Vitamin testing plays a crucial role in preventive healthcare by identifying deficiencies, toxicities, and metabolic imbalances. This guide explains fat-soluble and water-soluble vitamins, their functions, clinical relevance, and diagnostic importance.

Fat-soluble vitamins (A, D, E, K) are stored in body fat and liver, so both deficiency and excess are important.

Vitamin A: Supports vision, immunity, and skin. Low levels cause night blindness and dry skin; high levels can lead to toxicity and liver damage.

Vitamin D: Helps calcium absorption, bones, and immunity. Deficiency is very common and causes fatigue and weak bones; excess is rare but can affect calcium levels.

Vitamin E: Acts as an antioxidant. Low levels may cause nerve and muscle problems; high levels are rare but can affect clotting.

Vitamin K: Needed for blood clotting and bone health. Low levels lead to easy bruising and bleeding.

Water-soluble vitamins (B-complex and C) are not stored much, so regular intake is needed.

Vitamin B1: Energy and nerve function; low levels cause fatigue and nerve issues.

Vitamin B2: Supports energy, skin, and eyes; low levels cause cracked lips and sore throat.

Vitamin B3: Helps metabolism and DNA repair; deficiency causes pellagra.

Vitamin B5: Supports hormones and metabolism; deficiency is rare but causes fatigue.

Vitamin B6: Important for brain and blood; low levels cause anemia and nerve issues.

Vitamin B7: Supports hair, skin, nails; low levels cause hair fall.

Vitamin B9: Needed for DNA and pregnancy; low levels cause anemia and birth defects.

Vitamin B12: Important for nerves and red blood cells; deficiency causes fatigue and numbness.