Vitamin D is a fat-soluble steroid hormone precursor that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. Strictly speaking, it is not a vitamin, but is referred to as one for historical reasons. General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... This article is about the chemical element. ... A Vitamin is an organic molecule and micronutrient required by a living organism in minute amounts (usually less than one milligram daily) for normal growth and activity. ...

Often known as calciferol.

Forms of Vitamin D:

• Vitamin D₁: lamisterol
• Vitamin D₂: ergocalciferol (made from ergosterol)
• Vitamin D₃: cholecalciferol (made from 7-dehydrocholesterol)
• Vitamin D₄: dihydrotachysterol (22:23-dihydrovitamin D2)
• Vitamin D₅: 7-dehydrositosterol

Vitamin D₂ is derived from ergosterol in the diet, whereas vitamin D₃ is derived from cholesterol via 7-dehydrocholesterol. Ultraviolet light (UVB, which is wavelengths 290 to 315 nm), found in sunlight, is responsible for the production of the vitamin - 20,000 IU in one minimal erythemal dose of exposure. However, in certain parts of the world with reduced sunlight intensity there is the possibility that the quantity of vitamin D is not always sufficient. To prevent this possibility, milk may be fortified with vitamin D₂. A deficiency of vitamin D leads to rickets, which is a softening of the bones owing to faulty mineralization. Ergocalciferol is a form of Vitamin D with the systematic name (5Z,7E,22E)-(3S)-9,10-seco-5,7,10(19),22-ergostatetraen-3-ol. ... Ergosterol is the biological precursor to Vitamin D2. ... Cholecalciferol is a form of Vitamin D. Vitamin D3 is also a steroid much like testosterone, cholesterol and cortisol. ... Ergosterol is the biological precursor to Vitamin D2. ... Cholesterol is a steroid lipid, found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. ... In the skin 7-dehydrocholesterol (sometimes known as provitamin D3) is synthesized from cholesterol. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... A glass of cows milk Milk most often means the nutrient fluid produced by the mammary glands of female mammals. ... X-ray of the legs in a two-year-old child with rickets Rickets is a disorder of infancy and early childhood of multiple etiologies. ...

The active form of the vitamin is calcitriol which is synthesized from either D₂ or D₃ in the kidneys. Calcitriol binds to a protein transcription factor which then regulates gene expression. The outcome is the maintenance of calcium and phosphorus levels in the bone and blood with the assistance of parathyroid hormone and calcitonin. Vitamin D is a fat soluble vitamin that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. ... Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... This article is about the chemical element. ... Grays illustration of a human femur, a typically recognized bone. ... Red blood cells (erythrocytes) are present in the blood and help carry oxygen to the rest of the cells in the body Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells, platelets). ... Parathyroid hormone (PTH) is secreted by the parathyroid glands as a polypeptide containing 84 amino acids. ... textCalcitonin is a a 32 amino acid polypeptide hormone that is produced in humans primarily by the C cells of the thyroid. ...

Pioneering work in isolating vitamin D and determining its role in rickets was done by Edward Mellanby in 1918-1920. Professor Edward Mellanby (1884 - 1955) discovered vitamin D and the role of the vitamin in preventing rickets in 1919. ... 1918 was a common year starting on Tuesday of the Gregorian calendar (see link for calendar) or a common year starting on Wednesday of the Julian calendar. ... 1920 is a leap year starting on Thursday (link will take you to calendar) // Events January January 7 - Forces of Russian White admiral Kolchak surrender in Krasnoyarsk. ...

Vitamin D deficiency is also known to cause:

• Osteoporosis: a condition characterized by fragile bones.
• Osteomalacia: a bone-thinning disorder in adults that is similar to rickets.

