Roles of vitamin A in human body

Vitamin A -active compounds, defined as compounds having qualitatively the biological activity of retinal, are represented by retinoid and pro-vitamin A carotenoids.

Vitamin A is required for several essential life processes, including metabolism, haematopoeisis, bone development, pattern formation during embryogenesis, the maintenance of differentiated epithelia, and immune-competence.

These processes can be supported by all forms of vitamin A, including the pro-vitamin A carotenoids. The other vitamin functions namely in reproduction, growth, the maintenance of skin and mucous membranes and the visual process, require either retinol or retinaldehyde.

Retinol

Vitamin A is needed to process incoming light to visual images and to keep the eye’s surface healthy. Moreover, beta-carotene –a compound that the body converts to vitamin A - is an antioxidant and thus works to neutralize harmful substances known as free radicals.

As such, beta-carotene appears to help protect the body against a variety of disorders, including cancer and heart disease.

Vitamin A is known to be involved in fetal development and in the regulation of proliferation and differentiation of many types of cells throughout life. The effects of vitamin A on cellular differentiation are due to the control of gene expression by retinoic acid in selected tissues, the protein products being responsible for the effects.

It plays a role in immune function, both as a cell regulator and by helping maintain the skin and mucous membranes.
Roles of vitamin A in human body