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Typically recognized for their muscle-building effects, amino acids also contribute a few lesser known benefits. A recent pilot study published in the Journal of Dietary Supplements suggests that L-arginine, a conditionally essential amino acid, may help battle obesity by minimizing visceral adipose tissue (belly fat). Obesity characterized primarily by large stores of visceral fat in the abdomen has been linked to higher cardiovascular and metabolic risk than other types of obesity.

L-arginine has long been used as an ingredient in supplement formulations, particularly in those designed to improve libido, sport performance, and cardiovascular health. How does l-arginine have such a wide range of physiological effectors? As a nitrogenous amino acid, it serves as a precursor to nitric oxide (NO), a compound whose primary function is to dilate blood vessels. In addition to the biochemical consequences that include enhanced lipolysis (fatty acid metabolism), dilated blood vessels ease heart function, improve cardiovascular health (by lowering blood pressure) and reduce risk of the associated metabolic syndrome. Blood vessel dilation is also the basis of erectile dysfunction treatment; arginine has not only been linked to improved sexual performance but some studies also suggest that it also boosts the production of semen. The amino acid has also been suggested to help prevent renal dysfunction in type-2 diabetics.

Scientific Basis for Weight Loss Claims

The study, conducted by researchers at the Mayo Clinic, recruited 20 non-diabetic, obese women (waist circumference exceeded 89 cm.) between the ages of 18-40 with BMI scores ranging from 30 to 40. Participants consumed 3 grams of L-arginine 3 times daily for 12 weeks.

L-arginine supplementation led to:

  • Reduced waist circumference (WC). WC is a good indicator of central obesity, a result of the accumulation of visceral adipose tissue. Waist circumference was recorded at 109cm after 12 weeks, significantly below the 116cm baseline measurement taken at the study’s start.
  • Weight Loss. Participants recorded a 6.5 pound loss, on average, as well as lower BMI scores.

In this study, supplementation seemed to be well-tolerated, with no side effects observed. However, some studies have noted side-effects after L-arginine supplementation, including:

  1. A risk of reactivating otherwise dormant viruses. Lysine and arginine compete for intracellular transport, with the general idea being that when one is transported inside the cell, the other is not. Some studies suggest that lysine inhibits viral replication, while arginine is necessary for some viruses, such as the herpes simplex virus, to thrive.
  2. A six-month, clinical study evaluating the effect of l-arginine on blood vessel stiffness and improving overall heart function after a myocardial infarction (heart attack) suggested no beneficial effect.

Final Words

Awareness of potential sides effect should be an essential in supplementing decisions. It should be noted that this study does not irreversibly prove L-arginine’s safety or efficacy; larger scale studies will be needed to more accurately assess these effects. With the current evidence, however, it seems like short-term L-arginine supplementation (up to 12 weeks) is a promising way to increase fat metabolism, lower levels of visceral belly fat, and improve overall cardio-metabolic function.

Sources

  1. Header Image: Natasia Causse (Flickr)
  2. L-arginine May Help Blast Belly Fat - NewHope360, Functional Ingredients
  3. L-Arginine for the Treatment of Centrally Obese Subjects: A Pilot Study - Journal of Dietary Supplements
  4. L-arginine–a Cautionary Tale for Formulators - NewHope360, Functional Ingredients
  5. Regulatory Roles for L-arginine in Reducing White Adipose Tissue - Frontiers in Bioscience
     

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