Антиоксиданс — разлика између измена

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{{short description|Једињење које инхибира оксидацију других молекула}}{{рут}}
'''Антиоксиданс''' је [[молекул]] који може да спречи [[оксидо-редукција|оксидацију]] других молекула. [[Оксидо-редукција|Оксидација]] је [[хемијска реакција]] у којој се [[електрон]]и преносе са оксидационог средства на неки [[молекул]]. У оксидационим реакцијама могу настати [[слободни радикал]]и, који започињу [[ланчане реакција|ланчане реакције]]. Слободни радикали су реактивна једињења, која имају [[електрон]] вишка и зато ступају у реакције са другим молекулима, и на тај начин доводе до оштећења [[Ћелија (биологија)|ћелијских структура]]. Антиоксиданси спречавају ланчане реакције у којима се оштећују други молелули у ћелијама, тако што се сами оксидишу. Антиоксиданси су често редукциона средства ([[тиол]]и, [[полифенол]]и..).<ref name="Sies">{{cite journal |author=Sies H |title=Oxidative stress: oxidants and antioxidants |url=http://ep.physoc.org/cgi/reprint/82/2/291.pdf |journal=Exp Physiol |volume=82 |issue=2 |year=1997 |pmid=9129943 |format=PDF |access-date=18. 07. 2010 |archive-url=https://web.archive.org/web/20090325001126/http://ep.physoc.org/cgi/reprint/82/2/291.pdf |archive-date=25. 03. 2009 |url-status=dead | pages = 291–5 }}</ref><ref name="Vertuani">{{cite journal |vauthors=Vertuani S, Angusti A, Manfredini S |title=The antioxidants and pro-antioxidants network: an overview |journal=Curr Pharm Des |volume=10 |issue=14 |year=2004 |pmid=15134565 |doi=10.2174/1381612043384655| pages = 1677–94 }}</ref>
[[Image:Glutathione-skeletal.svg|thumb|250px|Структура антиоксиданса, [[глутатион]]а]]


'''Антиоксиданс''' је [[молекул]] који може да спречи [[оксидо-редукција|оксидацију]] других молекула. [[Оксидо-редукција|Оксидација]] је [[хемијска реакција]] у којој се [[електрон]]и преносе са оксидационог средства на неки [[молекул]]. У оксидационим реакцијама могу настати [[слободни радикал]]и, који започињу [[ланчане реакција|ланчане реакције]]. Слободни радикали су реактивна једињења, која имају [[електрон]] вишка и зато ступају у реакције са другим молекулима, и на тај начин доводе до оштећења [[Ћелија (биологија)|ћелијских структура]]. Антиоксиданси спречавају ланчане реакције у којима се оштећују други молелули у ћелијама, тако што се сами оксидишу. Антиоксиданси су често редукциона средства ([[тиол]]и, [[полифенол]]и..).<ref name="Sies">{{cite journal |author=Sies H |title=Oxidative stress: oxidants and antioxidants |url=http://ep.physoc.org/cgi/reprint/82/2/291.pdf |journal=Exp Physiol |volume=82 |issue=2 |year=1997 |pmid=9129943 |format=PDF |access-date=18. 07. 2010 |archive-url=https://web.archive.org/web/20090325001126/http://ep.physoc.org/cgi/reprint/82/2/291.pdf |archive-date=25. 03. 2009 |url-status=dead | pages = 291–5 }}</ref><ref name="Vertuani">{{cite journal |vauthors=Vertuani S, Angusti A, Manfredini S |title=The antioxidants and pro-antioxidants network: an overview |journal=Curr Pharm Des |volume=10 |issue=14 |year=2004 |pmid=15134565 |doi=10.2174/1381612043384655| pages = 1677–94 }}</ref>
Најзначајнији молекули у организму за спречавање оксидације ћелујских структура су: [[глутатион]], [[витамин C]], [[витамин Е]], ензими ([[каталаза|каталазе]], [[супероксид дисмутаза|супероксид дисмутазе]], [[пероксидаза|пероксидазе]]). Смањена концентрација антиоксиданаса у организму може довети до инхибиције [[антиоксидативни ензим|антиоксидативних ензима]], при чему настаје оксидативни стрес и може доћи до оштећења ћелија.

