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Antioxidant: Difference between revisions
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'''Antioxidants''' are compounds that can prevent or slow down the oxidation of other molecules. Oxidation is a chemical reaction that can produce free radicals, leading to chain reactions that may damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates and inhibiting other oxidation reactions. They do this by being oxidized themselves, making them crucial in the body's defense against oxidative stress.{{pmid|28441057}} | '''Antioxidants''' are compounds that can prevent or slow down the oxidation of other molecules. Oxidation is a chemical reaction that can produce free radicals, leading to chain reactions that may damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates and inhibiting other oxidation reactions. They do this by being oxidized themselves, making them crucial in the body's defense against [[Oxidative Stress|oxidative stress]].{{pmid|28441057}} | ||
Known dietary antioxidants are vitamins A, C, and E, but the term ''antioxidant'' has also been applied to numerous other dietary compounds that only have antioxidant properties in vitro, with little evidence for antioxidant properties in vivo.<ref name="nih">{{Cite web|date=1 November 2013|title=Antioxidants: In Depth|url=https://www.nccih.nih.gov/health/antioxidants-in-depth|access-date=17 March 2023|publisher=National Center for Complementary and Integrative Health, US National Institutes of Health|language=en}}</ref> Dietary supplements marketed as antioxidants have not been shown to maintain health or prevent disease in humans.<ref name="nih" /> | |||
== Types of Antioxidants == | |||
There are several types of antioxidants, each playing a distinct role in combating oxidative stress: | There are several types of antioxidants, each playing a distinct role in combating oxidative stress: | ||
*'''Enzymatic Antioxidants:''' These include enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase, which directly neutralize ROS. | *'''Enzymatic Antioxidants:''' These include enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase, which directly neutralize ROS. | ||
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*'''Alpha-Lipoic Acid''': A compound that works with mitochondria and the body's natural antioxidant defenses. | *'''Alpha-Lipoic Acid''': A compound that works with mitochondria and the body's natural antioxidant defenses. | ||
*'''Green Tea Extract''': Rich in catechins, green tea extract is renowned for its antioxidant properties. | *'''Green Tea Extract''': Rich in catechins, green tea extract is renowned for its antioxidant properties. | ||
== Antioxidant Stress == | |||
{{Main|Oxidative Stress|Antioxidative Stress}} | |||
The concept of antioxidative stress may best be described by excessive or detrimental nutritional consumption of a diet rich in antioxidants, unbalancing the immune systems' pathogenic response processes. Serious health conditions can result if these processes are chronically unbalanced, ranging from acute to chronic. Immunological stress by over-supplementation of antioxidants facilitates adverse health effects specifically including allergies, asthma, and physiological alterations (especially of the skin). | |||
== Oxygen Radical Absorbance Capacity (ORAC) == | |||
Measurement of polyphenol and carotenoid content in food is not a straightforward process, as antioxidants collectively are a diverse group of compounds with different reactivities to various reactive oxygen species. In food science analyses in vitro, the '''oxygen radical absorbance capacity (ORAC)''' was once an industry standard for estimating antioxidant strength of whole foods, juices and food additives, mainly from the presence of polyphenols.<ref>{{cite journal|vauthors=Cao G, Alessio HM, Cutler RG|title=Oxygen-radical absorbance capacity assay for antioxidants|journal=Free Radical Biology & Medicine|volume=14|issue=3|pages=303–11|date=March 1993|pmid=8458588|doi=10.1016/0891-5849(93)90027-R|url=https://zenodo.org/record/1258621}}</ref><ref>{{cite journal|vauthors=Ou B, Hampsch-Woodill M, Prior RL|title=Development and validation of an improved oxygen radical absorbance capacity assay using fluorescein as the fluorescent probe|journal=Journal of Agricultural and Food Chemistry|volume=49|issue=10|pages=4619–26|date=October 2001|pmid=11599998|doi=10.1021/jf010586o}}</ref> Earlier measurements and ratings by the United States Department of Agriculture were withdrawn in 2012 as biologically irrelevant to human health, referring to an absence of physiological evidence for polyphenols having antioxidant properties ''in vivo''.<ref name="USDAx">{{cite web|url=http://www.ars.usda.gov/services/docs.htm?docid=15866|title=Withdrawn: Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 (2010)|date=16 May 2012|publisher=United States Department of Agriculture, Agricultural Research Service|access-date=13 June 2012}}</ref> Consequently, the ORAC method, derived only from ''in vitro'' experiments, is no longer considered relevant to human diets or biology, as of 2010.<ref name="USDAx" /> | |||
== Legal == | |||
Other than for dietary antioxidant vitamins—vitamin A, vitamin C and vitamin E—no food compounds have been proved with antioxidant efficacy ''in vivo''. Accordingly, regulatory agencies such as the [[Food and Drug Administration]] of the United States and the [[European Food Safety Authority]] (EFSA) have published guidance forbidding food product labels to claim or imply an antioxidant benefit when no such physiological evidence exists.<ref>[https://www.fda.gov/food/guidanceregulation/guidancedocumentsregulatoryinformation/ucm063064.htm Guidance for Industry, Food Labeling; Nutrient Content Claims; Definition for "High Potency" and Definition for "Antioxidant" for Use in Nutrient Content Claims for Dietary Supplements and Conventional Foods] U.S. Department of Health and Human Services, Food and Drug Administration, Center for Food Safety and Applied Nutrition, June 2008</ref><ref name="efsa">{{cite journal|url=http://www.efsa.europa.eu/en/efsajournal/pub/1489|doi=10.2903/j.efsa.2010.1489|title=Scientific Opinion on the substantiation of health claims related to various food(s)/food constituent(s) and protection of cells from premature aging, antioxidant activity, antioxidant content and antioxidant properties, and protection of DNA, proteins and lipids from oxidative damage pursuant to Article 13(1) of Regulation (EC) No 1924/20061|author=EFSA Panel on Dietetic Products, Nutrition and Allergies|journal=EFSA Journal|year=2010|volume=8|issue=2|pages=1489|doi-access=free}}</ref> This guidance for the United States and European Union establishes it is illegal to imply potential health benefits on package labels of products with high ORAC. | |||
== See Also == | == See Also == | ||
* [[Oxidative Stress]] | * [[Oxidative Stress]] | ||
* {{SeeWikipedia| | * {{SeeWikipedia|Antioxidant|}} | ||
* {{SeeWikipedia|List of antioxidants in food|}} | |||
== References == | == References == | ||
<references /> | <references /> | ||
[[Category:Antioxidant Compounds|!Antioxidants]] | |||