Selenium, antioxidants, cardiovascular disease, and all cause mortality: a systematic review and meta analysis of randomized controlled trials The American Journal of Clinical Nutrition TJ. Glutathione peroxidase is an important enzyme in cellular antioxidant defense systems, detoxifying peroxides and hydroperoxides. As a component of the glutathione cycle, it protects the liver from reactive oxygen metabolites. Selenocysteine Assay for quantitative determination of glutathione and glutathione disulfide levels using enzymatic recycling method Nature Protocols Antioxidants Cause Reductive Stress Fire In A Bottle