L-citrulline

L-citrulline is a non-essential (conditionally essential) amino acid that the body cannot produce in sufficient amounts, especially during increased efforts, so it needs to be additionally ingested with supplements. Although it is not a component of most body proteins, citrulline is found in specific proteins in hair, skin, and nerve cells. It is primarily synthesized from glutamine in the intestines, and it is also naturally found in some foods, such as watermelon.

Citrulline regulates nitrogen levels and metabolic processes and serves as the foundation for the production of the popular amino acids L-arginine and L-ornithine among athletes. Citrulline plays a crucial role in vasodilation—after entering the body, most of it converts to arginine, which then transforms into nitric oxide, causing the muscles around the blood vessels to relax and expand. As a result, there is improved supply of oxygen and nutrients to the muscles and elimination of harmful substances. The dilation of blood vessels also lowers blood pressure, providing another benefit of citrulline supplementation.

Citrulline enhances aerobic performance and work capacity by influencing lactic acid to reduce fatigue. Studies suggest a reduction in mental and muscular fatigue and exhaustion in postoperative patients, and it may also lead to an increase in performance in athletes.