Vitamin E

Question 1

Vitamin E: Structures

Answer 1

• 4 tocopherols and 4 tocotrienols: all antioxidants
• All have chromanol ring
  
  • phenolic hydroxyl at 6 position that can donate H atom
  • Hydrophobic sidehain for penetrating biological membrane
• Tocopherol=8 steroisomer
• Natural=all R at 2,4,8 positions

Question 2

Vitamin E: Antioxidant Properties

Answer 2

• Resonance stabalized radical
• H atome to peroxyl radical to terminate lipid peroxidation
• Antioxidant potency: depends on pattern of methylation for pushing electrons into ring for stabilization
  
  • a-tocopherol most potent, delta least

Question 3

Vitamin E: Pharmacological Activity and Transport

Answer 3

• Alpha-tocopherol most important form
• RRR-alpha-tocopherol most biological active
  
  • Rat resorption-gestation test
• 2R configuration needed to meet vit E needs
• beta, gama and delta tocopherol/tocotrienols not meed requirement because poorly recognized by alpha-tocopherol transport protein in liver

Question 4

mg to IU of alpha-tocopherol

Answer 4

• RRR-alpha-tocopherol (natural)
  
  • 1mg=1.5 IU
• all-rac-alpha-tocopherol (synthetic)
  
  • 1mg=1.1 IU
• all-rac-alpha-tocopherol acetate (synthetic)
  
  • 1mg=1 IU

Question 5

Vitamin E: Daily Requirement

Answer 5

• DV: 30 IU (20 mg natural)
• UL: 1500 IU (1000 mg natural)

Question 6

Vitamin E Dietary Sources

Answer 6

• Everything
• Fortified margarine=fat americans source

Question 7

Vitamin E Deficiency

Answer 7

• Rare: usually fat malabsorption
• Rate sterility “Tokos”-Greek-birth
• adults: peripheral neuropathies from radical damage
• premies: hemolytic anemia; poor placental transfer
• diagnosis
  
  • Ratio plasma alpha-tocopherol to total plasma lipid: <0.8 mg/g
  • Plasma level <20 µM

Question 8

Vitamin E Toxicity

Answer 8

• Nontoxic
• Bleeding, rare less than 1000mg/day
• warfarin and VitE=nonono bad

Question 9

Vitamin E bleeding Mechansim

Answer 9

• inhibit gamma-carboxylase enzyme (GGCX) with metabolites
• direct platlet effect to make less sticky

Question 10

Vitamin E Use

Answer 10

• Cancer, heart disease: No benefit
• Alzhiemers: slow put not prevent
• Eye and lung damage in premies on oxygen
  
  • IV vitE (emulsified with polysorb 80)
• dose too low for benefit?

Question 11

Vitamin E: Consumer Counseling

Answer 11

• Supplements higher than 200 IU not benefit/could harm
• 30 IU in mutlivite adequate
• Natural RRR better utilized
• Health benefits not materialized
• If bleed easy, use caution