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Vitamin d is a group of fat-soluble circus steroids responsible for increasing intestinal absorption of calcium magnesium and phosphate and multiple other biological effects in humans the most important compounds in this group are vitamin d3 and vitamin d2 cholecalciferol an ergo calcifer all can be ingested from the diet and from supplements only a few foods
Contain vitamin d the major natural source of the vitamin is synthesis of cholecalciferol in the skin from cholesterol through a chemical reaction that is dependent on sun exposure dietary recommendations typically assume that all of a person’s vitamin d is taken by mouth as sun exposure in the population is variable in recommendations about the amount of
Sun exposure that is safe far uncertain in view of the skin cancer risk vitamin d from the diet or skin synthesis is biologically inactive enzymatic conversion in the liver and kidney is required for activation as vitamin d can be synthesized in adequate amounts by most mammals exposed to sufficient sunlight it is not an essential dietary factor and so not
Technically a vitamin instead it could be considered as a hormone with activation of the vitamin d prohormone resulting in the active form calcitriol which then produces effects via a nuclear receptor in multiple different locations cholecalciferol is converted in the liver to calcify dial or go calcifer all is converted to 25 hydroxy calcifer o these two vitamin d
Metabolites are measured in serum to determine a person’s vitamin d status calcifer dial is further hydroxylated by the kidneys to form calcite oriole the biologically active form of vitamin d calcitriol circulates as a hormone in the blood having a major role regulating the concentration of calcium and phosphate and promoting the healthy growth and remodelling of
Bone calcitriol also has other effects including samaan cell growth neuromuscular and immune functions and reduction of inflammation vitamin d has a significant role in calcium homeostasis and metabolism its discovery was due to effort to find the dietary substance lac children with rickets vitamin d supplements are given to treat our to prevent osteomalacia and
Rickets but the evidence for other health effects a vitamin d supplementation in the general population is inconsistent the effect of vitamin d supplementation on mortality is not clear with one meta-analysis finding a small decrease in mortality in elderly people and another concluding no clear justification exists for recommending supplementation for preventing
Many diseases and that further research of similar design is unneeded in these areas types several forms of vitamin d exist the two major forms are vitamin d2 or ergocalciferol and vitamin d3 or cholecalciferol vitamin d without a subscript refers to either d2 or d3 or both these are known collectively as calcifer all vitamin d2 was chemically characterized in 1931
In 1935 the chemical structure of vitamin d3 was established and proven to result from the ultraviolet irradiation of 7d hydro cholesterol chemically the various forms of vitamin d are succuss steroids ie steroids in which one of the bonds in the steroid rings is broken the structural difference between vitamin d2 and vitamin d3 is the sidechain of d2 contains
A double bond between carbons 22 and 23 and a methyl group on carbon 24 biology the active vitamin d metabolite calcitriol mediates its biological effects by binding to the vitamin d receptor which is principally located in the nuclei of target cells the binding of calcitriol to the vdr allows the vdr to act as a transcription factor that modulates the gene
Expression of transport proteins which are involved in calcium absorption in the intestine the vitamin d receptor belongs to the nuclear receptor superfamily of steroid / thyroid hormone receptors and vtr’s are expressed by cells in most organs including the brain heart skin gonads prostate and breast vdr activation in the intestine bone kidney and parathyroid
Glands cells leads to the maintenance of calcium and phosphorus levels in the blood and to the maintenance of bone content one of the most import roles of vitamin d is to maintain skeletal calcium balance by promoting calcium absorption in the intestines promoting bone resorption by increasing ostia class number maintaining calcium and phosphate levels for bone
Formation and allowing proper functioning of parathyroid hormone to maintain serum calcium levels vitamin d deficiency can result in lower bone mineral density and an increased risk of reduced bone density or bone fracture because a lack of vitamin d alters mineral metabolism in the body thus vitamin d is also critical for bone remodeling through its role as a
Potent stimulator of bone resorption the vdr may be involved in cell proliferation and differentiation vitamin d also affects the immune system and vtr’s are expressed in several white blood cells including monocytes and activated t and b cells in vitro vitamin d increases expression of the tyrosine hydroxylase gene and adrenal meta larry cells and affects the
Synthesis of neurotrophins nitric oxide synthase and glutathione deficiency a diet deficient in vitamin d in conjunction with inadequate sun exposure causes osteomalacia which is a softening of the bones in the developed world this is a rare disease however vitamin d deficiency has become a worldwide problem in the elderly and remains common in children and
