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What Are Star Ratings?

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for Why
2 Stars
2 to 3 grams three times per day
In one study, taking arginine improved the ability of angina sufferers to exercise. Detailed studies have proven that arginine works by stimulating blood vessel dilation.

Nitroglycerin and similar drugs cause dilation of arteries by interacting with nitric oxide, a potent stimulus for dilation. Nitric oxide is made from arginine, a common amino acid. Blood cells in people with angina are known to make insufficient nitric oxide,1 which may in part be due to abnormalities of arginine metabolism. Taking 2 grams of arginine three times per day for as little as three days has improved the ability of angina sufferers to exercise.2 Seven of ten people with severe angina improved dramatically after taking 9 grams of arginine per day for three months in an uncontrolled study.3 Detailed studies have investigated the mechanism of arginine and have proven it operates by stimulating blood vessel dilation.4

2 Stars
Congestive Heart Failure
5.6 to 15 grams per day with a doctor's supervision
The body needs arginine to make nitric oxide, which increases blood flow. This process is impaired in people with CHF. It also has been shown to improve kidney function in people with CHF.

The body needs arginine, another amino acid, to make nitric oxide, which increases blood flow. This process is impaired in people with CHF. Arginine supplementation (5.6–12.6 grams per day) has been used successfully in double-blind trials to treat CHF.5A double-blind trial has also found that arginine supplementation (5 grams three times daily) improves kidney function in people with CHF.6

2 Stars
Erectile Dysfunction
1,670 to 2,800 mg daily
Blood vessels need arginine to dilate and form an erection. Supplementing with arginine has been shown to help men with erectile dysfunction in some studies.

Dilation of blood vessels necessary for a normal erection depends on a substance called nitric oxide, and nitric oxide formation depends on the amino acid arginine. In a preliminary trial, men with ED were given 2,800 mg of arginine per day for two weeks. Six of the 15 men in the trial were helped, though none improved while taking placebo.7 In a larger double-blind trial, men with ED were given 1,670 mg of arginine per day or a matching placebo for six weeks.8 Arginine supplementation was found to be particularly effective at improving ED in men with abnormal nitric oxide metabolism. Although little is known about how effective arginine will be for men with ED or which subset of these men would be helped, available research looks promising and suggests that at least some men are likely to benefit.

2 Stars
HIV and AIDS Support and Preservation of Lean Body Mass (Glutamine, HMB)
1.5 grams of HMB, 7 grams of L-glutamine, and 7 grams of L-arginine twice per day
The combination of glutamine, arginine, and HMB may prevent loss of lean body mass in people with AIDS-associated wasting.

The combination of glutamine, arginine, and the amino acid derivative, hydroxymethylbutyrate (HMB), may prevent loss of lean body mass in people with AIDS-associated wasting. In a double-blind trial, AIDS patients who had lost 5% of their body weight in the previous three months received either placebo or a nutrient mixture containing 1.5 grams of HMB, 7 grams of L-glutamine, and 7 grams of L-arginine twice daily for eight weeks.9 Those supplemented with placebo gained an average of 0.37 pounds, mostly fat, but lost lean body mass. Those taking the nutrient mixture gained an average of 3 pounds, 85% of which was lean body weight.

2 Stars
Male Infertility
4 grams daily
The amino acid arginine is needed to produce sperm. Research shows that several months of L-arginine supplementation increases sperm count, quality, and fertility.

Arginine , an amino acid found in many foods, is needed to produce sperm. Research, most of which is preliminary shows that several months of L-arginine supplementation increases sperm count, quality,10 , 11 , 12 and fertility.13 , 14 However, when the initial sperm count was extremely low (such as less than 10 million per ml), L-arginine supplementation produced little or no benefit.15 , 16 While some pregnancies have been attributed to arginine supplementation in preliminary reports,17 no controlled research has confirmed these claims. For infertile men with sperm counts greater than 10 million per milliliter, many doctors recommend up to 4 grams of L-arginine per day for several months.

2 Stars
Pre- and Post-Surgery Health
12.5 to 18.75 grams daily before and after surgery
The amino acid arginine has a role in immune function, infection prevention, and tissue repair after injury, including surgery.

The amino acid arginine has a role in immune function, infection prevention, and tissue repair after injury, including surgery.18 Animal research suggests that supplemental arginine may improve the outcomes in cardiovascular19 and colon surgeries.20 Other animal studies suggest a possible role for arginine in prevention of adhesions, a painful type of internal scarring that can occur with surgery.21 Human trials of formulas including arginine are discussed below, but the benefits of supplemental arginine alone have not been studied in surgery patients.

