Definition
Vitamin A is a fat-soluble vitamin and is found in two forms, retinol and beta carotene. Retinol is found in the animal kingdom, beta carotene in the plant kingdom. Beta carotene is often called provitamin A, and is converted into retinol in humans in the small intestine mucosa. There are more than 150 different carotenes. You can also make artificial vitamin A and beta carotene. Vitamin A is stored in the liver, kidneys, lungs, eyes and in the fatty tissue, and it excretes with the stool and urine.
Zinc is important for the storage of vitamin A to be used.
Permitted daily doses
According to the government's nutrition council, the maximum daily dose is for:
Vitamin A: 1500μg
Beta carotene: 9000μg
In Norway, an intake of vitamin A is recommended at 1000μg.
We get Vitamin A through eating oily fish, fish liver, milk, cheese, eggs. Butter and margarine. Carrot and green vegetabeles, such as spinach, are rich in beta carotene.
Function
Vitamin A is part of a variety of biochemical and physiological processes in the body. It is important for sight, especially dark vision.
Vitamin A is important for growth, bone formation and normal fetus development, for reproduction and for the cells on the surface of skin and mucous membranes.
Beta carotene is an important antioxidant and therefore protects cells and other structures against damage caused by free radicals.
Vitamin A also works to strengthen the immune system and may be important in chronic diseases.
Practical use
Vitamin A deficiency symptoms are rare, but symptoms such as decreased night vision, dry skin bumps, tiled nails and sensitive airways mucous membranes may be indicative of deficiencies.
To prevent deficiencies, it is recommended to take:
Vitamin A: 2000μg per day
Beta carotene: 5000μg per day
Children:
Vitamin A: 400μg per day
Beta carotene: 600μg per day
Smokers, alcoholic and elderly consumers should take vitamin A.
Cancer patients can use up to 30,000μg daily for 4 weeks, then reduce the dose to 10,000μg daily over time. This must be done in consultation with a physician.
Psoriasis and acne can take up to 30,000μg daily for 4-8 weeks.
To get the best vitamin A supplement, it is important to add zinc, C, D and Vitamin E.
Pregnant should not take doses of more than 3000μg of vitamin A and 5000μg of beta carotene.