Medicine & USMLE

Vitamin C (Ascorbic Acid) Biochemistry

  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


Vitamin C (Ascorbic Acid) is a water-soluble vitamin important as a cofactor for hydroxylase enzymes. It is a cofactor for dopamine beta-hydroxylase, facilitating the conversion of dopamine to norepinephrine. Vitamin C is also involved in collagen synthesis, as a cofactor for hydroxylation of proline and lysine residues. As an antioxidant, Vitamin C also plays an important role in the reduction of iron (III) to iron (II), which is required for enteric absorption of iron. This property also makes vitamin C useful as an ancillary treatment for methemoglobinemia.

Key Points

  • Ascorbic Acid (Vitamin C)
    • Water-soluble antioxidant found in fruits and vegetables
    • Reduces iron: Fe3+ to Fe2+
      • Facilitates iron absorption at GI tract
      • Mechanism of treatment for methemoglobinemia
    • Key roles in hydroxylase enzymes

Find Vitamin C Biochemistry and other Vitamins among Pixorize's visual mnemonics for the USMLE Step 1 and NBME shelf exams.