Најзначајнији молекули у организму за спречавање оксидације ћелујских структура су: [[глутатион]], [[витамин C]], [[витамин Е]], ензими ([[каталаза|каталазе]], [[супероксид дисмутаза|супероксид дисмутазе]], [[пероксидаза|пероксидазе]]). Смањена концентрација антиоксиданаса у организму може довети до инхибиције [[антиоксидативни ензим|антиоксидативних ензима]], при чему настаје оксидативни стрес и може доћи до оштећења ћелија. The term ''antioxidant'' is also used for [[industrial chemical]]s added during manufacturing to prevent oxidation in [[synthetic rubber]], [[plastic]]s, and fuels, or as [[preservative]]s in food and [[cosmetics]].<ref name="Ullmann">{{cite encyclopedia |doi=10.1002/14356007.a16_719.pub2|chapter=Automotive Fuels |title=Ullmann's Encyclopedia of Industrial Chemistry |year=2007 |vauthors=Dabelstein W, Reglitzky A, Schütze A, Reders K |isbn=978-3-527-30673-2 |url=https://books.google.com/books?id=IY-YtwEACAAJ}}</ref>

[[Dietary supplement]]s marketed as antioxidants have not been shown to improve health or prevent disease in humans.<ref>{{Cite web|url=https://www.nccih.nih.gov/health/antioxidants-in-depth|title=Antioxidants: In Depth|publisher=NCCIH|language=en|access-date=April 17, 2021|date=November 2013}}</ref> Supplements of [[beta-carotene]], vitamin A, and vitamin E have no positive effect on [[mortality rate]]<ref>{{cite journal | vauthors = Bjelakovic G, Nikolova D, Gluud C | title = 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?|journal=PLOS ONE|volume=8|issue=9|pages=e74558| year=2013| pmid =24040282 | pmc = 3765487 | doi = 10.1371/journal.pone.0074558 |bibcode = 2013PLoSO...874558B }}</ref><ref>{{cite journal | vauthors = Abner EL, Schmitt FA, Mendiondo MS, Marcum JL, Kryscio RJ | title = Vitamin E and all-cause mortality: a meta-analysis | journal = Current Aging Science | volume = 4 | issue = 2 | pages = 158–70 | date = July 2011 | pmid = 21235492 | pmc = 4030744 | doi = 10.2174/1874609811104020158 }}</ref> or [[cancer]] risk.<ref>{{cite journal | vauthors = Cortés-Jofré M, Rueda JR, Corsini-Muñoz G, Fonseca-Cortés C, Caraballoso M, Bonfill Cosp X | title = Drugs for preventing lung cancer in healthy people | journal = The Cochrane Database of Systematic Reviews | volume = 10 | pages = CD002141 | year = 2012 | pmid = 23076895 | doi = 10.1002/14651858.CD002141.pub2 }}</ref>{{Update inline|reason=Updated version https://www.ncbi.nlm.nih.gov/pubmed/32130738|date = May 2020}}<ref>{{cite journal | vauthors = Jiang L, Yang KH, Tian JH, Guan QL, Yao N, Cao N, Mi DH, Wu J, Ma B, Yang SH | title = Efficacy of antioxidant vitamins and selenium supplement in prostate cancer prevention: a meta-analysis of randomized controlled trials | journal = Nutrition and Cancer | volume = 62 | issue = 6 | pages = 719–27 | year = 2010 | pmid = 20661819 | doi = 10.1080/01635581.2010.494335 | s2cid = 13611123 }}</ref> Additionally, supplementation with [[selenium]] or vitamin E does not reduce the risk of [[cardiovascular disease]].<ref>{{cite journal | vauthors = Rees K, Hartley L, Day C, Flowers N, Clarke A, Stranges S | title = Selenium supplementation for the primary prevention of cardiovascular disease | journal = The Cochrane Database of Systematic Reviews | volume = 1 | issue = 1 | pages = CD009671 | year = 2013 | pmid = 23440843 | doi = 10.1002/14651858.CD009671.pub2 | pmc = 7433291 | url = http://wrap.warwick.ac.uk/53654/1/WRAP_Clarke_CD009671.pdf | access-date = 23 July 2018 | archive-url = https://web.archive.org/web/20170812041745/http://wrap.warwick.ac.uk/53654/1/WRAP_Clarke_CD009671.pdf | archive-date = 12 August 2017 | url-status = dead }}</ref><ref>{{cite journal | vauthors = Shekelle PG, Morton SC, Jungvig LK, Udani J, Spar M, Tu W, J Suttorp M, Coulter I, Newberry SJ, Hardy M | title = Effect of supplemental vitamin E for the prevention and treatment of cardiovascular disease | journal = Journal of General Internal Medicine | volume = 19 | issue = 4 | pages = 380–9 | date = April 2004 | pmid = 15061748 | pmc = 1492195 | doi = 10.1111/j.1525-1497.2004.30090.x }}</ref>

