Abstract
Antioxidants offer protection against the damage potentially caused by free radicals, which usually involve an oxygen or nitrogen moiety, in living organisms. An antioxidant can be defined as a molecule that has the capability to inhibit the oxidation of another molecule, so, in other words, it is a reducing agent that is sufficiently stable to donate an electron to a circulating free radical and thereby result in its neutralization. Free radicals can be defined as any chemical species that has one or more mismatched electrons; these free radicals can cause a sequential reaction resulting in damage to multiple components of the organism, functioning either as an oxidant or a reductant by accepting or donating an electron, respectively. Oxidative stress can be defined as an imbalance between the production of free radicals and necessary antioxidant defenses. Therefore protection of the organism from these potentially damaging entities, when appropriate, is essential. Potential damage involves lipids, proteins, cell membranes, deoxyribonucleic acid (DNA), carbohydrates, and various enzymes, which can lead to cell death. Antioxidant protection from free radical-induced damage occurs via the donation of an electron with subsequent conversion of a free radical to a harmless chemical configuration that can no longer damage a cell and its components. Classes of antioxidants include, natural, nutrient, and supplemental. When antioxidant levels are low, there is a resultant increase in oxidative stress with a harmful increase in free radicals that can be associated with an increased risk for cardiovascular (CV) disease including atherosclerosis, various inflammatory diseases, and cancer. Major issues for the clinician to consider are what can be done to naturally increase antioxidants when deficient or when a directed increase might be beneficial such as in aging and degenerative disease, how nutrients can be altered or provided to increase antioxidant protection, and when or if to consider the use of supplements, frequently classified as alternative medicines.
Keywords: Antioxidants, free radicals, hydrogen peroxide, oxidative stress, reactive oxygen species, thioredoxin.
Graphical Abstract
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