L-arginine is an amino acid with its primary metabolic role being within the urea cycle, the biochemical pathway that metabolises nitrogen and protein. L-arginine stimulates the secretion of a number of important hormones including hypothalamic corticotropin releasing factor (CRF), pituitary growth hormone, and prolactin, pancreatice insulin, glucagons, pancreozymin and polypeptide, somatostatin, aldosterone, and adrenal catecholamines.

L-arginine is the precursor for the synthesis of NO (nitric oxide) known to be present in macrophages, and is thought to mediate a number of macrophage cytotoxic actions.

NO is believed to mediate many diverse physiological processes including vasorelaxation, immune responses, adhesion of leukocytes and platelets and neurotransmission.

Nitric oxide plays a role in many biochemical functions including; memory, attention and increases perfusion of the kidneys, lungs and liver by enhancing blood flow.

CARDIOVASCULAR HEALTH – arginine helps the arteries inner lining, called the endothelium, produce nitric oxide, which plays a role in the regulation of blood flow, and keeps blood platelets free from clumping or aggregation.

WEIGHT CONTROL – arginine is required for insulin production, blood sugar control and appears to also inhibit fat absorption.

WOUND HEALING – arginine has been shown to improve wound healing in injured and stressed humans

FERTILITY – arginine has been shown to increase sperm count and motility

ERECTILE DYSFUNCTION – l-arginine is required for the production of nitric oxide (NO) which is responsible for the male erection. The arteries supplying blood to the genitals depend on nitric oxide to allow them to relax and permit additional blood flow.

The drug VIAGRA also works through a mechanism that increases nitric oxide production in these arteries.

CHOLESTEROL LOWERING – the higher the arginine to lysine ratio the lower the cholesterol level

DETOXIFICATION – supports urea and ammonia detoxification

GROWTH PROMOTING – shown to elevate growth hormone and creatine synthesis

IMMUNE BOOSTING – arginine has been shown to stimulate the thymus gland

Dosage range: 500mg-6000mg daily

Potential applications: sports nutrition, exercise tolerance in cases of reduced blood flow, weight control, convalescence, recovery from surgery, sepsis and trauma, fertility and impotence, atherosclerosis, hypertension and angina.

Known contraindications: not recommended in cases of schizophrenia or herpes infection

Useful links: may be beneficial in weight control when combined with ornithine.

May be helpful in infertility cases alongside vitamin C, EFAs, l-carnitine, and antioxidants particularly pycnogenol and/or grape seed for regulation of nitric oxide.

Note: Take away from protein for maximum effect, ideally 30-60 minutes before or after a meal

Ornithine is a precursor of arginine and when taken orally, has very similar effects.

Arginine in sexual stimulation

Sexual stimulation causes activity in the nervous system which, in turn, causes local release of nitric oxide in the genitals. This stimulates a substance called cGMP that increases blood flow causing sexual arousal. L-arginine is popular in sexual dysfunction supplements as it is required to carry out the syntheses of nitric oxide.

A third of men showed improvements in a double blind placebo trial. It has not been tested on its own in women, but in combination with Panax ginseng, Ginkgo biloba, damiana and multiple vitamins and minerals, 71% reported increased sexual desire.

No arginine if herpes!