== Здравствена истраживања ==

=== Релација са дијетом ===

Although certain levels of antioxidant [[vitamins]] in the diet are required for good health, there is still considerable debate on whether antioxidant-rich foods or supplements have anti-disease activity. Moreover, if they are actually beneficial, it is unknown which antioxidants are health-promoting in the diet and in what amounts beyond typical dietary intake.<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 = February 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 = November 2005 | pmid = 16313697 | doi = 10.1079/PNS2005464 | doi-access = free }}</ref> Some authors dispute the hypothesis that antioxidant vitamins could prevent chronic diseases,<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 | doi-access = free }}</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> and some declare that the hypothesis is unproven and misguided.<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 = July 2008 | pmid = 18454943 | doi = 10.1016/j.freeradbiomed.2008.04.004 }}</ref> [[Polyphenol]]s, which have antioxidant properties [[in vitro]], have unknown antioxidant activity [[in vivo]] due to extensive [[metabolism]] following digestion and little [[clinical research|clinical evidence]] of efficacy.<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|access-date=24 July 2016}}</ref>

=== Интеракције ===
Common pharmaceuticals (and supplements) with antioxidant properties may interfere with the efficacy of certain [[anticancer]] medication and [[radiation therapy]].<ref name="Lemmo, W Potential interactions of prescription and over-the-counter medications having antioxidant capabilities with radiation and chemotherapy 2014">{{cite journal | vauthors = Lemmo W | title = Potential interactions of prescription and over-the-counter medications having antioxidant capabilities with radiation and chemotherapy | journal = International Journal of Cancer | volume = 137 | issue = 11 | pages = 2525–33 | date = September 2014 | pmid = 25220632 | doi = 10.1002/ijc.29208 | s2cid = 205951215 | doi-access = free }}</ref>

=== Нежељени ефекти ===
[[Image:Phytate.svg|thumb|right|250px|Структура хелатора метала [[фитинска киселина]]]]

Relatively strong reducing acids can have [[antinutrient]] effects by binding to [[dietary mineral]]s such as [[iron]] and [[zinc]] in the [[Human gastrointestinal tract|gastrointestinal tract]] and preventing them from being absorbed.<ref>{{cite journal | vauthors = Hurrell RF | title = Influence of vegetable protein sources on trace element and mineral bioavailability | journal = The Journal of Nutrition | volume = 133 | issue = 9 | pages = 2973S–7S | date = September 2003 | pmid = 12949395 | doi = 10.1093/jn/133.9.2973S | doi-access = free }}</ref> Examples are [[oxalic acid]], [[tannin]]s and [[phytic acid]], which are high in plant-based diets.<ref>{{cite journal | vauthors = Hunt JR | title = Bioavailability of iron, zinc, and other trace minerals from vegetarian diets | journal = The American Journal of Clinical Nutrition | volume = 78 | issue = 3 Suppl | pages = 633S–639S | date = September 2003 | pmid = 12936958 | doi = 10.1093/ajcn/78.3.633S | doi-access = free }}</ref> [[Calcium]] and iron deficiencies are not uncommon in diets in [[Developing country|developing countries]] where less meat is eaten and there is high consumption of phytic acid from beans and unleavened [[whole grain]] bread. However, germination, soaking, or microbial fermentation are all household strategies that reduce the phytate and polyphenol content of unrefined cereal. Increases in Fe, Zn and Ca absorption have been reported in adults fed dephytinized cereals compared with cereals containing their native phytate.<ref>{{cite journal | vauthors = Gibson RS, Perlas L, Hotz C | title = Improving the bioavailability of nutrients in plant foods at the household level | journal = The Proceedings of the Nutrition Society | volume = 65 | issue = 2 | pages = 160–8 | date = May 2006 | pmid = 16672077 | doi = 10.1079/PNS2006489 | doi-access = free }}</ref>

