Vitamin D: A vitamin that includes both CHOLECALCIFEROLS and ERGOCALCIFEROLS, which have the common effect of preventing or curing RICKETS in animals. It can also be viewed as a hormone since it can be formed in SKIN by action of ULTRAVIOLET RAYS upon the precursors, 7-dehydrocholesterol and ERGOSTEROL, and acts on VITAMIN D RECEPTORS to regulate CALCIUM in opposition to PARATHYROID HORMONE.Vitamin D Deficiency: A nutritional condition produced by a deficiency of VITAMIN D in the diet, insufficient production of vitamin D in the skin, inadequate absorption of vitamin D from the diet, or abnormal conversion of vitamin D to its bioactive metabolites. It is manifested clinically as RICKETS in children and OSTEOMALACIA in adults. (From Cecil Textbook of Medicine, 19th ed, p1406)Vitamin A: Retinol and derivatives of retinol that play an essential role in metabolic functioning of the retina, the growth of and differentiation of epithelial tissue, the growth of bone, reproduction, and the immune response. Dietary vitamin A is derived from a variety of CAROTENOIDS found in plants. It is enriched in the liver, egg yolks, and the fat component of dairy products.Vitamins: Organic substances that are required in small amounts for maintenance and growth, but which cannot be manufactured by the human body.Cholecalciferol: Derivative of 7-dehydroxycholesterol formed by ULTRAVIOLET RAYS breaking of the C9-C10 bond. It differs from ERGOCALCIFEROL in having a single bond between C22 and C23 and lacking a methyl group at C24.Vitamin E: A generic descriptor for all TOCOPHEROLS and TOCOTRIENOLS that exhibit ALPHA-TOCOPHEROL activity. By virtue of the phenolic hydrogen on the 2H-1-benzopyran-6-ol nucleus, these compounds exhibit varying degree of antioxidant activity, depending on the site and number of methyl groups and the type of ISOPRENOIDS.Vitamin B 12: A cobalt-containing coordination compound produced by intestinal micro-organisms and found also in soil and water. Higher plants do not concentrate vitamin B 12 from the soil and so are a poor source of the substance as compared with animal tissues. INTRINSIC FACTOR is important for the assimilation of vitamin B 12.Receptors, Calcitriol: Proteins, usually found in the cytoplasm, that specifically bind calcitriol, migrate to the nucleus, and regulate transcription of specific segments of DNA with the participation of D receptor interacting proteins (called DRIP). Vitamin D is converted in the liver and kidney to calcitriol and ultimately acts through these receptors.Vitamin A Deficiency: A nutritional condition produced by a deficiency of VITAMIN A in the diet, characterized by NIGHT BLINDNESS and other ocular manifestations such as dryness of the conjunctiva and later of the cornea (XEROPHTHALMIA). Vitamin A deficiency is a very common problem worldwide, particularly in developing countries as a consequence of famine or shortages of vitamin A-rich foods. In the United States it is found among the urban poor, the elderly, alcoholics, and patients with malabsorption. (From Cecil Textbook of Medicine, 19th ed, p1179)Calcifediol: The major circulating metabolite of VITAMIN D3. It is produced in the LIVER and is the best indicator of the body's vitamin D stores. It is effective in the treatment of RICKETS and OSTEOMALACIA, both in azotemic and non-azotemic patients. Calcifediol also has mineralizing properties.Calcitriol: The physiologically active form of vitamin D. It is formed primarily in the kidney by enzymatic hydroxylation of 25-hydroxycholecalciferol (CALCIFEDIOL). Its production is stimulated by low blood calcium levels and parathyroid hormone. Calcitriol increases intestinal absorption of calcium and phosphorus, and in concert with parathyroid hormone increases bone resorption.Ergocalciferols: Derivatives of ERGOSTEROL formed by ULTRAVIOLET RAYS breaking of the C9-C10 bond. They differ from CHOLECALCIFEROL in having a double bond between C22 and C23 and a methyl group at C24.Dietary Supplements: Products in capsule, tablet or liquid form that provide dietary ingredients, and that are intended to be taken by mouth to increase the intake of nutrients. Dietary supplements can include macronutrients, such as proteins, carbohydrates, and fats; and/or MICRONUTRIENTS, such as VITAMINS; MINERALS; and PHYTOCHEMICALS.Vitamin D-Binding Protein: An alpha-globulin found in the plasma of man and other vertebrates. It is apparently synthesized in the liver and carries vitamin D and its metabolites through the circulation and mediates the response of tissue. It is also known as group-specific component (Gc). Gc subtypes are used to determine specific phenotypes and gene frequencies. These data are employed in the classification of population groups, paternity investigations, and in forensic medicine.Vitamin K 1: A family of phylloquinones that contains a ring of 2-methyl-1,4-naphthoquinone and an isoprenoid side chain. Members of this group of vitamin K 1 have only one double bond on the proximal isoprene unit. Rich sources of vitamin K 1 include green plants, algae, and photosynthetic bacteria. Vitamin K1 has antihemorrhagic and prothrombogenic activity.Sunlight: Irradiation directly from the sun.Vitamin B 6: VITAMIN B 6 refers to several PICOLINES (especially PYRIDOXINE; PYRIDOXAL; & PYRIDOXAMINE) that are efficiently converted by the body to PYRIDOXAL PHOSPHATE