This document discusses the importance of vitamins in the human body, focusing on their role in maintaining health. It covers topics such as the discovery of vitamins, vitamin deficiencies, fat-soluble and water-soluble vitamins, cofactors, vitamin absorption, pro-vitamins, vitamin requirements during pregnancy and lactation, and the treatment of certain conditions with vitamins. The document also provides information on specific vitamins such as thiamine, riboflavin, niacin, vitamin C, vitamin D, and vitamin A, including their functions, sources, and potential deficiencies. Additionally, it explores the absorption and metabolism of vitamin A, carotenoids, and vitamin A toxicity. Overall, this document offers a comprehensive overview of the importance of vitamins in maintaining optimal health.