L-Citrulline and Endothelial Function

Effect of Oral L-Citrulline on the Peripheral and Central Endothelial Function in Young and Older Adults

The effect of L-Citrulline is well studied in relation to muscle strength, exhaustion, exercise performance, and endothelial function in health and disease. This study will extend current body of knowledge and will investigate the effect of L-Citrulline on brain vascular function.

Endothelial function is associated with nitric oxide (NO) availability for vasodilation, blood pressure and blood flow regulation, and vascular health. A large body of evidence demonstrates that aging is associated with a decrease in bioavailability of NO, with more pronounced decrease in sedentary individuals. NO can be produced via the NO synthase (NOS) enzymes, which catalyze the conversion of L-Arginine - a semi-essential amino acid found in fish, nuts and legumes amongst others - to L-Citrulline and produce NO as an endproduct. While the effect of L-Citrulline is extensively studied in relation to muscle strength, exhaustion, exercise performance, as well as on endothelial function in healthy and diseased individuals (including obese and those with heart failure), the effect of L-Citrulline on brain vascular function is not well studied.

Inclusion Criteria:

• Age 21-45 and ≥55-90 years of age
• Adequate hearing and visual acuity to participate in the examinations
• Ability to read and write in English
• Competence to provide informed consent

Exclusion Criteria:

• Active CNS disease including multiple sclerosis, uncontrolled seizures, active brain cancer
• Cerebrovascular accident other than TIA within 60 days prior to Visit 0
• Major psychiatric disease, including major depression not currently controlled on medications, alcohol or drug abuse
• Treatment with other Citrulline enhancers (L-Arginine, L-Citrulline Malate) within 4 weeks prior to Visit 0
• Any other medical condition which, in the opinion of investigator, would render the patient inappropriate or too unstable to complete the study protocol