L-Citrulline for Health and Fitness
What is L-Citrulline?
What does L-Citrulline do?
L-citrulline has quite a number of functions. It may be convenient to split the range of uses for L-citrulline into health-related and fitness-related uses, although in fact the two classes blur into each other. As usual when discussing health problems, one ought to say that if you intend to use L-citrulline to help with any health problem it is a good idea to do so with the help of a doctor or other qualified professional.
First, health issues. The first one to discuss, and the one in which results will probably be quickest, is hypertension (high blood pressure). A small digression may be useful here.
In 1998, Robert Furchgott was awarded the Nobel Prize for medicine for discovering (in 1980) that a substance called EDRF was responsible for making the artery walls relax and dilate, thus reducing blood pressure and increasing blood flow. It took several years after the initial discovery to find that this mysterious substance was in fact a remarkably simple compound called nitric oxide, formula NO, previously only known as a major component of various forms of air pollution.
As part of the work done on this subject, the mode of action of a class of drugs called nitrates was explained. Nitrates are used for angina pectoris and also to reduce blood pressure; the best known of these is nitroglycerine, better known as an explosive and usually referred to in medical use as glyceryl trinitrate or GTN. How these drugs work was previously unknown; it now turns out that nitrate drugs work by greatly increasing the level of NO in the blood vessel walls.
The way that L-citrulline works is a little complicated. L-citrulline is converted into L-arginine; subsequently the L-arginine is converted back into L-citrulline in a reaction that also creates NO.
NO is also used by the immune system to kill pathogens. In theory, higher levels of NO formation ought therefore to increase the activity of the immune system and therefore help the body fight off infectious disease; but at the time of writing no research has actually been done on this subject.
What is known for sure is that L-citrulline increases body levels of L-arginine, and L-arginine in turn increases the level of growth hormone in adults. Higher growth hormone has many benefits, including a more efficient immune system, greater muscle mass, lower body fat levels and tighter, more elastic skin. Therefore, L-citrulline will improve the immune system by this route even if it does not do so directly.
Incidentally, and quite paradoxically, administration of L-citrulline increases L-arginine levels even more than supplementing equivalent amounts of L-arginine does.
In short, the health benefits of L-citrulline include relief of hypertension, better blood flow, and higher growth hormone levels with all that the last implies.