That's where formulation starts to matter more than most labels will tell you
Liposomal Glutathione 500mg Liposomal glutathione with increased bioavailability and absorption
Measurement of superoxide dismutase, catalase and glutathione peroxidase in cultured cells and tissue
L-Glutathione Yeast Extract (Netherlands) 30.77%, Pullulan, Vitamin C, Lemon Juice Powder (Lemon Juice: US), Hydroxypropylmethylcellulose, Enzyme-treated Stevia, Milk Thistle Extract Powder (USA), -Cyclodextrin , glycerin, natural lemon flavor, citric acid anhydride, other processed edible oils and fats, vitamin E 50% mixture (dl--tocopheryl acetate, modified starch, maltodextrin mixture, silicon dioxide), gardenia yellow, L-cysteine hydrochloride, Modified Starch *Contains Milk