What is a provitamin?

A provitamin is defined as a nutrient that can be converted into a vitamin within the body. The term typically refers to substances that, although not vitamins themselves, have the capability to be metabolized to produce a vitamin. A classic example is beta-carotene, which the body can convert into vitamin A. This conversion process is significant because it highlights how certain compounds can aid in fulfilling nutritional needs through their transformation into essential vitamins.

In contrast, options that suggest a vitamin can be converted into a nutrient do not accurately describe the function of vitamins; they serve primarily as essential compounds that the body cannot synthesize independently and must obtain from external sources. The idea of an endogenous form of a vitamin also does not align with the definition of provitamins, as it refers to the naturally occurring variant of a vitamin rather than a precursor. Furthermore, the option referring to a man-made copy of a vitamin indicates a synthetic version, which does not encapsulate the concept of conversion that is central to the definition of provitamins. Thus, the option identifying a provitamin as a nutrient that can be transformed into a vitamin is accurate and reflects the biochemical processes that underpin nutritional science.