Antioksidant: Verskil tussen weergawes

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Nywerheidsantioksidante het uiteenlopende gebruike, soos as preserveermiddels in voedsel en [[grimering]] en as oksidantinhibeerders in [[brandstof]].<ref name=Ullmann>{{cite encyclopedia|doi=10.1002/14356007.a16_719.pub2|chapter=Automotive Fuels|title=Ullmann's Encyclopedia of Industrial Chemistry|year=2007|last1=Dabelstein|first1=Werner|last2=Reglitzky|first2=Arno|last3=Schütze|first3=Andrea|last4=Reders|first4=Klaus|isbn=3-527-30673-0 | name-list-format = vanc }}</ref>
Nywerheidsantioksidante het uiteenlopende gebruike, soos as preserveermiddels in voedsel en [[grimering]] en as oksidantinhibeerders in [[brandstof]].<ref name=Ullmann>{{cite encyclopedia|doi=10.1002/14356007.a16_719.pub2|chapter=Automotive Fuels|title=Ullmann's Encyclopedia of Industrial Chemistry|year=2007|last1=Dabelstein|first1=Werner|last2=Reglitzky|first2=Arno|last3=Schütze|first3=Andrea|last4=Reders|first4=Klaus|isbn=3-527-30673-0 | name-list-format = vanc }}</ref>

==Gesondheid==
===Dieet===
Hoewel sekere vlakke van antioksidant-[[vitamien]]e in die dieet nodig is vir goeie gesondheid, is daar ’n debat oor of antioksidantryke kos of aanvullings mense teen siektes beskerm. Verder is dit onduidelik, indien hulle voordelig is, watter antioksidant(e) uit ’n dieet nodig is en in watter hoeveelhede buite ’n tipiese dieet.<ref name="Stanner" /><ref name="Shenkin">{{cite journal | vauthors = Shenkin A | title = The key role of micronutrients | journal = Clinical Nutrition | volume = 25 | issue = 1 | pages = 1–13 | date = Feb 2006 | pmid = 16376462 | doi = 10.1016/j.clnu.2005.11.006 }}</ref><ref>{{cite journal | vauthors = Woodside JV, McCall D, McGartland C, Young IS | title = Micronutrients: dietary intake v. supplement use | journal = The Proceedings of the Nutrition Society | volume = 64 | issue = 4 | pages = 543–53 | date = Nov 2005 | pmid = 16313697 | doi = 10.1079/PNS2005464 }}</ref> Sommige skrywers bevraagteken die hipotese dat antioksidant-vitamiene chroniese siektes kan voorkom,<ref name="Stanner">{{cite journal | vauthors = Stanner SA, Hughes J, Kelly CN, Buttriss J | title = A review of the epidemiological evidence for the 'antioxidant hypothesis' | journal = Public Health Nutrition | volume = 7 | issue = 3 | pages = 407–22 | date = May 2004 | pmid = 15153272 | doi = 10.1079/PHN2003543 }}</ref><ref>''[http://www.dietandcancerreport.org/?p=ER Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective]''. World Cancer Research Fund (2007). {{ISBN|978-0-9722522-2-5}}.</ref> terwyl ander glo so ’n moontlikheid is onbewese en uit die staanspoor misleidend.<ref name=Hail>{{cite journal | vauthors = Hail N, Cortes M, Drake EN, Spallholz JE | title = Cancer chemoprevention: a radical perspective | journal = Free Radical Biology & Medicine | volume = 45 | issue = 2 | pages = 97–110 | date = Jul 2008 | pmid = 18454943 | doi = 10.1016/j.freeradbiomed.2008.04.004 }}</ref>