which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, and aminolevulinic acid. During transamination of amino acids, pyridoxal phosphate is transiently converted into PYRIDOXAMINE phosphate. Although pyridoxine and Vitamin B 6 are still frequently used as synonyms, especially by medical researchers, this practice is erroneous and sometimes misleading (EE Snell; Ann NY Acad Sci, vol 585 pg 1, 1990). Most of vitamin B6 is eventually degraded to PYRIDOXIC ACID and excreted in the urine.Vitamin E Deficiency: A nutritional condition produced by a deficiency of VITAMIN E in the diet, characterized by posterior column and spinocerebellar tract abnormalities, areflexia, ophthalmoplegia, and disturbances of gait, proprioception, and vibration. In premature infants vitamin E deficiency is associated with hemolytic anemia, thrombocytosis, edema, intraventricular hemorrhage, and increasing risk of retrolental fibroplasia and bronchopulmonary dysplasia. An apparent inborn error of vitamin E metabolism, named familial isolated vitamin E deficiency, has recently been identified. (Cecil Textbook of Medicine, 19th ed, p1181)Rickets: Disorders caused by interruption of BONE MINERALIZATION manifesting as OSTEOMALACIA in adults and characteristic deformities in infancy and childhood due to disturbances in normal BONE FORMATION. The mineralization process may be interrupted by disruption of VITAMIN D; PHOSPHORUS; or CALCIUM homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances.Vitamin B 12 Deficiency: A nutritional condition produced by a deficiency of VITAMIN B 12 in the diet, characterized by megaloblastic anemia. Since vitamin B 12 is not present in plants, humans have obtained their supply from animal products, from multivitamin supplements in the form of pills, and as additives to food preparations. A wide variety of neuropsychiatric abnormalities is also seen in vitamin B 12 deficiency and appears to be due to an undefined defect involving myelin synthesis. (From Cecil Textbook of Medicine, 19th ed, p848)25-Hydroxyvitamin D3 1-alpha-Hydroxylase: A mitochondrial cytochrome P450 enzyme that catalyzes the 1-alpha-hydroxylation of 25-hydroxyvitamin D3 (also known as 25-hydroxycholecalciferol) in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP27B1 gene, converts 25-hydroxyvitamin D3 to 1-alpha,25-dihydroxyvitamin D3 which is the active form of VITAMIN D in regulating bone growth and calcium metabolism. This enzyme is also active on plant 25-hydroxyvitamin D2 (ergocalciferol).Hydroxycholecalciferols: Hydroxy analogs of vitamin D 3; (CHOLECALCIFEROL); including CALCIFEDIOL; CALCITRIOL; and 24,25-DIHYDROXYVITAMIN D 3.Vitamin K Deficiency: A nutritional condition produced by a deficiency of VITAMIN K in the diet, characterized by an increased tendency to hemorrhage (HEMORRHAGIC DISORDERS). Such bleeding episodes may be particularly severe in newborn infants. (From Cecil Textbook of Medicine, 19th ed, p1182)Parathyroid Hormone: A polypeptide hormone (84 amino acid residues) secreted by the PARATHYROID GLANDS which performs the essential role of maintaining intracellular CALCIUM levels in the body. Parathyroid hormone increases intracellular calcium by promoting the release of CALCIUM from BONE, increases the intestinal absorption of calcium, increases the renal tubular reabsorption of calcium, and increases the renal excretion of phosphates.25-Hydroxyvitamin D 2: 9,10-Secoergosta-5,7,10(19),22-tetraene-3,25-diol. Biologically active metabolite of vitamin D2 which is more active in curing rickets than its parent. The compound is believed to attach to the same receptor as vitamin D2 and 25-hydroxyvitamin D3.Vitamin B 6 Deficiency: A nutritional condition produced by a deficiency of VITAMIN B 6 in the diet, characterized by dermatitis, glossitis, cheilosis, and stomatitis. Marked deficiency causes irritability, weakness, depression, dizziness, peripheral neuropathy, and seizures. In infants and children typical manifestations are diarrhea, anemia, and seizures. Deficiency can be caused by certain medications, such as isoniazid.Vitamin D Response Element: A DNA sequence that is found in the promoter region of vitamin D regulated genes. Vitamin D receptor (RECEPTOR, CALCITRIOL) binds to and regulates the activity of genes containing this element.Ascorbic Acid: A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant.Calcium, Dietary: Calcium compounds used as food supplements or in food to supply the body with calcium. Dietary calcium is needed during growth for bone development and for maintenance of skeletal integrity later in life to prevent osteoporosis.Dihydroxycholecalciferols: Cholecalciferols substituted with two hydroxy groups in any position.24,25-Dihydroxyvitamin D 3: A physiologically active metabolite of VITAMIN D. The compound is involved in the regulation of calcium metabolism, alkaline phosphatase activity, and enhances the calcemic effect of CALCITRIOL.Cholestanetriol 26-Monooxygenase: An NAPH-dependent cytochrome P450 enzyme that catalyzes the oxidation of the side chain of sterol intermediates such as the 27-hydroxylation of 5-beta-cholestane-3-alpha,7-alpha,12-alpha-triol.Diet: Regular course of eating and drinking adopted by a person or animal.Vitamin K 2: A group of substances similar to VITAMIN K 1 which contains a ring of 2-methyl-1,4-naphthoquinione and an isoprenoid side chain of varying number of isoprene units. In vitamin K 2, each isoprene unit contains a double bond. They are produced by bacteria including the normal intestinal flora.