Earlier we wrote about nitric oxide and NO boosters, products that would increase Nitric Oxide uptake and thus muscle growth. In the same article, we explained why the popular Arginine is not particularly suitable for this purpose and mentioned Citrulline as a better alternative.
Another investigated Nitric Oxide NO Booster is the combination of amino acids Glycine and Propionyl-L-carnitine, or GPLC.
Nitric Oxide: What is it again?
Nitric oxide is a compound of oxygen and nitrogen with the chemical formula NO. Hence the name NO booster, which stands for nitric oxide, namely Nitric Oxide.
The benefits of nitric oxide supplements stem from the specific enzymes that break down the amino acid Arginine, from which nitric oxide is released. This leads to vasodilation, which in turn promotes blood flow.
Increasing Nitric Oxide with GPLC
In studies conducted at the University of Memphis, initially untrained individuals and later people with an average of 8 years were administered GPLC. In the untrained subjects, administration of 1 to 3 grams of GPLC was sufficient to lead to higher NO levels. In the study on trained subjects, 4.5 grams were used twice daily for 4 weeks. The results showed that in most cases, NO levels had increased (statistically significant), but not in everyone. GPLC does not work for everyone. This also applies to several other supplements (for example, Creatine does not work for 30% of users because they naturally have high levels due to their diet).
An important difference compared to Arginine (and Citrulline, which is converted to Arginine in the body) is that Arginine and Citrulline work via and in combination with insulin. With GPLC, the diet (carbohydrates–>insulin) was found to have no effect on nitric oxide levels, leading them to conclude that GPLC also works without carbohydrates.
They do not know how GPLC does this. It is suspected that GPLC makes the endothelial enzyme nitric oxide synthase, responsible for the formation of nitric oxide, work harder. Another possibility is its inhibitory effect on an oxidative enzyme that lowers NO levels by forming free radicals.
At this point, it might be useful to point out that these studies were funded by Sigma-tau HealthSciences, a producer of GPLC products. For me, this is always a reason to look for other studies on the supplement by “independent” researchers.
GPLC is used in Europe as a medicine for heart conditions against heart failure and poor blood circulation. The heart preferably uses fat as an energy source. The Carnitine in GPLC helps with this by transferring the fat to the mitochondria of the cells (which is why Carnitine is often promoted as a fat burner).
“Glycine, a non-essential amino acid, promotes creatine synthesis, stimulates growth hormone levels, helps nerves transmit signals to muscles to contract, and increases NO levels. Carnitine, although technically not an amino acid, behaves like an amino acid and is responsible for strengthening the anabolic effects of testosterone, increasing fat burning, and increasing NO levels. Combine the two and you have the potential for many muscle-building benefits.”
Benefits of Increasing Nitric Oxide
In addition, GPLC has other potential benefits. It is said to have lowering effects on lactic acid. Furthermore, there are reports from users indicating less adverse effects of a ketogenic diet (very low carbohydrates). Finally, it promotes androgenic cell receptors, increasing the anabolic effect of testosterone. Preliminary studies also show that GPLC could help with (male) impotence.
More research would be very welcome. However, as long as there are no studies proving otherwise, there is only one reason why you wouldn’t try GPLC, the high price!
Sources:
- http://www.ergo-log.com/gplc.html
- http://www.ncbi.nlm.nih.gov/pubmed/20209464
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2211291/?report=abstract
- http://www.ironmanmagazine.com/site/another-no-booster/
