What is Citrulline?
Citrulline is a non-essential amino acid. In hepatocytes, L-citrulline is synthesized in the urea cycle by the addition of carbon dioxide and ammonia to ornithine. L-citrulline is converted into L-arginine by the enzymes argininosuccinate synthetase and argininosuccinate lyase in the presence of L-aspartate and ATP. Subsequently, L-arginine is converted to nitric oxide by nitric oxide synthase and L-citrulline is regenerated as a by-product.
Citrulline is an amino acid. It is made from ornithine and carbamoyl phosphate in one of the central reactions in the urea cycle. It is also produced from arginine as a by-product of the reaction catalyzed by NOS family. Its name is derived from citrullus, the Latin word for watermelon, from which it was first isolated.
Benefits of Citrulline Supplement
A study shows that “Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness.”
The purpose of the study was to determine the effects of a single dose of citrulline malate (CM) on the performance of flat barbell bench presses as an anaerobic exercise and in terms of decreasing muscle soreness after exercise. Forty-one men performed 2 consecutive pectoral training session protocols (16 sets). The study was performed as a randomized, double-blind, 2-period crossover design. Eight grams of CM was used in 1 of the 2 training sessions, and a placebo was used in the other. The subjects’ resistance was tested using the repetitions to fatigue test, at 80% of their predetermined 1 repetition maximum (RM), in the 8 sets of flat barbell bench presses during the pectoral training session (S1-4 and S1′-4′). The p-value was 0.05. The number of repetitions showed a significant increase from placebo treatment to CM treatment from the third set evaluated (p <0.0001). This increase was positively correlated with the number of sets, achieving 52.92% more repetitions and the 100% of response in the last set (S4′). A significant decrease of 40% in muscle soreness at 24 hours and 48 hours after the pectoral training session and a higher percentage response than 90% was achieved with CM supplementation. The only side effect reported was a feeling of stomach discomfort in 14.63% of the subjects. We conclude that the use of CM might be useful to increase athletic performance in high-intensity anaerobic exercises with short rest times and to relieve postexercise muscle soreness. Thus, athletes undergoing intensive preparation involving a high level of training or in competitive events might profit from CM.
“It helps remove ammonia from the body so that tiredness doesn’t set in as quickly. Using this supplement, athletes can work longer, increase endurance capacity and recover more quickly with less soreness.”
“Oral L-citrulline supplementation (as in [pre-workout]) enhances cycling time trial performance in healthy trained men.”
“Women who are pregnant or breastfeeding should not use citrulline supplements.”
The organic compound citrulline is an α-amino acid. Its name is derived from citrullus, the Latin word for watermelon, from which it was first isolated in 1914 by Koga & Odake. It was finally identified by Wada in 1930. It has the formula H2NC(O)NH(CH2)3CH(NH2)CO2H. It is a key intermediate in the urea cycle, the pathway by which mammals excrete ammonia.
In the body, citrulline is produced as a byproduct of the enzymatic production of nitric oxide from the amino acid arginine, catalyzed by nitric oxide synthase. This is an essential reaction in the body because nitric oxide is an important vasodilator required for regulating blood pressure.
Citrulline is made from ornithine and carbamoyl phosphate in one of the central reactions in the urea cycle. It is also produced from arginine as a by-product of the reaction catalyzed by NOS family (NOS; EC 22.214.171.124). It is made from arginine by the enzyme trichohyalin at the inner root sheath and medulla of hair follicles. Arginine is first oxidized into N-hydroxyl-arginine, which is then further oxidized to citrulline concomitant with release of nitric oxide.