USMLE

Vitamin E (Tocopherol/Tocotrienol)

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Vitamins
  1. Vitamin B1 (Thiamine) Biochemistry
  2. Vitamin B1 (Thiamine) Deficiency
  3. Vitamin B2 (Riboflavin)
  4. Vitamin B3 (Niacin) Biochemistry
  5. Vitamin B3 (Niacin) Deficiency and Excess
  6. Hartnup Disease
  7. Vitamin B5 (Pantothenic Acid)
  8. Vitamin B6 (Pyridoxine)
  9. Vitamin B7 (Biotin)
  10. Vitamin B9 (Folate)
  11. Vitamin B12 (Cobalamin) Biochemistry
  12. Vitamins B9 and B12 Deficiencies
  13. Vitamin A (Retinol) Biochemistry
  14. Vitamin A (Retinol) Deficiency and Excess
  15. Vitamin C (Ascorbic Acid) Biochemistry
  16. Vitamin C (Ascorbic Acid) Deficiency and Excess
  17. Vitamin D Biochemistry
  18. Vitamin D Deficiency and Excess
  19. Vitamin E (Tocopherol/Tocotrienol)
  20. Vitamin K Biochemistry
  21. Vitamin K Deficiency
  22. Zinc
  23. Kwashiorkor and Marasmus

Summary

Vitamin E refers to a group of fat-soluble vitamins including tocopherol and tocotrienol, for which the exact biological function is poorly understood. An excess of Vitamin E has been found to alter the function of vitamin K, enhancing warfarin's anticoagulant effects. Vitamin E deficiency can cause neurological problems, specifically affecting the spinocerebellar tract and dorsal columns. Deficiency can also lead to the finding of acanthocytosis (red blood cells with spiked cell membranes). As an antioxidant, deficiency of Vitamin E can lead to oxidative damage to red blood cells, resulting in hemolytic anemia.

Key Points

  • Vitamin E (tocopherol/tocotrienol)
    • Antioxidant
      • protects RBCs and membranes from free radical damage
    • Fat-soluble
    • Biological function is not well understood
    • High-dose supplementation alters function of vitamin K
      • increases warfarin anticoagulation
      • may increase risk of hemorrhage (e.g. hemorrhagic stroke)
  • Vitamin E Deficiency
    • Usually caused by fat malabsorption (e.g. gastric bypass, abetalipoproteinemia)
    • Acanthocytosis
      • red blood cells with spiny projections
    • Neurological abnormalities
      • Posterior column and spinocerebellar tract demyelination
        • often presents with progressive ataxia
      • retinitis pigmentosa
    • Hemolytic anemia and muscle weakness also seen



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