Effect of 4 Weeks of Citrulline and Glutathione Supplementation on Arterial Function

What Was Tested

In this not phased trial, researchers set out to test Glutathione.

Examining the effects of 4 weeks of Citrulline alone or in combination with glutathione on the arterial function of postmenopausal women.

It had three arms (groups): L-Citrulline + Glutathione (experimental), L-Citrulline (experimental) and Placebo (placebo comparator).

The registry classes the interventions as dietary supplement.

More on the Plan

L-Citrulline is a non-protein amino acid and an efficient precursor of L-arginine, the substrate for endothelial nitric oxide synthesis.

Glutathione is a tripeptide with antioxidant effects.

Who Took Part

The registry lists 39 actual participants took part.

It was open to women only aged from 50 years up to 79 years.

Healthy volunteers could join, not only people with the condition.

Examples of who could join: Generally healthy, postmenopausal women (defined as the absence of menstruation for at least 1 year). Between the ages of 50-79 years. Body mass index of 18.5 - 34.9 kg/m2. Brachial systolic blood pressure \< 150 mmHg, and diastolic blood pressure \< 90 mmHg. Sedentary (defined as \< 120 min/week of exercise).

The full record lists 7 inclusion and 8 exclusion criteria; among the exclusions: current or prior use of tobacco products, e-cigarettes or other inhaled substance; use of medications and/or any supplements that may affect outcome variables (such as arginine-containing supplements, nitroglycerin, statin drugs, but not limited to those.); taking hormone replacement therapy during the 3 months before the study.

How the Study Was Run

Design: randomized, parallel-group and double-blind.

Random assignment meant chance, not the researchers, decided who got Glutathione and who got the comparison, which limits bias.

The Glutathione group and the comparison group ran side by side rather than switching.

As a double-blind Glutathione study, the assignments were hidden from both participants and investigators until the end.

Those kept unaware of assignments: participant and investigator.

It started in 2020-07-01 with completion listed for 2022-04-27.

It ran at 1 site in United States.

Its stated primary purpose is basic science.

What Was Measured

Researchers chose this as the main measure: Change in endothelial function (time frame: 4 weeks). Change in arterial stiffness (time frame: 4 weeks). Blood pressure control during the cold pressor test (time frame: 4 weeks).

It also tracked 7 secondary outcomes, for example cardiovascular hemodynamics using pulse wave analysis during the cold pressor test, body composition, Muscle Strength, L-Citrulline levels, Glutathione peroxidase levels and Malondialdehyde.

What This Means in Plain Language

Put simply, this is a not phased, randomized trial of Glutathione in 39 people.

Its size is small, so on its own it can only give an early look.

The trial is marked completed; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the Glutathione compound page, all human trials.