Nutrition Antioxidant An Intracellular Antioxidant That Promotes Recycling of Vitamins C and E Gluten Free Dietary Supplement General Wellness Igen - Non-gmo Tested Glutathione is an abundant intracellular thiol (a compound containing a sulfhydryl group) and low molecular weight tripeptide found in living cells. Serving as an antioxidant in all types of tissues, the antioxidant functions of glutathione include recycling vitamins C and E to their antioxidant form to minimize oxidative stress.