According to Wiki, it’s arginine that, when metabolized, releases nitric oxide. Citrulline is what’s left afterwards. So arginine is what you want.
https://en.m.wikipedia.org/wiki/Citrulline
https://en.m.wikipedia.org/wiki/Arginine
Don’t go to Wikipedia for supplement advices.
Here’s what examine.com has to say
“L-Citrulline is an amino acid. It is turned into L-arginine in the kidneys after supplementation, which means L-citrulline supplementation is a more effective method of increasing L-arginine levels in the body than L-arginine supplementation.”
“Supplementing L-citrulline also increases ornithine and arginine plasma content. This means L-citrulline supplementation improves the ammonia recycling process and nitric oxide metabolism. L-citrulline is also used to alleviate erectile dysfunction caused by high blood pressure.
After supplementation, L-citrulline is converted into arginine in the kidneys. Supplemental L-arginine provides a spike of L-arginine in plasma, while supplemental L-citrulline increases arginine plasma levels over a longer period of time.
L-arginine and L-ornithine are subject to reduced absorption when supplemented in doses of 10g or more, which can result in diarrhea. L-Citrulline does not have this side-effect, and since it increases plasma levels of all three amino acids, it is generally preferred as a supplement over L-arginine.”
