Vitamin A Rich Foods, Deficiency Symptoms Risks You Need to Know Vitamin A, also known as retinol, has several important functions. • keeping skin and the lining of some parts of the body, such as the nose, • Increased Protection from Bacterial and Viral Infections - Vitamin A is essential for healthy surface linings of the eyes, mucous membranes, respiratory, urinary, and intestinal tracts, which help the body protect against infection. (4,5,6)