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Hormonal regulation of calcium and phosphorus homeostasis
Hormonal regulation of calcium and phosphorus homeostasis

... – 1, 25 (OH)2D3 receptor complex binds with vitamin D in the promoter region of PTH gene and inhibits transcription decreases the production of PTH – PTH synthesis can be enhanced by the size and number of PTH producing chief cells in cases of prolonged ...
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Simple Food Group Diversity as a Proxy Indicator for Iron and

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Via - Supplements and Performance Enhancers
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Feeding Insectivorous Reptiles and Amphibians

... with the Ca powder and shake. The dusted insects should be offered right away as they will groom off the Ca within several hours. Many geckos, particularly reproductively active females and young growing animals, will take powdered Ca directly from dishes left in the cage. Keep in mind that multivit ...
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... and the storage amount re use if needed , thus people can eat these vitamins less than their daily need for days, weeks, or months or years and also because of this fact ( Fat soluble vitamins not excreted but stored ) , the risk of toxicity is greater than water soluble vitamins. ...
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... saturated fats in meat and dairy because hydrogenation produces trans-fatty acids, which cause atherosclerosis. • Iron supplementation should generally be avoided unless prescribed for iron-deficiency anemia. Iron promotes oxidation and free-radical damage to cells and membranes. Iron may interfere ...
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Vitamin A



Vitamin A is a group of unsaturated nutritional organic compounds, that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids, and beta-carotene. Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vision. Vitamin A is needed by the retina of the eye in the form of retinal, which combines with protein opsin to form rhodopsin, the light-absorbing molecule necessary for both low-light (scotopic vision) and color vision. Vitamin A also functions in a very different role as retinoic acid (an irreversibly oxidized form of retinol), which is an important hormone-like growth factor for epithelial and other cells.In foods of animal origin, the major form of vitamin A is an ester, primarily retinyl palmitate, which is converted to retinol (chemically an alcohol) in the small intestine. The retinol form functions as a storage form of the vitamin, and can be converted to and from its visually active aldehyde form, retinal.All forms of vitamin A have a beta-ionone ring to which an isoprenoid chain is attached, called a retinyl group. Both structural features are essential for vitamin activity. The orange pigment of carrots (beta-carotene) can be represented as two connected retinyl groups, which are used in the body to contribute to vitamin A levels. Alpha-carotene and gamma-carotene also have a single retinyl group, which give them some vitamin activity. None of the other carotenes have vitamin activity. The carotenoid beta-cryptoxanthin possesses an ionone group and has vitamin activity in humans.Vitamin A can be found in two principal forms in foods:Retinol, the form of vitamin A absorbed when eating animal food sources, is a yellow, fat-soluble substance. Since the pure alcohol form is unstable, the vitamin is found in tissues in a form of retinyl ester. It is also commercially produced and administered as esters such as retinyl acetate or palmitate.The carotenes alpha-carotene, beta-carotene, gamma-carotene; and the xanthophyll beta-cryptoxanthin (all of which contain beta-ionone rings), but no other carotenoids, function as provitamin A in herbivores and omnivore animals, which possess the enzyme beta-carotene 15,15'-dioxygenase which cleaves beta-carotene in the intestinal mucosa and converts it to retinol. In general, carnivores are poor converters of ionone-containing carotenoids, and pure carnivores such as cats and ferrets lack beta-carotene 15,15'-dioxygenase and cannot convert any carotenoids to retinal (resulting in none of the carotenoids being forms of vitamin A for these species).↑ ↑ 2.0 2.1 ↑ ↑ ↑ ↑ ↑ ↑
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