L–ARGININE is a conditionally essential amino acid, which means that it may be needed in special conditions such as malnutrition, excessive ammonia production, burns, infections, peritoneal dialysis, rapid growth, urea synthesis disorders. Arginine supplement is used in sports, as it is said to increase nitric oxide (NO) activity in the body. NO helps dilate the blood vessels, and thus help improve the blood flow.

Just like many other supplements in the market, using L-Arginine supplement claims to enhance recovery by increasing the supply of fresh nutrients and oxygen via increased blood flow through vasodilation, which also means better protein synthesis. This also means an improvement in strength, power and better muscular recovery through better waste removal, such as lactate and ammonia.

But there is a big issue here, which general people get confused about. Firstly, arginine supplement in oral form does work. But there are two sides to it. Studies prove that arginine supplement helps in increasing NO production but only in subjects with some cardiovascular risk factors, high blood pressure, diabetes, insulin resistance, etc. No study has proven any benefit from even higher doses of oral L-Arginine supplement, in healthy disease-free individuals. This is also called “ARGININE PARADOX”

Very few studies which proved the benefit of L-Arginine in healthy individuals, also administered other amino acids, specially L-Citrulline, leucine, lysine, etc. to the subjects. Also, in subjects where arginine supplement worked because of the disease factor, the doses were very high, and doses in the range of 9gm/day for weeks together were not uncommon.

There was only one study, which supported the increase of growth hormone, with arginine supplement, but only when combined with exercise. This study was published in 2008, by J. A. Kanaley, in the journal Current Opinion in Clinical Nutrition and Metabolic Care. However, even in this study, the daily dose ranged from 5-9gms of oral L-Arginine. Similarly, a 2010 study in the Journal of Applied Physiology, by a team of British researchers, led by Stephen Bailey, found that arginine supplementation in 9 healthy men (19-38yrs), increased the time to exhaustion during severe intensity exercise. But even here the dose was a min of 6g/day.

A 2005 study published in the Growth Hormone & IGF research, by S. R. Collier and fellow researchers, studied the dose of oral arginine that elicits an optimal GH response and to determine the time course of the response. Eight healthy males (18-33 years) were studied. Researchers found that 5 and 9g of oral arginine caused a significant GH response. A 13g dose of arginine resulted in considerable gastrointestinal distress in most subjects without a rise in the GH response. The rise in GH concentration started approximately 30 min after ingestion and peaked approximately 60 min post-ingestion.

According to Will Brink, “The arginine-NO pathway is controlled by an enzyme called eNOS (endothelial nitric oxide synthase), which converts arginine into NO. The important thing to know is that even in people not taking an arginine supplement, the blood level of arginine is already high enough to saturate eNOS. And when an enzyme is saturated with a substrate (in this case L-arginine) more substrate won’t have an effect on a reaction. Therefore, if you’re healthy, when you supplement L-arginine (even in large doses) you won’t get more NO from the arginine-NO pathway, simply because L-arginine supplement is not rate-limiting for eNOS.”

Here is an extensive review of the studies which disapproves the use of L-Arginine supplement:

1. In a 2012 study, in the journal Nutrition & Metabolism, a team of Brazilian researchers led by T. S. Alvares tested seventeen healthy males, who were given either 6gms of oral L-Arginine supplementation or a placebo. The researchers found that L-arginine supplementation may help treat individuals with atherosclerosis risk factors, such as hypercholesterolemia, hypertension, diabetes mellitus, kidney failure, smoking, and aging—all of which are conditions that are associated with reduced NO biosynthesis. It was seen that only subjects with poor NO synthesis are likely to benefit from L-arginine supplementation. The study found that in healthy subjects 6 g of oral L-arginine supplementation did not stimulate an increase in NO production when compared to the placebo group.
2. A 2009 study in the Journal of Nutritional Biochemistry, by a team of Taiwanese researchers led by T. H. Liu, investigated the effect of short-term arginine supplementation on performance in intermittent anaerobic exercise in well-trained male athletes. Ten elite male college judo athletes participated with a randomized crossover, placebo-controlled design. The subjects consumed 6 g/day arginine or placebo for 3 days then performed an intermittent anaerobic exercise test on a cycle ergometer. Blood samples were collected before supplementation, before and during exercise and 0, 3, 6, 10, 30 and 60 min after exercise. The results of this study suggested that short-term arginine supplementation had no effect on nitric oxide production, lactate and ammonia metabolism and performance in intermittent anaerobic exercise in well-trained male athletes.