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Osteomalacia: Disorder caused by an interruption of the mineralization of organic bone matrix leading to bone softening, bone pain, and weakness. It is the adult form of rickets resulting from disruption of VITAMIN D; PHOSPHORUS; or CALCIUM homeostasis.Pyridoxine: The 4-methanol form of VITAMIN B 6 which is converted to PYRIDOXAL PHOSPHATE which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. Although pyridoxine and Vitamin B 6 are still frequently used as synonyms, especially by medical researchers, this practice is erroneous and sometimes misleading (EE Snell; Ann NY Acad Sci, vol 585 pg 1, 1990).Steroid Hydroxylases: Cytochrome P-450 monooxygenases (MIXED FUNCTION OXYGENASES) that are important in steroid biosynthesis and metabolism.Bone Density Conservation Agents: Agents that inhibit BONE RESORPTION and/or favor BONE MINERALIZATION and BONE REGENERATION. They are used to heal BONE FRACTURES and to treat METABOLIC BONE DISEASES such as OSTEOPOROSIS.Nutritional Status: State of the body in relation to the consumption and utilization of nutrients.Bone and Bones: A specialized CONNECTIVE TISSUE that is the main constituent of the SKELETON. The principle cellular component of bone is comprised of OSTEOBLASTS; OSTEOCYTES; and OSTEOCLASTS, while FIBRILLAR COLLAGENS and hydroxyapatite crystals form the BONE MATRIX.Seasons: Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Bone Density: The amount of mineral per square centimeter of BONE. This is the definition used in clinical practice. Actual bone density would be expressed in grams per milliliter. It is most frequently measured by X-RAY ABSORPTIOMETRY or TOMOGRAPHY, X RAY COMPUTED. Bone density is an important predictor for OSTEOPOROSIS.Avitaminosis: A condition due to a deficiency of one or more essential vitamins. (Dorland, 27th ed)Phosphorus: A non-metal element that has the atomic symbol P, atomic number 15, and atomic weight 31. It is an essential element that takes part in a broad variety of biochemical reactions.Nutritional Requirements: The amounts of various substances in food needed by an organism to sustain healthy life.Vitamin B Deficiency: A condition due to deficiency in any member of the VITAMIN B COMPLEX. These B vitamins are water-soluble and must be obtained from the diet because they are easily lost in the urine. Unlike the lipid-soluble vitamins, they cannot be stored in the body fat.Food, Fortified: Any food that has been supplemented with essential nutrients either in quantities that are greater than those present normally, or which are not present in the food normally. Fortified food includes also food to which various nutrients have been added to compensate for those removed by refinement or processing. (From Segen, Dictionary of Modern Medicine, 1992)Hypocalcemia: Reduction of the blood calcium below normal. Manifestations include hyperactive deep tendon reflexes, Chvostek's sign, muscle and abdominal cramps, and carpopedal spasm. (Dorland, 27th ed)Vitamin K 3: A synthetic naphthoquinone without the isoprenoid side chain and biological activity, but can be converted to active vitamin K2, menaquinone, after alkylation in vivo.Hyperparathyroidism, Secondary: Abnormally elevated PARATHYROID HORMONE secretion as a response to HYPOCALCEMIA. It is caused by chronic KIDNEY FAILURE or other abnormalities in the controls of bone and mineral metabolism, leading to various BONE DISEASES, such as RENAL OSTEODYSTROPHY.Antioxidants: Naturally occurring or synthetic substances that inhibit or retard the oxidation of a substance to which it is added. They counteract the harmful and damaging effects of oxidation in animal tissues.Nutrition Policy: Guidelines and objectives pertaining to food supply and nutrition including recommendations for healthy diet.Folic Acid: A member of the vitamin B family that stimulates the hematopoietic system. It is present in the liver and kidney and is found in mushrooms, spinach, yeast, green leaves, and grasses (POACEAE). Folic acid is used in the treatment and prevention of folate deficiencies and megaloblastic anemia.Hypercalcemia: Abnormally high level of calcium in the blood.Osteoporosis: Reduction of bone mass without alteration in the composition of bone, leading to fractures. Primary osteoporosis can be of two major types: postmenopausal osteoporosis (OSTEOPOROSIS, POSTMENOPAUSAL) and age-related or senile osteoporosis.