Amino acid L-citrulline bonds to a malic acid molecule to create citrulline malate.
L-citrulline is a naturally occurring amino acid produced in one of the reactions during the urea cycle. During this reaction, a carbamoyl group from carbamoyl phosphate is transferred to ornithine to form citrulline.
Malate is the ionized form of malic acid, an acid synthesized in the body during the citric acid cycle.
Both citrulline and malic acid are found in the body and in food sources like watermelons and apples.
Citrulline is converted into arginine and nitric oxide. Nitric oxide relaxes vascular smooth muscle and allows for enhanced blood flow throughout the body.
Citrulline malate is believed to improve blood circulation and optimize energy production. For this reason, many companies utilize this compound in performance-enhancing supplements
Citrulline malate is mainly used to enhance ATP production during exercise and also to combat muscle soreness.
In one study, 41 men performed 2 consecutive pectoral exercises totaling 16 sets. Before the exercises, the men were given either a placebo or a citrulline malate dose in a double blind fashion. Research reveals the number of repetitions increased from placebo to citrulline malate treatment. Also, muscle soreness at 24 and 48 hours after was significantly lower as a result from citrulline malate.
Another study takes a look at ATP production as a result of citrulline malate supplementation. Eighteen men suffering from fatigue were given citrulline malate and rest-exercise-recovery protocols were performed. Subjects experienced a reduction in fatigue sensation, a 34% increase rate increase in oxidative ATP production during exercise, and a 20% increase in phosphocreatine recovery rate post-exercise. Researchers determined citrulline malate supplementation changed muscle metabolism and indicate it may promote aerobic energy production.
Lastly, a French study conducted in 1970 indicated citrulline malate’s metabolic actions reduced fatigue by protecting against ammonia poisoning.
Though, some medical sources like NYU Langone Medical Center claim this study was not conducted at the level of modern scientific standards and needs to be followed up.
Citrulline malate use is not associated with any severe or toxic side effects. The only reported side effect reported during a clinical study was mild stomach discomfort in some users.
Women pregnant and breast-feeding are not recommended for citrulline malate use due to insufficient and reliable research.
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-  D Bendahan et al. “Citrulline/malate promotes aerobic energy production in human exercising muscle.” BR J Sports Med 2002,36:282-289 doi:10.1136/bjsm.36.4.282.
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-  “Citrulline.” NYU Langone Medical Center.
-  “L-Citrulline.” WebMD.