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Vitamin E was discovered by Evans and Bishop - ... Greek words
‘‘tokos’’ (childbirth), ‘‘phero’’ (to bring forth), and ‘‘ol’’...
DEFICIENCY SIGNS AND METHODS OF NUTRITIONAL ASSESSMENT - ...gs (241).
Whole-blood clotting times, which were used in early work, are notoriously inaccurate,
variable, and insensitive and should not be use...
The absorption of nonpolar lipids - ... but as much as 70–80% of the ingested phylloquinone was excreted unaltered
in the feces of patients with impaired fat absorption caused by o...
The discovery of vitamin K - ...e disease was subsequently observed by McFarlene et al. (2), who described
a clotting defect seen when chicks were fed ether-extracted fish or meat...
FOOD SOURCES OF VITAMIN D - ...f, unfortified milk, and butter supply only small quantities
of the vitamin. Plants are extremely poor sources of vitamin D; fruits and nuts contai...
Vitamin D isolation - ... (60).
Over the years, a wide variety of chromatographic techniques have been used to
separate vitamin D and its metabolites. These include pape...
Vitamin D designates a group of closely related compounds - ...1960s. Cholecalciferol is the form of vitamin D obtained when radiant energy
from the sun strikes the skin and converts the precursor 7-dehydrochol...
Preformed vitamin A of animal tissues - ...In the presence of bile salts, the globules are broken up into smaller lipid aggregates, which can be more easily digested by pancreatic lipase, retin...
Assessment of Vitamin A Status - ...integrated into a meaningful whole only by biological tests.
Biological methods for vitamin A include the classical growth response tests in
vit...
In nature vitamin A is largely found as an ester and - ...
from these oils by molecular distillation at very low pressure, a procedure that has been
used extensively for the commercial preparation of vit...
Vitamin E is involved in altering disease processes - ...sensitivity
skin tests, antibody production, lymphocyte proliferation, cytokine production, and
counts of the specific subgroups of white blood ...
Oxidation reactions are ubiquitous in biological cells and fluids - ...sses is largely accomplished by the free-radical transfer of electrons from highenergy
organic substrates to oxygen, forming carbon dioxide and wat...
LDLs become atherogenic when their basic - ...ation of LDL, and it has been proposed that part of the value of
diets rich in fruits and vegetables in reducing coronary disease is the provision ...
Ascorbic acid functions as a redox cofactor and catalyst - ...skin.
Aside from famine, scurvy has caused the most suffering of nutritional origin in human
history.
Those without access to fresh fruits an...
Choline is a dietary component that is important for normal functioning of all cells - ... methyl groups (3). Choline was discovered in 1862 and was chemically synthesized in
1866 (4). It was known to be a component of phospholipids, but...
Choline Deficiency in Animals - ...ment, bone abnormalities, decreased hematopoiesis, and hypertension (96–
99).
Choline Deficiency in Humans
Humans require chol...
BIOCHEMICAL FUNCTIONS of FOLATES - ...ate metabolism. Although the major pathways of
methionine, thymidylate, and purine synthesis occur in the cytosol, folate metabolism also
occurs...
The Folic Acid Functions - ...r and yeast and crystallized. Eventually, it was determined that the various antianemia
and growth factors all had a common structure, and they wer...
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Below is a list of all Vitamins articles. If you want to find a tutorial by keywords, all you have to do is a quick search in our directory. Just use the search option available at the top-right side of the page. The website search is powered by web-articles. Or, if you want to read specific Vitamins tutorial, just point to it. The newest articles and tutorials are shown first in the list. To access the last ones, browse the pages 2, 3, 4... at the bottom. Also, you may browse articles alphabetically ordered.
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Vitamin E was discovered by Evans and Bishop (11/30/2007)
(...) Subsequent studies have shown that neurologic abnormalities do occur in association with malabsorption syndromes of various etiologies (9,11,12). In recent years, the involvement of free radicals in the pathogenesis of degenerative diseases and the possible prevention or slow-down of the disease process by antioxidants have promoted a renewed and expanded interest in vitamin E. Intestinal Absorption Similar to lipid components, intestinal absorption of vitamin E depends on pancreatic function, biliary secretion, micelle formation, and transport across intestinal membrane (26,27). (...)