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Vitamin K Deficiency Bleeding: Hemorrhage caused by vitamin K deficiency.alpha-Tocopherol: A natural tocopherol and one of the most potent antioxidant tocopherols. It exhibits antioxidant activity by virtue of the phenolic hydrogen on the 2H-1-benzopyran-6-ol nucleus. It has four methyl groups on the 6-chromanol nucleus. The natural d form of alpha-tocopherol is more active than its synthetic dl-alpha-tocopherol racemic mixture.Skin Pigmentation: Coloration of the skin.beta Carotene: A carotenoid that is a precursor of VITAMIN A. It is administered to reduce the severity of photosensitivity reactions in patients with erythropoietic protoporphyria (PORPHYRIA, ERYTHROPOIETIC). (From Reynolds JEF(Ed): Martindale: The Extra Pharmacopoeia (electronic version). Micromedex, Inc, Engewood, CO, 1995.)Double-Blind Method: A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.Osteocalcin: Vitamin K-dependent calcium-binding protein synthesized by OSTEOBLASTS and found primarily in BONES. Serum osteocalcin measurements provide a noninvasive specific marker of bone metabolism. The protein contains three residues of the amino acid gamma-carboxyglutamic acid (Gla), which, in the presence of CALCIUM, promotes binding to HYDROXYAPATITE and subsequent accumulation in BONE MATRIX.Intestinal Absorption: Uptake of substances through the lining of the INTESTINES.Cross-Sectional Studies: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.Minerals: Native, inorganic or fossilized organic substances having a definite chemical composition and formed by inorganic reactions. They may occur as individual crystals or may be disseminated in some other mineral or rock. (Grant & Hackh's Chemical Dictionary, 5th ed; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Sodium-Coupled Vitamin C Transporters: Membrane transport proteins that actively co-transport ASCORBIC ACID and sodium ions across the CELL MEMBRANE. Dietary absorption of VITAMIN C is highly dependent upon this class of transporters and a subset of SODIUM GLUCOSE TRANSPORTERS which transport the oxidized form of vitamin C, DEHYDROASCORBIC ACID.Biological Markers: Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Retinoid X Receptors: A subtype of RETINOIC ACID RECEPTORS that are specific for 9-cis-retinoic acid which function as nuclear TRANSCRIPTION FACTORS that regulate multiple signaling pathways.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Parathyroid Glands: Two pairs of small oval-shaped glands located in the front and the base of the NECK and adjacent to the two lobes of THYROID GLAND. They secrete PARATHYROID HORMONE that regulates the balance of CALCIUM; PHOSPHORUS; and MAGNESIUM in the body.Tocopherols: A collective name for a group of closely related lipids that contain substitutions on the 2H-1-benzopyran-6-ol nucleus and a long hydrocarbon chain of isoprenoid units. They are antioxidants by virtue of the phenolic hydrogen. Tocopherols react with the most reactive form of oxygen and protect unsaturated fatty acids from oxidation.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Vitamin K Epoxide Reductases: OXIDOREDUCTASES which mediate vitamin K metabolism by converting inactive vitamin K 2,3-epoxide to active vitamin K.Hypophosphatemia, Familial: An inherited condition of abnormally low serum levels of PHOSPHATES (below 1 mg/liter) which can occur in a number of genetic diseases with defective reabsorption of inorganic phosphorus by the PROXIMAL RENAL TUBULES. This leads to phosphaturia, HYPOPHOSPHATEMIA, and disturbances of cellular and organ functions such as those in X-LINKED HYPOPHOSPHATEMIC RICKETS; OSTEOMALACIA; and FANCONI SYNDROME.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Homocysteine: A thiol-containing amino acid formed by a demethylation of METHIONINE.Phosphates: Inorganic salts of phosphoric acid.Transcobalamins: A group of carrier proteins which bind with VITAMIN B12 in the BLOOD and aid in its transport. Transcobalamin I migrates electrophoretically as a beta-globulin, while transcobalamins II and III migrate as alpha-globulins.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Fractures, Bone: Breaks in bones.Dihydrotachysterol: A VITAMIN D that can be regarded as a reduction product of vitamin D2.Alkaline Phosphatase: An enzyme that catalyzes the conversion of an orthophosphoric monoester and water to an alcohol and orthophosphate. EC A condition caused by a deficiency of PARATHYROID HORMONE (or PTH). It is characterized by HYPOCALCEMIA and hyperphosphatemia. Hypocalcemia leads to TETANY. The acquired form is due to removal or injuries to the PARATHYROID GLANDS. The congenital form is due to mutations of genes, such as TBX1; (see DIGEORGE SYNDROME); CASR encoding CALCIUM-SENSING RECEPTOR; or PTH encoding parathyroid hormone.Methylmalonic Acid: A malonic acid derivative which is a vital intermediate in the metabolism of fat and protein. Abnormalities in methylmalonic acid metabolism lead to methylmalonic aciduria. This metabolic disease is attributed to a block in the enzymatic conversion of methylmalonyl CoA to succinyl CoA.Administration, Oral: The giving of drugs, chemicals, or other substances by mouth.Dehydrocholesterols: Cholesterol derivatives having an additional double bond in any position. 24-Dehydrocholesterol is DESMOSTEROL. The other most prevalent dehydrocholesterol is the 7-isomer. This compound is a precursor of cholesterol and of vitamin D3.Micronutrients: Essential dietary elements or organic compounds that are required in only small quantities for normal physiologic processes to occur.Carotenoids: The general name for a group of fat-soluble pigments found in green, yellow, and leafy vegetables, and yellow fruits. They are aliphatic hydrocarbons consisting of a polyisoprene backbone.Carbon-Carbon Ligases: Enzymes that catalyze the joining of two molecules by the formation of a carbon-carbon bond. These are the carboxylating enzymes and are mostly biotinyl-proteins. EC 6.4.Calcium Carbonate: Carbonic acid calcium salt (CaCO3). An odorless, tasteless powder or crystal that occurs in nature. It is used therapeutically as a phosphate buffer in hemodialysis patients and as a calcium supplement.