CHAPTER ONE1.1 IntroductionThe human body has a complex system of natural enzymatic and non-enzymatic antioxidant defenses which counteract the harmful effects of free radicals and other oxidants. Free radicals are responsible for causing a large number of diseases including cancer (Kinnula and Crapo, 2004), cardiovascular disease (Singh and Jialal, 2006), neural disorders (Sas et al., 2007), Alzheimer’s disease (Smith et al., 2000), mild cognitive impairment (Guidi et al., 2006), Parkinson’s disease (Bolton et al., 2000), alcohol induced liver disease (Arteel, 2003), ulcer-ative colitis (Ramakrishna et al., 1997), aging (Hyun et al., 2006) and atherosclerosis (Upston et al., 2003). Protection against free radicals can be enhanced by ample intake of dietary antioxidants. Substantial evidence indicates that foods containing antioxidants and possibly in particular the antioxidant nutrients may be of major importance in disease prevention. There is, however, a growing consensus among scientists that a combination of antioxidants, rather than single entities, may be more effective over the long term. Antioxidants may be of great benefit in improving the quality of life by preventing or postponing the onset of degenerative diseases. In addition, they have a potential for substantial savings in the cost of health care delivery.Any chemical compound or substance that inhibits oxidation is an antioxidant. Oxidation is a chemical reaction that can produce free radicals (an atom, molecule or ion with an unpaired valence electron) leading to chain reactions that may damage cells. Antioxidants terminate these chain reactions. Though human beings require oxygen for existence, oxygen is a highly reactive molecule that may damage living cells by producing Reactive Oxygen Species (ROS) like Superoxides, hydroxyl radicals, etc.Having a biological context in mind, it is expected that ROS are formed as a natural byproduct of the normal metabolism of the oxygen and have significant roles in cell signaling and homeostatis (Devasagayam et al., 2004). The function of antioxidant systems is not to remove antioxidants entirely, but instead to keep them at an optimum level (Rhee, 2006).ROS can actually damage cells by starting chemical chain reactions like lipid peroxidation (oxidative degradation of lipids) or by oxidizing DNA or proteins. Lipid peroxidation is simply the oxidative degradation of lipids where free radicals ‘steal’ electrons from lipids in cell membranes thus leading to cell damage. Most often lipids peroxidation involves polyunsaturated fatty acids because they contain multiple double bonds in between which lie methylene bridges (-CH2-) that have especially reactive hydrogen atoms. Just like any radical reaction, this reaction consists of three major steps: Initiation, Propagation and Termination. And its chemical products are called Lipid peroxides or Lipids Oxidation Products (LOPS).Though oxidation is a normal chemical process that occurs every day in the human body, it can be accelerated by stress, unhealthy lifestyles like cigarette smoking, and alcohol. When there are disruptions in the natural oxidation process, the highly unstable and potentially damaging molecules called free radicals are created. Left uncontrolled, they can cause damage to body cells. It can be likened to a chemical reaction that creates rust on a bicycle thereby damaging the bicycle if left unchecked. If we picture the body as a busy smooth road, we know that sometimes cracks and potholes can occur in the road. Free radicals are likened to the cracks while antioxidants are the materials used to fill those cracks to make the road normal again. Also, as humans, when we grow older, we tend to become less active, our physiological systems function less optimally, and the probability of illness may increase. Antioxidants work by significantly slowing or preventing the oxidative damage from free radicals. These free radicals are hazardous and can damage body cells thus causing aging and disease. They can cause cell dysfunction and onset of problems like heart disease, diabetes, inflammation and cancer.