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List of antioxidants in food

From Wikipedia, the free encyclopedia

This is a list of antioxidants naturally occurring in food. Vitamin C and vitamin E – which are ubiquitous among raw plant foods – are confirmed as dietary antioxidants, whereas vitamin A becomes an antioxidant following metabolism of provitamin A beta-carotene and cryptoxanthin. Most food compounds listed as antioxidants – such as polyphenols common in colorful, edible plants – have antioxidant activity only in vitro, as their fate in vivo is to be rapidly metabolized and excreted, and the in vivo properties of their metabolites remain poorly understood. For antioxidants added to food to preserve them, see butylated hydroxyanisole and butylated hydroxytoluene.

Regulatory guidance

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In the following discussion, the term "antioxidant" refers mainly to non-nutrient compounds in foods, such as polyphenols, which have antioxidant capacity in vitro and so provide an artificial index of antioxidant strength – the oxygen radical absorbance capacity (ORAC) measurement. Other than for dietary antioxidant vitamins – vitamin A, vitamin C and vitamin E – no food compounds have been proved to be antioxidants in vivo. Accordingly, regulatory agencies like the Food and Drug Administration of the United States and the European Food Safety Authority (EFSA) have published guidance disallowing food product labels to claim an inferred antioxidant benefit when no such physiological evidence exists.[1][2]

Physiological context

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Despite the above discussion implying that ORAC-rich foods with polyphenols may provide antioxidant benefits when in the diet, there remains no physiological evidence that any polyphenols have such actions or that ORAC has any relevance in the human body.

On the contrary, research indicates that although polyphenols are antioxidants in vitro, antioxidant effects in vivo are probably negligible or absent.[3][4][5] By non-antioxidant mechanisms still undefined, polyphenols may affect mechanisms of cardiovascular disease or cancer.[6]

The increase in antioxidant capacity of blood seen after the consumption of polyphenol-rich (ORAC-rich) foods is not caused directly by the polyphenols, but most likely results from increased uric acid levels derived from metabolism of flavonoids.[7][8] According to Frei, "we can now follow the activity of flavonoids in the body, and one thing that is clear is that the body sees them as foreign compounds and is trying to get rid of them."[8] Another mechanism may be the increase in activities of paraoxonases by dietary antioxidants which can reduce oxidative stress.[9]

Vitamins

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Vitamin cofactors and minerals

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Hormones

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Carotenoid terpenoids

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  • Alpha-carotene - found in carrots, winter squash, tomatoes, green beans, cilantro, Swiss chard
  • Astaxanthin - found naturally in red algae and animals higher in the marine food chain. It is a red pigment familiarly recognized in crustacean shells and salmon flesh/roe.
  • Beta-carotene - found in high concentrations in butternut squash, carrots, orange bell peppers, pumpkins, kale, peaches, apricots, mango, turnip greens, broccoli, spinach, and sweet potatoes.
  • Canthaxanthin
  • Cryptoxanthin - present in papaya, egg yolk, butter, apples
  • Lutein - found in high concentration in spinach, kale, Swiss chard, collard greens, beet and mustard greens, endive, red pepper and okra
  • Lycopene - found in high concentration in cooked red tomato products like canned tomatoes, tomato sauce, tomato juice and garden cocktails, guava and watermelons.
  • Zeaxanthin - best sources are kale, collard greens, spinach, turnip greens, Swiss chard, mustard and beet greens, corn, and broccoli

Polyphenols

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Natural phenols are a class of molecules found in abundance in plants. Many common foods contain rich sources of polyphenols which have antioxidant properties only in test tube studies. As interpreted by the Linus Pauling Institute, dietary polyphenols have little or no direct antioxidant food value following digestion.[7] Not like controlled test tube conditions, the fate of flavones or polyphenols in vivo shows they are poorly absorbed and poorly conserved (less than 5%), so that most of what is absorbed exists as metabolites modified during digestion, destined for rapid excretion.[8]

Spices, herbs, and essential oils are rich in polyphenols in the plant itself and shown with antioxidant potential in vitro. Red wine is high in total polyphenol count which supplies antioxidant quality which is unlikely to be conserved following digestion (see section below).

