What is vitamin A? What are the sources of vitamin A? These are the top two questions many people ask daily about this all-important vitamin. This vitamin is involved in numerous bodily processes.
Function of vitamin A:
vision, growth, bone and tooth development, maintenance of the health of the skin and mucosa, and protection against cancer. Additionally, carotenes and carotenoids are antioxidants, so they protect the heart and the arteries.
Chemical composition of vitamin A: two substances are included under the name vitamin A:
- Vitamin A itself: retinol and dehydroretinol. They are found in animal-based foods. In large amounts, they are toxic.
- Provitamin A: carotenes and similar substances called carotenoids. There are about ten different carotenes, the most active of which is beta-carotene. They transform to vitamin A in the intestine, answering the body’s needs and presenting no risk of toxicity.
Sources of vitamin A
- Vitamin A (retinol): animal liver and milk fat are the richest sources.
- Provitamin A (carotenes and carotenoids): all red and orange vegetables, particularly carrots and peppers, and some dark green spinach.
- Units of measurement: the amount of active vitamin A in foods is measured in micrograms of retinol equivalent (µg RE).
- 1 µg RE= 1 µg of retinol = 6 µg of beta carotene = 12 µg of other carotenoids = 3.33 IU of vitamin A = 10 IU of carotenes 1 IU of vitamin A = 0.3 µg RE
| Food | Quantity |
|---|---|
| Sweet corn | 28.0 µg RE |
| Red tomato | 62.0 µg RE |
| Loquat | 153 µg RE |
| Broccoli | 154 µg RE |
| Squash | 160 µg RE |
| Lettuce | 260 µg RE |
| Cantaloupe melon | 322 µg RE |
| Mango | 389 µg RE |
| Watercress | 470 µg RE |
| Sweet red pepper | 570 µg RE |
| Chard | 610 µg RE |
| Spinach | 672 µg RE |
| Lamb’s lettuce | 709 µg RE |
| Dried apricot | 724 µg RE |
| Corn oil margarine | 799 µg RE |
| Carrot | 2,813 µg RE |
| Beef | 0.000 µg RE |
| Pork | 2.00 µg RE |
| Chicken | 16.0 µg RE |
| Tuna, canned in oil | 23.0 µg RE |
| Herring | 28.0 µg RE |
| Whole cow’s milk | 31.0 µg RE |
| Grouper | 43.0 µg RE |
| Baked chicken | 47.0 µg RE |
| Nonfat milk | 61.0 µg RE |
| Sardine | 70.0 µg RE |
| Fresh egg | 191 µg RE |
| Whipping cream | 421 µg RE |
| Butter | 754 µg RE |
| Beef liver | 4,427 µg RE |
Plant-based foods provide more vitamin A than animal products, and without the risk of over-accumulation and toxic effects.
Vitamin Deficiency Symptoms:
Vision disorders, dry skin, and fetal developmental disorders.
Increased need:
Growth periods (children and adolescents), pregnancy, and nursing.
Loss during the processing of foods:
15% to 35% of the vitamin A is lost through cooking. Dehydration and exposure to light, particularly ultraviolet, destroy provitamin, and vitamin A. Freezing has little effect on vitamin A.
REFERENCES
George D. Pamplona-Roger, M.D. “Encyclopedia of Foods and Their Healing Power.” George D. Pamplona-Roger, M.D. Encyclopedia of Foods and Their Healing Power. Trans. Annette Melgosa. Vol. 1. Chai Wan: Editorial Safeliz, 2005. 389. Print. [sources of vitamin A]
