Selenium is one of the few nutrients that directly controls how your body handles oxygen at the cellular level. Every time your cells produce energy, they generate peroxides as a byproduct. That Selenium Supplement Antioxidant Support for Immunity & Thyroid Health Selenium, antioxidants, cardiovascular disease, and all cause mortality: a systematic review and meta analysis of randomized controlled trials The American Journal of Clinical Nutrition Nature's Way Selenium Non Yeast Source Potent Antioxidant 200 mcg per Serving 100 Capsules Vitacost Selenium dependent glutathione peroxidase 1 regulates transcription of elongase 3 in murine tissues ScienceDirect