Combined L-citrulline and glutathione supplementation increases the concentration of markers indicative of nitric oxide synthesis.

McKinley-Barnard S, Andre T, Morita M2, Willoughby DS. J Int Soc Sports Nutr. 2015 Jun 10;12:27. doi: 10.1186/s12970-015-0086-7. eCollection 2015.

Background

Nitric oxide (NO) is endogenously synthesized from L-arginine and L-citrulline. Due to its effects on nitric oxide synthase (NOS), reduced glutathione (GSH) may protect against the oxidative reduction of NO. The present study determined the effectiveness of L-citrulline and/or GSH on markers indicative of NO synthesis in in vivo conditions with rodents and humans and also in an in vitro condition.

Conclusions

Combining L-citrulline with GSH augments increases in nitrite and NOx levels during in vitro and in vivo conditions.

See the research on NCBI PubMed

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4472409/