It’s 33% of the amino acids in collagen counting amino acids. It’s less if you count them by weight/mass as glycine is lighter than other amino acids.
This was a mistake on my part and I’ll correct the article.
Masterjohn’s lower bound of 10g matches Meléndez-Hevia et al. 2009, which explicitly accounts for glycine recycling, while 60g is the highest dose used in schizophrenia treatment. He didn’t cite sources in the linked piece, though, so I’ll add a footnote with the sourcing I could find.
I haven’t been able to find evidence that typical oral supplement doses of NAC meaningfully reduce hypertrophy. I did find one paper reporting that an NAC infusion can blunt some ROS signaling after exercise, and a 2017 meta-analysis found no benefits from NAC supplementation on exercise performance, but I can’t find evidence of harm at oral doses.
I still endorse the very limited recommendation I made that people with specific reason to think they have elevated need or meaningfully limited supply of cysteine “may benefit” from the supplement.
Having thought about NAC a bit more, I think I agree with you. The one paper about the signaling seems to be less important than the actual observed effect in exercise. Additionally, even if given NAC to a normal person who has a glycine deficit leads to more glutathione synthesis at the cost of less collagen synthesis which could have a negative effect on hypertrophy that concern is less if you just supply both NAC and glycine.
This was a mistake on my part and I’ll correct the article.
Masterjohn’s lower bound of 10g matches Meléndez-Hevia et al. 2009, which explicitly accounts for glycine recycling, while 60g is the highest dose used in schizophrenia treatment. He didn’t cite sources in the linked piece, though, so I’ll add a footnote with the sourcing I could find.
I haven’t been able to find evidence that typical oral supplement doses of NAC meaningfully reduce hypertrophy. I did find one paper reporting that an NAC infusion can blunt some ROS signaling after exercise, and a 2017 meta-analysis found no benefits from NAC supplementation on exercise performance, but I can’t find evidence of harm at oral doses.
I still endorse the very limited recommendation I made that people with specific reason to think they have elevated need or meaningfully limited supply of cysteine “may benefit” from the supplement.
Having thought about NAC a bit more, I think I agree with you. The one paper about the signaling seems to be less important than the actual observed effect in exercise. Additionally, even if given NAC to a normal person who has a glycine deficit leads to more glutathione synthesis at the cost of less collagen synthesis which could have a negative effect on hypertrophy that concern is less if you just supply both NAC and glycine.