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

Not Applicable

Completed

• Conditions: Menopause; Metabolic Syndrome
• Interventions: Dietary Supplement: L-Citrulline supplementation; Dietary Supplement: Placebo

• Registration Number: NCT06025357
• Lead Sponsor: Texas Tech University

Brief Summary

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.

Detailed Description

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).

Study Timeline

• Study Start: 2023-01-01
• Study First Submitted: 2023-07-27
• Status Verified: 2023-08
• Study First Submitted QC: 2023-08-29
• Study First Posted: 2023-09-06
• Primary Completion: 2024-05-01
• Study Completion: 2024-08-01
• Last Update Submitted: 2025-05-12
• Last Update Posted: 2025-05-15

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 24

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
L-citrulline	L-Citrulline supplementation	L-citrulline: 10 grams/day
Placebo	Placebo	Microcrystalline Cellulose

Primary Outcome Measures

Name	Time	Method
Microvascular digital endothelial function in the fasted condition	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.
Central and peripheral arterial stiffness in the fasted condition	4 weeks	Arterial stiffness will be measured using central (carotid-femoral) and peripheral (femoral-ankle) PWV at baseline and after 4 weeks of supplementation.
Macrovascular Endothelial function during acute hyperglycemia	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.
Microvascular forearm endothelial function during acute hyperglycemia	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.
Blood pressure in the fasted condition	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.
Stroke volume in the fasted condition	4 weeks	Stroke volume will be measured using an automated photoplethysmography finger cuff (Finometer) at baseline and after 4 weeks of supplementation.
Central arterial stiffness during acute hyperglycemia	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.
Blood pressure during acute hyperglycemia	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.
Macrovascular Endothelial function in the fasted condition	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.
Microvascular endothelial function in the fasted condition	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.
Total peripheral resistance in the fasted condition.	4 weeks	Total peripheral resistance will be measured using an automated photoplethysmography finger cuff (Finometer) at baseline and after 4 weeks of supplementation.
Total peripheral resistance during acute hyperglycemia	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.
Stroke volume during acute hyperglycemia	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.
24-hour ambulatory blood pressure monitoring	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 Outcome Measures

Name	Time	Method
Serum Nitric Oxide levels	4 weeks	Serum nitric oxide levels will be tested at baseline and after 4 weeks of supplementation.
Serum Endothelin-1 levels	4 weeks	Serum endothelin-1 levels will be tested at baseline and after 4 weeks of supplementation.
Serum arginine levels	4 weeks	Serum L-Arginine levels will be tested at baseline and after 4 weeks of supplementation.
Serum arginase levels	4 weeks	Serum arginase levels will be tested at baseline and after 4 weeks of supplementation.
Serum glucose and insulin levels.	4 weeks	Serum glucose and insulin levels will be tested at baseline and after 4 weeks of supplementation.

Trial Locations

Locations (1)

TTU Kinesiology and Sport Management Building; 🇺🇸 Lubbock, Texas, United States