provitamiin

A provitamin is a substance that can be converted into a vitamin within the body. These compounds are biologically inactive on their own but become active after undergoing a metabolic transformation. This conversion process typically involves enzymatic reactions that alter the chemical structure of the provitamin, transforming it into its corresponding vitamin form.

Provitamins serve as a storage or transport mechanism for vitamins, allowing for easier absorption, stability, or delivery to target tissues. The body's ability to convert provitamins into active vitamins is a crucial aspect of nutrient utilization and maintaining overall health. Deficiencies in specific enzymes required for this conversion can lead to a functional deficiency of the vitamin, even if the provitamin is present in adequate amounts.

A well-known example is beta-carotene, a provitamin A. Beta-carotene, found in many fruits and vegetables, is cleaved in the intestines and liver to produce retinol, the active form of vitamin A. Another example is ergosterol, a provitamin D2, which is converted to vitamin D2 in the skin upon exposure to ultraviolet radiation. Understanding the concept of provitamins is important for dietary planning and understanding how the body obtains essential micronutrients.