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Maternal Nutritional Physiological Phenomena: Nutrition of a mother which affects the health of the FETUS and INFANT as well as herself.Riboflavin: Nutritional factor found in milk, eggs, malted barley, liver, kidney, heart, and leafy vegetables. The richest natural source is yeast. It occurs in the free form only in the retina of the eye, in whey, and in urine; its principal forms in tissues and cells are as FLAVIN MONONUCLEOTIDE and FLAVIN-ADENINE DINUCLEOTIDE.Nutrition Surveys: A systematic collection of factual data pertaining to the nutritional status of a human population within a given geographic area. Data from these surveys are used in preparing NUTRITION ASSESSMENTS.Receptors, Retinoic Acid: Proteins in the nucleus or cytoplasm that specifically bind RETINOIC ACID or RETINOL and trigger changes in the behavior of cells. Retinoic acid receptors, like steroid receptors, are ligand-activated transcription regulators. Several types have been recognized.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Pyridoxal Phosphate: This is the active form of VITAMIN B 6 serving as a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. During transamination of amino acids, pyridoxal phosphate is transiently converted into pyridoxamine phosphate (PYRIDOXAMINE).S100 Calcium Binding Protein G: A calbindin protein found in many mammalian tissues, including the UTERUS, PLACENTA, BONE, PITUITARY GLAND, and KIDNEYS. In intestinal ENTEROCYTES it mediates intracellular calcium transport from apical to basolateral membranes via calcium binding at two EF-HAND MOTIFS. Expression is regulated in some tissues by VITAMIN D.Bone Diseases, MetabolicMilk: The white liquid secreted by the mammary glands. It contains proteins, sugar, lipids, vitamins, and minerals.Xerophthalmia: Dryness of the eye surfaces caused by deficiency of tears or conjunctival secretions. It may be associated with vitamin A deficiency, trauma, or any condition in which the eyelids do not close completely.Osteoporosis, Postmenopausal: Metabolic disorder associated with fractures of the femoral neck, vertebrae, and distal forearm. It occurs commonly in women within 15-20 years after menopause, and is caused by factors associated with menopause including estrogen deficiency.Bone Diseases: Diseases of BONES.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Hypervitaminosis A: A symptom complex resulting from ingesting excessive amounts of VITAMIN A.Receptors, Steroid: Proteins found usually in the cytoplasm or nucleus that specifically bind steroid hormones and trigger changes influencing the behavior of cells. The steroid receptor-steroid hormone complex regulates the transcription of specific genes.Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.Ultraviolet Rays: That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.Infant, Newborn: An infant during the first month after birth.Tretinoin: An important regulator of GENE EXPRESSION during growth and development, and in NEOPLASMS. Tretinoin, also known as retinoic acid and derived from maternal VITAMIN A, is essential for normal GROWTH; and EMBRYONIC DEVELOPMENT. An excess of tretinoin can be teratogenic. It is used in the treatment of PSORIASIS; ACNE VULGARIS; and several other SKIN DISEASES. It has also been approved for use in promyelocytic leukemia (LEUKEMIA, PROMYELOCYTIC, ACUTE).Sunscreening Agents: Chemical or physical agents that protect the skin from sunburn and erythema by absorbing or blocking ultraviolet radiation.Kidney: Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.Calbindins: Calcium-binding proteins that are found in DISTAL KIDNEY TUBULES, INTESTINES, BRAIN, and other tissues where they bind, buffer and transport cytoplasmic calcium. Calbindins possess a variable number of EF-HAND MOTIFS which contain calcium-binding sites. Some isoforms are regulated by VITAMIN D.Pyridoxic Acid: The catabolic product of most of VITAMIN B 6; (PYRIDOXINE; PYRIDOXAL; and PYRIDOXAMINE) which is excreted in the urine.Postmenopause: The physiological period following the MENOPAUSE, the permanent cessation of the menstrual life.Linear Models: Statistical models in which the value of a parameter for a given value of a factor is assumed to be equal to a + bx, where a and b are constants. The models predict a linear regression.Secosteroids: Steroids in which fission of one or more ring structures and concomitant addition of a hydrogen atom at each terminal group has occurred.Renal Osteodystrophy: Decalcification of bone or abnormal bone development due to chronic KIDNEY DISEASES, in which 1,25-DIHYDROXYVITAMIN D3 synthesis by the kidneys is impaired, leading to reduced negative feedback on PARATHYROID HORMONE. The resulting SECONDARY HYPERPARATHYROIDISM eventually leads to bone disorders.Hydroxylation: Placing of a hydroxyl group on a compound in a position where one did not exist before. (Stedman, 26th ed)Bone Development: The growth and development of bones from fetus to adult. It includes two principal mechanisms of bone growth: growth in length of long bones at the epiphyseal cartilages and growth in thickness by depositing new bone (OSTEOGENESIS) with the actions of OSTEOBLASTS and OSTEOCLASTS.Placebos: Any dummy medication or treatment. Although placebos originally were medicinal preparations having no specific pharmacological activity against a targeted condition, the concept has been extended to include treatments or procedures, especially those administered to control groups in clinical trials in order to provide baseline measurements for the experimental protocol.Body Weight: The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.Thiamine: 3-((4-Amino-2-methyl-5-pyrimidinyl)methyl)-5-(2- hydroxyethyl)-4-methylthiazolium chloride.Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.European Continental Ancestry Group: Individuals whose ancestral origins are in the continent of Europe.Dairy Products: Raw and processed or manufactured milk and milk-derived products. These are usually from cows (bovine) but are also from goats, sheep, reindeer, and water buffalo.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Milk, HumanGenotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Biological Availability: The extent to which the active ingredient of a drug dosage form becomes available at the site of drug action or in a biological medium believed to reflect accessibility to a site of action.Selenium: An element with the atomic symbol Se, atomic number 34, and atomic weight 78.96. It is an essential micronutrient for mammals and other animals but is toxic in large amounts. Selenium protects intracellular structures against oxidative damage. It is an essential component of GLUTATHIONE PEROXIDASE.Absorptiometry, Photon: A noninvasive method for assessing BODY COMPOSITION. It is based on the differential absorption of X-RAYS (or GAMMA RAYS) by different tissues such as bone, fat and other soft tissues. The source of (X-ray or gamma-ray) photon beam is generated either from radioisotopes such as GADOLINIUM 153, IODINE 125, or Americanium 241 which emit GAMMA RAYS in the appropriate range; or from an X-ray tube which produces X-RAYS in the desired range. It is primarily used for quantitating BONE MINERAL CONTENT, especially for the diagnosis of OSTEOPOROSIS, and also in measuring BONE MINERALIZATION.Observational Study as Topic: A clinical study in which participants may receive diagnostic, therapeutic, or other types of interventions, but the investigator does not assign participants to specific interventions (as in an interventional study).Folic Acid Deficiency: A nutritional condition produced by a deficiency of FOLIC ACID in the diet. Many plant and animal tissues contain folic acid, abundant in green leafy vegetables, yeast, liver, and mushrooms but destroyed by long-term cooking. Alcohol interferes with its intermediate metabolism and absorption. Folic acid deficiency may develop in long-term anticonvulsant therapy or with use of oral contraceptives. This deficiency causes anemia, macrocytic anemia, and megaloblastic anemia. It is indistinguishable from vitamin B 12 deficiency in peripheral blood and bone marrow findings, but the neurologic lesions seen in B 12 deficiency do not occur. (Merck Manual, 16th ed)gamma-Tocopherol: A natural tocopherol with less antioxidant activity than ALPHA-TOCOPHEROL. It exhibits antioxidant activity by virtue of the phenolic hydrogen on the 2H-1-benzopyran-6-ol nucleus. As in BETA-TOCOPHEROL, it also has three methyl groups on the 6-chromanol nucleus but at different sites.Cobalt Isotopes: Stable cobalt atoms that have the same atomic number as the element cobalt, but differ in atomic weight. Co-59 is a stable cobalt isotope.Retinol-Binding Proteins: Proteins which bind with RETINOL. The retinol-binding protein found in plasma has an alpha-1 mobility on electrophoresis and a molecular weight of about 21 kDa. The retinol-protein complex (MW=80-90 kDa) circulates in plasma in the form of a protein-protein complex with prealbumin. The retinol-binding protein found in tissue has a molecular weight of 14 kDa and carries retinol as a non-covalently-bound ligand.Nutritional Physiological Phenomena: The processes and properties of living organisms by which they take in and balance the use of nutritive materials for energy, heat production, or building material for the growth, maintenance, or repair of tissues and the nutritive properties of FOOD.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Reference Values: The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.Food Analysis: Measurement and evaluation of the components of substances to be taken as FOOD.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Phosphorus, Dietary: Phosphorus used in foods or obtained from food. This element is a major intracellular component which plays an important role in many biochemical pathways relating to normal physiological functions. High concentrations of dietary phosphorus can cause nephrocalcinosis which is associated with impaired kidney function. Low concentrations of dietary phosphorus cause an increase in calcitriol in the blood and osteoporosis.United StatesHyperparathyroidism: A condition of abnormally elevated output of PARATHYROID HORMONE (or PTH) triggering responses that increase blood CALCIUM. It is characterized by HYPERCALCEMIA and BONE RESORPTION, eventually leading to bone diseases. PRIMARY HYPERPARATHYROIDISM is caused by parathyroid HYPERPLASIA or PARATHYROID NEOPLASMS. SECONDARY HYPERPARATHYROIDISM is increased PTH secretion in response to HYPOCALCEMIA, usually