Vitamin A is a grouping of organic compounds that enable important bodily functions and processes to take place. Vitamin A is used in fighting off and preventing infection, the production of white blood cells, immune system regulation, cell differentiation and division, reproduction, vision and bone growth.

Two main categorizations of vitamin A exist:

Vitamin A from animal products tends to be found as preformed vitamin A. Preformed vitamin A is absorbed into your body as retinol (a very user-friendly/ active form of vitamin structure). Whole milk, livers and various fortified foods are good preformed vitamin A sources. Once in our bodies retinol is often changed in structure, e.g. to become retinal or retinoic acid, depending upon its designated use.

Vitamin A also comes from plant products, e.g. colorful vegetables and fruits. Initially it enters the body as provitamin A carotenoids, only to get changed to retinol. Examples of commonly found vitamin A carotenoids are alpha-carotene, beta-cryptoxanthin and beta-carotene (most efficiently converted into retinol).

563 carotenoids are known, only 10% are able to be converted by us into vitamin A (retinol). Health promoting qualities can come from many uncovertable carotenoids such as lycopene, zeaxanthin and lutein.

Antioxidant effects have been attributed to vitamin A in animals other than humans, which bodes well for us. Free radicals, harmful oxygen metabolism products, can lead to various chronic forms of disease.

Recommended daily allowances (RDA) of vitamin a vary depending upon your situation. Babies should have an intake of 400 micrograms (mcg) for their first 6 months, then 500mcg to the age of 1. Children aged 1-3 require 300mcg at 4-8 they need 400mcg, at the ages 9-13 600mcg is needed. Males aged 14+ require 900mcg, females of the same ages requiring 700mcg. Pregnancy dictates that 750mcg is suitable for 14-18 year old females, 770mcg from 19+. Female lactation requires the need for 1200mcg for 14-18 years of age, and 1300mcg for women of 19 and over.

Deficiencies in vitamin A can lead to night blindness (is required in retina pigments) and a reduced ability of you body to fight infections (lung epithelial cells become poor at removing pathogens), potentially leading to pneumonia. Small deficiencies in children can promote diarrheal and respiratory infections, slowed bone/ general body growth and an decreased effectiveness of their bodies fighting strong illnesses. Alcohol lowers the vitamin A stored quantities.

Vitamin A is fat soluble, meaning it is stored in the body when not being used. Too much of this vitamin becomes toxic leading to hypervitaminosis whereby liver complications, birth defects, disorders of the central nervous system and decreased mineral density in your bones can occur.