What does it do? The amino acid arginine has several roles in the body, such as assisting in wound healing, helping remove excess ammonia from the body, stimulating immune function, and promoting secretion of several hormones including glucagon, insulin, and growth hormone.

The effect on growth hormone levels¹ has interested body builders. In a controlled trial, when combined with weight training and ornithine (taken as 500 mg of each, twice per day, five times per week), a greater decrease in body fat was obtained after only five weeks than when the same exercise was combined with placebo.²

Arginine is also needed to increase protein synthesis, which can in turn increase cellular replication. Therefore, arginine may help people with inadequate numbers of certain cells. For example, some,³ though not all,⁴ studies have found that men with low sperm counts experienced an increase in the number of sperm when supplemented with arginine.

Arginine’s effect on increasing protein synthesis improves wound healing. This effect has been shown in both animals⁵ and, at 17 grams per day, in people as well.⁶ Arginine is also a precursor to nitric oxide, which the body uses to keep blood vessels dilated, allowing the heart to receive adequate oxygen. Preliminary evidence suggests that arginine may help regulate cholesterol levels.⁷ Arginine also appears to act as a natural blood thinner by reducing platelet aggregation.⁸

According to researchers, the effect arginine has on increasing nitric oxide might help people with interstitial cystitis. In a preliminary trial using 1.5 grams of arginine per day, symptoms of this condition were significantly reduced.⁹

Where is it found? Dairy, meat, poultry, and fish are good sources of arginine. Nuts and chocolate also contain significant amounts of this amino acid.

Arginine has been used in connection with the following conditions

Who is likely to be deficient? Normally, the body makes enough arginine, even when it is lacking in the diet. However, during times of unusual stress (including infection, burns, and injury), the body may not be able to keep up with increased requirements.

Are there any side effects or interactions? Arginine has so far appeared to be free of obvious side effects, although some doctors are concerned that increases in growth hormone triggered by arginine could overwork the pancreas.

Individuals with kidney or liver disease should consult their nutritionally oriented doctor before supplementing with arginine. Individuals with herpes (either cold sores or genital herpes) should not take arginine supplements, because arginine can stimulate replication of the virus. Add Lysine (500 - 1000 mg) along with Arginine can help with cold sores cause by herpes infection.

Large amounts of arginine in animals can both promote¹⁰ and interfere with cancer growth.¹¹ In preliminary research, high intake (30 grams per day) of arginine has increased cancer cell growth in humans.¹² On the other hand, in people with cancer, arginine has been found to stimulate the immune system.¹³ At this time it remains unclear whether arginine is dangerous or helpful for people with cancer.

Arginine works with ornithine in the synthesis of growth hormone.

At the time of writing, there were no well-known drug interactions with arginine.

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References:

1. Besset A, Bonardet A, Rondouin G, et al. Increase in sleep related GH and Prl secretion after chronic arginine aspartate administration in man. Acta Endocrinologica 1982;99:18–23.
2. Elam RP. Morphological changes in adult males from resistance exercise and amino acid supplementation. J Sports Med Phys Fitness 1988;28:35–39.
3. Schacter A, Goldman JA, Zukerman Z. Treatment of oligospermia with the amino acid arginine. J Urol 1973;110:311–13.
4. Pryor JP, Blandy JP, Evans P, et al. Controlled clinical trial of arginine for infertile men with oligozoospermia. Br J Urol 1978;50:47059.
5. Barbul A, Rettura G, Levenson SM, et al. Wound healing and thymotropic effects of arginine: a pituitary mechanism of action. Am J Clin Nutr 1983;37:786–94.
6. Kirk SJ, Hurson M, Regan MC, et al. Arginine stimulates wound healing and immune function in elderly human beings. Surgery 1993;114:155–60.
7. Kohls KJ, Kies C, Fox HM. Serum lipid levels of humans given arginine, lysine and tryptophan supplements without food. Nutr Rep Internat 1987;35:5–13.
8. Wolf A, Zalpour C, Theilmeier G, et al. Dietary L-arginine supplementation normalizes platelet aggregation in hypercholesterolemic humans. J Am Coll Cardiol 1997;29:479–85.
9. Smith SD, Wheeler MA, Foster HE Jr , Weiss RM. Improvement in interstitial cystitis symptom scores during treatment with oral K-arginine. J Urol 1997;158:703–8.
10. Park KGM. The immunological and metabolic effects of L-arginine in human cancer. Proc Nutr Soc 1993;52:387–401.
11. Takeda Y, Tominga T, Tei N, et al. Inhibitory effect of L-arginine on growth of rat mammary tumors induced by 7, 12, Dimethlybenz(a)anthracine. Cancer Res 1975;35:390–93.
12. Park KGM. The immunological and metabolic effects of L-arginine in human cancer. Proc Nutr Soc 1993;52:387–401.
13. Brittenden J, Park KGM, Heys SD, et al. L-arginine stimulates host defenses in patients with breast cancer. Surgery 1994;115:205–12.