Arginine

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 of arginine on growth hormone levels1 has interested body builders. In a controlled trial, when arginine and ornithine (500 mg of each, twice per day, five times per week) were combined with weight training, a greater decrease in body fat was obtained after only five weeks, than when the same exercise was combined with a placebo.2 In another study, however, 5 grams of arginine powder, taken orally 30 minutes prior to exercise, failed to affect growth hormone release and may have even impaired the release of growth hormone in younger adults.3

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,4 though not all,5 studies have found that men with low sperm counts experienced an increase in the number of sperm when they supplemented with arginine.

Arginine’s effect on increasing protein synthesis improves wound healing. This effect has been shown in both animals6 and people (at 17 grams per day).7

Arginine is also a precursor to nitric oxide, which the body uses to keep blood vessels dilated, allowing the heart to receive adequate oxygen. Researchers have begun to use arginine in people with angina and congestive heart failure.

Nitric oxide metabolism is also altered in people with interstitial cystitis, a condition of the bladder. Preliminary research found that supplementation with 1.5 grams of arginine per day for six months led to a significant decrease in most symptoms, including pain,8 though short-term supplementation (five weeks) has not been effective, even at higher (3–10 grams per day) intakes.9 In 1999, a double-blind study using 1.5 grams of arginine for three months in a group of women with interstitial cystitis, reported considerable improvement compared with the effect of a placebo in a variety of indices. Perhaps due to the small size of the study, some of these changes did not quite reach statistical significance.10

Preliminary evidence suggests that arginine may help regulate cholesterol levels.11 Arginine also appears to act as a natural blood thinner by reducing platelet aggregation.12

Where is it found? Dairy, meat and 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 (refer to the individual health concern for complete information):

Rating Health Concerns
2Stars Angina
Congestive heart failure
HIV support (in combination with glutamine and HMB)
Infertility (male)
Intermittent claudication (I.V. only)
Interstitial cystitis
Pre- and post-surgery health
1Star Athletic performance (for body composition and strength)
Erectile dysfunction
Female infertility (for in vitro fertilization)
Gastritis
High blood pressure
Wound healing
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

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.

How much is usually taken? Most people do not need to take extra arginine. While some people with serious infections, burns, or other trauma should take arginine, appropriate amounts must be determined by a doctor. Levels used in research vary considerably (2–30 grams per day). Most research on cardiovascular disease has used between 6 and 20 grams per day. Optimal intakes remain unknown and are likely to vary depending upon the individual.

Are there any side effects or interactions? Arginine has so far appeared to be free of obvious side effects. However, longer-term studies are needed to confirm its safety.

People with kidney or liver disease should consult their doctor before supplementing with arginine. Some doctors believe that people with herpes (either cold sores or genital herpes) should not take arginine supplements, because of the possibility that arginine might stimulate replication of the virus.

Administration of large amounts of arginine to animals has been found both to promote13 and to interfere with cancer growth.14 In preliminary research, high intake (30 grams per day) of arginine has increased cancer cell growth in humans.15 On the other hand, in people with cancer, arginine has been found to stimulate the immune system.16 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.

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 Endocrinol 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;28:35–9.

3. Marcell TJ, Taaffe DR, Hawkins SA, et al. Oral arginine does not stimulate basal or augment exercise-induced GH secretion in either young or old adults. J Gerontol A Biol Sci Med Sci 1999;54:M395–9.

4. Schacter A, Goldman JA, Zukerman Z. Treatment of oligospermia with the amino acid arginine. J Urol 1973;110:311–3.

5. Pryor JP, Blandy JP, Evans P, et al. Controlled clinical trial of arginine for infertile men with oligozoospermia. Br J Urol 1978;50:47–50.

6. 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.

7. Kirk SJ, Hurson M, Regan MC, et al. Arginine stimulates wound healing and immune function in elderly human beings. Surgery 1993;114:155–60.

8. Smith SD, Wheeler MA, Foster HE Jr, Weiss RM. Improvement in interstitial cystitis symptom scores during treatment with oral L-arginine. J Urol 1997;158:703–8.

9. Ehrén I, Lundberg JO, Adolfsson J. Effects of L-arginine treatment on symptoms and bladder nitric oxide levels in patients with interstitial cystitis. Urology 1998;52:1026–9.

10. Korting GE, Smith SD, Wheeler MA, et al. A randomized double-blind trial of oral L-arginine for treatment of interstitial cystitis. J Urol 1999;161:558–65.

11. Kohls KJ, Kies C, Fox HM. Serum lipid levels of humans given arginine, lysine and tryptophan supplements without food. Nutr Rep Int 1987;35:5–13.

12. 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.

13. Park KGM. The immunological and metabolic effects of L-arginine in human cancer. Proc Nutr Soc 1993;52:387–401.

14. 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;35:2390–3.

15. Park KGM. The immunological and metabolic effects of L-arginine in human cancer. Proc Nutr Soc 1993;52:387–401.

16. Brittenden J, Park KGM, Heys SD, et al. L-arginine stimulates host defenses in patients with breast cancer. Surgery 1994;115:205–12.