{| class="wikitable" style="margin-left: auto; margin-right: auto;"
|-
!Храна
!Редукција присутне киселине
|-
| style="text-align:center;"|[[Cocoa bean]] and chocolate, [[spinach]], [[turnip]] and [[rhubarb]]<ref name="Mosha">{{cite journal | vauthors = Mosha TC, Gaga HE, Pace RD, Laswai HS, Mtebe K | title = Effect of blanching on the content of antinutritional factors in selected vegetables | journal = Plant Foods for Human Nutrition | volume = 47 | issue = 4 | pages = 361–7 | date = June 1995 | pmid = 8577655 | doi = 10.1007/BF01088275 | s2cid = 1118651 }}</ref>
| style="text-align:center;"|[[Oxalic acid]]
|-
| style="text-align:center;"|[[Whole grain]]s, maize, [[legume]]s<ref>{{cite journal | vauthors = Sandberg AS | title = Bioavailability of minerals in legumes | journal = The British Journal of Nutrition | volume = 88 Suppl 3 | issue = Suppl 3 | pages = S281–5 | date = December 2002 | pmid = 12498628 | doi = 10.1079/BJN/2002718 | doi-access = free }}</ref>
| style="text-align:center;"|[[Phytic acid]]
|-
| style="text-align:center;"|Tea, [[bean]]s, [[cabbage]]<ref name="Mosha" /><ref name="Beecher">{{cite journal | vauthors = Beecher GR | title = Overview of dietary flavonoids: nomenclature, occurrence and intake | journal = The Journal of Nutrition | volume = 133 | issue = 10 | pages = 3248S–3254S | date = October 2003 | pmid = 14519822 | doi = 10.1093/jn/133.10.3248S | doi-access = free }}</ref>
| style="text-align:center;"|[[Tannin]]s
|}

High doses of some antioxidants may have harmful long-term effects. The ''[[Beta-Carotene]] and [[Retinol]] Efficacy Trial'' (CARET) study of lung cancer patients found that smokers given supplements containing beta-carotene and vitamin A had increased rates of lung cancer.<ref>{{cite journal | vauthors = Omenn GS, Goodman GE, Thornquist MD, Balmes J, Cullen MR, Glass A, Keogh JP, Meyskens FL, Valanis B, Williams JH, Barnhart S, Cherniack MG, Brodkin CA, Hammar S | title = Risk factors for lung cancer and for intervention effects in CARET, the Beta-Carotene and Retinol Efficacy Trial | journal = Journal of the National Cancer Institute | volume = 88 | issue = 21 | pages = 1550–9 | date = November 1996 | pmid = 8901853 | doi = 10.1093/jnci/88.21.1550 | url = https://academic.oup.com/jnci/article-pdf/88/21/1550/7811338/88-21-1550.pdf | doi-access = free }}</ref> Subsequent studies confirmed these adverse effects.<ref>{{cite journal | vauthors = Albanes D | title = Beta-carotene and lung cancer: a case study | journal = The American Journal of Clinical Nutrition | volume = 69 | issue = 6 | pages = 1345S–50S | date = June 1999 | pmid = 10359235 | doi = 10.1093/ajcn/69.6.1345S | doi-access = free }}</ref> These harmful effects may also be seen in non-smokers, as one [[meta-analysis]] including data from approximately 230,000 patients showed that β-carotene, vitamin A or vitamin E supplementation is associated with increased mortality, but saw no significant effect from vitamin C.<ref name=Bjelakovic>{{cite journal | vauthors = Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C | title = Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis | journal = JAMA | volume = 297 | issue = 8 | pages = 842–57 | date = February 2007 | pmid = 17327526 | doi = 10.1001/jama.297.8.842 }}</ref> No health risk was seen when all the randomized controlled studies were examined together, but an increase in mortality was detected when only high-quality and low-bias risk trials were examined separately.<ref name=Bj2012/> As the majority of these low-bias trials dealt with either [[Old age|elderly people]], or people with disease, these results may not apply to the general population.<ref>[https://www.sciencedaily.com/releases/2007/02/070228172604.htm Study Citing Antioxidant Vitamin Risks Based On Flawed Methodology, Experts Argue] News release from [[Oregon State University]] published on ScienceDaily. Retrieved 19 April 2007</ref> This meta-analysis was later repeated and extended by the same authors, confirming the previous results.<ref name=Bj2012>{{cite journal | vauthors = Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C | title = Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases | journal = The Cochrane Database of Systematic Reviews | volume = 3 | issue = 3 | pages = CD007176 | date = 14 March 2012 | pmid = 22419320 | doi = 10.1002/14651858.CD007176.pub2 | hdl = 10138/136201 | hdl-access = free }}</ref> These two publications are consistent with some previous meta-analyses that also suggested that vitamin E supplementation increased mortality,<ref>{{cite journal | vauthors = Miller ER, Pastor-Barriuso R, Dalal D, Riemersma RA, Appel LJ, Guallar E | title = Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality | journal = Annals of Internal Medicine | volume = 142 | issue = 1 | pages = 37–46 | date = January 2005 | pmid = 15537682 | doi = 10.7326/0003-4819-142-1-200501040-00110 | doi-access = free }}</ref> and that antioxidant supplements increased the risk of [[Colorectal cancer|colon cancer]].<ref name="Bjelakovic G 2036">{{cite journal | vauthors = Bjelakovic G, Nagorni A, Nikolova D, Simonetti RG, Bjelakovic M, Gluud C | title = Meta-analysis: antioxidant supplements for primary and secondary prevention of colorectal adenoma | journal = Alimentary Pharmacology & Therapeutics | volume = 24 | issue = 2 | pages = 281–91 | date = July 2006 | pmid = 16842454 | doi = 10.1111/j.1365-2036.2006.02970.x | s2cid = 20452618 }}</ref> [[Beta-carotene]] may also increase [[lung cancer]].<ref name="Bjelakovic G 2036"/><ref>{{Cite journal|last1=Cortés-Jofré|first1=Marcela|last2=Rueda|first2=José-Ramón|last3=Asenjo-Lobos|first3=Claudia|last4=Madrid|first4=Eva|last5=Bonfill Cosp|first5=Xavier|date=4 March 2020|title=Drugs for preventing lung cancer in healthy people|journal=The Cochrane Database of Systematic Reviews|volume=3|pages=CD002141|doi=10.1002/14651858.CD002141.pub3|issn=1469-493X|pmc=7059884|pmid=32130738}}</ref> Overall, the large number of clinical trials carried out on antioxidant supplements suggest that either these products have no effect on health, or that they cause a small increase in mortality in elderly or vulnerable populations.<ref name="Stanner" /><ref name="Shenkin" /><ref name="Bjelakovic" />


