In supplements, glutathione is generally in its "reduced" (GSH) form, the active antioxidant
Oral vitamin D supplementation induces cathelicidin production in the skin of atopic dermatitis patients
As an analog of a natural hormone, its effects fall within physiological parameters rather than creating unprecedented biological states
Maiorino M, Aumann KD, Brigelius-Floh R, Doria D, van den Heuvel J, McCarthy J, Roveri A, Ursini F, Flohet L (1995) Probing the presumed catalytic triad of selenium-containing peroxidases by mutational analysis of phospholipid hydroperoxide glutathione peroxidase (PHGPx)
Conversely, when removing a tattoo from a very dark skin type, you must proceed with caution and use a gentler setting so as not to create hyper or hypo pigmentation (dark or white spots)