(...) Subsequent studies have shown that neurologic abnormalities do occur in association with malabsorption syndromes of various etiologies (9,11,12). In recent years, the involvement of free radicals in the pathogenesis of degenerative diseases and the possible prevention or slow-down of the disease process by antioxidants have promoted a renewed and expanded interest in vitamin E. Intestinal Absorption Similar to lipid components, intestinal absorption of vitamin E depends on pancreatic function, biliary secretion, micelle formation, and transport across intestinal membrane (26,27). (...)
DEFICIENCY SIGNS AND METHODS OF NUTRITIONAL ASSESSMENT (11/30/2007)
(...) Specific assays for factors VII and X are also available but are seldom used in studies of vitamin K sufficiency. The classic assay for prothrombin is a ‘‘two-stage’’ assay in which thrombin is generated from prothrombin in one tube and a sample of this added to fibrinogen in a second tube to measure thrombin concentration. This is a much more tedious procedure; although capable of giving an accurate measurement of the amount of prothrombin in a plasma sample, it has seldom been used for routine assay of vitamin K status. (...)
(...) Specific assays for factors VII and X are also available but are seldom used in studies of vitamin K sufficiency. The classic assay for prothrombin is a ‘‘two-stage’’ assay in which thrombin is generated from prothrombin in one tube and a sample of this added to fibrinogen in a second tube to measure thrombin concentration. This is a much more tedious procedure; although capable of giving an accurate measurement of the amount of prothrombin in a plasma sample, it has seldom been used for routine assay of vitamin K status. (...)
The absorption of nonpolar lipids (11/30/2007)
(...) The potential for absorption of the large-bowel menaquinone pool has been reviewed (90,91). Early, rather nonphysiological, experiments (92) demonstrated that MK-9 disappeared from the lumen of the isolated rat ileum or large intestine but did not document its appearance in plasma or lymph. Ichihashi et al. (...)
(...) The potential for absorption of the large-bowel menaquinone pool has been reviewed (90,91). Early, rather nonphysiological, experiments (92) demonstrated that MK-9 disappeared from the lumen of the isolated rat ileum or large intestine but did not document its appearance in plasma or lymph. Ichihashi et al. (...)
The discovery of vitamin K (11/30/2007)
(...) (8) succeeded in preparing a crude plasma prothrombin fraction and demonstrating that its activity was decreased when it was obtained from vitamin K–deficient chick plasma. At about the same period of time, the hemorrhagic condition resulting from obstructive jaundice or biliary problems was shown to be due to poor utilization of vitamin K by these patients, and the bleeding episodes were attributed to a lack of plasma prothrombin. The prothrombin assays used at that time were not specific for prothrombin, and it was widely believed that the defect in the plasma of animals fed vitamin K–deficient diets was due solely to a lack of prothrombin. (...)
(...) (8) succeeded in preparing a crude plasma prothrombin fraction and demonstrating that its activity was decreased when it was obtained from vitamin K–deficient chick plasma. At about the same period of time, the hemorrhagic condition resulting from obstructive jaundice or biliary problems was shown to be due to poor utilization of vitamin K by these patients, and the bleeding episodes were attributed to a lack of plasma prothrombin. The prothrombin assays used at that time were not specific for prothrombin, and it was widely believed that the defect in the plasma of animals fed vitamin K–deficient diets was due solely to a lack of prothrombin. (...)
FOOD SOURCES OF VITAMIN D (11/30/2007)
(...) (324). Humans A deficiency of vitamin D results in inadequate intestinal absorption and renal reabsorption of calcium and phosphate. As a consequence, serum calcium and phosphate levels fall and serum alkaline phosphatase activity increases. (...)
(...) (324). Humans A deficiency of vitamin D results in inadequate intestinal absorption and renal reabsorption of calcium and phosphate. As a consequence, serum calcium and phosphate levels fall and serum alkaline phosphatase activity increases. (...)
Vitamin D isolation (11/30/2007)
(...) Gas chromatography can separate these two compounds, but in the process vitamin D is thermally converted to pyrocalciferol and isopyrocalciferol, resulting in two peaks. High-performance liquid chromatography (HPLC) has become the method of choice for the separation of vitamin D and its metabolites (61,62). This powerful technique is rapid and gives good recovery with high resolution. (...)
(...) Gas chromatography can separate these two compounds, but in the process vitamin D is thermally converted to pyrocalciferol and isopyrocalciferol, resulting in two peaks. High-performance liquid chromatography (HPLC) has become the method of choice for the separation of vitamin D and its metabolites (61,62). This powerful technique is rapid and gives good recovery with high resolution. (...)
