Vitamin A is found in both animal and vegetable sources. From animal sources, vitamin A comes complete in the forms of retinal and dehydroretinol. From vegetable sources we can get four different forms of carotene, alpha, beta, gamma, and crypto, and our bodies can manufacture vitamin A if we have enough beta-carotene.
1) Vitamin A is needed for healthy skin and good night vision.
2) The immune system is assisted by vitamin A and it is thought that vitamin A is an antioxidant that protects against cancer, air pollution, and other diseases.
3) Vitamin A is involved in the formation of teeth and bones.
4) The storage of fat is aided by vitamin A.
5) Vitamin A is an essential nutrient for the synthesis of glycogen and protein.
6) Vitamin A helps to develop and maintain the mucus membranes.
7) The digestive and urinary tracts require vitamin A to function properly.
8) Vitamin A can be toxic if recommended dosage levels are exceeded.
9) A deficiency of Vitamin A when young may impair growth.
10) Soaking foods in water that are rich in beta-carotene for long periods of time can destroy the nutrient and result in little, or no, vitamin A being manufactured from them.
Good food sources of vitamin A, or those high in the beta-carotene our bodies turn into vitamin A, include dark green leafy vegetables, yellow fruits, carrots, liver, egg yolks, and milk. The recommended daily allowances of vitamin A are 5,000 IU (international units) for males and 4,000 IU of vitamin A for women. Above 15,000 IU per day vitamin A can be toxic - and some people experience toxicity at lower levels. If ever somebody tries to feed you polar bear liver, watch out! A half pound of it gives you about 9,000,000 IU of vitamin A - enough to cause serious trouble (other animals’ livers are not so vitamin A dense).
Pregnant women must be careful of their vitamin A intake because high levels of it can cause birth defects. Most people get enough vitamin A in their normal diets, but, should your diet not include many of the foods that feature vitamin A, or if you are a heavy drinker, vitamin A supplements are easily available, just be careful of the amount you take - and don’t order the polar bear liver!
Copyright © Dennis Becker, 2004.
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