The organic compound l-citrulline is an α-amino acid and is considered non-essential. It is an amino acid that participates in and is a key intermediate in the important Urea cycle which is the pathway by which mammals excrete ammonia.
The rind of watermelon (Citrullus lanatus) is the highest source of l-citrulline. Garlic and onions also have some trace amounts of l-citrulline. Due to the fact that these food sources have little amounts of l-citrulline, it is necessary to consume a l-citrulline supplement to achieve the therapeutic effects.
L-Citrulline is an amino acid that plays an important role in nitric oxide metabolism and regulation. L-Citrulline is converted to L-Arginine in the body to support L-Arginine and nitric oxide levels. Increased production of nitric oxide (NO) promotes vascular dilation which improves oxygen and blood circulation throughout the body.
The ingestion of l-citrulline can abrogate the state of oxidative stress and reverse the progression of atherosclerosis. This approach may have clinical utility in the treatment of atherosclerosis in humans. 1
L-citrulline malate stimulates hepatic ureogenesis and favorizes the renal reabsorption of bicarbonates. These metabolic actions had a protective effect against acidosis and ammonia poisoning and explain the anti-fatigue properties of citrulline malate in man. 2
Malic acid is commonly combined with l-citrulline in supplement form. Malic acid is a superior alpha hydroxy acid for the elimination of aluminum from the body. In a study that compared the efficacies of nine chelating agents on the toxicity of aluminum in mice, malic and succinic acids demonstrated the most effectiveness in chelating aluminum from the body. 3