3. A 2011 study in the Journal of Nutrition, by a team of Canadian researchers led by J. E. Tang, investigated the ergogenic potential of arginine on NO synthesis, muscle blood flow, and skeletal muscle protein synthesis. Eight healthy young men, with an average between 20-24, were recruited and were given 10gms of essential amino acids with 10gms of L-arginine, along with performing a leg resistance exercise. However, the researchers failed to see an increase in NO synthesis or muscle blood flow, after arginine supplementation after or during exercise.
4. Studies have shown that NO may protect arteries from atherosclerosis. A 2000 study, in the Journal of American College of Cardiology, by A. Blum and fellow researchers, was carried out to study the effects of NO on postmenopausal women, through L-Arginine supplementation, as estrogen therapy which is shown to increase NO production, is not acceptable by many women for long term use. 10 postmenopausal women, with an additional risk of atherosclerosis, received 9gms of arginine or a placebo daily for one month. However, the researchers saw that oral L-arginine failed to augment NO synthesis and release in postmenopausal women and is thus unlikely to be of general benefit to healthy postmenopausal women in protection from the development of atherosclerosis.

5. A 2004 study in the Journal of Nutritional Biochemistry, by R. W. Evans and fellow researchers, found that the dietary supplements of L-arginine, may promote the formation of nitric oxide and thus may be of clinical benefit. However, the optimal level of the L-arginine supplement intake is unclear. The objective of this study was to evaluate the response of healthy individuals to increasing doses of L-arginine. Twelve healthy subjects were recruited and instructed to take L-arginine for 1-week periods at daily doses of 3, 9, 21, and 30 g. At the end of each week, 24-hour urine and fasting blood samples were collected, and weight, diastolic blood pressure, and systolic blood pressure were recorded. Ten subjects reported adverse side effects at initial L-arginine doses of 21 g/day (five subjects) or 30 g/day (five subjects). Mean values indicate that supplementation with 9 g/day of L-arginine, a dose associated with minimal adverse side effects, is sufficient to increase circulating L-arginine concentrations. However, subjects varied widely in their responses, indicating that L-arginine supplementation needs to be tailored to individuals.
6. A 2014 study in the journal Nutrition Research, by T. S. Alvares, investigated the effects of 4-weeks of L-Arginine supplementation, in 15 healthy runners, who took either 6gm/day of L-Arginine supplementation or a placebo, before exercise. However, 4 weeks of l-arginine supplementation did not cause beneficial changes in metabolic and hormonal parameters, beyond those achieved with exercise alone.

7. A 2015 study in the journal Nitric Oxide, by a team of European researchers led by S. B. Sandbakk, examined the effects of acute supplementation with L-arginine and nitrate on running economy, endurance and sprint performance in endurance-trained athletes. In a randomized cross-over, double-blinded study the researchers compared the effects of combined supplementation with 6 g L-arginine and 614 mg nitrate against 614 mg nitrate alone and placebo in 18yr-old, nine male elite cross-country skiers. The plasma concentrations indicate greater nitric oxide availability both following acute supplementation of L-arginine + nitrate and with nitrate alone compared to placebo, but no additional effect was revealed when L-arginine was added to nitrate. Still, there were no effects of supplementation on exercise economy or endurance running performance in endurance-trained cross-country skiers.

