What is an antioxidant
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Understanding Antioxidants: Definition, Mechanisms, and Health Benefits
What is an Antioxidant?
An antioxidant is a substance that, even at low concentrations, can delay or prevent the oxidation of other molecules. This process is crucial because oxidation can produce free radicals, which can cause damage to cells and contribute to various diseases 139. Antioxidants are found in many foods, including fruits and vegetables, and are also available as dietary supplements .
Mechanisms of Action
Chemical Mechanisms
Antioxidants operate through several chemical mechanisms, including hydrogen atom transfer (HAT), single electron transfer (SET), and the ability to chelate transition metals. These mechanisms help neutralize free radicals and prevent oxidative damage . The chemical structure of an antioxidant determines its specific reaction mechanism, which can involve multiple pathways or a predominant one .
Biological Mechanisms
In the human body, antioxidants can be categorized into enzymatic and non-enzymatic types. Enzymatic antioxidants, such as superoxide dismutases (SOD), catalases, and glutathione peroxidases (GPx), degrade harmful oxidizing species like superoxide and hydroperoxides 57. Non-enzymatic antioxidants include vitamins C and E, carotenoids, and flavonoids, which scavenge free radicals and protect cellular components like DNA, proteins, and lipids 457.
Antioxidants in Food Science
In food science, antioxidants are used to prolong the shelf life of products by preventing lipid peroxidation and other oxidative reactions. This helps maintain the freshness, taste, and nutritional quality of foods 29. Common food antioxidants include vitamin C, vitamin E, and various polyphenols .
Health Benefits and Controversies
Disease Prevention
Antioxidants are believed to play a role in preventing chronic diseases such as cardiovascular disease, cancer, and neurodegenerative disorders. They achieve this by neutralizing free radicals and reducing oxidative stress 348. However, the evidence supporting the health benefits of dietary antioxidants is mixed. While some studies show positive effects, others do not find significant benefits 27.
Potential Risks
At high concentrations, some antioxidants can act as pro-oxidants, potentially increasing oxidative stress and causing toxicity 27. This dual role complicates the understanding of their overall impact on health.
Conclusion
Antioxidants are vital compounds that protect the body from oxidative damage by neutralizing free radicals. They are found in various foods and are also available as supplements. While they offer potential health benefits, particularly in preventing chronic diseases, the evidence is not unequivocal, and excessive intake may pose risks. Understanding the mechanisms and effects of antioxidants is crucial for optimizing their use in both food science and health.
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