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 Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT

nachricht Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>