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problem or disease, or prescribing any medication. Information about each product is taken from the labels of the products or from the
manufacturer's advertising material. Straight from the Clay.com. is not responsible for any statements or claims that various
manufacturers make about their products. We cannot be held responsible for typographical errors or product formulation changes. You
should read carefully all product packaging. If you have or suspect that you have a medical problem, promptly contact your health
care provider. Information and statements regarding dietary supplements have not been evaluated by the Food and Drug
Administration and are not intended to diagnose, treat, cure, or prevent any disease.
physician or other medical professional. You should not use the information contained herein for diagnosing or treating a health
problem or disease, or prescribing any medication. Information about each product is taken from the labels of the products or from the
manufacturer's advertising material. Straight from the Clay.com. is not responsible for any statements or claims that various
manufacturers make about their products. We cannot be held responsible for typographical errors or product formulation changes. You
should read carefully all product packaging. If you have or suspect that you have a medical problem, promptly contact your health
care provider. Information and statements regarding dietary supplements have not been evaluated by the Food and Drug
Administration and are not intended to diagnose, treat, cure, or prevent any disease.
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Digestive Enzymes, Probiotics, Vitamins, Minerals, Phytonutrients, Fatty Acids
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| Complementary Alternative Medicine (CAM). |
Water Soluble Vitamins
Fat Soluble Vitamins
Fat Soluble Vitamins
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Vitamins
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Vitamin A (Retinol)
See also: Beta-carotene
General description
Vitamin A is a fat-soluble nutrient involved in a wide variety of bodily functions.
In its pure, isolated form, vitamin A appears as a yellow, crystalline substance
known as retinol or preformed vitamin A. The body readily converts retinol into
the active forms retinal (or retinaldehyde) and retinoic acid. Beta-carotene, a
pigment found in green, orange, and yellow vegetables, can be metabolized in
the body to yield retinol and is the best nonanimal source of the vitamin. For
this reason, beta-carotene is often described as a provitamin A carotenoid.
Food sources
Good sources of preformed vitamin A include liver, fish liver oils, eggs, and
dairy products. Rich sources of beta-carotene include carrots, spinach, sweet
potatoes, bell peppers, squash, broccoli, and apricots.
Health applications
Vision
Immune function
Skin health
Growth and development
Functions and uses
Vitamin A is known to play an essential role in eye function.1 Vitamin A is also
required for normal growth and development of the body, hormone production,
immune system function, and for maintaining healthy skin. It is also important
for maintaining the integrity of the mucous membranes in the respiratory,
urinary, and digestive tracts.
Vision
Vitamin A is a key component of rhodopsin, a pigment needed by the eye to
initiate biochemical responses to visual stimuli. Low serum vitamin A levels
have been associated with night blindness,2-4 and numerous studies have
shown night blindness to improve with vitamin A supplementation.3-5
Dosage/toxicity
Vitamin A has traditionally been measured in international units (IU), but can
also be measured in micrograms (mcg) or retinol equivalents (RE). Although
optimum intake of vitamin A may vary with age and gender, 5,000 IU per day is
considered adequate for most people. Because vitamin A is a fat-soluble
compound that is stored in the liver, long-term, high-dose supplementation
(over 50,000 IU per day for adults, over 25,000 IU per day for children) can
result in toxic accumulations. For adult men and post-menopausal women, up
to 25,000 IU per day is generally considered safe. Because high retinol intake
has been associated with increased risk for birth defects, women who are or
may become pregnant should not consume more than 10,000 IU per day.17
Beta-carotene may be a safer source of vitamin A for these women because it
is not associated with birth-defect risk.18,19
See also: Beta-carotene
General description
Vitamin A is a fat-soluble nutrient involved in a wide variety of bodily functions.
In its pure, isolated form, vitamin A appears as a yellow, crystalline substance
known as retinol or preformed vitamin A. The body readily converts retinol into
the active forms retinal (or retinaldehyde) and retinoic acid. Beta-carotene, a
pigment found in green, orange, and yellow vegetables, can be metabolized in
the body to yield retinol and is the best nonanimal source of the vitamin. For
this reason, beta-carotene is often described as a provitamin A carotenoid.
Food sources
Good sources of preformed vitamin A include liver, fish liver oils, eggs, and
dairy products. Rich sources of beta-carotene include carrots, spinach, sweet
potatoes, bell peppers, squash, broccoli, and apricots.
Health applications
Vision
Immune function
Skin health
Growth and development
Functions and uses
Vitamin A is known to play an essential role in eye function.1 Vitamin A is also
required for normal growth and development of the body, hormone production,
immune system function, and for maintaining healthy skin. It is also important
for maintaining the integrity of the mucous membranes in the respiratory,
urinary, and digestive tracts.
Vision
Vitamin A is a key component of rhodopsin, a pigment needed by the eye to
initiate biochemical responses to visual stimuli. Low serum vitamin A levels
have been associated with night blindness,2-4 and numerous studies have
shown night blindness to improve with vitamin A supplementation.3-5
Dosage/toxicity
Vitamin A has traditionally been measured in international units (IU), but can
also be measured in micrograms (mcg) or retinol equivalents (RE). Although
optimum intake of vitamin A may vary with age and gender, 5,000 IU per day is
considered adequate for most people. Because vitamin A is a fat-soluble
compound that is stored in the liver, long-term, high-dose supplementation
(over 50,000 IU per day for adults, over 25,000 IU per day for children) can
result in toxic accumulations. For adult men and post-menopausal women, up
to 25,000 IU per day is generally considered safe. Because high retinol intake
has been associated with increased risk for birth defects, women who are or
may become pregnant should not consume more than 10,000 IU per day.17
Beta-carotene may be a safer source of vitamin A for these women because it
is not associated with birth-defect risk.18,19