The compound citrulline is a classed as a non-essential, non-standard alpha-amino acid. It is normally derived from ornithine in the body as a part of the urea cycle and does not form a component for any of the major proteins and enzymes normally composed of amino acids - it is derived from ornithine and is changed into arginine in the bio-chemical processes of the urea cycle. The compound citrulline is still necessary for the smooth functioning of the human immune system and provides for all the bio-chemical processes connected to the production of metabolic energy in the human body. There is no need to consume citrulline from food sources as it is a non-essential amino acid and the nature of citrulline precludes its inclusion in any of the proteins or enzymes of the human body.
The compound citrulline is a not a common amino acid and is not included in most proteins or enzymes. However, there are a number of different chemical and biological reactions that require citrulline in the metabolic pathway. Citrulline synthesis occurs from ornithine during the cycle of the urea, and it in turn forms arginine. The process continues as citrulline is mixed with aspartic acid to create arginosuccinic acid, this moves on farther in the metabolic pathway to form L-arginine-which is the biologically available form of the amino acid.
The citrulline to arginine transformation pathway is a fundamental metabolic process of the body's homeostasis mechanism concerning certain toxicities that can arise in the human body. The creation of urea in the liver involves the amino acid arginine as a vital component and biochemical stasis is centered on the urea cycle of ornithine to citrulline to arginine. The conversion of metabolic citrulline to arginine directly affects all the biologically important processes of eliminating nitrogen metabolites from the body during nitrogen metabolism. Excessive accumulation of nitrogen in the body is synergistically eliminated by the citrulline, the citric acid, aspartic acid, and magnesium. These thus help in the process of digestion of food, aid in proper absorption of nitrogenous metabolites and their elimination, and are all important players in the metabolic processes involving the use and elimination of particular proteins in the body.
One major function of citrulline in the body is its importance in the detoxification pathways involving ammonia; it is one of the essential intermediaries during the processes of oxidative waste excretion in the human body in the reactions of the urea cycle along with other chemical compounds. Citrulline is also necessary to treat a form of urea cycle disorder in the form of the enzyme ornithine transcarbamylase. A deficiency in one of the enzymes necessary for sustaining the pace of the urea cycle disorder is caused by a genetic defectiveness in one of the essential urea cycle enzymes. The general functioning of the immune system is also buffered by citrulline and the compound is of critical importance in bringing about an improvement in any of the immune system associated deficiencies. Many fruits have an abundance of a form of malic acid, or citrulline malate derived as a salt form of this amino acid, this acid may boost the effects of the main compound citrulline in the body.
The process of energy production via the Kreb's cycle has malic acid as a key intermediary. The malic acid conditions and aids the movement of pyruvate and lactate in the achievement of an anabolic state rather than a catabolic state in the biochemical pathway. An increase in the energy production in the body is registered on supplementing with this non-essential amino acid - the presence of the compound in the body also leads to significant reduction in the amount of physical fatigue felt by a person. The metabolic rate in the body is also increased to a significant degree by supplementing with citrulline, the presence of this compound in the body also improves overall aerobic performance, and helps in reducing the chances of sudden muscular fatigue in a person.
There are thus two major ways in which supplements of citrulline malate and citrulline can help a person. One, they can boost the performance of the body in extended physical exertion, two, they also provide a useful biochemical pathway of removing the breakdown products of the amino acids during the metabolism of proteins in the body. Citrulline is also deemed to be equally important during the detoxification of lactate and ammonium present in the human blood.
The highest amounts of the compound citrulline is present in the liver. In general, the citrulline present in the body is a compound that promotes energy utilization in the body, it also aids in stimulating the immune system. In the urea citrulline is metabolized into L-arginine, and is an important compound in the gradual detoxification of ammonia inside the body, excess ammonia damages living cells and disrupts biochemical pathways. Most of the body's citrulline is primarily present in the liver and is transported from there to other parts of the body.
Supplemental dosage of citrulline can include taking 3 to 4 grams, two times a day. This dosage has been proven in many clinical studies measuring citrulline use in the body. The beneficial results can generally be expected within 3 to 5 days of continuous dosage administration.
The recommendation of the U.S. National Academy of Sciences for healthy people is to achieve 0.36 grams of highly bio-available protein for every pound of bodyweight. That is equivalent to 0.8 gr of protein, for every kg of bodyweight in a person.