Vitamin D designates a group of closely related compounds (11/30/2007)
(...) Vitamin D is also important for phosphorus homeostasis (5,6). Calcium and phosphorus are required for a wide variety of biological processes (Table 1). Calcium is necessary for muscle contraction, nerve pulse transmission, blood clotting, and membrane structure. (...)
(...) Vitamin D is also important for phosphorus homeostasis (5,6). Calcium and phosphorus are required for a wide variety of biological processes (Table 1). Calcium is necessary for muscle contraction, nerve pulse transmission, blood clotting, and membrane structure. (...)
Preformed vitamin A of animal tissues (11/30/2007)
(...) Some types of fiber, e.g., highly methoxylated pectins, markedly reduce carotenoid absorption (43). (...)
(...) Some types of fiber, e.g., highly methoxylated pectins, markedly reduce carotenoid absorption (43). (...)
Assessment of Vitamin A Status (11/30/2007)
(...) The very richest sources are liver oils of shark; of marine fish, such as halibut; and of marine mammals, such as polar bear. With respect to carotenoids, carrots and green leafy vegetables, such as spinach and amaranth, generally contain large amounts. Although tomato contains some vitamin A– active carotenoids, the major pigment is lycopene, which has no nutritional activity. (...)
(...) The very richest sources are liver oils of shark; of marine fish, such as halibut; and of marine mammals, such as polar bear. With respect to carotenoids, carrots and green leafy vegetables, such as spinach and amaranth, generally contain large amounts. Although tomato contains some vitamin A– active carotenoids, the major pigment is lycopene, which has no nutritional activity. (...)
In nature vitamin A is largely found as an ester and (11/30/2007)
(...) 1e, which is the chromophore of the visual pigments rhodopsin and iodopsin; 9-cis retinoic acid (. 1f), which is the ligand for the retinoid X receptor (RXR) transcription factors; and 13-cis retinal, which serves lightdependent functions in halobacteria. As the number of cis bonds increase, both the absorption maximum of the isomer and its absorbance tend to decrease. (...)
(...) 1e, which is the chromophore of the visual pigments rhodopsin and iodopsin; 9-cis retinoic acid (. 1f), which is the ligand for the retinoid X receptor (RXR) transcription factors; and 13-cis retinal, which serves lightdependent functions in halobacteria. As the number of cis bonds increase, both the absorption maximum of the isomer and its absorbance tend to decrease. (...)
Vitamin E is involved in altering disease processes (11/30/2007)
(...) Vitamin E may protect against cancer development by reacting directly with mutagens/carcinogens, altering metabolic activation, enhancing the immune system, inhibiting cell proliferation, or other mechanisms. A large number of observational and experimental studies have been performed to determine the relationship between vitamin E status and cancer risk (163,164). Also, a number of well-designed large-scale chemoprevention trials for antioxidant micronutrients have been conducted in recent years (165–167). (...)
(...) Vitamin E may protect against cancer development by reacting directly with mutagens/carcinogens, altering metabolic activation, enhancing the immune system, inhibiting cell proliferation, or other mechanisms. A large number of observational and experimental studies have been performed to determine the relationship between vitamin E status and cancer risk (163,164). Also, a number of well-designed large-scale chemoprevention trials for antioxidant micronutrients have been conducted in recent years (165–167). (...)
Oxidation reactions are ubiquitous in biological cells and fluids (11/30/2007)
(...) As a result of the utility and potential destructiveness of free-radical reactions, biological cells have evolved a genuinely spectacular array of defensive, preventive, responsive, and repair systems to minimize the damage associated with carrying out free-radical reactions and producing free-radical intermediates. Not surprisingly, both the extent of free-radical production and the efficacy of the defense and repair systems are influenced by an individual’s nutritional status generally and the abundance of redox active nutrients specifically. This article describes the basic chemistry of oxidation reactions and their prevention via readily oxidized molecules (typically referred to as antioxidants), and discusses the role of antioxidants in preventing and delimiting these reactions in human cells and tissues. (...)