2 Stars
Sickle Cell Anemia and Pulmonary Hypertension (L-Arginine)
100 mg per 2.2 lbs (1 kg) of body weight, three times per day
People with pulmonary hypertension (a life-threatening complication of sickle cell anemia) who received L-arginine had significant improvement in one study.

In a preliminary study, individuals with pulmonary hypertension (a life-threatening complication of sickle cell anemia) received L-arginine in the amount of 100 mg per 2.2 pounds of body weight, three times per day for five days. L-arginine treatment resulted in a significant improvement in pulmonary hypertension, as determined by a 15% decline in the pulmonary artery systolic pressure.22 Longer-term studies are needed to confirm these preliminary results.

1 Star
Athletic Performance and Body Composition and Strength
Refer to label instructions
At very high intakes, the amino acid arginine has increased growth hormone levels, which stimulate muscle growth. Trials combining weight training with arginine and ornithine showed decreases in body fat and increases in total strength and lean body mass.

At very high intakes (approximately 250 mg per 2.2 pounds of body weight), the amino acid arginine has increased growth hormone levels,23 an effect that has interested body builders due to the role of growth hormone in stimulating muscle growth.24 However, at lower amounts recommended by some manufacturers (5 grams taken 30 minutes before exercise), arginine failed to increase growth hormone release and may even have impaired the release of growth hormone in younger adults.25 Large quantities (170 mg per 2.2 pounds of body weight per day) of a related amino acid, ornithine, have also raised growth hormone levels in some athletes.26 High amounts of arginine or ornithine do not appear to raise levels of insulin,27 , 28 another anabolic (bodybuilding) hormone. More modest amounts of a combination of these amino acids have not had measurable effects on any anabolic hormone levels during exercise.29 , 30

Nonetheless, double-blind trials conducted by one group of researchers, combining weight training with either arginine and ornithine (500 mg of each, twice per day, five times per week) or placebo, found the amino-acid combination produced decreases in body fat,31 resulted in higher total strength and lean body mass, and reduced evidence of tissue breakdown after only five weeks.32

1 Star
Female Infertility and In Vitro Fertilization
Refer to label instructions
Supplementing with L-arginine has been shown to improve fertility in women with a history of failed attempts at in vitro fertilization.

Supplementation with the amino acid, L-arginine (16 grams per day), has been shown to improve fertilization rates in women with a previous history of failed attempts at in vitro (test tube) fertilization.33

1 Star
Refer to label instructions
The amino acid arginine may both protect the stomach and increase its blood flow.

Various amino acids have shown promise for people with gastritis. In a double-blind trial, taking 200 mg of cysteine four times daily provided significant benefit for people with bleeding gastritis caused by NSAIDs (such as aspirin).34 Cysteine is a sulfur-containing amino acid that stimulates healing of gastritis. In a preliminary trial, 1–4 grams per day of NAC (N-acetyl cysteine) given to people with atrophic gastritis for four weeks appeared to increase healing.35 Glutamine, another amino acid is a main energy source for cells in the stomach and supplementation may increase blood flow to this region.36 Patients in surgical intensive care units often develop gastrointestinal problems related to a glutamine deficiency.37 When burn victims were supplemented with glutamine, they did not develop stress ulcers, even after several operations.38 Nevertheless, it remains unclear to what extent glutamine supplementation might prevent or help existing gastritis. Preliminary evidence suggests the amino acid arginine may both protect the stomach and increase its blood flow,39 but research has yet to investigate the effects of arginine supplementation in people with gastritis.

1 Star
Refer to label instructions
The amino acid arginine is needed by the body to make nitric oxide, a substance that allows blood vessels to dilate, thus reducing blood pressure. Arginine given orally and intravenously has been reported to help reduce blood pressure.

The amino acid arginine is needed by the body to make nitric oxide, a substance that allows blood vessels to dilate, thus leading to reduced blood pressure. Intravenous administration of arginine has reduced blood pressure in humans in some reports.40 In one controlled trial, people not responding to conventional medication for their hypertension were found to respond to a combination of conventional medication and oral arginine (2 grams taken three times per day.)41

1 Star
Wound Healing
Refer to label instructions
Arginine appears to improve wound healing by increasing protein synthesis.

Arginine supplementation increases protein synthesis and improves wound healing in animals.42 Two controlled trials have shown increased tissue synthesis in surgical wounds in people given 17–25 grams of oral arginine per day.43 , 44

How It Works

How to Use It

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.

