Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

L-arginine: Supplement tested on fit, athletic men shows no advantage

23.11.2011
Popular supplement goes under the microscope, reveals no metabolic or hormonal enhancement for athletes at rest

One of the most recent, popular supplements for athletes looking to boost performance comes in the form of a naturally-occurring amino acid called L-arginine.

The reason for its popularity is twofold says Scott Forbes, a doctoral student in exercise physiology. "First, L-arginine is a precursor for nitric oxide that is known to improve blood flow, which in turn may aid the delivery of important nutrients to working muscles and assist with metabolic waste product removal. Secondly, L-arginine has been shown to increase growth hormone levels in the blood."

The benefits of growth hormone are diverse, including increasing the use of fat as a fuel as well as insulin and insulin-growth factor-1 (IGF-1) levels. However, most of the research conducted on L-arginine has been in a clinical setting and the benefits for physically active individuals are not as established. In some cases they are conflicting.

"One of the reasons for this is that the amount an individual has to consume has not been clearly established and this information is rarely provided by the manufacturers of such products," explains Forbes, a doctoral student in exercise physiology.

For Forbes it was a theory worth testing – and he wanted to test two different L-arginine doses on healthy, athletic men – the group most likely to purchase this readily-available supplement.

"L-arginine is interesting for a few reasons," says Forbes. "It can increase growth hormone response, and so can increase muscle mass. Also it has an impact on insulin, which is another anabolic hormone. A recent hot topic has been about nitric oxide as a vasodilator. The theory is that if you can vasodilate your arteries you can potentially enhance blood flow to the muscles and enhance nutrient delivery and waste product removal."

L-arginine is also often prescribed for older adults with cardiovascular disease, endothelial dysfunction or hypertension for its vasodilation properties and is rarely studied in younger, more vigorous populations.

For this study, Forbes recruited 14, active, physically fit men (age: 25±5yrs; weight: 78.0±8.5kg; height: 179.4±4.7cm), who were free of nutritional supplements, to examine a low and high dose of oral L-arginine on blood L-arginine, markers of nitric oxide, growth hormone, insulin, and insulin-like growth factor-1. In the double-blind, randomized, placebo-controlled study participants were first pre-screened, completing a one-day food record which was analyzed for carbohydrates, protein and fat consumption and caloric intake, then required to follow a modified diet to regulate intake of food and water prior to being dosed with L-arginine.

"After a 10-hour overnight fast, and no breakfast, we gave them a different dose of L-arginine – either .075 g per kilogram of body mass for the low dose, .15 g per kg of body mass for the high dose, or a placebo," says Forbes.

Blood samples were drawn with the athlete at rest, every half hour for three hours after the L-arginine or placebo dose. The reason explains Forbes, is that "Previous studies show that two hours after consumption L-arginine tends to reach baseline again."

What Forbes found was that in healthy, young, physically active males the two different doses significantly elevated L-arginine concentrations in the blood at rest, and both a low dose and a high dose were equally effective in doing so, but neither dose promoted a significant increase in nitric oxide, growth hormone, insulin, or insulin-like growth factor-1.

So, according to the study, it appears that L-arginine's impact depends on one's current health status: the more healthy and athletic the person, the less they'll benefit from it.

Now that he's established how L-arginine impacts the fit, young body at rest, he's embarked on two more studies – one with strength-trained athletes and one with aerobically-trained athletes – cyclists in this case – to look at the impacts of L-arginine on the body during exercise. "This time we're looking at the effects of supplements under two extremes: aerobic and strength exercise.

"There's a lot of money in nutritional supplements," he adds. "The industry might not be too happy when they see the results at rest, but who knows, it may be different with exercise."

Forbes has completed both of the exercise studies and hopes to publish the results in the near future.

His paper, "The acute effects of a low and high dose of oral L-arginine supplementation in young, active males at rest," was published in Applied Physiology, Nutrition and Metabolism. 2011, 36(3): 405-411.

Jane Hurly | EurekAlert!
Further information:
http://www.ualberta.ca

More articles from Studies and Analyses:

nachricht A sudden drop in outdoor temperature increases the risk of respiratory infections
11.01.2017 | University of Gothenburg

nachricht Urbanization to convert 300,000 km2 of prime croplands
27.12.2016 | Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>