Members of the Food and Nutrition Board of the National Research Council in the United States have recently defined a dietary antioxidant as “a substance in foods that reduces the adverse effects of reactive oxygen species, reactive nitrogen species, or both on general physiology function in humans.” The continuous consumption of used oil, unhealthy diet, and stress adversely affect the human body by generating free radicals. Free radical causes tissue damage, alters lipids, proteins, DNA, and trigger a number of human diseases. Antioxidants are free radical scavengers that neutralize these free radical autoxidation reactions. Antioxidants are secondary metabolites, and most of them are obtained by natural sources such as roots, leaves, fruits, seeds, and herbs. Natural plant pigments also contribute their antioxidant properties in human benefits. There are several techniques to extract, purify, and quantify antioxidants. Nowadays, there is a vast variety of oral supplements that can be procured from the market. Natural (functional foods) as well as synthetic antioxidants can serve their essential role in the management of human health.