7. VITAMINS

Vitamins

Vitamins are essential micronutrients required by the body in small amounts for growth, metabolism, immunity and maintaining good health. They cannot be produced in sufficient amounts by the body and must be obtained from food. These notes explain vitamins in simple language for D.Pharmacy students.

Vitamins: Definition, Classification, Sources, Functions, Coenzymes, RDA and Deficiency Diseases

Vitamins are essential micronutrients required by the body in small amounts for growth, metabolism, immunity and maintaining good health. They cannot be produced in sufficient amounts by the body and must be obtained from food.

Definition of Vitamins

Vitamins are organic compounds required in small quantities for normal body functions such as energy production, immunity, vision, blood formation and tissue repair. They do not provide energy but help the body use proteins, carbohydrates and fats effectively.

Classification of Vitamins

1. Fat‑Soluble Vitamins

These vitamins dissolve in fats and are stored in liver and fatty tissues.

• Vitamin A (Retinol)
• Vitamin D (Cholecalciferol)
• Vitamin E (Tocopherol)
• Vitamin K (Phylloquinone)

2. Water‑Soluble Vitamins

Dissolve in water and are not stored in the body; excess is excreted in urine.

• Vitamin B Complex (B1, B2, B3, B5, B6, B7, B9, B12)
• Vitamin C (Ascorbic acid)

Fat‑Soluble Vitamins

Vitamin A (Retinol)

• Sources: Carrots, spinach, eggs, liver, milk.
• Chemical nature: Unsaturated alcohol with beta‑ionone ring.
• Functions: Vision, skin health, immunity, growth.
• Coenzyme form: Retinal (in vision cycle).
• RDA: 600–900 μg/day.
• Deficiency: Night blindness, dry skin, xerophthalmia.

Vitamin D (Cholecalciferol)

• Sources: Sunlight, fish oil, milk, egg yolk.
• Chemical nature: Steroid derivative.
• Functions: Calcium absorption, bone health.
• Coenzyme form: Calcitriol (active form).
• RDA: 400–800 IU/day.
• Deficiency: Rickets in children, osteomalacia in adults.

Vitamin E (Tocopherol)

• Sources: Vegetable oils, nuts, seeds, green vegetables.
• Chemical nature: Tocopherols and tocotrienols.
• Functions: Antioxidant, protects cell membranes.
• Coenzyme form: None (acts as antioxidant).
• RDA: 8–15 mg/day.
• Deficiency: Muscle weakness, hemolytic anemia.

Vitamin K (Phylloquinone)

• Sources: Green leafy vegetables, cabbage, liver.
• Chemical nature: Quinone derivative.
• Functions: Blood clotting (synthesis of clotting factors).
• Coenzyme form: Vitamin K hydroquinone.
• RDA: 75–120 μg/day.
• Deficiency: Bleeding disorders, delayed clotting.

Water‑Soluble Vitamins

Vitamin B1 (Thiamine)

• Sources: Whole grains, nuts, pork, cereals.
• Functions: Energy metabolism.
• Coenzyme form: TPP (Thiamine pyrophosphate).
• Deficiency: Beri‑beri, Wernicke’s syndrome.

Vitamin B2 (Riboflavin)

• Sources: Milk, eggs, green vegetables.
• Functions: Helps in oxidation–reduction reactions.
• Coenzyme form: FMN, FAD.
• Deficiency: Cracks at mouth corners, dermatitis.

Vitamin B3 (Niacin)

• Sources: Meat, grains, peanuts.
• Functions: Energy production.
• Coenzyme form: NAD, NADP.
• Deficiency: Pellagra (Dermatitis, Diarrhea, Dementia).

Vitamin B5 (Pantothenic Acid)

• Sources: Meat, eggs, whole grains.
• Functions: Part of Coenzyme A.
• Deficiency: Fatigue, burning feet syndrome.

Vitamin B6 (Pyridoxine)

• Sources: Fish, bananas, nuts.
• Functions: Amino acid metabolism.
• Coenzyme form: PLP (Pyridoxal phosphate).
• Deficiency: Anemia, nerve problems.

Vitamin B7 (Biotin)

• Sources: Egg yolk, nuts, soybeans.
• Functions: Carboxylation reactions.
• Deficiency: Hair loss, dermatitis.

Vitamin B9 (Folic Acid)

• Sources: Green leafy vegetables, liver, legumes.
• Functions: DNA synthesis, RBC formation.
• Coenzyme form: THF (Tetrahydrofolate).
• Deficiency: Megaloblastic anemia, birth defects.

Vitamin B12 (Cobalamin)

• Sources: Meat, fish, milk (not in plant foods).
• Functions: Nerve function, RBC formation.
• Coenzyme form: Methylcobalamin, Adenosylcobalamin.
• Deficiency: Pernicious anemia, nerve damage.

Vitamin C (Ascorbic Acid)

• Sources: Citrus fruits, amla, tomatoes.
• Functions: Collagen synthesis, wound healing, antioxidant.
• Coenzyme form: None (acts directly).
• RDA: 65–90 mg/day.
• Deficiency: Scurvy (bleeding gums, poor wound healing).

Summary:

Vitamins are essential organic micronutrients required in small amounts for growth, metabolism, immunity and overall health. They are divided into fat‑soluble vitamins (A, D, E, K) that are stored in liver and fat tissues, and water‑soluble vitamins (B‑complex and C) that are not stored and excess is excreted in urine. Each vitamin has specific food sources, biochemical functions, and often a coenzyme form that participates in metabolic reactions. Deficiency produces characteristic diseases such as night blindness, rickets, beri‑beri, pellagra, scurvy and anemias, while excessive intake (especially of fat‑soluble vitamins) can be toxic. This overview helps D.Pharmacy students link vitamin functions and deficiencies with clinical signs, drug therapy and dietary supplementation.