Vitamin A

There are two sources of dietary vitamin A, active forms and precursors. Active forms of vitamin A are obtained from animal products. These are known as retinoids which include retinal and retinol. Another sources of vitamin A is precursors. It is also known as provitamins. Provitamins are obtained from fruits and vegetables containing yellow, orange and dark green pigments. These pigments are known as carotenoids, the most well-known being beta-carotene. Our body can convert carotenes into retinol. Adequate intake of beta-carotenes has been linked with low risk of certain cancers.

Vitamin A is essential for the following body functions:

• Healthy vision
• Eyes
• Skin health
• Immune function
• Embryonic development and reproduction
• Bone grow
• Gene transcription
• Reducing risk of heart disease
• Antioxidant Activity

Sources of Vitamin A:

µ = one millionth, 0.000001

Dietary Reference Intake

RDA = Recommended Dietary Allowances
AI* = Adequate Intakes
UL = Upper Limit
µ = one millionth, 0.000001

Vitamin A Deficiency

Vitamin A deficiency may occurs when a person

• consumes inadequate vitamin A from diet
• has chronic malabosortion of lipids problem.
• has impaired bile production and release problem.
• is practicing low fat diet
• is exposed to oxidant, such as cigarette smoke, regularly
• has zinc deficiency.

Symptoms of deficiency include:

• poor night vision
• gradual lose of sight
• reduced resistance to infection

Vitamin A Overdose

Excessive vitamin A is stored in liver. This can cause liver, bone damage, double vision, headache and other side effects because excessive vitamin A can be poisoness.