Some Facts about Vitamin A
Filed Under Nutritional Supplements
The detection of vitamin A have fallen within a period from 1906 to 1917 when a “fat-soluble factor A” (vitamin A) was discovered practically shortly before a “water-soluble factor B” (Vitamin B). It was first synthesized in 1947 by two David Adriaan van Dorp and Jozef Ferdinand Arens.
This vitamin plays an essential role in vision, particularly night vision, normal bone and tooth development, reproduction, and the health of skin and mucous membranes (the mucus-secreting layer that lines body regions such as the respiratory tract). Vitamin A is also a well known antioxidant, a protective chemical that may reduce the risk of certain cancers.
So Vitamin A is significant in a variety of body functions, such as:
• Vision
• Gene transcription
• Immune function
• Embryonic development and reproduction
• Bone metabolism
• Haematopoiesis
• Skin health (is necessary to maintain normal skin health)
• Reducing risk of heart disease
• Antioxidant Activity
There are two sources of dietary vitamin A. Active forms, which are immediately available to the body, are derived from animal products. These forms are known as retinoids. Precursors, also known as provitamins, which must be converted to active forms by the body, are obtained from fruits and vegetables containing yellow, orange and dark green pigments, known as carotenoids, the most well-known being beta-carotene.
Vitamin A is abundant in
- Animal products: liver, butter, milk toppings, cheese, vitellus, fish-oil, liver of sea animals;
- Bright orange vegetables: carrots, a pumpkin, a sweet potato, tomatoes;
- Dark green sheet vegetables: spinach, dock, sheet cabbage, beet leaves, marrow squash, grass, chicory;
- Bright orange fruit: apricots, a melon-muskmelon, a mango, watermelon, sea-buckthorn;
- Sea-buckthorn-oil.
Vitamin A is fat-soluble and body can preserve it. Most of the vitamin A you get is preserved in the liver. When it is necessary, the liver releases some vitamin A, and it is delivered by the blood to the particular part of the body.
Recommended daily intake:
Children: 1-3 years – 300 mgday, 4-8 years – 400 mgday;
Teens: boys 9-13 years – 600 mgday, boys 14 -18 years – 900 mgday, girls 9-13 years – 600 mgday, girls 14 -18 years – 700 mgday;
Females: after 20 years – 700 mgday;
Pregnancy: before 19 years – 750 mgday, after 19 years – 770 mgday;
Lactation: before 19 years – 1200 mgday, after 19 years – 1300 mgday;
Males: after 20 years – 900 mgday.
Carole is the author of some web-blogs in Health category. You can find more interesting and useful information at Vitamins And Minerals Blog and Ideal Weight Blog. Article Source:http://www.articlesbase.com/supplements-and-vitamins-articles/some-facts-about-vitamin-a-1167216.html