[[Polifenol]]e, wat dikwels antioksidant-eienskappe [[in vitro]] het, is nie noodwendig antioksidante [[in vivo]] nie vanweë uitgebreide metabolisme.<ref name="lpi">{{cite web|url=http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/flavonoids|title=Flavonoids|publisher=Linus Pauling Institute, Oregon State University, Corvallis|date=2016|accessdate=24 July 2016}}</ref> In baie polifenole tree die [[katesjol]]groep as [[elektron]]ontvangers op en is dit dus verantwoordelik vir die antioksidant-aktiwiteit.<ref>{{cite journal|pmid=26867192|year=2016|author1=Csepregi|first1=K|title=Comparative Evaluation of Total Antioxidant Capacities of Plant Polyphenols|journal=Molecules|volume=21|issue=2|pages=208|last2=Neugart|first2=S|last3=Schreiner|first3=M|last4=Hideg|first4=Éva|doi=10.3390/molecules21020208}}</ref> Hierdie katesjolgroep ondergaan egter uitgebreide metabolisme wanneer dit in die menslike liggaam opgeneem word en is dan nie meer in staat om as elektronontvangers op te tree nie. Baie polifenole het dalk nie-antioksidatiewe rolle in klein konsentrasies wat seine tussen selle, reseptorsensitiwiteit, ontstekingsensiem-aktiwiteit of [[geen]]regulasie beïnvloed.<ref name=Williams>{{cite journal | vauthors = Williams RJ, Spencer JP, Rice-Evans C | title = Flavonoids: antioxidants or signalling molecules? | journal = Free Radical Biology & Medicine | volume = 36 | issue = 7 | pages = 838–49 | date = Apr 2004 | pmid = 15019969 | doi = 10.1016/j.freeradbiomed.2004.01.001 }}</ref><ref name="aggarwal">{{cite journal | vauthors = Aggarwal BB, Shishodia S | title = Molecular targets of dietary agents for prevention and therapy of cancer | journal = Biochemical Pharmacology | volume = 71 | issue = 10 | pages = 1397–421 | date = May 2006 | pmid = 16563357 | doi = 10.1016/j.bcp.2006.02.009 }}</ref><ref name="Azzi">{{cite journal | vauthors = Azzi A | title = Molecular mechanism of alpha-tocopherol action | journal = Free Radical Biology & Medicine | volume = 43 | issue = 1 | pages = 16–21 | date = Jul 2007 | pmid = 17561089 | doi = 10.1016/j.freeradbiomed.2007.03.013 }}</ref><ref name=Virgili>{{cite journal | vauthors = Virgili F, Marino M | title = Regulation of cellular signals from nutritional molecules: a specific role for phytochemicals, beyond antioxidant activity | journal = Free Radical Biology & Medicine | volume = 45 | issue = 9 | pages = 1205–16 | date = Nov 2008 | pmid = 18762244 | doi = 10.1016/j.freeradbiomed.2008.08.001 }}</ref>

Hoewel dieet-antioksidante al ondersoek is vir ’n moontlike uitwerking op [[Senuwee|neurodegeneratiewe]] siektes soos [[Alzheimersiekte|alzheimers]] en [[Parkinson se siekte|parkinsons]],<ref>{{cite journal | vauthors = Di Matteo V, Esposito E | title = Biochemical and therapeutic effects of antioxidants in the treatment of Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis | journal = Current Drug Targets. CNS and Neurological Disorders | volume = 2 | issue = 2 | pages = 95–107 | date = Apr 2003 | pmid = 12769802 | doi = 10.2174/1568007033482959 }}</ref><ref>{{cite journal | vauthors = Rao AV, Balachandran B | title = Role of oxidative stress and antioxidants in neurodegenerative diseases | journal = Nutritional Neuroscience | volume = 5 | issue = 5 | pages = 291–309 | date = Oct 2002 | pmid = 12385592 | doi = 10.1080/1028415021000033767 }}</ref> het hierdie studies nie uitsluitsel gegee nie.<ref>{{cite journal | vauthors = Crichton GE, Bryan J, Murphy KJ | title = Dietary antioxidants, cognitive function and dementia--a systematic review | journal = Plant Foods for Human Nutrition | volume = 68 | issue = 3 | pages = 279–92 | date = Sep 2013 | pmid = 23881465 | doi = 10.1007/s11130-013-0370-0 }}</ref><ref>{{cite journal | vauthors = Takeda A, Nyssen OP, Syed A, Jansen E, Bueno-de-Mesquita B, Gallo V | title = Vitamin A and carotenoids and the risk of Parkinson's disease: a systematic review and meta-analysis | journal = Neuroepidemiology | volume = 42 | issue = 1 | pages = 25–38 | year = 2014 | pmid = 24356061 | doi = 10.1159/000355849 }}</ref><ref>{{cite journal | vauthors = Harrison FE | title = A critical review of vitamin C for the prevention of age-related cognitive decline and Alzheimer's disease | journal = Journal of Alzheimer's Disease | volume = 29 | issue = 4 | pages = 711–26 | year = 2012 | pmid = 22366772 | pmc = 3727637 | doi = 10.3233/JAD-2012-111853}}</ref>


==Verwysings==
==Verwysings==

Wysiging soos op 17:00, 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]

Gesondheid

Dieet

Hoewel sekere vlakke van antioksidant-vitamiene in die dieet nodig is vir goeie gesondheid, is daar ’n debat oor of antioksidantryke kos of aanvullings mense teen siektes beskerm. Verder is dit onduidelik, indien hulle voordelig is, watter antioksidant(e) uit ’n dieet nodig is en in watter hoeveelhede buite ’n tipiese dieet.[8][9][10] Sommige skrywers bevraagteken die hipotese dat antioksidant-vitamiene chroniese siektes kan voorkom,[8][11] terwyl ander glo so ’n moontlikheid is onbewese en uit die staanspoor misleidend.[12]

Polifenole, wat dikwels antioksidant-eienskappe in vitro het, is nie noodwendig antioksidante in vivo nie vanweë uitgebreide metabolisme.[13] In baie polifenole tree die katesjolgroep as elektronontvangers op en is dit dus verantwoordelik vir die antioksidant-aktiwiteit.[14] Hierdie katesjolgroep ondergaan egter uitgebreide metabolisme wanneer dit in die menslike liggaam opgeneem word en is dan nie meer in staat om as elektronontvangers op te tree nie. Baie polifenole het dalk nie-antioksidatiewe rolle in klein konsentrasies wat seine tussen selle, reseptorsensitiwiteit, ontstekingsensiem-aktiwiteit of geenregulasie beïnvloed.[15][16][17][18]