== Извори ==
== Извори ==
{{reflist}}
{{reflist}}

{{-}}
== Литература ==
{{Антиоксиданси}}
{{refbegin}}
* Halliwell, Barry. and John M. C. Gutteridge, ''Free Radicals in Biology and Medicine'' (Oxford University Press, 2007), {{ISBN|0-19-856869-X}}
* Lane, Nick, ''Oxygen: The Molecule That Made the World'' (Oxford University Press, 2003), {{ISBN|0-19-860783-0}}
* Pokorny, Jan, Nelly Yanishlieva, and Michael H. Gordon, ''Antioxidants in Food: Practical Applications'' (CRC Press, 2001), {{ISBN|0-8493-1222-1}}
{{refend}}


== Спољашње везе ==
== Спољашње везе ==
{{Commonscat|Antioxidants}}
{{Commonscat|Antioxidants}}
* [http://www.navidiku.rs/firme/antioksidanti Antioksidansi]
* [http://www.navidiku.rs/firme/antioksidanti Antioksidansi]

{{Антиоксиданси}}
{{Authority control}}


[[Категорија:Антиоксиданси]]
[[Категорија:Антиоксиданси]]

Верзија на датум 25. јул 2021. у 00:37

Структура антиоксиданса, глутатиона

Антиоксиданс је молекул који може да спречи оксидацију других молекула. Оксидација је хемијска реакција у којој се електрони преносе са оксидационог средства на неки молекул. У оксидационим реакцијама могу настати слободни радикали, који започињу ланчане реакције. Слободни радикали су реактивна једињења, која имају електрон вишка и зато ступају у реакције са другим молекулима, и на тај начин доводе до оштећења ћелијских структура. Антиоксиданси спречавају ланчане реакције у којима се оштећују други молелули у ћелијама, тако што се сами оксидишу. Антиоксиданси су често редукциона средства (тиоли, полифеноли..).[1][2]

