Skip to main content
OpenTrials
Completed

NCT Number: NCT06025357

Effects of L-citrulline Supplementation on Vascular Function in Metabolic Syndrome

The objective of this project is to provide evidence that L-Citrulline (CIT) supplementation can improve vascular function in the fasted and acute hyperglycemia conditions in middle-aged and older women with metabolic syndrome.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Metabolic Syndrome Body Weight Cardiovascular Diseases Glucose Metabolism Disorders Hyperinsulinism Hypertension Insulin Resistance Menopause Metabolic Diseases Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Pathological Conditions, Signs and Symptoms Signs and Symptoms Vascular Diseases

Age range

45 year–79 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

TTU Kinesiology and Sport Management Building

Lubbock, Texas, 79409, United States

About this study

Using a double-blind, randomized, placebo-controlled, and parallel design, middle-aged and older women with metabolic syndrome will be randomized into receiving either CIT supplementation (10g/day) or placebo (Microcrystalline Cellulose) for 4 weeks.

The first visit will be approximately 1hr and 30 minutes. The 2nd and 3rd visits will each be approximately 2hrs and 30 minutes, separated by 4 weeks in between each visit. During visits 2 and 3, vascular measurements will be assessed in the fasted state and 30, 60, and 90 minutes after acute glucose ingestion (75g).

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

Must present at least 3 of the following 5 cardiometabolic risk factors

  • Waist circumference ≥88 cm
  • Fasting glucose between 100-125 mg/dL or HbA1c between 5.7-6.4%.
  • Blood pressure ≥130 mm Hg
  • Triglyceride ≥ 150 mg/dL
  • HDL <50 mg/dL

The following are also inclusion criteria's:

  • Women aged 45-79 years old
  • Body mass index ≤ 39.9 kg/m2
  • Sedentary (defined as < 120 min/week of exercise)
  • Abstain from any dietary supplements with vascular effects for one month prior to the beginning of the study and until participation in study has terminated.

Exclusion criteria

  • < 45 and > 79 years of age
  • Use of medications and/or any supplements that may affect outcome variables (such as arginine-containing supplements, nitroglycerin, statin drugs, biguanides, insulin, beta blockers, statins, verapamil)
  • Systolic blood pressure ≥ 160 mmHg
  • BMI > 40 kg/m2
  • Recent changes in medication (3 months)
  • Current smoking any tobacco use
  • Cardiovascular disease, diabetes (Type 1 or 2), and other metabolic or chronic diseases
  • More than 7 alcoholic drinks/week of consumption

Treatment and study plan

L-Citrulline supplementation

Dietary Supplement

4 weeks of L-Citrulline supplementation (10 grams/day).

Placebo

Dietary Supplement

4 weeks of microcrystalline Cellulose supplementation.

Primary outcomes

  1. Macrovascular Endothelial function in the fasted condition

    Time frame: 4 weeks

    Endothelial function will be measured via brachial artery flow mediated dilation (ultrasonography) during reactive hyperemia at baseline and after 4 weeks of supplementation.

  2. Microvascular endothelial function in the fasted condition

    Time frame: 4 weeks

    Endothelial function will be measured using forearm muscle oxygenation (near-infrared spectroscopy) will assessed during reactive hyperemia at baseline and after 4 weeks of supplementation.

  3. Microvascular digital endothelial function in the fasted condition

    Time frame: 4 weeks

    Endothelial function will be measured using peripheral (finger) arterial tonometry (EndoPAT device) during reactive hyperemia at baseline and after 4 weeks of supplementation.

  4. Macrovascular Endothelial function during acute hyperglycemia

    Time frame: 4 weeks

    Endothelial function will be measured via brachial artery flow mediated dilation (ultrasonography) during reactive hyperemia at 30, 60, and 90 minutes after oral glucose ingestion at baseline and after 4 weeks of supplementation.

