Summary

Times of physical and emotional stress or trauma — common to many of us — and even intense exercise can all result in a notable decline in levels of the amino acid arginine. In addition to aiding protein synthesis and boosting the immune and nervous systems, arginine is also known for increasing growth hormone levels; thus, it's become popular with people seeking to build a lean, muscular body and stimulate fat loss.

Other names for Arginine

L-arginine

Where to find Arginine

Arginine is naturally created in the pituitary gland, and the highest concentrations are found in meat, fish, poultry, and dairy products. It's also contained in nuts and nut butters.

Popup: Foods highest in Arginine

Why athletes use Arginine

Arginine is used by athletes who wish to increase the production of growth hormone, insulin, and creatine phosphate, which may encourage an increase in lean mass and enhanced fat loss as well as potentially improve immune and cognitive functioning.

Ways that Arginine can enhance Muscle Gain & Recovery:

• Increase strength and lean body mass, along with fat loss, by promoting the secretion of growth hormone and insulin
• Suppress tissue breakdown and improve muscle recovery rates by metabolizing protein byproducts

Ways that Arginine can enhance Energy & Endurance:

• As a precursor to nitric oxide, which dilates blood vessels, it may increase oxygen levels to the heart

Signs of Arginine deficiency

No deficiency conditions are known to exist.

Potential uses for Arginine

Research indicates that Arginine may be useful in the treatment of:

• Cardiovascular disease
• Cognitive dysfunction
• Infertility
• Wounds/injuries
• Hypertension (high blood pressure)
• Erectile dysfunction
• Interstitial cystitis
• Prior anabolic steroid effects

More about Arginine

In addition to aiding protein synthesis and boosting the immune and nervous systems, the amino acid arginine is also known — most notably to the athlete — for increasing the natural release of growth hormone (GH) in the body.

GH and insulin benefits

Arginine is one of the few ingestible nutrients that has been shown to be effective for increasing GH, insulin, and muscle creatine levels. These facts combined have made this a popular supplement among those seeking to build lean, muscular bodies while stimulating fat loss.

Natural GH often declines with age and may be related to loss of lean mass and an increase in fat accumulation in the body. Arginine causes GH to be released by the pituitary gland, which enables protein synthesis to remain more "youthful" and also improves muscle-building metabolism. Other potential benefits are improved recovery and enhanced memory.

The insulin secretion stimulated by the presence of arginine helps transport key nutrients, such as glucose and other amino acids, into cells more effectively, where they can be used as fuel — for greater energy and to build muscle.

While arginine does appear to create an increase in GH and insulin, it is not clear whether it has a long-lasting impact on muscle size and fat loss. Many studies have shown seemingly adequate results, though some experts are looking for more proof. Still, most researchers are certain that arginine helps increase muscle recovery by aiding collagen formation and ridding the body of toxic byproducts from the breakdown of proteins — byproducts that are increased with intense exercise, so all in all, benefits are assured.

Creatine synergy

As a precursor to creatine phosphate (an important energy source), arginine may boost performance during anaerobic training sessions (like weight training), plus enhance muscle and strength capacity. Studies have shown a definite increase in creatine levels within muscle cells with arginine supplementation.

Nitric oxide production

Arginine is essentially a natural blood thinner and is involved in our bodies' natural process of nitric oxide production as well, which enables our blood vessels to remain dilated. Together, NO and arginine increase blood flow, allowing for greater cognitive function, heart health, and sexual enhancement for men. This is further improved by the arginine-NO role in relaxing the corpus cavernosum, stimulating penile erections. An added benefit, for some, is the increase in sperm count that is often a result of increased arginine.

As an immune enhancer

Additionally, by stimulating the thymus gland, where disease-fighting T cells reside, it has been suggested that arginine may help stimulate immune functioning and aid in the body's defense against some diseases.

In conclusion

While the body does create arginine naturally, production slows during times of physical and emotional stress or trauma — common to many of us. Actually, even intense exercise can cause a notable decline. These deficiency states can clearly lead to complications, and the reverse can add measurable benefits. Arginine is considered "conditionally essential," meaning that in certain conditions, it is necessary.

Amount

Amounts vary significantly, from 3 to 20 grams per day, depending on the individual and the intended results. Note that studies show most manufacturers recommend far less than the amounts that have been documented to be most effective.

• For growth-hormone release, three grams of arginine may be taken one hour before vigorous exercise and just before sleep.
• Studies indicate between 15 and 18 grams a day may promote wound healing.
• Between 6 and 13 grams per day are reportedly effective for promoting heart health.
• Two grams taken three times daily may lead to reduced blood pressure.
• Four grams per day for several months may help increase sperm count.
• Between 6 and 18 grams 45 minutes before sex may improve sexual functioning.

Timing

Arginine appears to be most effective on an empty stomach and used five days a week. Some experts recommend using the supplement for two to three weeks, followed by a break of one to two weeks.

Synergists of Arginine

Taken with ornithine, synthesis of growth hormone may be increased.

When supplemented with glycine, it's been shown to increase muscle creatine content.

When taken with omega-3 fatty acids and ribonucleic acid, it may improve immune function.

Taken with yohimbine (the active ingredient in the herb yohimbe), arginine has been shown to alleviate mild to moderate erectile dysfunction. A recent study found in European Urology found this is true even when this combination is taken "on demand." (A one-time administration before desired activity.)

Safety of Arginine

If you have cold sores or herpes, be careful using arginine. It should only be used in these cases in a 4:1 ratio of lysine to arginine. It may otherwise stimulate cellular replication of the viral cells.

Individuals with diabetes should not use arginine as it can influence blood sugar levels.

Toxicity of Arginine

None reported. As long as amounts are under 25 grams per day, it is generally safe.

Bans and restrictions

None reported.

• Evoy, D., et al., "Immunonutrition: The Role of Arginine," Nutrition 14.7-8 (1998) : 611-7.
  
• Lebret, T., "Efficacy and Safety of a Novel Combination of L-Arginine Glutamate and Yohimbine Hydrochloride: A New Oral Therapy for Erectile Dysfunction," European Urology 41 (2002) : 608-13.
  
• Schachter, A., et al., "Treatment of Oligospermia with the Amino Acid Arginine," J Urol 110.3 (1973) : 311-3.
  
• Suminski, R.R., et al., "Acute Effect of Amino Acid Ingestion and Resistance Exercise on Plasma Growth Hormone Concentration in Young Men," Int J Sport Nutr 7.1 (1997) : 48-60.
  
• Tenenbaum, et al., "L-Arginine: Rediscovery in Progress," Cardiology 90.3 (1998) : 153-9.