Well, the word "vitamin" comes from the term "vital amine," and vitamins A, B, C, D, and E were named in order of their discovery.
This makes vitamin A the first compound officially recognized as being essential to health.
Why Do We Need Vitamin A?Vitamin A is necessary for much more than growth. It’s essential for the health of your eyes, protection of your lungs and skin, formation of bones and teeth, prevention of infections and tumors, and much more.
It’s also necessary for all of the cells that line every area of your body. While severe deficiency is rare in the West, it’s actually a common cause of blindness in developing countries.
Dietary Sources of Vitamin ASome carotenoids, particularly beta-carotene, can be converted to vitamin A when needed by the body. Beta-carotene gives yellow and orange vegetables, such as squash, pumpkins, sweet potatoes and carrots, their golden hue.
The amount of carotene needed to produce vitamin A varies, since it depends upon the amount of fat ingested with carotenes, which increases their absorption. However, some people — due to inherited conditions, digestive problems or other conditions — do not efficiently convert carotenoids from beta-carotene. These people must obtain vitamin A from food (liver, for example) or from supplements.
How Much Vitamin A is Too Much?It’s certainly possible to get too much vitamin A. It’s fat soluble, which means that it’s stored in the fatty tissues of your body. Although rare, higher doses taken for long periods of time may increase the risk of toxicity.
Unlike water-soluble vitamins, which should be taken throughout the day, vitamin A can be taken once per day. There is no harm in taking frequent doses as long as they are low.
A couple of recent studies have associated high vitamin A intake with an increased risk of osteoporosis. However, a study published in 2009 involving over 75,000 postmenopausal women failed to find an increased risk of hip or total fractures1.
Regardless, it’s important to limit your intake according to your requirements, unless suggested otherwise by a doctor.
The Bottom LineThe importance of vitamin A, "the first vitamin," shouldn't be minimized - make sure that your diet contains adequate amounts of this vital nutrient. If not, supplement as needed!
- Caire-Juvera G et al. Am J Clin Nutr. 2009 Jan;89(1):323-30.
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