis,
  • Smoking

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: Other
  • Allocation: Non-Randomized
  • Interventional Model: Parallel 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: Kefir Consumption Group
Commercial lactose-free kefir (Altinkilic, Turkey) beverage, which is produced from cow milk with 3.1% fat and 7.5% protein content and stored in appropriate conditions, was used in this study. The kefir (intervention) group was provided with 250 mL of plain lactose-free kefir containing at least 107-1010 probiotic bacterial strains (Lactobacillus, Lactic acid, Streptococcus, Acetic acid bacteria sp) and yeasts (Kluyveromyces marxianus, Torulaspora delbrueckii, Saccharomyces cerevisiae, Candida). The participants were asked to consume 250 mL of plain lactose-free kefir daily for 6 weeks. Any particular time was not specified for kefir consumption. Kefir consumption routine of participants was followed up by regular phone calls every week and evaluated by examining their consumption records.
Other: kefir
Commercial lactose-free kefir (Altinkilic, Turkey) beverage, which is produced from cow milk with 3.1% fat and 7.5% protein content and stored in appropriate conditions, was used in this study. The kefir (intervention) group was provided with 250 mL of plain lactose-free kefir containing at least 107-1010 probiotic bacterial strains (Lactobacillus, Lactic acid, Streptococcus, Acetic acid bacteria sp) and yeasts (Kluyveromyces marxianus, Torulaspora delbrueckii, Saccharomyces cerevisiae, Candida). The participants were asked to consume 250 mL of plain lactose-free kefir daily for 6 weeks. Any particular time was not specified for kefir consumption. Kefir consumption routine of participants was followed up by regular phone calls every week and evaluated by examining their consumption records. Those who consumed less than 85.0% (skipping kefir consumption maximum once a week) of the planned kefir consumption during the study period were excluded from the study.
No Intervention: Control Group
Short Physical Activity Assessment Tool was used for evaluating physical activity levels of the participants, mental health status by The Warwick-Edinburgh Mental Well-Being Scale (WEMWBS). Gastrointestinal system symptoms were evaluated by using the Gastrointestinal Symptom Rating Scale (GSRS), sleep quality by the Pittsburg Sleep Quality Index (PSQI) and diet quality by the Healthy Eating Index-2015 (HEI-2015). Measurements were recorded prior to kefir intervention (initial measurement) and post kefir intervention (final measurement) for kefir and control groups.

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
Evaluation of Gastrointestinal Health
Time Frame: From enrollment to the end of treatment at 6 weeks
Gastrointestinal Symptom Rating Scale developed by Revicki et al and validated in Turkish by Turan et al. (2017) was used to evaluate gastrointestinal health of participants. GSRS is a disease specific instrument comprising of 15 items combined into 5 symptom clusters namely abdominal pain (items 1, 4 and 5), reflux (items 2 and 3), indigestion (items 6, 7, 8 and 9), diarrhea (items 11,12 and 14) and constipation (items 10, 13 and 15). In order to score the items, participants state how he/she felt about these problems in the past week. GSRS questions are rated on a 7-point Likert scale ranging from "no discomfort" to "very severe discomfort". A score of 1 is given for the absence of symptoms, and 7 for frequent and severe symptoms. High scores indicate severity of symptoms and diseased state.
From enrollment to the end of treatment at 6 weeks
Body Composition and Anthropometric Measurements
Time Frame: From enrollment to the end of treatment at 6 weeks
Body composition analysis, of the participants, was performed with TANITA MC-780 body composition analyser. By means of bioelectrical impedance analysis, basal metabolic rate and body composition (fat mass, muscle mass, fluid mass, lean mass, bone mineral mass, visceral fat, phase angle and edema index) were evaluated. Height (with SECA 206), body weight (with TANITA MC-780), neck and waist circumferences (with SECA 201) of participants were recorded. Heights were measured while standing upright and without shoes, feet were placed side by side, head was placed on the Frankfort Horizontal Plane, occipital region toucing the stadiometer. The body mass index (BMI) of the participants was calculated by dividing the body weight (kg) by the square the height (metres) and the evaluation was made according to the classification of the World Health Organization.
From enrollment to the end of treatment at 6 weeks
Mental Health
Time Frame: From enrollment to the end of treatment at 6 weeks
The Warwick-Edinburgh Mental Well-Being Scale developed by Tennant et al. (2007) and validated in Turkish by Keldal (2015), was used to evaluate the mental health status of individuals. The WEMWBS total score is calculated by adding the scores assigned to each of the 14 items (1=never to 5=always). The minimum score that can be obtained is 14, whereas the maximum score obtained is 70. Higher scores are associated with higher mental well-being.
From enrollment to the end of treatment at 6 weeks
Immunity and Systemic-Inflammation
Time Frame: From enrollment to the end of treatment at 6 weeks
Evaluation of immunity and systemic inflammation was performed using complete blood cell count and the SII, which is an important marker in reflecting inflammation and immune response. Although platelet-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR) are associated with disease activity, however, it has been suggested that SII, which is calculated by using platelet, neutrophil, and lymphocyte counts together, is a much more important marker in showing inflammation and immune response as compared to PLR and NLR values alone. Furthermore, SII is associated with various diseases such as cancer and cardiovascular disease. SII value is calculated with a formula (SII=P×N/L, P; platelet, N; neutrophil, L; lymphocyte) and high scores are associated with adverse health outcomes.
From enrollment to the end of treatment at 6 weeks

