Effects of Calamansi on Blood Glucose and Insulin Levels

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: Recruiting
• Conditions: Calamansi Powder Capsule Supplementation
• Intervention / Treatment: Other: MMC powder capsule; Dietary supplement: Calamansi powder capsule

• Study Type: Interventional
• Enrollment (Estimated): 54
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Piyapong Prasertsri, Ph.D.; Phone Number: 6638103166; Email: piyapong@buu.ac.th
• Study Contact Backup: Name: Kulwara Poolpol, Ph.D.; Phone Number: 6638103147; Email: kulwara@go.buu.ac.th

Study Locations

• Thailand
  • Burapha University
    • Mueang, Burapha University, Thailand, 20131
      • Recruiting
      • Piyapong Prasertsri
      • Contact: Piyapong Prasertsri, Ph.D.; Phone Number: 6638103166; Email: piyapong@buu.ac.th
      • Contact: Kulwara Poolpol, Ph.D.; Phone Number: 6638103147; Email: kulwara@go.buu.ac.th

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
Concentrations of blood glucose	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	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	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

Outcome Measure	Measure Description	Time Frame
Levels of heart rate variability	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

• Sponsor: Burapha University
• Collaborators: Faculty of Allied Health Sciences
• Investigators: Principal Investigator: Piyapong Prasertsri, Ph.D., Faculty of Allied Health Sciences, Burapha University

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2026
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): January 31, 2027

Study Registration Dates

• First Submitted: May 8, 2026
• First Submitted That Met QC Criteria: May 8, 2026
• First Posted (Actual): May 14, 2026

Study Record Updates

• Last Update Posted (Actual): May 15, 2026
• Last Update Submitted That Met QC Criteria: May 13, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Other Study ID 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