Nutritional products, compositions, functional ingredients, medical foods, pharmaceutical preparations and methods of use are disclosed for support and improvement of athletic performance (strength, flexibility, endurance, balance, and conditioning), and prevention and repair of injuries, including improving or maintaining muscle mitochondrial health, stimulating muscle mitochondrial biogenesis as well as other indications as set forth herein. In addition, pharmaceutical, nutraceutical and nutritional medical food compositions that are useful in conditions, normal or abnormal, associated with mitochondrial dysfunction and altered biogenesis in organ systems consisting of skeletal muscle, smooth muscle and cardiac muscle are also disclosed. L-Ergothioneine (also referred to as Ergothioneine or ET), Vitamin D2 (Ergocalciferol) and/or other antioxidants are disclosed for use in pharmaceutical, nutraceutical and nutritional medical food compositions for uses to stimulate production of bioactive molecules, including but not limited to glutathione, alpha synuclein, and IL-6.