Adults low blood calcified il can result from avoiding the sun deficiency results in impaired bone mineralization and bone damage which leads to bone softening diseases including rickets and osteomalacia being deficient in vitamin d can cause intestinal absorption of dietary calcium to fall to 15% when not deficient an individual usually absorbs between 60 to
80 percent deficiency rickets rickets a childhood disease is characterized by impeded growth and soft weak deformed long bones that bend and bow under their weight as children start to walk this condition is characterized by bowlegs which can be caused by calcium or phosphorus deficiency as well as a lack of vitamin d today it is largely found in low-income
Countries in africa asia or the middle east and in those with genetic – orders such as suta vitamin d deficiency rickets maternal vitamin d deficiency may cause overt bone disease from before birth an impairment of bone quality after birth nutritional rickets exists in countries with intense year-round sunlight such as nigeria and can occur without vitamin d
Deficiency although rickets and osteomalacia are now rare in britain outbreaks have happened in some immigrant communities in which osteomalacia sufferers included women with seemingly adequate daylight outdoor exposure wearing western clothing having darker skin and reduced exposure to sunshine did not produce rickets unless the diet deviated from a western
Omnivore pattern characterized by high intakes of meat fish and eggs and low intakes of high extraction cereals the dietary risk factors for rickets include abstaining from animal foods vitamin d deficiency remains the main cause of rickets among young infants in most countries because breast milk is low in vitamin d and social customs and climatic conditions can
Prevent adequate sun exposure in sunny countries such as nigeria south africa and bangladesh where rickets occurs among older toddlers and children it has been attributed to low dietary calcium intakes which are characteristic of cereal based diets with limited access to dairy products rickets was formerly a major public health problem among the u.s. population
In denver where ultraviolet rays are about 20% stronger than at sea level on the same latitude almost two-thirds of 500 children had mild rickets in the late 1920s an increase in the proportion of animal protein in the 20th century american diet coupled with increased consumption of milk fortified with relatively small quantities of vitamin d coincided with a
Dramatic decline in the number of rickets cases also in the united states and canada vitamin d fortified milk infant vitamin supplements and vitamin supplements have helped to eradicate the majority of cases of rickets for children with fat malabsorption conditions deficiency osteomalacia osteomalacia is a disease in adults that results from vitamin d deficiency
Characteristics of this disease are softening of the bones leading to bending of the spine bowing of the legs procs muscle weakness bone fragility and increased risk for fractures osteomalacia reduces calcium absorption and increases calcium loss from bone which increases the risk for bone fractures osteomalacia is usually present when 25 hydroxy vitamin d
Levels are less than about 10 nanograms per milliliter although the effects of osteomalacia are thought to contribute to chronic musculoskeletal pain there is no persuasive evidence of lower vitamin d levels and chronic pain sufferers or that supplementation alleviates chronic nonspecific musculoskeletal pain deficiency skin pigmentation dark-skinned people
Living in temperate climates have been shown to have low vitamin d levels but the significance of this is not certain dark-skinned people may be less efficient at making vitamin d because melanin in the skin hinders vitamin d synthesis use of supplements the effects of vitamin d supplementation on health are uncertain a 2013 review did not find any effect from
Supplementation on the rates of disease other than a tentative decrease in mortality in the elderly vitamin d supplements do not alter the outcomes for myocardial infarction stroke or cerebrovascular disease cancer bone fractures or knee osteoarthritis low vitamin d levels may result from disease rather than cause disease a united states institute of medicine report
States outcomes related to cancer cardiovascular disease and hypertension and diabetes and metabolic syndrome false and physical performance immune functioning and autoimmune disorders infections neuropsychological functioning and preeclampsia could not be linked reliably with calcium or vitamin d intake and were often conflicting some researchers claim the iom
Was too definitive in its recommendations and made a mathematical mistake when calculating the blood level of vitamin d associated with bone health members of the iron panel maintained that they used a standard procedure for dietary recommendations and that the report is solidly based on the data research on vitamin d supplements including large-scale clinical trials his continued
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Vitamin D #AlexaExplains By Useful Knowledge! by ALEXA