Vitamin D malnutrition may also be linked to chronic diseases such as cancer (breast, ovarian, colon, prostate, lung and skin), chronic pain, weakness, chronic fatigue, autoimmune diseases like multiple sclerosis and Type 1 diabetes, high blood pressure, mental illnesses (depression, seasonal affective disorder and possibly schizophrenia) heart disease, rheumatoid arthritis, psoriasis, tuberculosis, periodontal disease and inflammatory bowel disease. Osteoporosis is a disease of bone in which the amount of bone is decreased and the strength of trabecular bone is reduced, cortical bone becomes thin and bones are susceptible to fracture. ... Osteomalacia is the painful softening of the bones, usually caused by a definency in vitamin D or calcium. ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... Breast cancer is cancer of breast tissue. ... Ovarian cancer is a malignant ovarian neoplasm (an abnormal growth located on the ovaries). ... Diagram of the stomach, colon, and rectum Colorectal cancer includes cancerous growths in the colon, rectum and appendix. ... Prostate cancer is a group of cancerous cells (a malignant tumor) that begins most often in the outer part of the prostate. ... The incidence of lung cancer is highly correlated with smoking. ... In medicine (dermatology), there are several different types of cancer referred to under the general label of skin cancer. ... This article is about the disease that features high blood sugar. ... For other forms of hypertension see hypertension (disambiguation) Hypertension or high blood pressure is a medical condition where the blood pressure in the arteries is chronically elevated. ... Clinical depression is a health condition of depression with mental and physical components reaching criteria generally accepted by clinicians. ... Seasonal affective disorder, or SAD, is an affective, or mood disorder. ... There are different forms of heart disease: Coronary heart disease Ischaemic heart disease Cardiovascular disease The study of heart disease is Cardiology This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ... Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disorder that causes the immune system to attack the joints. ... Tuberculous lungs show up on an X-ray image Tuberculosis is an infection with the bacterium Mycobacterium tuberculosis, which most commonly affects the lungs (pulmonary TB) but can also affect the central nervous system (meningitis), lymphatic system, circulatory system (miliary TB), genitourinary system, bones and joints. ...

Who may need extra vitamin D to prevent a deficiency?

Older people (greater than age 50) have a higher risk of developing vitamin D deficiency. The ability of skin to convert 7-dehydrocholesterol to pre-vitamin D₃ is decreased in older people. The kidneys, which help convert calcidiol to its active form, sometimes do not work as well when people age. Therefore, many older people may need vitamin D supplementation. Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ...

Newborn infants who are exclusively breastfed may require vitamin D supplements. Breast milk does not contain significant levels of the vitamin, and although infants could receive this vitamin from sunlight, it is usually not recommended that small infants be exposed to sunlight in the levels required to produce a sufficient amount of vitamin D. Infant formula is generally fortified with vitamin D, so this requirement only applies to breastfed infants. A breastfeeding infant Breastfeeding is when a woman feeds an infant, toddler or a young child with milk produced from her breasts, usually directly from the nipples. ... Breast milk usually refers to the milk produced by a human female which is usually fed to infants by breastfeeding. ... An infant being fed by bottle. ...

Those who avoid or are not exposed to the midday sunshine may also require Vitamin D supplements. In particular, recent studies have shown Australians and New Zealanders are Vitamin D deficient [1], particularly after the successful "Slip-Slop-Slap" health campaign encouraging Australians to cover up when exposed to sunlight to prevent skin cancer. Ironically, a vitamin D deficiency too may lead to skin cancer. Still, only a few minutes of exposure is all that is required; the production is very rapid. Sunlight is also the trade name of the worlds first packaged, branded laundry soap producted by Lever Brothers. ... Slip-Slop-Slap is the name for a health campaign in Australia exhorting people to slip on a shirt, slop on sunscreen, and slap on a hat when they go out into the sun in order to prevent skin cancer. ... In medicine (dermatology), there are several different types of cancer referred to under the general label of skin cancer. ...

Recent research suggests that adult human beings can handle up to 5,000 international units (IU) per day long-term, although the metabolic pathways have not yet been identified. Given this, and given that humans on vitamin pills of 200 IU per day become deficient if not exposed to sunlight, there is reasonably convincing evidence that the Recommended Dietary Allowance (RDA) of 200 IU (5 micrograms) may be rather too small. An International unit (IU) is a unit of measurement in pharmacology. ... Recommended Dietary Allowance (RDA) is the daily dietary intake level of a nutrient that is considered sufficient to meet the requirements of nearly all (97-98%) healthy individuals in each life-stage and gender group. ...

Human Skin Production of vitamin D

Human skin can produce quantities as large as 20,000 IU without any apparent toxicity in just a few minutes of exposure.

However merely being exposed to sunlight does not automatically mean that vitamin D is produced, only the UVB in sunlight triggers vitamin D₃ production, but UVB only reaches ground level when the sun is high in the sky. At higher latitudes this only occurs in the summertime close to solar midday (1 pm summertime). In the US, those living above a line from San Francisco to Atlanta will not be able to produce it at all for 3 to 6 months a year. Wikiquote has a collection of quotations by or about: United States Wikinews has news related to this article: United States United States government CIA World Factbook Entry for United States House. ... This page is a candidate for speedy deletion. ... This article is about the state capital of Georgia. ...

Exposure to sunlight also destroys vitamin D, so long term exposure to sunlight cannot cause toxicity, since levels are self-adjusting.

Oral overdose of vitamin D3

Overdose is extremely rare; in fact, mild deficiencies are very common.

