Coenzyme Q 10 (CoQ 10 ), an endogenously produced compound, is found in all human cells. Within the mitochondria, it plays a substantial role in energy production by acting as a mobile electron carrier in the electron transport chain. Outside the mitochondria, it acts as an excellent antioxidant by sequestering free radicals and working synergistically with other antioxidants, including vitamin E. Dietary contribution is limited, making endogenous production the primary source for optimal function. Now widely available as an over-the-counter supplement, CoQ 10 has gained attention for its possible therapeutic use in minimizing the outcomes of certain metabolic diseases, notably cardiovascular disease, diabetes, neurodegenerative disease, and cancer. Research has shown positive results in subjects supplemented with CoQ 10 , especially in relation to upregulating antioxidant capability. Emerging research suggests beneficial effects of CoQ 10 supplementation in individuals on statin medications. CoQ 10 supplementation in individuals participating in strenuous exercise seems to exert some beneficial effects, although the data are conflicting with other types of physical activity. This broad review of current CoQ 10 literature, while outlining its physiological/functional significance in health and disease conditions, also offers a dietitian's perspective on its potential use as a supplement in the promotion of health and management of disease conditions.