Your mother always told you to make sure you got your vitamins---from A to Z. Actually, there isn't a vitamin Z, but there are over 12 different vitamins that are necessary for the human body to function properly. Let's take a look at the first one on the list---vitamin A.
Vitamin A was discovered in 1917. It was actually discovered simultaneously by two separate researchers at two different universities. As the first fat-soluble vitamin to be actually isolated and named, it was dubbed "fat-soluble factor A." At that point, there was very little known about vitamins, but they did know that this new vitamin could help to cure rickets in rats.
What is Vitamin A Good For?
Now, scientists have an impressive list of the benefits of vitamin A. The most well-known benefit is the health of our vision. The reason carrots are good for your eyes is because they are chock full of vitamin A. Also, this vitamin strengthens the immune system as well as promotes healthy cell reproduction. A form of vitamin A is also one of the most effective treatments for acne.
Recommended Daily Allowance
Because of it's importance in cell growth and reproduction, infants have a high adequate intake (AI) for vitamin A. An official RDA has not been set for infants. Males generally need more than females, but breast-feeding mothers need nearly twice the normal levels.
Infants: 500 mcg Age 1 to 3: 300 mcg Age 4 to 8: 400 mcg Age 9 to 13: 600 mcg Age 14 to Adult, Male: 900 mcg Age 14 to Adult, Female: 700 mcg Breastfeeding Mothers: 1,300 mcg
How to Get Your Vitamin A
Many foods are rich in vitamin A, and it is not hard to get the recommended daily allowance. The best animal source of vitamin A is beef liver. Liver was used to cure vitamin A deficiency even before vitamin A was isolated and named. Pretty much any brightly colored vegetable will have plenty of vitamin A. Some particularly rich foods are carrots, spinach, kale and cantaloupe.
Since this is a fat-soluble vitamin, there is a much higher risk of overdose and toxicity than with water-soluble vitamins such as vitamin C. Any excess fat-soluble vitamin is stored in the body instead of being passed like excess water-soluble vitamins are. There is a disease associated with vitamin A toxicity with the formidable name of "hypervitaminosis A," which causes osteoporosis and nervous disorders. Adults should not consume over 2,800 mcg of preformed vitamin A per day, and children should not have more than 600 to 900 mcg. A one cup serving of carrots has over 600 percent of the RDA of vitamin A. One cup of boiled spinach contains 150 percent. Similarly sized servings of cantaloupe and kale both have close to 100 percent. This sounds pretty scary, but you don't need to worry about eating too many carrots. Toxicity from vegetable forms of vitamin A is very rare; it occurs only in overdose of preformed vitamin A, which is the kind you get in dietary supplements. If you are eating plenty of fresh fruits and vegetables, you don't need to take vitamin A supplements at all.