This document classifies vitamins into two main groups: fat-soluble vitamins (A, D, E, K) and water-soluble vitamins. Fat-soluble vitamins are hydrophobic, transported in the blood bound to proteins, and can accumulate in the body and cause toxicity. Water-soluble vitamins are hydrophilic, not readily stored, and excreted from the body so daily intake is important. The water-soluble vitamins include the B vitamins (thiamine, riboflavin, niacin, pantothenic acid, biotin, pyridoxine, folic acid, cobalamin) and vitamin C.

1. SIMS 305- Clinical Biochemistry
Dr. Ali Raza
Senior Lecturer
Centre for Human Genetics and Molecular Medicine (CHGMM),
Sindh Institute of Medical Sciences (SIMS), SIUT.

2. Classification of Vitamins
• Vitamins are classified by their biological and chemical
activity.
• 13 vitamins
Divided into two groups according to solubility.
1. Fat-soluble Vitamins
2. Water-soluble Vitamins

3. Lipid-soluble vitamins (A, D, E and K)
• Hydrophobic compounds
• Transport in the blood in lipoproteins or attached to
specific binding proteins,
• Accumulate in the body, cause hypervitaminosis

4. Fat soluble vitamins
Vit. A (Retinol, Retinal, Retinoic acid)
Vit. D (Vit. D3: Cholecalciferol,
Vit. D2: Ergocalciferol)
Vit. E (α-Tocopherol)
Vit. K (Vit. K1: Phylloquinones,
Vit. K2: Menaquinones)

5. Water-Soluble vitamins
hydrophilic compounds
• Not readily stored
• Excreted from the body
• Daily intake is important
• Function: Enzyme cofactors

6. 2-Water soluble vitamins:
Vit. B group
B1 (Thiamin)
B2 (Riboflavin)
B3 (Niacin)
B5 (Pantothenic acid)
B7 (Biotin)
B6 (Pyridoxine)
B9 (Folic acid)
B12 (Cyanocobalamin)
Vit. C : (Ascorbic acid)