Најзначајнији молекули у организму за спречавање оксидације ћелујских структура су: глутатион, витамин C, витамин Е, ензими (каталазе, супероксид дисмутазе, пероксидазе). Смањена концентрација антиоксиданаса у организму може довети до инхибиције антиоксидативних ензима, при чему настаје оксидативни стрес и може доћи до оштећења ћелија. The term antioxidant is also used for industrial chemicals added during manufacturing to prevent oxidation in synthetic rubber, plastics, and fuels, or as preservatives in food and cosmetics.[3]

Dietary supplements marketed as antioxidants have not been shown to improve health or prevent disease in humans.[4] Supplements of beta-carotene, vitamin A, and vitamin E have no positive effect on mortality rate[5][6] or cancer risk.[7]Шаблон:Update inline[8] Additionally, supplementation with selenium or vitamin E does not reduce the risk of cardiovascular disease.[9][10]

Здравствена истраживања

Релација са дијетом

Although certain levels of antioxidant vitamins in the diet are required for good health, there is still considerable debate on whether antioxidant-rich foods or supplements have anti-disease activity. Moreover, if they are actually beneficial, it is unknown which antioxidants are health-promoting in the diet and in what amounts beyond typical dietary intake.[11][12][13] Some authors dispute the hypothesis that antioxidant vitamins could prevent chronic diseases,[11][14] and some declare that the hypothesis is unproven and misguided.[15] Polyphenols, which have antioxidant properties in vitro, have unknown antioxidant activity in vivo due to extensive metabolism following digestion and little clinical evidence of efficacy.[16]

Интеракције

Common pharmaceuticals (and supplements) with antioxidant properties may interfere with the efficacy of certain anticancer medication and radiation therapy.[17]

Нежељени ефекти

Структура хелатора метала фитинска киселина

Relatively strong reducing acids can have antinutrient effects by binding to dietary minerals such as iron and zinc in the gastrointestinal tract and preventing them from being absorbed.[18] Examples are oxalic acid, tannins and phytic acid, which are high in plant-based diets.[19] Calcium and iron deficiencies are not uncommon in diets in developing countries where less meat is eaten and there is high consumption of phytic acid from beans and unleavened whole grain bread. However, germination, soaking, or microbial fermentation are all household strategies that reduce the phytate and polyphenol content of unrefined cereal. Increases in Fe, Zn and Ca absorption have been reported in adults fed dephytinized cereals compared with cereals containing their native phytate.[20]

Храна Редукција присутне киселине
Cocoa bean and chocolate, spinach, turnip and rhubarb[21] Oxalic acid
Whole grains, maize, legumes[22] Phytic acid
Tea, beans, cabbage[21][23] Tannins

High doses of some antioxidants may have harmful long-term effects. The Beta-Carotene and Retinol Efficacy Trial (CARET) study of lung cancer patients found that smokers given supplements containing beta-carotene and vitamin A had increased rates of lung cancer.[24] Subsequent studies confirmed these adverse effects.[25] These harmful effects may also be seen in non-smokers, as one meta-analysis including data from approximately 230,000 patients showed that β-carotene, vitamin A or vitamin E supplementation is associated with increased mortality, but saw no significant effect from vitamin C.[26] No health risk was seen when all the randomized controlled studies were examined together, but an increase in mortality was detected when only high-quality and low-bias risk trials were examined separately.[27] As the majority of these low-bias trials dealt with either elderly people, or people with disease, these results may not apply to the general population.[28] This meta-analysis was later repeated and extended by the same authors, confirming the previous results.[27] These two publications are consistent with some previous meta-analyses that also suggested that vitamin E supplementation increased mortality,[29] and that antioxidant supplements increased the risk of colon cancer.[30] Beta-carotene may also increase lung cancer.[30][31] Overall, the large number of clinical trials carried out on antioxidant supplements suggest that either these products have no effect on health, or that they cause a small increase in mortality in elderly or vulnerable populations.[11][12][26]

Извори

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  14. ^ Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. World Cancer Research Fund (2007). ISBN 978-0-9722522-2-5.
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Литература

  • Halliwell, Barry. and John M. C. Gutteridge, Free Radicals in Biology and Medicine (Oxford University Press, 2007), ISBN 0-19-856869-X
  • Lane, Nick, Oxygen: The Molecule That Made the World (Oxford University Press, 2003), ISBN 0-19-860783-0
  • Pokorny, Jan, Nelly Yanishlieva, and Michael H. Gordon, Antioxidants in Food: Practical Applications (CRC Press, 2001), ISBN 0-8493-1222-1

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