Fat-soluble vitamins (A, D, E, K) are insoluble in water, stored in liver and adipose tissues, while water-soluble vitamins (B group, C) must be regularly supplied in the diet due to easy excretion except for vitamin B₁₂.

Coined from “vital” + “amine,” the term “vitamin” originally suggested compounds with amino groups. However, since most vitamins lack amino groups, the letter ‘e’ was dropped, and the term is used to describe essential organic compounds for health and growth.

Vitamins are organic compounds required in small amounts for specific biological functions, and their deficiency can lead to diseases. While most vitamins cannot be synthesized in our body, plants and gut bacteria contribute to our vitamin intake.

Enzymes, like chemical catalysts, lower activation energy for reactions. For instance, while acid hydrolysis of sucrose has an activation energy of 6.22 kJ mol⁻¹, sucrase, an enzyme, reduces it to 2.15 kJ mol⁻¹, demonstrating the efficiency of enzyme action.