Hoewel dieet-antioksidante al ondersoek is vir ’n moontlike uitwerking op neurodegeneratiewe siektes soos alzheimers en parkinsons,[19][20] het hierdie studies nie uitsluitsel gegee nie.[21][22][23]

Verwysings

  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.
  7. ↑ "Ullmann's Encyclopedia of Industrial Chemistry".. (2007). DOI:10.1002/14356007.a16_719.pub2. ISBN 3-527-30673-0. 
  8. ↑ 8,0 8,1 Stanner SA, Hughes J, Kelly CN, Buttriss J (Mei 2004). "A review of the epidemiological evidence for the 'antioxidant hypothesis'". Public Health Nutrition. 7 (3): 407–22. doi:10.1079/PHN2003543. PMID 15153272.
  9. ↑ Shenkin A (Februarie 2006). "The key role of micronutrients". Clinical Nutrition. 25 (1): 1–13. doi:10.1016/j.clnu.2005.11.006. PMID 16376462.
  10. ↑ Woodside JV, McCall D, McGartland C, Young IS (November 2005). "Micronutrients: dietary intake v. supplement use". The Proceedings of the Nutrition Society. 64 (4): 543–53. doi:10.1079/PNS2005464. PMID 16313697.
  11. ↑ Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. World Cancer Research Fund (2007). ISBN 978-0-9722522-2-5.
  12. ↑ Hail N, Cortes M, Drake EN, Spallholz JE (Julie 2008). "Cancer chemoprevention: a radical perspective". Free Radical Biology & Medicine. 45 (2): 97–110. doi:10.1016/j.freeradbiomed.2008.04.004. PMID 18454943.
  13. ↑ "Flavonoids". Linus Pauling Institute, Oregon State University, Corvallis. 2016. Besoek op 24 Julie 2016.
  14. ↑ Csepregi, K; Neugart, S; Schreiner, M; Hideg, Éva (2016). "Comparative Evaluation of Total Antioxidant Capacities of Plant Polyphenols". Molecules. 21 (2): 208. doi:10.3390/molecules21020208. PMID 26867192.
  15. ↑ Williams RJ, Spencer JP, Rice-Evans C (April 2004). "Flavonoids: antioxidants or signalling molecules?". Free Radical Biology & Medicine. 36 (7): 838–49. doi:10.1016/j.freeradbiomed.2004.01.001. PMID 15019969.
  16. ↑ Aggarwal BB, Shishodia S (Mei 2006). "Molecular targets of dietary agents for prevention and therapy of cancer". Biochemical Pharmacology. 71 (10): 1397–421. doi:10.1016/j.bcp.2006.02.009. PMID 16563357.
  17. ↑ Azzi A (Julie 2007). "Molecular mechanism of alpha-tocopherol action". Free Radical Biology & Medicine. 43 (1): 16–21. doi:10.1016/j.freeradbiomed.2007.03.013. PMID 17561089.
  18. ↑ Virgili F, Marino M (November 2008). "Regulation of cellular signals from nutritional molecules: a specific role for phytochemicals, beyond antioxidant activity". Free Radical Biology & Medicine. 45 (9): 1205–16. doi:10.1016/j.freeradbiomed.2008.08.001. PMID 18762244.
  19. ↑ Di Matteo V, Esposito E (April 2003). "Biochemical and therapeutic effects of antioxidants in the treatment of Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis". Current Drug Targets. CNS and Neurological Disorders. 2 (2): 95–107. doi:10.2174/1568007033482959. PMID 12769802.
  20. ↑ Rao AV, Balachandran B (Oktober 2002). "Role of oxidative stress and antioxidants in neurodegenerative diseases". Nutritional Neuroscience. 5 (5): 291–309. doi:10.1080/1028415021000033767. PMID 12385592.
  21. ↑ Crichton GE, Bryan J, Murphy KJ (September 2013). "Dietary antioxidants, cognitive function and dementia--a systematic review". Plant Foods for Human Nutrition. 68 (3): 279–92. doi:10.1007/s11130-013-0370-0. PMID 23881465.
  22. ↑ Takeda A, Nyssen OP, Syed A, Jansen E, Bueno-de-Mesquita B, Gallo V (2014). "Vitamin A and carotenoids and the risk of Parkinson's disease: a systematic review and meta-analysis". Neuroepidemiology. 42 (1): 25–38. doi:10.1159/000355849. PMID 24356061.
  23. ↑ Harrison FE (2012). "A critical review of vitamin C for the prevention of age-related cognitive decline and Alzheimer's disease". Journal of Alzheimer's Disease. 29 (4): 711–26. doi:10.3233/JAD-2012-111853. PMC 3727637. PMID 22366772.

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