  5. Microvascular forearm endothelial function during acute hyperglycemia

    Time frame: 4 weeks

    Endothelial function will be measured using forearm muscle oxygenation (near-infrared spectroscopy) during reactive hyperemia at 30, 60, and 90 minutes after oral glucose ingestion at baseline and after 4 weeks of supplementation.

  6. Central and peripheral arterial stiffness in the fasted condition

    Time frame: 4 weeks

    Arterial stiffness will be measured using central (carotid-femoral) and peripheral (femoral-ankle) PWV at baseline and after 4 weeks of supplementation.

  7. Central arterial stiffness during acute hyperglycemia

    Time frame: 4 weeks

    Arterial stiffness will be measured using central (carotid-femoral) PWV at 30, 60, and 90 minutes after oral glucose ingestion at baseline and after 4 weeks of supplementation.

  8. Blood pressure in the fasted condition

    Time frame: 4 weeks

    Brachial and aortic blood pressures will be assessed using an automated sphygmomanometry arm cuff (SphygmoCor XCEL). Beat-to-beat blood pressure will be measured using an automated photoplethysmography finger cuff (Fineometer). Blood pressure will be measured at baseline and after 4 weeks of supplementation.

  9. Blood pressure during acute hyperglycemia

    Time frame: 4 weeks

    Brachial and aortic blood pressures (systolic and diastolic) will be assessed using an automated sphygmomanometry arm cuff (SphygmoCor XCEL). Beat-to-beat blood pressure will be measured using an automated photoplethysmography finger cuff (Fineometer). Blood pressure will be measured after an oral glucose ingestion at 30, 60, and 90 minutes at baseline and after 4 weeks of supplementation.

  10. Total peripheral resistance in the fasted condition.

    Time frame: 4 weeks

    Total peripheral resistance will be measured using an automated photoplethysmography finger cuff (Finometer) at baseline and after 4 weeks of supplementation.

  11. Total peripheral resistance during acute hyperglycemia

    Time frame: 4 weeks

    Total peripheral resistance will be measured using an automated photoplethysmography finger cuff (Finometer) at 30, 60, and 90 minutes after oral glucose ingestion at baseline and after 4 weeks of supplementation.

  12. Stroke volume in the fasted condition

    Time frame: 4 weeks

    Stroke volume will be measured using an automated photoplethysmography finger cuff (Finometer) at baseline and after 4 weeks of supplementation.

  13. Stroke volume during acute hyperglycemia

    Time frame: 4 weeks

    Stroke volume will be measured using an automated photoplethysmography finger cuff (Finometer) at 30, 60, and 90 minutes after oral glucose ingestion at baseline and after 4 weeks of supplementation.

  14. 24-hour ambulatory blood pressure monitoring

    Time frame: 4 weeks

    An ambulatory blood pressure cuff, measuring blood pressure for 24-hours will be obtained on two separate days at baseline and after 4 weeks of supplementation.

Secondary outcomes

  1. Serum glucose and insulin levels.

    Time frame: 4 weeks

    Serum glucose and insulin levels will be tested at baseline and after 4 weeks of supplementation.

  2. Serum arginine levels

    Time frame: 4 weeks

    Serum L-Arginine levels will be tested at baseline and after 4 weeks of supplementation.

  3. Serum arginase levels

    Time frame: 4 weeks

    Serum arginase levels will be tested at baseline and after 4 weeks of supplementation.

  4. Serum Nitric Oxide levels

    Time frame: 4 weeks

    Serum nitric oxide levels will be tested at baseline and after 4 weeks of supplementation.

  5. Serum Endothelin-1 levels

    Time frame: 4 weeks

    Serum endothelin-1 levels will be tested at baseline and after 4 weeks of supplementation.

Sponsors and collaborators

Lead sponsor

Texas Tech University

Other

Registry information

Official study title

Effects of L-Citrulline Supplementation on Vascular Function During Fasted and Acute Hyperglycemia in Middle-aged and Older Women With Metabolic Syndrome

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Sep 6, 2023
Registry last updated
May 15, 2025

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.

Related clinical trials

Published trials that share one or more normalized conditions with this study.