Vitamina
An is one of a grouping of fat soluble vitamins that are necessary for life and health.
Vitamin A plays a critical role in :
Vision
Epithelial differentiation
Expansion
Reproduction
Pattern formation during embryogenesis
Bone development
Hematopoiesis
Brain development
Immunological response function
Vitamina
Certain carotenoids, such as beta-carotene alpha-carotene and beta-cryptoxanthin, are dietary precursors of vitamin A. Communally, these substances are called provitamin
A.
All the fat soluble vitamins, including A,D,E,K and F are stored in the body tissues and can accumulate poisonous quantities if used too frequently. Inadequacies of these vitamins are also answerable for a spread of health and disease Problems. It is , vital to maintain the intake of fat soluble vitamins between the deficiency and toxicity levels.
Vitamina
Preformed vitamin A springs from animal sources while provitamin A, or the carotenes, are obtained from plant sources. Preformed vitamin An is present in food in the shape of retinyl esters. The principal nutritive supplement types of preformed vitamin An are retinyl palmitate and retinyl acetate. Preformed vitamin An is efficiently soaked up from the small intestines with a potency of from 60%-90%. Vitamin An absorption needs bile salts, pancreatic enzymes and dietary fat.
The carotenes, provitamin A, are water-soluble and readily soaked up. Excess consumption of carotenes can cause the skin and whites of the eyes to turn yellow. This is not dangerous and goes away when carotene consumption is reduced.
Vitamin A Deficiency
Notwithstanding vitamin A's reputation for potential poisonousness, vitamin A deficiency is far more common than cases of poisonousness. There are an estimated 2 hundred cases of hypervitaminosis An annually versus one million persons developing vitamin A deficiency each year. In underdeveloped nations vitamin A deficiency is the second most typical health problem and leads to progressive blindness. In the States, the NHANES II study showed twenty percent or even more of the populace was receiving less than seventy pc of the RDA of vitamin A. A deficit is particularly urgent while carrying a child when a vitamin A deficiency can result in birth imperfections. The World Health Organisation guesstimates that there are 250 million preschool-age kids worldwide whose health may be compromised by vitamin A deficiency.
Vitamina
Danger to the fetus from high measures of preformed vitamin A ( as well as from a vitamin A deficiency ) is a risk in the initial few weeks of pregnancy. The intake of vitamin An and vitamin An equivalents must be adequate, and not excessive in the month before pregnancy and while carrying a child. The most ordinarily reported source of excess vitamin A-caused birth defects is the dermatological use of vitamin An analogs like Accutane, Roaccutane, and Tigasan. These, then, need to be used under a physician's supervision and abandoned a month or even more prior to any pregnancy.
Vitamin A deficiency can be due to :
Insufficient nutritional intake of vitamin An or provitamin A
Malabsorption syndromes ( cystic fibrosis, Whipple's illness, Crohn's disease, ulcerative colitis, short bowel syndrome )
Pancreatic disease
Protracted liver disease
Weightloss Surgery
Vitamina
Forms of Vitamin A
The parent compound of the vitamin A family is all-trans-retinol. It is also the most abundant dietary form of vitamin A. All-trans-retinol occurs commonly in the kind of greasy acid esters,eg vitamin A palmitate ( retinyl palmitate ). Vitamin A palmitate and vitamin An acetate ( retinyl acetate ) are the principal forms used as nutritional additions. Natural sources, for example fish liver oils are also used as sorces of vitamin A.
The carotenes particularly beta carotene are often confused with vitamin A. Carotenes are not vitamin A. Rather, they are compounds that can be converted by the liver into vitamin A. Carotenes by themselves don't have vitamin An activity or poisonousness. They are thus not as efficient as a vitamin A supplement nor as toxic as vitamin A when utilized in excess amounts.
An is one of a grouping of fat soluble vitamins that are necessary for life and health.
Vitamin A plays a critical role in :
Vision
Epithelial differentiation
Expansion
Reproduction
Pattern formation during embryogenesis
Bone development
Hematopoiesis
Brain development
Immunological response function
Vitamina
Certain carotenoids, such as beta-carotene alpha-carotene and beta-cryptoxanthin, are dietary precursors of vitamin A. Communally, these substances are called provitamin
A.
All the fat soluble vitamins, including A,D,E,K and F are stored in the body tissues and can accumulate poisonous quantities if used too frequently. Inadequacies of these vitamins are also answerable for a spread of health and disease Problems. It is , vital to maintain the intake of fat soluble vitamins between the deficiency and toxicity levels.
Vitamina
Preformed vitamin A springs from animal sources while provitamin A, or the carotenes, are obtained from plant sources. Preformed vitamin An is present in food in the shape of retinyl esters. The principal nutritive supplement types of preformed vitamin An are retinyl palmitate and retinyl acetate. Preformed vitamin An is efficiently soaked up from the small intestines with a potency of from 60%-90%. Vitamin An absorption needs bile salts, pancreatic enzymes and dietary fat.
The carotenes, provitamin A, are water-soluble and readily soaked up. Excess consumption of carotenes can cause the skin and whites of the eyes to turn yellow. This is not dangerous and goes away when carotene consumption is reduced.
Vitamin A Deficiency
Notwithstanding vitamin A's reputation for potential poisonousness, vitamin A deficiency is far more common than cases of poisonousness. There are an estimated 2 hundred cases of hypervitaminosis An annually versus one million persons developing vitamin A deficiency each year. In underdeveloped nations vitamin A deficiency is the second most typical health problem and leads to progressive blindness. In the States, the NHANES II study showed twenty percent or even more of the populace was receiving less than seventy pc of the RDA of vitamin A. A deficit is particularly urgent while carrying a child when a vitamin A deficiency can result in birth imperfections. The World Health Organisation guesstimates that there are 250 million preschool-age kids worldwide whose health may be compromised by vitamin A deficiency.
Vitamina
Danger to the fetus from high measures of preformed vitamin A ( as well as from a vitamin A deficiency ) is a risk in the initial few weeks of pregnancy. The intake of vitamin An and vitamin An equivalents must be adequate, and not excessive in the month before pregnancy and while carrying a child. The most ordinarily reported source of excess vitamin A-caused birth defects is the dermatological use of vitamin An analogs like Accutane, Roaccutane, and Tigasan. These, then, need to be used under a physician's supervision and abandoned a month or even more prior to any pregnancy.
Vitamin A deficiency can be due to :
Insufficient nutritional intake of vitamin An or provitamin A
Malabsorption syndromes ( cystic fibrosis, Whipple's illness, Crohn's disease, ulcerative colitis, short bowel syndrome )
Pancreatic disease
Protracted liver disease
Weightloss Surgery
Vitamina
Forms of Vitamin A
The parent compound of the vitamin A family is all-trans-retinol. It is also the most abundant dietary form of vitamin A. All-trans-retinol occurs commonly in the kind of greasy acid esters,eg vitamin A palmitate ( retinyl palmitate ). Vitamin A palmitate and vitamin An acetate ( retinyl acetate ) are the principal forms used as nutritional additions. Natural sources, for example fish liver oils are also used as sorces of vitamin A.
The carotenes particularly beta carotene are often confused with vitamin A. Carotenes are not vitamin A. Rather, they are compounds that can be converted by the liver into vitamin A. Carotenes by themselves don't have vitamin An activity or poisonousness. They are thus not as efficient as a vitamin A supplement nor as toxic as vitamin A when utilized in excess amounts.
Source...