Antioksidant: Verskil tussen weergawes

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Wysiging soos op 16:26, 23 September 2017

’n Model van die antioksidant metabolietglutatioon. Die geel sfeer is die redoksaktiewe swaelatoom wat antioksidant-aktiwiteit verskaf, terwyl die rooi, blou, wit en donkergrys sfere onderskeidelik suurstof-, stikstof-, waterstof- en koolstofatome voorstel.

’n Antioksidant is ’n molekule wat die oksidasie van ander molekules stuit. Oksidasie is ’n chemiese reaksie wat vrye radikale kan voortbring en dit kan lei tot kettingreaksies wat selle kan beskadig. Antioksidante soos tiols of askorbiensuur (vitamien C) beëindig hierdie kettingreaksies. Die term "antioksidant" word vir hoofsaaklik twee verskillende groepe stowwe gebruik: nywerheidschemikalieë wat by produkte gevoeg word om oksidasie te keer, en natuurlike chemikalieë wat in voedsel en liggaamsweefsel aangetref word en na bewering gesondheidsvoordele het.

Om die oksidatiewe toestand te balanseer, handhaaf plante en diere komplekse stelsels van oorvleuelende antioksidante, soos glutatioon en ensieme (byvoorbeeld katalase en superoksieddismutase) wat intern vervaardig word of die dieet-antioksidante: vitamien A, vitamien C en vitamien E.

Dieetaanvullings met antioksidante verbeter nie gesondheid en is nie doeltreffend in die voorkoming van siektes nie, soos bewys in proefnemings. Aanvullings van betakaroteen, vitamien A en vitamien E, apart of in verskillende kombinasies toegedien, het geen invloed op sterftesyfers^[1]^[2] of die risiko vir kanker nie.^[3]^[4] Aanvullings met seleen of vitamien E verlaag nie die risiko vir hartbloedvatsiektes nie.^[5]^[6] Oksidatiewe stres kan beskou word as óf die oorsaak óf die gevolg van sekere siektes.

Nywerheidsantioksidante het uiteenlopende gebruike, soos as preserveermiddels in voedsel en grimering en as oksidantinhibeerders in brandstof.^[7]

Verwysings

↑ Bjelakovic G, Nikolova D, Gluud C (2013). "Meta-regression analyses, meta-analyses, and trial sequential analyses of the effects of supplementation with beta-carotene, vitamin A, and vitamin E singly or in different combinations on all-cause mortality: do we have evidence for lack of harm?". PLoS ONE. 8 (9): e74558. Bibcode:2013PLoSO...874558B. doi:10.1371/journal.pone.0074558. PMC 3765487. PMID 24040282.
↑ Abner EL, Schmitt FA, Mendiondo MS, Marcum JL, Kryscio RJ (Julie 2011). "Vitamin E and all-cause mortality: a meta-analysis". Current Aging Science. 4 (2): 158–70. doi:10.2174/1874609811104020158. PMC 4030744. PMID 21235492.
↑ Cortés-Jofré M, Rueda JR, Corsini-Muñoz G, Fonseca-Cortés C, Caraballoso M, Bonfill Cosp X (2012). "Drugs for preventing lung cancer in healthy people". The Cochrane Database of Systematic Reviews. 10: CD002141. doi:10.1002/14651858.CD002141.pub2. PMID 23076895.
↑ Jiang L, Yang KH, Tian JH, Guan QL, Yao N, Cao N, Mi DH, Wu J, Ma B, Yang SH (2010). "Efficacy of antioxidant vitamins and selenium supplement in prostate cancer prevention: a meta-analysis of randomized controlled trials". Nutrition and Cancer. 62 (6): 719–27. doi:10.1080/01635581.2010.494335. PMID 20661819.
↑ Rees K, Hartley L, Day C, Flowers N, Clarke A, Stranges S (2013). "Selenium supplementation for the primary prevention of cardiovascular disease". The Cochrane Database of Systematic Reviews. 1 (1): CD009671. doi:10.1002/14651858.CD009671.pub2. PMID 23440843.
↑ Shekelle PG, Morton SC, Jungvig LK, Udani J, Spar M, Tu W, J Suttorp M, Coulter I, Newberry SJ, Hardy M (April 2004). "Effect of supplemental vitamin E for the prevention and treatment of cardiovascular disease". Journal of General Internal Medicine. 19 (4): 380–9. doi:10.1111/j.1525-1497.2004.30090.x. PMC 1492195. PMID 15061748.
↑ "Ullmann's Encyclopedia of Industrial Chemistry".. (2007). DOI:10.1002/14356007.a16_719.pub2. ISBN 3-527-30673-0.

Eksterne skakels

Hierdie artikel is vertaal uit die Engelse Wikipedia

[1] Bjelakovic G, Nikolova D, Gluud C (2013). "Meta-regression analyses, meta-analyses, and trial sequential analyses of the effects of supplementation with beta-carotene, vitamin A, and vitamin E singly or in different combinations on all-cause mortality: do we have evidence for lack of harm?". PLoS ONE. 8 (9): e74558. Bibcode:2013PLoSO...874558B. doi:10.1371/journal.pone.0074558. PMC 3765487. PMID 24040282.

[2] Abner EL, Schmitt FA, Mendiondo MS, Marcum JL, Kryscio RJ (Julie 2011). "Vitamin E and all-cause mortality: a meta-analysis". Current Aging Science. 4 (2): 158–70. doi:10.2174/1874609811104020158. PMC 4030744. PMID 21235492.

[3] Cortés-Jofré M, Rueda JR, Corsini-Muñoz G, Fonseca-Cortés C, Caraballoso M, Bonfill Cosp X (2012). "Drugs for preventing lung cancer in healthy people". The Cochrane Database of Systematic Reviews. 10: CD002141. doi:10.1002/14651858.CD002141.pub2. PMID 23076895.

[4] Jiang L, Yang KH, Tian JH, Guan QL, Yao N, Cao N, Mi DH, Wu J, Ma B, Yang SH (2010). "Efficacy of antioxidant vitamins and selenium supplement in prostate cancer prevention: a meta-analysis of randomized controlled trials". Nutrition and Cancer. 62 (6): 719–27. doi:10.1080/01635581.2010.494335. PMID 20661819.

[5] Rees K, Hartley L, Day C, Flowers N, Clarke A, Stranges S (2013). "Selenium supplementation for the primary prevention of cardiovascular disease". The Cochrane Database of Systematic Reviews. 1 (1): CD009671. doi:10.1002/14651858.CD009671.pub2. PMID 23440843.

[6] Shekelle PG, Morton SC, Jungvig LK, Udani J, Spar M, Tu W, J Suttorp M, Coulter I, Newberry SJ, Hardy M (April 2004). "Effect of supplemental vitamin E for the prevention and treatment of cardiovascular disease". Journal of General Internal Medicine. 19 (4): 380–9. doi:10.1111/j.1525-1497.2004.30090.x. PMC 1492195. PMID 15061748.

[Ullmann-7] "Ullmann's Encyclopedia of Industrial Chemistry".. (2007). DOI:10.1002/14356007.a16_719.pub2. ISBN 3-527-30673-0.

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