8. A 2005 study in the International Journal of Sports Medicine, by a team of researchers led by T. Abel, investigated the daily intake of two different dosages of arginine asparate during four weeks affects selected parameters of overtraining syndrome-like performance, metabolic and endocrine parameters. Thirty male endurance-trained athletes were included in a randomized, double-blind, placebo-controlled trial and divided into three groups. During four weeks, they ingested either arginine aspartate with a high concentration of 5.7g arginine and 8.7g aspartate, with a low concentration of 2.8g arginine and 2.2g aspartate or placebo. Compared to placebo, no significant differences in endurance performance (VO2 peak, time to exhaustion), endocrine (concentration of GH, glucagon, cortisol, and testosterone) and metabolic parameters (concentration of lactate and urea) were found after chronic arginine aspartate supplementation. The chronic intake of arginine asparate during four weeks by male endurance athletes showed independent of dosage no influence on performance, selected metabolic or endocrine parameters. Consequently, there seems to be no apparent reason why the supplementation of arginine aspartate should be an effective ergogenic aid.
9. A 1999 study in the European Journal of Nutrition, by P. C. Colombani, investigated the general metabolic impact of chronic supplementation with arginine aspartate in endurance-trained athletes at rest and during a marathon run. Fourteen endurance-trained runners participated in this field study. 15 g of arginine aspartate or a carbohydrate-based placebo were supplemented daily for 14 days before a marathon run. Blood samples for analysis of metabolites and hormones were collected shortly before the run, after 31 km, at the end of the run, and after a recovery period of two hours. The study derived no obvious metabolic benefits from chronic supplementation with arginine aspartate.
10. The effect of arginine supplementation was tested in resistance training men in a study in the Journal of International Society of Sports Nutrition, by B. Wax and fellow researchers. This study examined the efficacy of acute ingestion of L-arginine alpha-ketoglutarate (AAKG) muscular strength and endurance in resistance-trained and untrained men. Eight resistance-trained and eight untrained healthy males ingested either 3000mg of AAKG or a placebo 45 minutes prior to a resistance exercise protocol. One-repetition maximum (1RM) on the standard barbell bench press and leg press were obtained. Upon determination of 1RM, subjects completed repetitions to failure at 60% 1RM on both the standard barbell bench press and leg press. Heart rate was measured pre and post-exercise. One week later, subjects ingested the other supplement and performed the identical resistance exercise protocol. The results from the study indicated that acute AAKG supplementation provides no ergogenic benefit on 1RM as measured by the standard barbell bench press and leg press, regardless of the subject’s training status.

11. A 2016 study in the European Journal of Nutrition, by a team of Brazilian researchers led by A. F. Aquiar examined the effects of L-arginine supplementation on vasodilatation and muscle performance in older women. In this double-blind, randomized, placebo-controlled study, 20 elderly women were randomly assigned to either an L-arginine or placebo group. However, L-arginine supplementation provided no ergogenic effect on blood flow and muscle performance in older women.
12. Some people think that taking arginine with the post-workout carbohydrate drink will enhance the absorption of glucose by the cells in the muscles. A 2003 study in the journal Medicine and Science in Sports and Exercise, by a team of British researchers led by T. M. Robinson, found that a10-g oral dose of L-arginine had no effect on blood glucose disposal in human subjects after oral carbohydrate ingestion, either when rested or after different modes of exercise known to differentially affect glucose disposal. These results suggest that the addition of L-arginine to a carbohydrate beverage would not augment post-exercise carbohydrate replenishment in healthy human subjects.
13. L-arginine supplements have also been hypothesized to improve exercise performance by increasing levels of insulin and growth hormone (GH). A study in the journal Food & Nutrition Research in 2014, by a team of Brazilian researchers led by D. V. T. DaSilva, evaluated the effect of L-arginine supplementation on serum insulin, GH, Growth Factor Insulin-like (IGF-1), cortisol, and exercise performance, in response to exercise. Fifteen trained runners were divided into groups supplemented with 6g of L-arginine or placebo. Blood samples were collected before supplementation, immediately after the first exercise session, after the second exercise session, and after 20 min of rest. The exercise consisted of two bouts of a 5 km time-trial running test. However, the supplementation of L-arginine did not appear to stimulate the production of insulin, GH, and IGF-1 and, thus, provided no benefit in hormonal response or exercise performance in trained runners.
14. A 2013 study in the International Journal of Sports Nutrition and Exercise Metabolism, by a team of Canadian researchers led by S. C. Forbes, investigated the effect of acute L-arginine ingestion on the hormonal and metabolic response during submaximal exercise in trained cyclists. Fifteen aerobically trained men (age: 23-33yrs) participated in a randomized, double-blind, crossover study. Subjects consumed L-arginine (0.075g/kg body mass) or a placebo before performing an acute bout of submaximal exercise. Again, the acute ingestion of L-arginine did not alter any hormonal, metabolic, or cardio-respiratory responses during submaximal exercise.

So, all those people who think that your regular intake of arginine supplement based 1000mg/1g tablets or pre-workout drinks are going to make any difference, then you know what the supplement companies think you are. Yup, simply Stupid!