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L-Arginine is an amino acid and its use as a dietary supplement has been the subject of review by both scientists and consumers. According to reviews, L-arginine products may support muscle growth, recovery after a workout and athletic performance.
L-Arginine is a substrate for nitric oxide synthase, the enzyme responsible for the production of nitric oxide. Nitric oxide is a powerful vasodilator, meaning it helps widen blood vessels, which may improve blood flow.
In very high quantities, L-arginine has been observed to increase the production of human growth hormone (HGH), which is why it is sometimes taken by athletes and bodybuilders.
L-arginine reviews show that this supplement is commonly taken by bodybuilders, to promote general health and wellness, to support the immune system and to promote weight loss. What does the available research say about the effectiveness of this supplement for its popular uses?
Pre-Workout
Muscle Growth
Sexual Health- Boosts nitric oxide production for workouts
- Reduces fatigue & promotes muscle growth
- Supports immune function & sexual health
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Related Topics
- L-Arginine
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- Benefits for Men
- Benefits for Bodybuilding
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- Arginine Ornithine and Lysine
- Suggested Dosages
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- Comparison to L-Citrulline
- Best Supplement
- Topical Cream
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- Side Effects
Arginine is naturally produced in the body from citrulline, but in rare cases arginine needs to be supplemented. Most people do not need to take L-arginine to maintain healthy levels in the body.
However, some people opt to supplement with L-arginine in the hopes of achieving additional benefits from the amino acid. L-Arginine is taken for a number of purposes, including weight loss, bodybuilding, high blood pressure and erectile dysfunction, to name a few.
Scientific review of L-arginine for the above indications is limited. There are limited human studies and some of the available results have been contradictory. This article briefly summarizes some of the uses of supplemental L-arginine and discusses both scientific and consumer reviews of these uses.
L-Arginine Review for Weight Loss
L-Arginine has become popular for weight loss after it was recommended by Dr. Mehmet Oz of The Doctor Oz Show. Dr. Oz recommended L-arginine because it has been observed to increase human growth hormone (HGH) levels, which may support weight loss.
However, only very high levels of L-arginine have been observed to increase HGH levels. This is discussed in more detail in the following section (on bodybuilding).
While the amino acid has been observed to help reduce fat mass in preliminary animal trials, only one clinical trial has been completed in relation to arginine and obesity. [2]
In a 2006 study, obese male participants diagnosed with type II diabetes were divided into either a placebo or control group. Members of both groups adhered to a calorie-restricted diet (1,000 kcal/day) and engaged in regular exercise. The treatment group received L-arginine.
Participants in the treatment group lost slightly more weight than members of the placebo group. However, what is perhaps more notable is that the weight lost by treatment group members was 100 % fat whereas members of the placebo group lost both fat and lean muscle mass. [4, 5]
L-Arginine Review for Bodybuilding
Some bodybuilders and athletes supplement with L-arginine to improve endurance and promote muscle development. There are two main ways that L-arginine is hypothesized to support fitness: by increasing nitric oxide synthesis and elevating human growth hormone (HGH) levels.
Arginine and Nitric Oxide: L-Arginine is a substrate for the enzyme nitric oxide synthase. As the name suggests, this enzyme produces nitric oxide, a potent vasodilator.
Vasodilators have the ability to relax the smooth muscle tissue lining arteries and blood vessels, allowing them to widen and improving blood flow. Athletes are interested in blood flow because it means proteins, oxygen and other nutrients are being delivered to their muscles, promoting endurance and improving recovery times.
Although L-arginine is a known precursor to nitric oxide, studies indicate arginine does not always increase blood flow.
For instance, arginine supplementation has been observed to increase blood flow in healthy individuals at rest and in individuals with a host of medical conditions, including diabetes and cardiac disorders. However, it did not increase blood flow in healthy individuals during exercise. [1]
That said, arginine supplementation has been observed to reduce ammonia and lactate levels in the blood. A build up of these compounds during exercise can lead to fatigue. [1]
L-Arginine and Human Growth Hormone: The relationship between HGH and arginine is one of the main reasons why some bodybuilders supplement with L-arginine.
However, the University of Michigan notes in their review that only very high levels of L-arginine have been observed to affect HGH levels. For instance, 250 mg for every 2.2 lbs of bodyweight has been observed to increase HGH levels. [2]
This level of supplementation causes diarrhea and stomach cramps, according to a number of user reviews.
While oral arginine supplementation may not have a strong connection with improved HGH levels, a combination of L-arginine and ornithine (500 mg each per day) was observed to reduce body fat and improve strength and lean body mass when combined with a regular weight routine. [2]
L-Arginine and Erectile Function
L-Arginine is sometimes used for erectile dysfunction because it is thought to improve blood flow.
Consumer reviews for L-arginine and erectile dysfunction are often quite positive. Additionally, men who took 5 g/day of L-arginine subjectively reported improvements in their organic erectile dysfunction. However, doses less than 5 g per day may not be effective. [3]
To promote sexual performance and erectile function, this supplement is often combined with other products that can enhance penile circulation, such as Pycnogenol.
L-arginine Side Effects Review
The Natural Medicines Comprehensive Database rates L-arginine as “Possibly Safe” when taken orally for short periods of time. However, the long-term effects of L-arginine supplementation remain ill-defined. [3]
L-Arginine may interact with a number of prescription and over-the-counter medications. In addition, it may not be suitable for individuals with pre-existing medical conditions.
Speak to your doctor to review the possible side effects and interactions of L-arginine to make sure the supplement is right for you.
- Rob Egbers. How much do you NO? Posted: 2007 Aug 1. Accessed: 2016 Feb 17. University of Michigan Medical School. .
- Arginine: Uses. Health Library, University of Michigan Health System. Reviewed 2015 Mar 31. Accessed 2016 Feb 16.
- Natural Medicines. L-Arginine: Professional Monograph. Reviewed May 2013.
- Lucotti P, Setola E, Monti LD, et al. Beneficial effects of a long-term oral L-arginine treatment added to a hypocaloric diet and exercise training program in obese, insulin-resistant type 2 diabetic patients. Am J Physiol Endocrinol Metab. 2006 Nov;291(5):E906-12.
- McKnight JR, Satterfield MC, Jobgen WS, Smith SB, Spencer TE, Meininger CJ, McNeal CJ, Wu G. Beneficial effects of L-arginine on reducing obesity: potential mechanisms and important implications for human health. Amino Acids. 2010 Jul;39(2):349-57.
Article last updated on: March 13th, 2018 by Nootriment