D Calciferol

Note A vitamin is defined as an organic dietary substance required in trace amounts (pg to mg/d) by humans for health. 

It is found in spinach, cabbage, and other green leafy vegetables pork, liver, and green tea. 

It is found in fortified milk and butter, egg yolks, fatty fish and fish-liver oils. It is also made by 

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D Calciferol Maintenance of calcium balance enhances intestinal absorption of Ca and mobilizes bone mineral Rickets = poor mineralization of bone osteomalacia = bone demineralization... 

Vitamin D (calciferol) Produced in skin by action of ultraviolet Controls calcium uptake into the body and... 

Vitamin D (calciferol) Helps incorporate calcium into body Weak bones... 

However, it was not until 1924, when Steenbock and Hess showed that irradiation of certain foods generated protective activity against the disease, that vitamin D (calciferol) was recognized as a second lipid-soluble vitamin. Vitamin D is a family of compounds formed by the irradiation of A5/7-unsaturated sterols such as ergosterol and 7-dehydrocholesterol. The former yields ergocalciferol (vitamin D2) and the latter cholecalciferol (vitamin D3). 

As a brief introductory summary, vitamin D substances perform the following fundamental physiological functions (1) promote normal growth (via bone growth) (2) enhance calcium and phosphorus absorption from the intestine (3) serve to prevent rickets (4) increase tubular phosphorus reabsorpiion (5) increase citrate blood levels (6) maintain and activate alkaline phosphatase m bone (7) maintain serum calcium and phosphorus levels. A deficiency of D substances may be manifested in the form of rickets, osteomalacia, and hypoparathyroidism. Vitamin D substances are required by vertebrates, who synthesize these substances in the skin when under ultraviolet radiation, Animals requiring exogenous sources include infant vertebrates and deficient adult vertebrates, Included there are vitamin D (calciferol ergocalciferol) and vitamin D< (activated 7-dehydrocholesterol cholecalciferol). 

In 1918, Mellanby produced experimental rickets in dogs. In 1919, Huldschinsky ameliorated rachitic symptoms in children with ultraviolet radiation. Hess, in 1922, showed that liver oils contain the same antirachitic factor as sunlight In that same year, McCollum increased calcium deposition in rachitic rats with cod liver oil factor. In 1924. Steenbook and Hess demonstrated irradiated foods have antirachitic properties, It was in 1925 that McCollum named antirachitic factor as vitamin D. In 1931, Angus isolated crystalline vitamin D (calciferol). In 1936, Windaus isolated vitamin D3 (activated 7-dehydrocholesterol). 

Naturally occurring fats contain small amounts of soluble minor consituents pigments (carotenoids, chlorophyll, etc.), sterols (phytosterols in plant fats, cholesterol in animal fats), vitamin A (from carotenes), vitamin D (calciferol), waxes (esters of long-chain alcohols and fatty acids), ethers, and degradation products of fatty acids, proteins, and carbohydrates. Most of these minor compounds are removed in processing, and some are valuable by-products. 

Vitamin D [calciferol) Men women 5-15 pg/d Maintain serum calcium and phosphorus concentrations prevents rickets Hypercalcemia secondary to elevated vitamin D metabolites in plasma... 

FIGURE 29.5 Chemical structure of vitamin D (calciferol, term for a collection of fat-soluble steroid-like substances that are regulating the calcium and phosphate metabolism). Cholecalciferol (R =R2=R3=H), Calcitriol (R1=R2=OH, R3=H). 

Ergosterol is converted into vitamin D (calciferol) by cutting the second ring between two carbon atoms and forming a methylene group as follows ... 

Calcium is essential for the normal growth and development of the body, especially (in the form of calcium phosphate) of the bones and teeth. Its level in the blood is regulated by the opposing actions of the thyroid hormone calcitonin, and the parathyroid hormone parathormone. Its uptake from food is enhanced by vitamin D (calciferol). Forms of calcium used therapeutically include the folinic acid supplement calcium foiinate, and the mineral supplements calcium bicarbonate, calcium carbonate, calcium gluconate and calcium lactate. 

Vitamin D) (Calciferol, Deltalin, Gelseals, Drisdol, Vitamin D capsules)... 

D (calciferol) Fish-Uver oils, fortified mUk Regulation of calcium and phosphorus metabolism Rickets (maifonnation of the bones)... 

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