Vitamin A

Vitamin A is a family of fat-soluble compounds that contribute to cell division, keeping the surface lining of the eyes, respiratory, urinary and intestinal tracts healthy, bone growth, and reproduction.  It regulates the immune system and aids lymphocytes (white blood cells) in fighting infections.

Vitamin A is found in three main forms: retinol (Vitamin A1 is found in liver and whole milk), 3,4-didehydroretinol (Vitamin A2), and 3-hydroxy-retinol (Vitamin A3). Good food sources of Vitamin A include liver, sweet potatoes, carrots, milk, egg yolks and mozzarella cheese.

Provitamin A carotenoids are dark colored pigments that are found in plant foods and can be converted to vitamin A.  Carotenoids found in foods are beta-carotene, alpha-carotene, lutein, zeaxanthin, lycopene, and cryptoxanthin. There have been 563 identified carotenoids, but less 10% are used for vitamin A. Beta-carotene is the most efficient at being converted to retinol. Alpha-carotene and beta-cryptoxanthin can be converted to vitamin A, but are much less efficient than beta-carotene.  Lycopene, Lutein, and zeaxanthin do not convert to vitamin A, but are still good for your health.