{"id":630,"date":"2017-10-26T15:24:47","date_gmt":"2017-10-26T15:24:47","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/sunynutrition\/?post_type=chapter&p=630"},"modified":"2017-11-13T20:43:41","modified_gmt":"2017-11-13T20:43:41","slug":"9-2-vitamin-e","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-nutrition\/chapter\/9-2-vitamin-e\/","title":{"raw":"9.2 Vitamin E","rendered":"9.2 Vitamin E"},"content":{"raw":"
\r\n\r\nThere are 8 different forms of vitamin E: 4 tocopherols and 4 tocotrienols. The difference between tocopherols and tocotrienols is that the former have a saturated tail, while the latter have an unsaturated tail. Within tocopherols and tocotrienols, the difference between the different forms is the position of the methyl groups on the ring. The 4 different forms within the tocopherol and tocotrienols are designated by the Greek letters: alpha, beta, gamma, and delta. The difference in these structures is shown in the figures below.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"1150\"]\"\" Figure 9.21 Structures of the different forms of vitamin E[\/caption]\r\n\r\n<\/div>\r\nFor reasons that will be covered in a later subsection, the primary form of vitamin E found in the body is alpha-tocopherol. The major, and possibly only, function of vitamin E is as an antioxidant. When it serves as an antioxidant it forms an alpha-tocopherol radical, as shown below.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"318\"]\"\" Figure 9.23 Alpha-tocopherol radical1<\/sup>[\/caption]\r\n\r\n<\/div>\r\nAlpha-tocopherol is believed to be the first part of an antioxidant network (shown below) where it is oxidized to donate an electron to stabilize reactive oxygen species. Alpha-tocopherol radical can then be reduced by the donation of an electron from ascorbate.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"1102\"]\"\" Figure 9.24 The theorized antioxidant network2<\/sup>[\/caption]\r\n\r\n<\/div>\r\nTo help protect the antioxidant function of alpha-tocopherol (by preventing the formation of alpha-tocopherol radical) in foods and during digestion, some manufacturers have added compounds to this site of alpha-tocopherol through ester bonds. These are referred to as alpha-tocopherol derivatives or alpha-tocopherol esters. The most common forms are alpha-tocopherol acetate, alpha-tocopherol succinate, and alpha-tocopherol phosphate (Ester-E\u00ae). The figures below show the structure of alpha-tocopherol acetate, and the structure of succinic acid.\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"900\"]\"\" Figure 9.25 Alpha-tocopherol acetate[\/caption]\r\n\r\n<\/div>\r\n
\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"221\"]\"\" Figure 9.26 Succinic acid3<\/sup>[\/caption]\r\n\r\n<\/div>\r\nAlpha-tocopherol derivatives, such as acetate in alpha-tocopherol acetate, are cleaved prior to absorption in the small intestine by esterases, meaning that alpha-tocopherol is absorbed, not the alpha-tocopherol derivative.\r\n\r\nSubsections:\r\n\r\n9.21 Alpha-Tocopherol: Natural vs. Synthetic<\/a>\r\n\r\n9.22 Absorption, Metabolism & Excretion of Vitamin E<\/a>\r\n\r\n9.23 Dietary Vitamin E & Amounts Found in Body<\/a>\r\n\r\n9.24 Vitamin E Deficiency & Toxicity<\/a>\r\n\r\n9.25 Vitamin E DRI & IUs<\/a>\r\n\r\n

References & Links<\/h3>\r\n\r\n1. https:\/\/en.wikipedia.org\/wiki\/Radical_(chemistry)#\/media\/File:VitE.gif\r\n\r\n2. Packer L, Weber SU, Rimbach G. (2001) Molecular aspects of alpha-tocotrienol antioxidant action and cell signalling. J Nutr 131(2): 369S-373S\r\n\r\n3. http:\/\/en.wikipedia.org\/wiki\/File:Bernsteins%C3%A4ure2.svg\r\n\r\n<\/div>","rendered":"
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There are 8 different forms of vitamin E: 4 tocopherols and 4 tocotrienols. The difference between tocopherols and tocotrienols is that the former have a saturated tail, while the latter have an unsaturated tail. Within tocopherols and tocotrienols, the difference between the different forms is the position of the methyl groups on the ring. The 4 different forms within the tocopherol and tocotrienols are designated by the Greek letters: alpha, beta, gamma, and delta. The difference in these structures is shown in the figures below.<\/p>\n

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Figure 9.21 Structures of the different forms of vitamin E<\/p>\n<\/div>\n<\/div>\n

For reasons that will be covered in a later subsection, the primary form of vitamin E found in the body is alpha-tocopherol. The major, and possibly only, function of vitamin E is as an antioxidant. When it serves as an antioxidant it forms an alpha-tocopherol radical, as shown below.<\/p>\n

\n
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Figure 9.23 Alpha-tocopherol radical1<\/sup><\/p>\n<\/div>\n<\/div>\n

Alpha-tocopherol is believed to be the first part of an antioxidant network (shown below) where it is oxidized to donate an electron to stabilize reactive oxygen species. Alpha-tocopherol radical can then be reduced by the donation of an electron from ascorbate.<\/p>\n

\n
\"\"<\/p>\n

Figure 9.24 The theorized antioxidant network2<\/sup><\/p>\n<\/div>\n<\/div>\n

To help protect the antioxidant function of alpha-tocopherol (by preventing the formation of alpha-tocopherol radical) in foods and during digestion, some manufacturers have added compounds to this site of alpha-tocopherol through ester bonds. These are referred to as alpha-tocopherol derivatives or alpha-tocopherol esters. The most common forms are alpha-tocopherol acetate, alpha-tocopherol succinate, and alpha-tocopherol phosphate (Ester-E\u00ae). The figures below show the structure of alpha-tocopherol acetate, and the structure of succinic acid.<\/p>\n

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Figure 9.25 Alpha-tocopherol acetate<\/p>\n<\/div>\n<\/div>\n

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Figure 9.26 Succinic acid3<\/sup><\/p>\n<\/div>\n<\/div>\n

Alpha-tocopherol derivatives, such as acetate in alpha-tocopherol acetate, are cleaved prior to absorption in the small intestine by esterases, meaning that alpha-tocopherol is absorbed, not the alpha-tocopherol derivative.<\/p>\n

Subsections:<\/p>\n

9.21 Alpha-Tocopherol: Natural vs. Synthetic<\/a><\/p>\n

9.22 Absorption, Metabolism & Excretion of Vitamin E<\/a><\/p>\n

9.23 Dietary Vitamin E & Amounts Found in Body<\/a><\/p>\n

9.24 Vitamin E Deficiency & Toxicity<\/a><\/p>\n

9.25 Vitamin E DRI & IUs<\/a><\/p>\n

References & Links<\/h3>\n

1. https:\/\/en.wikipedia.org\/wiki\/Radical_(chemistry)#\/media\/File:VitE.gif<\/p>\n

2. Packer L, Weber SU, Rimbach G. (2001) Molecular aspects of alpha-tocotrienol antioxidant action and cell signalling. J Nutr 131(2): 369S-373S<\/p>\n

3. http:\/\/en.wikipedia.org\/wiki\/File:Bernsteins%C3%A4ure2.svg<\/p>\n<\/div>\n\n\t\t\t

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Candela Citations<\/h3>\n\t\t\t\t\t
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