Difference between active and inactive forms of vitamins?

Active forms of vitamins are the biologically functional versions that the body can immediately utilize for various physiological processes, such as coenzymes in metabolic reactions. In contrast, inactive forms, often referred to as precursors or provitamins, require conversion through metabolic processes to become active. For example, vitamin A exists in both active (retinol) and inactive (beta-carotene) forms, with the latter needing to be converted into retinol for use by the body. This distinction is crucial for understanding dietary requirements and the effectiveness of vitamin supplementation.