AboutVitamin A is a fat-soluble, essential vitamin that plays a key role in vision, cell differentiation, embryonic development, and immune system function. There are two main categories of Vitamin A; retinoids and carotenoids. ꞵ-Carotene the carotenoid form that has the potential to yield Vitamin A after conversion in the body, also known as Provitamin A. The retinol forms of this vitamin are more bioavailable and come from your nutritious diet. Both forms are necessary for healthy growth and development.