(...) As a result of the utility and potential destructiveness of free-radical reactions, biological cells have evolved a genuinely spectacular array of defensive, preventive, responsive, and repair systems to minimize the damage associated with carrying out free-radical reactions and producing free-radical intermediates. Not surprisingly, both the extent of free-radical production and the efficacy of the defense and repair systems are influenced by an individual’s nutritional status generally and the abundance of redox active nutrients specifically. This article describes the basic chemistry of oxidation reactions and their prevention via readily oxidized molecules (typically referred to as antioxidants), and discusses the role of antioxidants in preventing and delimiting these reactions in human cells and tissues. (...)
LDLs become atherogenic when their basic (11/30/2007)
(...) B. Free-Radical Lipid Oxidation The free-radical oxidation of lipids is a complex series of reactions with three distinct phases: initiation, propagation, and termination. Lipid oxidation should be recognized as a highly dynamic and complex result of the interplay between substrates, circumstances, and time (10). (...)
(...) B. Free-Radical Lipid Oxidation The free-radical oxidation of lipids is a complex series of reactions with three distinct phases: initiation, propagation, and termination. Lipid oxidation should be recognized as a highly dynamic and complex result of the interplay between substrates, circumstances, and time (10). (...)
Ascorbic acid functions as a redox cofactor and catalyst (11/30/2007)
(...) By the end of the 1800s, the connection between scurvy and diet was established. The observation in 1907 that guinea pigs were susceptible to scurvy was an important breakthrough in the understanding of scurvy. It was also one of the earliest examples of the use of an animal model to study a nutritional disease. (...)
(...) By the end of the 1800s, the connection between scurvy and diet was established. The observation in 1907 that guinea pigs were susceptible to scurvy was an important breakthrough in the understanding of scurvy. It was also one of the earliest examples of the use of an animal model to study a nutritional disease. (...)
Choline is a dietary component that is important for normal functioning of all cells (11/30/2007)
(...) In the subsequent 50 years, this model has been used to develop an understanding of the mechanisms which initiate and promote carcinogenesis (10–12). In 1975, it was discovered that administration of choline accelerated the synthesis and release of acetylcholine by neurons (13–18). This led to an increased interest in dietary choline and brain function. (...)
(...) In the subsequent 50 years, this model has been used to develop an understanding of the mechanisms which initiate and promote carcinogenesis (10–12). In 1975, it was discovered that administration of choline accelerated the synthesis and release of acetylcholine by neurons (13–18). This led to an increased interest in dietary choline and brain function. (...)
Choline Deficiency in Animals (11/30/2007)
(...) This requirement may be more apparent in special human populations. The demand for choline in normal adults is likely to be smaller than the demand for choline in the infant, as large amounts of choline must be used to make phospholipids in growing organs (37). The observed changes that occurred in choline-deficient adult humans might have been greater had we studied growing children. (...)
(...) This requirement may be more apparent in special human populations. The demand for choline in normal adults is likely to be smaller than the demand for choline in the infant, as large amounts of choline must be used to make phospholipids in growing organs (37). The observed changes that occurred in choline-deficient adult humans might have been greater had we studied growing children. (...)
BIOCHEMICAL FUNCTIONS of FOLATES (11/30/2007)
(...) Other sources include formate, much of which is derived from serine metabolism in the mitochondria, and the C-2 of histidine. Many of the enzymes involved in folate metabolism are multifunctional or are part of multiprotein complexes which allows channeling of polyglutamate intermediates between active sites without release of intermediate products from the complex (94). Some folate-requiring enzymes are used for biosynthetic purposes, whereas others are used only for interconversion of the various forms of the vitamin. (...)
(...) Other sources include formate, much of which is derived from serine metabolism in the mitochondria, and the C-2 of histidine. Many of the enzymes involved in folate metabolism are multifunctional or are part of multiprotein complexes which allows channeling of polyglutamate intermediates between active sites without release of intermediate products from the complex (94). Some folate-requiring enzymes are used for biosynthetic purposes, whereas others are used only for interconversion of the various forms of the vitamin. (...)
The Folic Acid Functions (11/30/2007)
(...) The biochemical functions of folate were first determined with bacteria. Purines or thymine could partly replace the nutritional requirements for folate or for p-aminobenzoic acid (PABA). Similarly, the inhibition of bacterial growth by folate analogues could be overcome by adding purines or thymine to the growth medium. (...)
(...) The biochemical functions of folate were first determined with bacteria. Purines or thymine could partly replace the nutritional requirements for folate or for p-aminobenzoic acid (PABA). Similarly, the inhibition of bacterial growth by folate analogues could be overcome by adding purines or thymine to the growth medium. (...)
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