Glutathione: pharmacological aspects and implications for clinical use Geriatric Care Enhancing the Oral Bioavailability of Glutathione Using Innovative Analogue Approaches Oral administration of glutamylcysteine increases intracellular glutathione levels above homeostasis in a randomised human trial pilot study ScienceDirect A Targeted Metabolomic Assessment of Oral Glutathione Bioavailability and Safety in Humans: A Randomized Crossover Clinical Trial