Dietary Reference Intakes The Essential Guide to Nutrient Requirements (2006) / Chapter Skim
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From page 234... ...
TABLE 1 Dietary Reference Intakes for Vitamin E (a -Tocopherol a) by Life Stage Group DRI values (mga/day)
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From page 235... ...
PART III: VITAMIN E 235 VITAMIN E V itamin E is a fat-soluble nutrient that functions as a chain-breaking antioxidant in the body by preventing the spread of free-radical reac tions. Of the eight naturally occurring forms of vitamin E only the a-tocopherol form of the vitamin is maintained in the plasma.
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DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 236 On the molecular level, vitamin E (a-tocopherol form) inhibits protein ki nase C activity (involved in cell proliferation and differentiation)
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PART III: VITAMIN E 237 Determining Requirements The adult requirements for vitamin E are based largely on induced vitamin E deficiency in humans and the intake that correlated with in vitro hydrogen peroxide–induced red blood cell hemolysis and plasma a-tocopherol concentrations. Although some studies have reported a possible protective effect of vitamin E on conditions such as cardiovascular and neurological diseases, cancer, cataracts, and diseases of the immune system, the data are inadequate to support population-wide dietary recommendations that are specifically based on preventing these diseases.
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From page 238... ...
DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 238 Pregnancy £ 18 y through 50 y Age-specific requirement + plasma concentration Lactation £ 18 y through 50 y Age-specific requirement + vitamin E secreted in milk The UL The Tolerable Upper Intake Level (UL) is the highest level of daily nutrient intake that is likely to pose no risk of adverse effects for almost all people.
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From page 239... ...
PART III: VITAMIN E 239 TABLE 2 Amounts in International Units (IU) of Any Forms of a -Tocopherola Contained in Vitamin Eb Supplements Equivalent to the UL for Adultsc UL for Adults Total a-Tocopherol Sources of Vitamin E IU from Source Available as Supplements (mg/day)
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From page 240... ...
DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 240 Estimating a-tocopherol content of foods and diets: As discussed, many data bases of nutrient content and many food-intake surveys list vitamin E in the form of a-tocopherol equivalents (a-TE) rather than a-tocopherol.
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From page 241... ...
PART III: VITAMIN E 241 See Appendix F on conversion factors on converting IUs of vitamin E to a-tocopherol. Bioavailability Because vitamin E is a fat-soluble nutrient, its absorption is enhanced when it is consumed in a meal that contains fat; however, the optimal amount of fat to enhance absorption has not been reported.
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From page 242... ...
DRIs: THE ESSENTIAL GUIDE TO NUTRIENT REQUIREMENTS 242 EXCESS INTAKE There is no evidence of adverse effects from the excess consumption of vita min E naturally occurring in foods. With regard to supplemental vitamin E intake in the form of synthetic α-tocopherol (as a supplement, food fortificant, or pharmacological agent)
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From page 243... ...
PART III: VITAMIN E 243 KEY POINTS FOR VITAMIN E Vitamin E (a-tocopherol) is a fat-soluble nutrient that functions 3 as a chain-breaking antioxidant in the body by preventing the spread of free-radical reactions.
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