Which inactive form of vitamin A is activated by the body?

The inactive form of vitamin A that is activated by the body is beta-carotene. Beta-carotene is a provitamin A carotenoid found in various fruits and vegetables, especially those that are orange and green in color, such as carrots and spinach. The human body can convert beta-carotene into retinol, which is the active form of vitamin A that plays a crucial role in vision, immune function, and skin health.

When beta-carotene is ingested, it undergoes enzymatic conversion in the intestine and liver before it is transported to other tissues where it contributes to vitamin A functions. This conversion ability is unique to beta-carotene and similar carotenoids, making it an essential component of the diet, especially in populations where animal sources of vitamin A are limited.

In contrast, retinol is an already active form of vitamin A, while carotenoids is a broader term that encompasses beta-carotene and other plant pigments that have antioxidant properties but may not all be converted to active vitamin A. Vitamin D, while important for bone health and immune function, is not a form of vitamin A and serves different biological functions in the body.