- Promotes synthesis of nitric oxide, a vasodilatory compound.
- Helps reduce ammonia build-up in the body.
- Helps prevent cramps, stiffness and muscle fatigue.
- Helps increase the body’s metabolic rate.
L-Citrulline is a natural supplement containing citrulline, a non-essential amino acid which is converted in the body into arginine. It is the only amino acid to escape splanchnic sequestration, a process which reduces amino acid circulation in older people.
Citrulline is a non-essential amino acid produced in the small intestine from glutamine and arginine. In the 1980s, Windmueller and Spaeth showed that citrulline is released continually by the small intestine and that it enters the systemic circulation in a free form.
Its name comes from Citrullus vulgaris, the Latin for watermelon, one of the few foods in which it is found naturally (1).
Together with ornithine and arginine, it plays a particularly important role in what is known as the urea cycle. This is a collection of biochemical reactions which take place in the liver and which enable the body to purify neurotoxic ammonia.
Citrulline is a non-proteinogenic amino acid – it is not directly involved in making proteins and peptides.
Supplementing with citrulline increases the availability of citrulline and arginine, with very low levels of urinary loss (2).
When intake of proteinogenic amino acids such as arginine is judged to be excessive by the body, large-scale purification of these amino acids takes place in the liver. The majority of these amino acids are thus sequestrated and play no part in supporting optimal muscle synthesis. This is what’s known as splanchnic sequestration.. But citrulline is special: it escapes this sequestration and, unregulated by the liver, is able to circulate in the body and be converted into arginine.
As citrulline is not metabolised by the liver and is instantly converted into arginine, taking an oral citrulline supplement is actually more effective at increasing circulating arginine levels than taking arginine itself!
Sarcopenia is the name given to the decline in muscle mass associated with ageing. It’s the result of a physiological process that begins at the age of 30 in men, and after the menopause in women. Over time, it becomes pathological as it tends to engender dependency and a reduction in everyday activities.
Once ingested, citrulline is converted into arginine in the kidneys, which helps produce nitric oxide (NO), a gas involved in vasodilation, neurotransmission and production of ATP (cellular energy).
Plasma concentrations of citrulline and arginine increase rapidly in proportion to the dose of citrulline ingested (3). These concentrations return to their initial values after a period of about six hours.
Citrulline also crosses the blood-brain barrier without any difficulty, which is fortunate given that citrulline concentrations in the brain decline with age.
Long-term supplementation with citrulline produces no adverse side-effects, unlike ornithine and arginine (4). It is completely safe (5-7). It can be incorporated into other synergistic supplements:
|Daily dose: 3 scoops
Number of doses per pack: 14
|Amount per dose|
juin 2007;137(6 Suppl 2):1693S‑1701S.
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