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03.10.2010

Glycine Propionyl-L-Carnitine as an NO booster

If you're into NO boosters, you might be interested in glycine propionyl-L-carnitine. This cocktail boosts the nitrogen monoxide [NO] concentration in the body in a different way from L-arginine.

Three years ago sports scientists at the University of Memphis published the results of a trial in which they gave 15 men in their twenties a combination of glycine and propionyl-L-carnitine. The structural formulae of the compounds they used are shown here. The men had already been training for an average of 8 years with weights.

In an earlier study, which was published later, the researchers gave the same mix to men who did not do any sports. In that study they noticed that thecompounds raised the NO concentration in the subjects' blood. [Int J Vitam Nutr Res. 2009 May; 79(3): 131-41.]

Because nitrogen monoxide stimulates stem cells to develop into normal muscle cells after training, the cocktail might be interesting for athletes, was the reasoning. At least, if glycine propionyl-L-carnitine boosts the production of NO in athletes too.

To determine whether this was the case the researchers gave their athletes 4.5 g glycine propionyl-L-carnitine every day. The subjects divided this dose over two moments in the day, one in the morning and one in the afternoon. They took the supplement for 4 weeks. On another occasion the athletes took a placebo for 4 weeks.

At the end of the experiment and the placebo period, the researchers restricted the blood flow in the subjects' upper arm and got them to squeeze handgrips. Afterwards they let the subjects' blood flow again. This procedure boosts the production of NO in the blood vessels. When the researchers measured the amount of NO in the subjects' blood immediately afterwards, they found higher concentrations during the GPLC period.

Most of the subjects reacted positively to the supplement, but some athletes did not. So GPLC doesn't work for everyone.

There was no relationship between the subjects' diet and the effectiveness of the supplement. L-carnitine only enters the cells in combination with carbohydrates and insulin, but apparently GPLC doesn't need carbs.

The researchers haven't yet worked out exactly how GPLC works. One theory is the GPLC makes the enzyme nitric oxide synthase work harder. This is the enzyme that makes NO.

So could you stack GPLC with L-arginine or L-citrulline?

The research was funded by Sigma-tau HealthSciences, a manufacturer of glycine propionyl-L-carnitine. Sigma-tau's preparation is called GlycoCarn.

Source:
J Int Soc Sports Nutr. 2007 Dec 3; 4:22.

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