Define vitamin.
Vitamins are organic substances in food that are needed by humans in very small amounts for growth, maintaining good health, and preventing disorders of metabolism. They are divided into water-soluble and fat-soluble vitamins. Most water-soluble vitamins, such as the vitamin B complex, act as catalysts and coenzymes in metabolic processes and energy transfer and are excreted fairly rapidly. Fat-soluble vitamins, such as vitamins A, D, and E are necessary for the function or structural integrity of specific body tissues and membranes and are retained in the body.

Water-soluble vitamins