|From a physiological perspective NO is not primarily there to make you look vascular and pumped, boys.|
Now that you've got the primer on "nitric oxide beyond the pump" you may be happy to hear that a very common NO supplement, i.e. citrulline, actually delivers. But there's more: In a very recent study, scientists from the Baylor University demonstrated for KYOWA HAKKO BIO CO (so this is sponsored research) that a combined treatment with citrulline and glutathione leads to significant increases in the levels of cGMP, nitrite, and NOx (nitric oxide metabolite) in cells, rodents and humans.
|Figure 1: Overview of the design of the "human part" of the study (McKinley-Barnard. 2015).|
What is glutathione and why would you combine it with citrulline? Glutathione is a low molecular weight, water-soluble tripeptide composed of the amino acids cysteine, glutamic acid, and glycine. Glutathione is an important antioxidant and plays a major role in the detoxification of endogenous metabolic products, including lipid peroxides.Each participant ingested all four capsules containing their respective daily supplement dose each evening for six consecutive days until at Visit 3 (Day 7), participants were provided the final daily dose of their respective supplement ingested one hour prior to performing a previously familiarized biceps training program consisting of 3 sets of 15 repetitions with as much weight as they could lift per set (typically 70–75 % of 1RM | 10s rest between sets, only) on a selectorized weight machine (Body Master, Rayne, LA).
In some cell types, GSH appears to be necessary for NO synthesis and NO has been shown to be correlated with intracellular GSH (Ghigo. 1996). GSH stimulates total L-arginine turnover and, in the
presence of GSH, NOS activity is increased (Hofmann. 1995). For the authors of the study at hand this means that "GSH may play an important role in protection against oxidative reaction of NO, thus contributing to the sustained release of NO" (McKinley-Barnard. 2015) - reason enough for them to believe that "combining L-citrulline with GSH may augment the production of NO" (ibid).
|Contrary to what many believe, oral GSH supplements work | more|
|Figure 2: Nitrate concentration and change in plasma NOx in rodents (NO metabolites | McKinley-Barnard. 2015).|
|Figure 3: Changes in NO metabolites (NOx) and cGMP levels (McKinley-Barnard. 2015) in the human study.|
This is in contrast to your regular "pump" formula (using only citrulline), where the levels drop back to baseline ( and potentially even lower - after all only 30 min were monitored) after the workout.
Why is that important? Well, if you look back at the "nitric oxide beyond the pump" list from the introductory paragraph, you will notice that almost all of these "beyond the pump" effects are health-relevant during, but also and even more so after the workout.
- Ghigo, D., et al. "Correlation between nitric oxide synthase activity and reduced glutathione level in human and murine endothelial cells." Amino acids 10.3 (1996): 277-281.
- Hofmann, Heinrich, and Harald HHW Schmidt. "Thiol dependence of nitric oxide synthase." Biochemistry 34.41 (1995): 13443-13452.
- McKinley-Barnard, Sarah, et al. "Combined L-citrulline and glutathione supplementation increases the concentration of markers indicative of nitric oxide synthesis." Journal of the International Society of Sports Nutrition 12.1 (2015): 27.