Why do we need vitamins?

Answer: Cofactors for enzyme reactions

They provide energy calories — Wrong. Vitamins don't provide energy or calories. Energy comes from macronutrients: carbohydrates (4 cal/g), proteins (4 cal/g), and fats (9 cal/g). Vitamins are needed in tiny amounts to help enzymes function, not for energy.

Cofactors for enzyme reactions ✓ — Correct! Vitamins are important micronutrients that act as cofactors or coenzymes for hundreds of enzyme reactions. For example, B vitamins help enzymes convert food to energy, vitamin K enables blood clotting enzymes, vitamin C helps collagen synthesis enzymes. Without these vitamins, critical enzyme reactions can't occur efficiently. Deficiencies cause specific diseases: no vitamin C = scurvy, no vitamin D = rickets!

Build muscle and bone tissue — Wrong. While some vitamins support bone health (vitamin D helps calcium absorption, vitamin K activates bone proteins), vitamins don't directly build tissue. Proteins, calcium, and phosphorus are structural materials. Vitamins enable the enzymes that build and maintain these structures.