From Ergo Log
The literature on the performance-enhancing effect of NO boosters is confusing. Some studies say that supplements containing amino acids such as L-arginine, L-ornithine or L-citrulline improve sports performances; others say they don't. Japanese researchers at the Morinaga and Company confectionery manufacturers published the results of an in-vitro study which suggests that nutritional factors also probably determine how you react to NO boosters. They may work better if you ingest substances such as piceatannol via your food.
Nitrogen monoxide is a key factor in muscle growth, muscle recovery, blood supply and sexual performance. In the body enzymes extract nitrogen monoxide from certain amino acids – and the supplements industry looks for ways of using these in NO boosters.
However, some researchers have questioned whether these supplements actually work. They base their reasoning on studies such as a piece of Brazilian research published in 2012 in Nutrition & Metabolism, from which the figure below comes.
The figure shows the effect of 6 g L-arginine taken by inactive subjects on the concentration of NO in their blood. [Nutr Metab (Lond). 2012 Jun 12;9(1):54.] The researchers monitored the subjects' blood for two hours and observed no statistically significant effects.
The enzyme that converts arginine into nitrogen monoxide is called nitric oxide synthase [NOS]. It's found in blood vessel cells [eNOS], muscle cells and nerve cells [nNOS] and immune cells [iNOS]. The Japanese studied the effect of resveratrol and piceatannol, a metabolite of resveratrol, on the synthesis and activity of eNOS in EA.hy926 cells. These are the cells of the blood vessel walls in humans.
Both substances enhanced the activity of eNOS, but piceatannol worked slightly better than resveratrol. The actual synthesis of the enzyme also increased – and once again piceatannol did better than resveratrol.
In other experiments the Japanese demonstrated that the effect of piceatannol becomes stronger the longer the exposure to it. They were also able to show that the piceatannol-induced NOS enzyme was active.
Piceatannol metabolises fast in the body. Enzymes attach sugar groups to it. But there are also studies that suggest that metabolised piceatannol molecules may still be active.
Sex supplements manufacturers discovered the combination of plant-based compounds and L-arginine years ago – and have used it in products. One example is Horphag's Prelox, which contains a combination of L-arginine and Pycnogenol.
The Japanese haven't bothered to speculate about combinations of L-arginine and improved NO boosters. They confine themselves to a remark that a diet that is rich in piceatannol and related compounds probably helps to keep blood vessels healthy.
Biochem Biophys Res Commun. 2013 Jan 18;430(3):1164-8.