caused by chronic KIDNEY DISEASES.Bone Resorption: Bone loss due to osteoclastic activity.Familial Hypophosphatemic Rickets: A hereditary disorder characterized by HYPOPHOSPHATEMIA; RICKETS; OSTEOMALACIA; renal defects in phosphate reabsorption and vitamin D metabolism; and growth retardation. Autosomal and X-linked dominant and recessive variants have been reported.Ultraviolet Therapy: The use of ultraviolet electromagnetic radiation in the treatment of disease, usually of the skin. This is the part of the sun's spectrum that causes sunburn and tanning. Ultraviolet A, used in PUVA, is closer to visible light and less damaging than Ultraviolet B, which is ionizing.African Americans: Persons living in the United States having origins in any of the black groups of Africa.Infant Nutritional Physiological Phenomena: Nutritional physiology of children from birth to 2 years of age.Aging: The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.Lactation: The processes of milk secretion by the maternal MAMMARY GLANDS after PARTURITION. The proliferation of the mammary glandular tissue, milk synthesis, and milk expulsion or let down are regulated by the interactions of several hormones including ESTRADIOL; PROGESTERONE; PROLACTIN; and OXYTOCIN.Malabsorption Syndromes: General term for a group of MALNUTRITION syndromes caused by failure of normal INTESTINAL ABSORPTION of nutrients.Oxidative Stress: A disturbance in the prooxidant-antioxidant balance in favor of the former, leading to potential damage. Indicators of oxidative stress include damaged DNA bases, protein oxidation products, and lipid peroxidation products (Sies, Oxidative Stress, 1991, pxv-xvi).Hypercalciuria: Excretion of abnormally high level of CALCIUM in the URINE, greater than 4 mg/kg/day.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Pyridoxal: The 4-carboxyaldehyde form of VITAMIN B 6 which is converted to PYRIDOXAL PHOSPHATE which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid.Cardiovascular Diseases: Pathological conditions involving the CARDIOVASCULAR SYSTEM including the HEART; the BLOOD VESSELS; or the PERICARDIUM.Randomized Controlled Trials as Topic: Works about clinical trials that involve at least one test treatment and one control treatment, concurrent enrollment and follow-up of the test- and control-treated groups, and in which the treatments to be administered are selected by a random process, such as the use of a random-numbers table.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Body Mass Index: An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)Renal Dialysis: Therapy for the insufficient cleansing of the BLOOD by the kidneys based on dialysis and including hemodialysis, PERITONEAL DIALYSIS, and HEMODIAFILTRATION.Kidney Failure, Chronic: The end-stage of CHRONIC RENAL INSUFFICIENCY. It is characterized by the severe irreversible kidney damage (as measured by the level of PROTEINURIA) and the reduction in GLOMERULAR FILTRATION RATE to less than 15 ml per min (Kidney Foundation: Kidney Disease Outcome Quality Initiative, 2002). These patients generally require HEMODIALYSIS or KIDNEY TRANSPLANTATION.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Chickens: Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Gene Expression Regulation: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.Breast Feeding: The nursing of an infant at the breast.Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Bone Remodeling: The continuous turnover of BONE MATRIX and mineral that involves first an increase in BONE RESORPTION (osteoclastic activity) and later, reactive BONE FORMATION (osteoblastic activity). The process of bone remodeling takes place in the adult skeleton at discrete foci. The process ensures the mechanical integrity of the skeleton throughout life and plays an important role in calcium HOMEOSTASIS. An imbalance in the regulation of bone remodeling's two contrasting events, bone resorption and bone formation, results in many of the metabolic bone diseases, such as OSTEOPOROSIS.Pregnancy Complications: Conditions or pathological processes associated with pregnancy. They can occur during or after pregnancy, and range from minor discomforts to serious diseases that require medical interventions. They include diseases in pregnant females, and pregnancies in females with diseases.Cytochrome P-450 Enzyme System: A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism.Duodenum: The shortest and widest portion of the SMALL INTESTINE adjacent to the PYLORUS of the STOMACH. It is named for having the length equal to about the width of 12 fingers.Retinoids: A group of tetraterpenes, with four terpene units joined head-to-tail. Biologically active members of this class are used clinically in the treatment of severe cystic ACNE; PSORIASIS; and other disorders of keratinization.Odds Ratio: The ratio of two odds. The exposure-odds ratio for case control data is the ratio of the odds in favor of exposure among cases to the odds in favor of exposure among noncases. The disease-odds ratio for a cohort or cross section is the ratio of the odds in favor of disease among the exposed to the odds in favor of disease among the unexposed. The prevalence-odds ratio refers to an odds ratio derived cross-sectionally from studies of prevalent cases.Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.Renal Insufficiency, Chronic: Conditions in which the KIDNEYS perform below the normal level for more than three months. Chronic kidney insufficiency is classified by five stages according to the decline in GLOMERULAR FILTRATION RATE and the degree of kidney damage (as measured by the level of PROTEINURIA). The most severe form is the end-stage renal disease (CHRONIC KIDNEY FAILURE). (Kidney Foundation: Kidney Disease Outcome Quality Initiative, 2002)Diet Surveys: Systematic collections of factual data pertaining to the diet of a human population within a given geographic area.Recommended Dietary Allowances: The amounts of various substances in the diet recommended by governmental guidelines as needed to sustain healthy life.Lipid Peroxidation: Peroxidase catalyzed oxidation of lipids using hydrogen peroxide as an electron acceptor.Random Allocation: A process involving chance used in therapeutic trials or other research endeavor for allocating experimental subjects, human or animal, between treatment and control groups, or among treatment groups. It may also apply to experiments on inanimate objects.Diet Records: Records of nutrient intake over a specific period of time, usually kept by the patient.Intestines: The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE.Low Density Lipoprotein Receptor-Related Protein-2: An LDL-RECEPTOR RELATED PROTEIN found in the neuroepithelium and in proximal tubular cells of the kidney. It is considered a multiligand receptor in that it binds to a variety of ligands with relatively high affinity and may function in mediating the uptake and lysosomal degradation of macromolecules such as: LIPOPROTEINS; ENDOPEPTIDASES; and PROTEASE INHIBITORS.Tocotrienols: Natural analogs of TOCOPHEROLS exhibiting antioxidant activity. These tocol derivatives and isomers contain a benzopyran ring and an unsaturated isoprenoid side chain.Postmortem Changes: Physiological changes that occur in bodies after death.Homeostasis: The processes whereby the internal environment of an organism tends to remain balanced and stable.Hip Fractures: Fractures of the FEMUR HEAD; the FEMUR NECK; (FEMORAL NECK FRACTURES); the trochanters; or the inter- or subtrochanteric region. Excludes fractures of the acetabulum and fractures of the femoral shaft below the subtrochanteric region (FEMORAL FRACTURES).HL-60 Cells: A promyelocytic cell line derived from a patient with ACUTE PROMYELOCYTIC LEUKEMIA. HL-60 cells lack specific markers for LYMPHOID CELLS but express surface receptors for FC FRAGMENTS and COMPLEMENT SYSTEM PROTEINS. They also exhibit phagocytic activity and responsiveness to chemotactic stimuli. (From Hay et al., American Type Culture Collection, 7th ed, pp127-8)Diphosphonates: Organic compounds which contain P-C-P bonds, where P stands for phosphonates or phosphonic acids. These compounds affect calcium metabolism. They inhibit ectopic calcification and slow down bone resorption and bone turnover. Technetium complexes of diphosphonates have been used successfully as bone scanning agents.Cell Differentiation: Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.Polymorphism, Single Nucleotide: A single nucleotide variation in a genetic sequence that occurs at appreciable frequency in the population.Logistic Models: Statistical models which describe the relationship between a qualitative dependent variable (that is, one which can take only certain discrete values, such as the presence or absence of a disease) and an independent variable. A common application is in epidemiology for estimating an individual's risk (probability of a disease) as a function of a given risk factor.Fat Substitutes: Compounds used in food or in food preparation to replace dietary fats. They may be carbohydrate-, protein-, or fat-based. Fat substitutes are usually lower in calories but provide the same texture as fats.Tasmania: An island south of Australia and the smallest state of the Commonwealth. Its capital is Hobart. It was discovered and named Van Diemen's Island in 1642 by Abel Tasman, a Dutch navigator, in honor of the Dutch governor-general of the Dutch East Indian colonies. It was renamed for the discoverer in 1853. In 1803 it was taken over by Great Britain and was used as a penal colony. It was granted government in 1856 and federated as a state in 1901. (From Webster's New Geographical Dictionary, 1988, p1190 & Room, Brewer's Dictionary of Names, p535)Chronic Disease: Diseases which have one or more of the following characteristics: they are permanent, leave residual disability, are caused by nonreversible pathological alteration, require special training of the patient for rehabilitation, or may be expected to require a long period of supervision, observation, or care. (Dictionary of Health Services Management, 2d ed)Calcium Channel Agonists: Agents that increase calcium influx into calcium channels of excitable tissues. This causes vasoconstriction in VASCULAR SMOOTH MUSCLE and/or CARDIAC MUSCLE cells as well as stimulation of insulin release from pancreatic islets. Therefore, tissue-selective calcium agonists have the potential to combat cardiac failure and endocrinological disorders. They have been used primarily in experimental studies in cell and tissue culture.Calcium Metabolism Disorders: Disorders in the processing of calcium in the body: its absorption, transport, storage, and utilization.