Effects of Calamansi on Blood Glucose and Insulin Levels

May 13, 2026 updated by: Piyapong Prasertsri, Burapha University

The Effects of Calamansi (Citrus x Macrocarpa Bunge) Supplementation on Blood Glucose and Insulin Levels in Healthy Volunteers

Fifty-four healthy sedentary male and female participants aged 18-30 years will be recruited for this study. Participants will be randomly assigned to one of two groups: a control group receiving placebo MMC capsules (n = 27) or a calamansi capsule supplementation group (n = 27). All participants will undergo health screening procedures, including medical history assessment, mental health questionnaire evaluation, and measurements of vital signs, height, body weight, and body composition. Venous blood samples will subsequently be collected to determine blood glucose, insulin, creatinine, alanine aminotransferase (ALT), and malondialdehyde (MDA) levels. These assessments will be performed at three time points: 1) before capsule supplementation (baseline), 2) following a single dose of capsule supplementation, and 3) after 12 weeks of supplementation.

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.
54

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

Study Locations

  • Thailand
    • Burapha University
      • Mueang, Burapha University, Thailand, 20131
        • Recruiting
        • Piyapong Prasertsri
        • Contact:
        • Contact:

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:

  • Healthy individuals who have not been diagnosed with diabetes or prediabetes, with a fasting blood glucose level (after 8 hours of fasting) of less than 100 mg/dL.
  • Aged between 18-30 years, both male and female
  • Body Mass Index (BMI) between 18.5 and 22.9 kg/m²
  • No diseases affecting blood sugar levels, such as liver or pancreatic diseases

Exclusion Criteria:

  • Pregnant or breastfeeding women
  • Regular smokers
  • Regular alcohol consumers
  • Individuals with a history of allergies to citrus fruits or citrus-derived ingredients
  • Individuals taking medications that affect glucose metabolism and fat distribution in the body, including steroids, protease inhibitors, and psychiatric medications. These refer to drugs that act on the central nervous system and may affect blood sugar levels or energy metabolism, such as antidepressants, antipsychotics, and mood stabilizers.

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: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

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.
Placebo Comparator: MMC powder capsule
Participants will be randomly assigned to an intervention arm. During the short-term phase, participants in the control group will receive microcrystalline cellulose (MMC) capsules and will be instructed to consume 1,500 mg/day (three capsules). During the long-term phase, participants will continue consuming MMC at a dose of 1,500 mg/day (three capsules), taken within 15-30 min after breakfast. All supplementation will be administered at the participants' residences.
Other: MMC powder capsule
Each capsule contains MMC powder for 500 mg
Experimental: Calamansi powder capsule
Participants will be randomly assigned to an intervention arm. During the short-term phase, participants in the calamansi group will receive calamansi powder capsules and will be instructed to consume 1,500 mg/day (three capsules). During the long-term phase, participants will continue consuming calamansi powder capsules at a dose of 1,500 mg/day (three capsules), taken within 15-30 min after breakfast. All supplementation will be administered at the participants' residences.
Dietary supplement: Calamansi powder capsule
Each capsule contains calamansi powder for 500 mg

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
Concentrations of blood glucose
Time Frame: At 0 minute before consumption, at 30, 60, 90, 120 minutes after consumption, and at days 91 after consumption
Concentrations of blood glucose were measured before and after MMC capsules or calamansi capsule consumption at 500 mg in mg/dL unit
At 0 minute before consumption, at 30, 60, 90, 120 minutes after consumption, and at days 91 after consumption
Concentrations of blood insulin
Time Frame: At 0 minute before consumption, at 120 minute after consumption, and at days 91 after consumption
Concentrations of blood insulin were measured before and after MMC capsules or calamansi capsule consumption at 500 mg in uU/mL (microunit/milliliter) unit
At 0 minute before consumption, at 120 minute after consumption, and at days 91 after consumption
Concentrations of blood malondialdehyde
Time Frame: At 0 minute before consumption, at 120 minute after consumption, and at days 91 after consumption
Concentrations of blood malondialdehyde were measured before and after MMC capsules or calamansi capsule consumption at 500 mg in uM (micromolar) unit
At 0 minute before consumption, at 120 minute after consumption, and at days 91 after consumption

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
Levels of heart rate variability
Time Frame: At 0-10 minutes before consumption, at 110-120 minutes after consumption, and at days 91 after consumption for 10 minutes
Heart rate variability were measured before and after MMC capsules or calamansi capsule consumption at 500 mg in ms (milliseconds) and ms2 (millisecond squared) unit
At 0-10 minutes before consumption, at 110-120 minutes after consumption, and at days 91 after consumption for 10 minutes

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.
Burapha University

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Faculty of Allied Health Sciences

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: Piyapong Prasertsri, Ph.D., Faculty of Allied Health Sciences, Burapha 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.
May 1, 2026

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.
December 31, 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.
January 31, 2027

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).
May 8, 2026

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.
May 8, 2026

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 14, 2026

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.
May 15, 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.
May 13, 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.
May 1, 2026

More Information

Terms related to this study

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.
  • IRB1-033/2569

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

There is no plan to make individual participant data available to other researchers.

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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