For overdose to occur in adults, chronic doses of 1-2mg (over 200 times the RDA) over many months are normally required. Intriguingly, the RDA itself is in fact more than 200x less than the amount that may be generated in about 20 minutes of midday sunshine. But while the sunshine-generated quantity is self-limiting, vitamin pills are not; this has led to widespread concern, which may or may not be misplaced.

In practice, all common foods and correctly-formulated vitamin pills essentially contain far too little for overdose to ever occur in normal circumstances. Indeed, Stoss therapy involves taking a dose over a thousand times the daily RDA once every few months, and even then often fails to normalise vitamin D3 levels in the body.

However, oral overdose has been recorded due to manufacturing and industrial accidents (it leads to hypercalcemia and atherosclerosis), so overdose is very definitely possible.

Acute one-time overdose requires over 50mg (ten thousand times the RDA).

Vitamin D and cancer recovery

Recent research suggests that cancer patients who have their surgery/treatment in the summer - and therefore get more vitamin D - have a much better chance of surviving the disease than those who have their treatment in the winter when they are exposed to less sunlight. [2]

Vitamin D food sources

Fortified foods are the major dietary sources of vitamin D. Prior to the fortification of milk products in the 1930s, rickets was a major public health problem. In the United States milk is fortified with 10 micrograms (400 IU) of vitamin D per quart, and rickets is now uncommon in the US. An International unit (IU) is a unit of measurement in pharmacology. ... A quart is a unit of measurement for volume. ...

One cup of vitamin D fortified milk supplies about one-fourth of the estimated daily need for this vitamin for adults. Although milk is fortified with vitamin D, dairy products made from milk (cheese, yogurt, ice cream, etc.) are generally not fortified with vitamin D. Only a few foods naturally contain significant amounts of vitamin D, including: The acronym CUP could be used to mean: Cambridge University Press Canadian University Press, the press association of Canadian student newspapers The Committee of Union and Progress: a Turkish political party The ISO 4217 code for the Cuban Peso California University of Pennsylvania Control Unit Port see also Cup This...

• fish oils, such as cod liver oil, 1 Tbs., 1,360 IU
• fatty fish, such as:
  • salmon, cooked, 3.5 oz, 360 IU
  • mackerel, cooked, 3.5 oz, 345 IU
  • sardines, canned in oil, drained, 3.5 oz, 270 IU
  • eel, cooked, 3.5 oz, 200 IU
• one whole egg, 25 IU
• Beef liver, cooked, 3½ ounces 15 IU

Sources: National Institutes of Health, National Osteoporosis Society Cod liver oil is an oil extracted from cod livers. ... The Chinook or King Salmon is the largest salmon in North America and can grow up to 58 long and 126 pounds. ... The ounce is the name for a number of different units of mass (oz), and also of two units of fluid volume (fl oz) and of one unit of force, the ounce-force (ozf). ... Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. ... Sardines or pilchards are a group of several types of small oily fish related to herrings, family Clupeidae. ... Families Suborder Anguilloidei Anguillidae (freshwater eels) Heterenchelyidae Moringuidae (worm eels) Xenocongridae (false morays) Muraenidae (moray eels) Myrocongridae Suborder Nemichthyoidei Nemichthyidae (snipe eels) Serrivomeridae (sawtooth snipe eels) Cyemidae (bobtail snipe eels) Suborder Congroidei Congridae (congers) Muraenesocidae (conger pikes) Nettastomatidae (witch eels) Nessorhamphidae (duckbilled eels) Derichthyidae (neck eels) Ophichthidae (snake eels) Macrocephenchelyidae... The National Institutes of Health is an institution of the United States government which focuses on medical research. ...

Synthesis

Vitamin D₃

Vitamin D₃ is synthesized from 7-dehydrocholesterol, a derivative of cholesterol, which is then photolyzed by ultraviolet light. The product is Previtamin D₃. Cholesterol is a steroid lipid, found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... Wikipedia does not have an article with this exact name. ...

Previtamin D₃ then spontaneously isomerizes to Vitamin D₃ Wikipedia does not have an article with this exact name. ...

Vitamin D₃ (cholecalciferol) is then hydroxylated in the liver to 25-hydroxycholecalciferol (calcidiol) and then further hydroxylated in the kidneys to the main biologically active form 1,25-dihydroxycholecalciferol (calcitriol): Wikipedia does not have an article with this exact name. ...

External links

• Medical Encyclopedia article (note: not a public domain resource)
• Food Sources of Vitamin D.
• How much Vitamin D is too much? Half of the world seem to be deficient...
• Vitamin D information
• Vitamin toxicity