1. Vitamin E Requirements in Parenteral Nutrition
Hans K. Biesalski 
Gastroenterology 
Volume 137, Issue 5, Pages S92-S104 (November 2009)
DOI: /j.gastro
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2. Figure 1
Structures of RRR-α-tocopherol and the seven stereoisomers. The mixture of all 8 stereoisomers is called all-rac-α-tocopherol.
Gastroenterology  , S92-S104DOI: ( /j.gastro )
Copyright © 2009 AGA Institute Terms and Conditions

3. Figure 2 Structure of the naturally occurring tocotrienols.
Gastroenterology  , S92-S104DOI: ( /j.gastro )
Copyright © 2009 AGA Institute Terms and Conditions

4. Figure 3
Antioxidant function of vitamin E. Located in the inner- and outer leaflet of the membrane, vitamin E can stop the free radical–induced lipid peroxidation of membrane-forming unsaturated lipids. Either extra- or intracellular vitamin C can reduce the vitamin E–radical to form again vitamin E. Finally, vitamin C–radical is reduced via other water soluble redox systems.
Gastroenterology  , S92-S104DOI: ( /j.gastro )
Copyright © 2009 AGA Institute Terms and Conditions

5. Figure 4
Uptake of ascorbic acid (AA) or dehydro ascorbic acid (DHA) via the sodium dependent transporter (SVCT 1/2) or via insulin-dependent glucose transporter (GLUT). DHA, which is the oxidized form of AA, is much better transported via GLUT than AA, which is preferably transported through SVCT. Intracellular DHA is reduced to form AA, which is necessary to protect the cell from free radicals formed during cellular respiration and to a higher degree in cases of hyperglycemia. Extracellular glucose might compete with the uptake of DHA via GLUT, which subsequently might alter the intracellular level of DHA and at least AA.
Gastroenterology  , S92-S104DOI: ( /j.gastro )
Copyright © 2009 AGA Institute Terms and Conditions