how do you know glutathione is working 8 Ways to Boost Glutathione for Skin Lightening :

Smoking, immunity, and DNA damage

This should only be done under medical supervision

Enhancements in immune function markers were also observed

For histopathological evaluation, skin specimens were collected on Days 7, 14, and 21 using 4-millimeter punch biopsy instruments from different corners of the left-side wound of each rabbit, immediately after planimetry

Navrot N, Collin V, Gualberto J, Gelhaye E, Hirasawa M, Rey P, Knaff DB, Issakidis E, Jacquot J-P, Rouhier N (2006) Plant glutathione peroxidases are functional peroxiredoxins distributed in several subcellular compartments and regulated during biotic and abiotic stresses