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
Physical Activity
Time Frame: From enrollment to the end of treatment at 6 weeks
Participants were asked to maintain their usual physical activities. The physical activity levels of the participants were evaluated with the Short Physical Activity Assessment Tool. The tool consisted of two questions focusing on 20 minutes of vigorous physical activity (running, weightlifting, cycling, etc.) and 30 minutes of moderate physical activity (mowing grass, lifting light loads, etc.). A maximum score of 8 and a minimum score of 0 could be obtained by this tool. A total score of 0-3 was considered insufficiently active, and a score of ≥4 was considered sufficiently active.
From enrollment to the end of treatment at 6 weeks
Biochemical Parameters
Time Frame: From enrollment to the end of treatment at 6 weeks
Blood analysis for the following parameters (fasting blood glucose, high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL), total cholesterol, triglyceride, alanine transaminase (ALT), aspartate transaminase (AST), blood urea nitrogen (BUN), urea, uric acid, creatinine, bilirubin, C-reactive protein (CRP), iron, iron binding capacity) was performed and the hemogram obtained at the beginning and end (pre and post intervention) of the study. The systemic immune-inflammation index (SII) was calculated from the hemogram findings.
From enrollment to the end of treatment at 6 weeks
Dietary Patterns
Time Frame: From enrollment to the end of treatment at 6 weeks
Participants were asked to maintain their usual eating habits. They were asked to record 24-hour food consumption for three non-consecutive days, one of which was required to be a weekend. This food record was taken twice; once at the beginning (prior to kefir intervention) and the other at the end (post kefir intervention) of the study. The records were collected from the participants retrospectively. The average daily energy and nutrient intakes of the individuals were determined by taking the average of the food consumption consumption values of the three days. The dietary quality of the participants was evaluated with the HEI-2015, which was calculated using data from food consumption records. If the HEI-2015 score of the participants was ≤50 points, the diet quality was evaluated as "poor diet quality", 51-80 points as "diet quality to be improved", and >80 points as "good diet quality".
From enrollment to the end of treatment at 6 weeks

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Sleep Quality
Time Frame: From enrollment to the end of treatment at 6 weeks
Pittsburg Sleep Quality Index , developed by Buysse et al. (1989) and validated in Turkish by Ağargün et al. (1996), was used to assess sleep quality.. The tool comprises of 7 sub-components and 18 items, including subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication and daytime dysfunction. The total score is calculated by evaluating the sub-components of the scale over 0-3 points. A score of 0-4 indicates good sleep quality, and a total score of 5-21 points indicates poor sleep quality.
From enrollment to the end of treatment at 6 weeks

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.
Medipol University

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.
February 1, 2023

Primary Completion (Actual)

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.
June 30, 2023

Study Completion (Actual)

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.
June 30, 2023

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).
September 23, 2024

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.
September 23, 2024

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.
September 25, 2024

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.
September 25, 2024

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.
September 23, 2024

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.
September 1, 2024

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.
  • 720

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

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