Where to Find It

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

Possible Deficiencies

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.


Interactions with Supplements, Foods, & Other Compounds

Arginine works with ornithine in the synthesis of growth hormone.

Interactions with Medicines

As of the last update, we found no reported interactions between this supplement and medicines. It is possible that unknown interactions exist. If you take medication, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Side Effects

For most people, arginine has so far appeared to be free of obvious side effects. However, longer-term studies are needed to confirm its safety.

In a double-blind study, supplementation with 9 grams of arginine per day for six months, beginning within 3 to 21 days after a heart attack, resulted in an increase in the mortality rate.45 Therefore, people who have recently suffered a heart attack should probably not take large amounts of arginine. Arginine is beneficial for other manifestations of heart disease, such as heart failure and angina. However, because of the potential for arginine to cause adverse effects in heart patients, people with heart disease should consult a doctor before taking arginine.

There have been two case reports of severe allergic reactions following intravenous administration of L-arginine;46 however, allergic reactions have not been reported after oral administration.

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 promote47 and to interfere with cancer growth.48 In preliminary research, high intake (30 grams per day) of arginine has increased cancer cell growth in humans.49 On the other hand, in people with cancer, arginine has been found to stimulate the immune system.50 At this time it remains unclear whether arginine is dangerous or helpful for people with cancer.


1. Mollace V, Romeo F, Martuscelli E, et al. Low formation of nitric oxide in polymorphonuclear cells in unstable angina pectoris. Am J Cardiol 1994;74:65–8.

2. Ceremuzynski L, Chamiec T, Herbaczynska-Cedro K. Effect of supplemental oral L-arginine on exercise capacity in patients with stable angina pectoris. Am J Cardiol 1997;80:331–3.

3. Blum A, Porat R, Rosenschein U, et al. Clinical and inflammatory effects of dietary L-arginine in patients with intractable angina pectoris. Am J Cardiol 1999;83:1488–90.

4. Egashira K, Hirooka Y, Kuga T, et al. Effects of L-arginine supplementation on endothelium-dependent coronary vasodilation in patients with angina pectoris and normal coronary arteriograms. Circulation 1996;94:130–4.

5. Rector TS, Bank A, Mullen KA, et al. Randomized, double-blind, placebo controlled study of supplemental oral L-arginine in patients with heart failure. Circulation 1996;93:2135–41.

6. Watanabe G, Tomiyama H, Doba N. Effects of oral administration of L-arginine on renal function in patients with heart failure. J Hypertens 2000;18:229–34.

7. Zorgniotti AW, Lizza EF. Effect of large doses of the nitric oxide precursor, L-arginine, on erectile dysfunction. Int J Impot Res 1994;6:33–6.

8. Chen J, Wollman Y, Chernichovsky T, et al. Effect of oral administration of high-dose nitric oxide donor L-arginine in men with organic erectile dysfunction: results of a double-blind, randomized study. BJU Int 1999;83:269–73.

9. Clark RH, Feleke G, Din M, et al. Nutritional treatment for acquired immunodeficiency virus-associated wasting using beta-hydroxy beta-methylbutyrate, glutamine, and arginine: a randomized, double-blind, placebo-controlled study. JPEN J Parenter Enteral Nutr 2000;24:133–9.

10. De Aloysio D, Mantuano R, Mauloni M, Nicoletti G. The clinical use of arginine aspartate in male infertility. Acta Eur Fertil 1982;13:133–67.

11. Tanimura J. Studies on arginine in human semen. Part II. The effects of medication with L-arginine-HCl on male infertility. Bull Osaka Med School 1967;13:84–9.

12. Scibona M, Meschini P, Capparelli S, et al. L-arginine and male infertility. Minerva Urol Nefrol 1994;46:251–3.

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

14. Schacter A, Friedman S, Goldman JA, Eckerling B. Treatment of oligospermia with the amino acid arginine. Int J Gynaecol Obstet 1973;11:206–9.

15. Mroueh A. Effect of arginine on oligospermia. Fertil Steril 1970:21:217–9.

16. 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.

17. Aydin S, Inci O, Alagol B. The role of arginine, indomethacin and kallikrein in the treatment of oligoasthenospermia. Int Urol Nephrol 1995;27:199–202.

18. Evoy D, Lieberman MD, Fahey TJ 3rd, Daly JM. Immunonutrition: the role of arginine. Nutrition 1998;14:611–7 [review].

19. Szabo G, Bahrle S, Batkai S, et al. L-arginine: effect on reperfusion injury after heart transplantation. World J Surg 1998;22:791–7.

