Digestive System

• Fat-soluble vitamins

  A, D, E, K
• Vitamin A


  • Stored as retinol; abundant in dark green leafy vegetables
• Vitamin D

  • Exists as D2 (ergocalciferol) and D3 (cholecalciferol); D3 is synthesized in the skin after sun exposure
• Vitamin E

  • Alpha tocopherol is the predominant form; best known for its antioxidant activity
• Vitamin K


  • Necessary for the activation of certain clotting factors
• Vitamin C

  • Active in the body as L-ascorbic acid; deficiency can cause scurvy
• Vitamin B1 (Thiamine)


  • Serves as coenzyme for essential chemical reactions
• Vitamin B2 (Riboflavin)

  • Functions in redox reactions for energy production
• Vitamin B3 (Niacin)


  • Converted to NAD+ and NADP+ that acts as coenzymes
• Vitamin B5 (Pantothenic acid)


  • Required for the formation of coenzyme A
• Vitamin B6 (Pyridoxine)

  • Acts as a coenzyme
• Vitamin B7 (biotin)


  • Acts as a coenzyme
• Vitamin B9 (Folic acid)


  • Essential for cell growth, DNA formation, and amino acid metabolism; deficiency can cause neurodevelopmental problems in the fetus during pregnancy
• Vitamin B12 (Cobalamin)


  • Acts as a coenzyme; also important for brain function and development
• Vitamin B3 (niacin)


  Convert to NAD+ and NADP+   that acts as coenzyme 
• vitamin B5 (Pantothenic acid) 


  required for the formation of coenzyme A