It has never been studied in a human clinical trial, so the figures that circulate most commonly 5-20 mg per day, once daily, with some references reaching 20-30 mg come entirely from vendor copy and forum threads such as LongeCity, not from pharmacokinetic data
Acta 2008, 1780 (11), 13041317
doi: Mielgo-Ayuso, J., Pietrantonio, L., Viribay, A., Calleja-Gonzlez, J., Gonzlez-Bernal, J
66 These findings demonstrate that GSH buffers antibiotic-generated oxidative stress, whereas a deficiency in GSH or an overload of ROS renders bacteria significantly more vulnerable
PLoS ONE 9 (4), e93589 (2014)
Its often referred to as the bodys master antioxidant because of its central role in protecting cells from oxidative stress and supporting overall cellular health, says Chaudhry