20. Shashidharan M, Lin KM, Ternent CA, et al. Influence of arginine dietary supplementation on healing colonic anastomosis in the rat. Dis Colon Rectum 1999;42:1613–7.

21. Kaleli B, Ozden A, Aybek Z, Bostanci B. The effect of L-arginine and pentoxifylline on postoperative adhesion formation. Acta Obstet Gynecol Scand 1998;77:377–80.

22. Morris CR, Morris SM Jr, Hagar W, et al. Arginine therapy: a new treatment for pulmonary hypertension in sickle cell disease? Am J Respir Crit Care Med 2003;168:63–9.

23. 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.

24. Macintyre JG. Growth hormone and athletes. Sports Med 1987;4:129–42 [review].

25. 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.

26. Bucci L, Hickson JF, Pivarnik JF, et al. Ornithine ingestion and growth hormone release in body-builders. Nutr Res 1990;10:239–45.

27. Gater DR, Gater DA, Uribe JM, et al. Effects of arginine/lysine supplementation and resistance training on glucose tolerance. J Appl Physiol 1992;72:1279–84.

28. Bucci LR, Hickson JF Jr, Wolinsky I, et al. Ornithine supplementation and insulin release in bodybuilders. Int J Sport Nutr 1992;2:287–91.

29. Suminski RR, Robertson RJ, Goss FL, et al. Acute effect of amino acid ingestion and resistance exercise on plasma growth hormone concentration in young men. Int J Sport Nutr 1997;7:48–60.

30. Fogelholm GM, Naveri HK, Kiilavuori KT, et al. Low-dose amino acid supplementation: no effects on serum human growth hormone and insulin in male weightlifters. Int J Sport Nutr 1993;3:290–7.

31. Elam RP. Morphological changes in adult males from resistance exercise and amino acid supplementation. J Sports Med Phys Fitness 1988;28:35–9.

32. Elam RP, Hardin DH, Sutton RA, et al. Effects of arginine and ornithine on strength, lean body mass and urinary hydroxyproline in adult males. J Sports Med Phys Fitness 1989;29:52–6.

33. Battaglia C, Salvatori M, Maxia N, et al. Adjuvant L-arginine treatment for in-vitro fertilization in poor responder patients. Hum Reprod 1999;14:1690–7.

34. Salim AS. Sulfhydryl-containing agents in the treatment of gastric bleeding induced by non-steroidal anti-inflammatory drugs. Can J Surg 1993;36(1):53–8.

35. Farinati F, Cardin R, Della Libera G, et al. Effects of N-acetyl-L-cysteine in patients with chronic atrophic gastritis and nonulcer dyspepsia: a phase III pilot study. Curr Ther Res 1997;58:724–33.

36. Houdijk AP, Van Leeuwen PA, Boermeester MA, et al. Glutamine-enriched enteral diet increases splanchnic blood flow in the rat. Am J Physiol 1994;267(6 Pt 1):G1035–40.

37. Wilmore DW, Smith RJ, O’Dwyer ST, et al. The gut: a central organ after surgical stress. Surgery 1988;104:917–23.

38. Yan R, Sun Y, Sun R. Early enteral feeding and supplement of glutamine prevent occurrence of stress ulcer following severe thermal injury. Chung Hua Cheng Hsing Shao Shang Wai Ko Tsa Chih 1995;11(3):189–92.

39. Brzozowski T, Konturek SJ, Sliwowski Z, et al. Role of L-arginine, a substrate for nitric oxide-synthase, in gastroprotection and ulcer healing. J Gastroenterol 1997;32(4):442–52.

40. Calver A, Collier J, Vallance P. Dilator actions of arginine in human peripheral vasculature. Clin Sci 1991;81:695–700.

41. Pezza V, Bernardini F, Pezza E, et al. Study of supplemental oral l-arginine in hypertensives treated with enalapril + hydrochlorothiazide. Am J Hypertens 1998;11:1267–70 [letter].

42. 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.

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

44. Barbul A, Lazarou SA, Efron DT, et al. Arginine enhances wound healing and lymphocyte immune responses in humans. Surgery 1990;108:331–7.

45. Schulman SP, Becker LC, Kass DA, et al. L-arginine therapy in acute myocardial infarction: the Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) randomized clinical trial. JAMA 2006;295:58–64.

46. Resnick DJ, Softness B, Murphy AR, et al. Case report of an anaphylactoid reaction to arginine. Ann Allergy Asthma Immunol 2002;88:67–8.

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

48. 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.

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

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

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