Vitamin A is a fat-soluble vitamin with four major functions in the body.

Also indexed as: A Vitamin, Retinol (Vitamin A)

1. It helps cells reproduce normally—a process called differentiation (cells that have not properly differentiated are more likely to undergo pre-cancerous changes).

2. It is required for vision; vitamin A maintains healthy cells in various structures of the eye and is required for the transduction of light into nerve signals in the retina.

3. It is required for normal growth and development of the embryo and fetus, influencing genes that determine the sequential development of organs in embryonic development.

4. It may be required for normal reproductive function, with influences on the function and development of sperm, ovaries and placenta.

How to Use It

For most people, up to 25,000 IU (7,500 mcg) of vitamin A per day is considered safe. However, people over age 65 and those with liver disease should probably not supplement with more than 15,000 IU per day, unless supervised by a doctor. In women who could become pregnant, the maximum safe intake is being re-evaluated. However, less than 10,000 IU (3,000 mcg) per day is generally accepted as safe. There is concern that larger intakes could cause birth defects. Whether the average person would benefit from vitamin A supplementation remains unclear.

Where to Find It

Liver, dairy products, and cod liver oil are good sources of vitamin A. Vitamin A is also available in supplement form.

---