Vitamins

The essentials

Vitamins are organic compounds needed in small amounts in the diet for normal growth and health. Most cannot be made by the body (or not in sufficient amounts), so their absence causes specific deficiency diseases. They are named by letters (A, B, C, D, E, K); the B vitamins form a group (B₁, B₂, B₆, B₁₂ and others).

Key points

• Fat-soluble vitamins: A, D, E and K. They are stored in the liver and adipose (fat) tissue.
• Water-soluble vitamins: the B group and C. They are excreted in urine and cannot be stored (except B₁₂), so they must be supplied regularly in the diet.
• Vitamin A — sources: fish liver oil, carrots, butter, milk. Deficiency: xerophthalmia (hardening of the cornea) and night blindness.
• Vitamin B₁ (thiamine) — yeast, milk, green vegetables, cereals. Deficiency: beriberi (loss of appetite, retarded growth).
• Vitamin B₂ (riboflavin) — milk, egg white, liver, kidney. Deficiency: cheilosis (cracking at the corners of the mouth and lips), digestive disorders, burning sensation of the skin.
• Vitamin B₆ (pyridoxine) — yeast, milk, egg yolk, cereals, grams. Deficiency: convulsions.
• Vitamin B₁₂ (cyanocobalamin) — meat, fish, egg, curd. Deficiency: pernicious anaemia (RBCs deficient in haemoglobin).
• Vitamin C (ascorbic acid) — citrus fruits, amla, green leafy vegetables. Deficiency: scurvy (bleeding gums).
• Vitamin D — exposure to sunlight, fish, egg yolk. Deficiency: rickets in children and osteomalacia (soft bones) in adults.
• Vitamin E — vegetable oils such as wheat germ oil and sunflower oil. Deficiency: increased fragility of red blood cells and muscular weakness.
• Vitamin K — green leafy vegetables. Deficiency: increased blood clotting time.

Exam tips

• Group the four fat-soluble vitamins as "A, D, E, K".
• Vitamin B₁₂ is the water-soluble vitamin that is stored in the liver.

Common mistakes

• Swapping rickets (vitamin D) and scurvy (vitamin C), or beriberi (B₁) and pernicious anaemia (B₁₂).