Antioxidants are components that scavenge free radicals in the body to fight oxidative stress (Nasri, Baradaran, Shirzad, & Rafieian-Kopaei, 2014). Free radicals have negative effects in the body by reacting with other molecules and causing damage to cell membranes, DNA, and proteins (Gale, 2014). Antioxidants are considered neutraceuticals because they are used for both nutrition and medicine due to their beneficial effects on health.
Antioxidants can generally be classified as antioxidant vitamins, such as vitamins A, C, and E; phytochemicals, bioactive plant components with health benefits, that have antioxidant properties including flavonoids and carotenoids such as beta-carotene and lycopene; minerals that play antioxidant functions, such as manganese, copper, selenium, and zinc; and antioxidant compounds and enzymes made in the body, like coenzyme Q10 or ubiquinone, superoxide dismutase, and glutathione (Gale, 2014; Mahan, Escott-Stump, & Raymond, 2012; Nasri et al., 2014; Pizzorno & Murray, 2013; Schlenker & Roth, 2011). Other examples of antioxidants include curcumin, lutein, and turmerin (Gale, 2014; Mahan et al., 2012; Nasri et al., 2014). Antioxidants can be made in the body, can be found naturally in fruits, vegetables, grains, nuts, meats, and seafood, or can be taken as supplements (Gale, 2014; Mahan et al., 2012; Nasri et al., 2014; Schlenker & Roth, 2011).
Oxidative Stress & Free Radicals
The most important beneficial effect antioxidants have is reducing damage from oxidative stress. Oxidative stress is the result of metabolic processes caused by an increase in oxidants from cellular reactions, a decrease in antioxidants protecting the body, or a failure in the cellular processes in the body to repair damage caused by oxidative reactions (Mahan et al., 2012). Oxidants that cause this damage are known as reactive oxygen species (ROS), which consist of “free radicals, reactive anions containing oxygen atoms, or molecules containing oxygen atoms that can either produce free radicals or are chemically activated by them” (Mahan et al., 2012, p. 203). ROS are formed as part of normal metabolic processes that involve oxygen, and can also be caused when the body is exposed to chemicals, radiation, and toxins (Gale, 2014). Another example of a ROS is the hydroxyl radical -OH, which is one of the most reactive. Reactive nitrogen species include peroxynitrite and other molecules including NO2 (Pizzorno & Murray, 2013).
Free radicals are molecules with unpaired electrons, and are unstable until they are able to steal from, or give up, an electron to another molecule (Gale, 2014). Free radicals include molecules such as nitric oxide NO-, superoxide O2-, and hydrogen peroxide H2O2 (Pizzorno & Murray, 2013). They are believed to contribute to causing or worsening diseases, and because free radicals have an unpaired electron, they cause damage when they seek to balance this negative charge with DNA, proteins, and lipid molecules. Antioxidants bind to free radicals, stabilizing them, and thus reducing the damage they may cause (Gale, 2014).
Ginger contains different antioxidant properties, which have been found to help fight hypertension (Nasri et al., 2014). Many antioxidants are helpful in cancer prevention. For instance, lycopene decreases oxidative stress and damage to DNA, and works mostly in the adrenals, prostates, skin, and testes, where it protects against cancer (Nasri et al., 2014). Beta-carotene has one of the highest antioxidant activities of all types of carotenes. Lipoic acid is an antioxidant that protects against the complications from diabetes, and treats diabetic naturopathy (Nasri et al., 2014). Macular degeneration due to age has been treated with antioxidants, such as beta-carotene, coenzyme Q10, garlic, green tea, lycopene, polyphenols, and vitamins C and E (Nasri et al., 2014).
Some clinical studies have yielded results against the benefits of antioxidants. A study reviewing 68 clinical trials found that the risk of dying on the 232,600 patients who took antioxidants supplements may have increased by 5% (Gale, 2014). In addition, supplementation of beta-carotene was tested on 29,000 men who smoked and resulted in an 18% higher rate of developing lung cancer (Gale, 2014). These studies tested antioxidant supplements, however this may not be the recommended form of intake.
It is best to consume antioxidants from natural sources rather than from supplements. Supplements contain much higher levels of antioxidants than those naturally found in food, and although ill effects are not expected from antioxidants in food, there is a possibility of contraindications from supplements due the higher doses in these (Gale, 2014). Antioxidant supplementation can be deleterious to health (Pizzorno & Murray, 2013). There is no single nutrient, supplement, or food that can fight all oxidative stress that occurs in the body, because there are too many oxidants that need to be neutralized. To get the best source of antioxidants, it is encouraged to follow a varied diet with high amounts of colored fruits, vegetables, and whole grains, and adequate intake of nuts, meats, poultry, and seafood; and to lead a healthy lifestyle with regular exercise, proper stress management, and no smoking (Pizzorno & Murray, 2013).
Gale (2014). The Gale Encyclopedia of Alternative Medicine, (4th Ed). Farmington Hilla, MI: Gale Cengage Learning.
Mahan, L. K., Escott-Stump, S., & Raymond, J. L. (2012). Krause’s Food and The Nutrition Care Process (13th ed.). St. Louis, MO: Elsevier Saunders.
Nasri, H., Baradaran, A., Shirzad, H., & Rafieian-Kopaie, M. (2014). New concepts in nutraceuticals as alternative for pharmaceuticals. International Journal of Preventative Medicine, 5(12), 1487-1499. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4336979/?report=printable
Pizzorno, J. E. & Murray, M. T. (2013). Textbook of Natural Medicine (4th ed.). St. Louis, MO: Churchill Livingstone.
Schlenker, E. D. & Roth, S. L. (2011). Williams’ Essentials of Nutrition and Diet Therapy- Revised Reprint (10th ed.). St. Louis, MO: Elsevier Mosby.