Deeply pigmented fruits like cranberries, blueberries, plums, blackberries, raspberries, strawberries, blackcurrants, and other fruits like figs, cherries, guava, oranges, mango, grape juice and pomegranate juice also have significant polyphenol content.[10]

Sorghum bran, cocoa powder, and cinnamon are rich sources of procyanidins, which are large molecular weight compounds found in many fruits and some vegetables. Partly due to the large molecular weight (size) of these compounds, their amount actually absorbed in the body is low, an effect also resulting from the action of stomach acids, enzymes, and bacteria in the gastrointestinal tract where smaller derivatives are metabolized and excreted.[7][8]

Flavonoids

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Flavonoids, a subset of polyphenol antioxidants, are present in many berries, as well as in coffee and tea. Examples:

Phenolic acids and their esters

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Examples:

  • Chicoric acid - another caffeic acid derivative, is found in chicory and Echinacea.
  • Chlorogenic acid - found in high concentration in coffee (more concentrated in robusta than arabica beans), blueberries and tomatoes. Produced from esterification of caffeic acid.
  • Cinnamic acid and its derivatives, such as ferulic acid - found in seeds of plants such as in brown rice, whole wheat and oats, as well as in coffee, apple, artichoke, peanut, orange and pineapple.
  • Ellagic acid - found in high concentration in raspberry and strawberry, and in ester form in barrel-aged alcohol such as red wine and whisky.
  • Ellagitannins - hydrolysable tannin polymer formed when ellagic acid, a polyphenol monomer, esterifies and binds with the hydroxyl group of a polyol carbohydrate such as glucose.
  • Gallic acid - found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and many other plants.
  • Rosmarinic acid - found in high concentration in rosemary, oregano, lemon balm, sage, and marjoram.
  • Salicylic acid - found in most vegetables, fruits, and herbs; but most abundantly in the bark of willow trees, from where it was extracted for use in the early manufacture of aspirin.

Other nonflavonoid phenolics

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  • Curcumin - Curcumin has low bioavailability, because, much of it is excreted through glucuronidation. However, bioavailability is substantially enhanced by solubilization in a lipid (oil or lecithin) or by heat.[11]
  • Flavonolignans - e.g. silymarin - a mixture of flavonolignans extracted from milk thistle.

Other compounds

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See also

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References

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  1. ^ 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
  2. ^ EFSA Panel on Dietetic Products, Nutrition and Allergies (2010). "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 1924/2006". EFSA Journal. 8 (2): 1489. doi:10.2903/j.efsa.2010.1489.
  3. ^ Williams, Robert J; Spencer, Jeremy P.E; Rice-Evans, Catherine (2004). "Flavonoids: antioxidants or signalling molecules?☆". Free Radical Biology and Medicine. 36 (7): 838–49. doi:10.1016/j.freeradbiomed.2004.01.001. PMID 15019969.
  4. ^ Gross, P (2009). "New Roles for Polyphenols. A 3-Part report on Current Regulations & the State of Science". Nutraceuticals World. Rodman Media. Retrieved April 11, 2013.
  5. ^ Jonny Bowden (16 Dec 2012). "ORAC no more!". Huffington Post. Retrieved 12 Dec 2012.
  6. ^ Arts, IC; Hollman, PC (2005). "Polyphenols and disease risk in epidemiologic studies". The American Journal of Clinical Nutrition. 81 (1 Suppl): 317S–325S. doi:10.1093/ajcn/81.1.317S. PMID 15640497.
  7. ^ a b c Lotito, S; Frei, B (2006). "Consumption of flavonoid-rich foods and increased plasma antioxidant capacity in humans: Cause, consequence, or epiphenomenon?". Free Radical Biology and Medicine. 41 (12): 1727–46. doi:10.1016/j.freeradbiomed.2006.04.033. PMID 17157175.
  8. ^ a b c d David Stauth (5 March 2007). "Studies force new view on biology of flavonoids". EurekAlert!; Adapted from a news release issued by Oregon State University.
  9. ^ Aviram, M; Rosenblat, M (2005). "Paraoxonases and cardiovascular diseases: pharmacological and nutritional influences". Current Opinion in Lipidology. 16 (4): 393–9. doi:10.1097/01.mol.0000174398.84185.0f. PMID 15990587. S2CID 21585623.
  10. ^ Hidalgo, Gádor-Indra; Almajano, María Pilar (2017). "Red Fruits: Extraction of Antioxidants, Phenolic Content, and Radical Scavenging Determination: A Review". Antioxidants. 6 (1): 7. doi:10.3390/antiox6010007. PMC 5384171. PMID 28106822.
  11. ^ Kurien, Biji T.; Singh, Anil; Matsumoto, Hiroyuki; Scofield, R. Hal (2007). "Improving the Solubility and Pharmacological Efficacy of Curcumin by Heat Treatment". ASSAY and Drug Development Technologies. 5 (4): 567–76. doi:10.1089/adt.2007.064. PMID 17767425.
  12. ^ Stocker, R; Yamamoto, Y; McDonagh, A.; Glazer, A.; Ames, B. (1987). "Bilirubin is an antioxidant of possible physiological importance". Science. 235 (4792): 1043–6. Bibcode:1987Sci...235.1043S. doi:10.1126/science.3029864. PMID 3029864.
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