What is "vitamin d"

vitamin D \vitamin D\ n. any of several chemically related fat-soluble vitamins that prevent rickets. It is found in fish-liver oils, egg yolks and milk. Component vitamin D2 is also called calciferol, and vitamin D3 is called cholecalciferol.

Syn: calciferol, ergocalciferol, cholecalciferol.

n. Either of a number of fat-soluble vitamins, required for normal bone development and that prevents rickets; can be manufactured in the skin on exposure to sunlight.

n. a fat-soluble vitamin that prevents rickets [syn: calciferol, viosterol, ergocalciferol, cholecarciferol, D]

"Vitamin D" is the sixth episode of the American television series Glee. The episode premiered on the Fox network on October 7, 2009. It was written by series creator Ryan Murphy and directed by Elodie Keene. In the episode, glee club director Will Schuester ( Matthew Morrison) pits the male and female club members against each other for a mash-up competition. Will's wife Terri ( Jessalyn Gilsig) takes a job as the school nurse to stop him becoming closer to guidance counsellor Emma Pillsbury ( Jayma Mays), but is fired after giving the students performance-enhancing pseudoephedrine tablets.

The episode features mash-up covers of " It's My Life" by Bon Jovi and " Confessions Part II" by Usher, and " Halo" by Beyoncé Knowles and " Walking on Sunshine" by Katrina and the Waves. Both tracks were released as singles, available for digital download. "Vitamin D" was watched by 7.30 million US viewers, and received generally positive reviews from critics. Performances by Morrison, Mays and Jane Lynch as cheerleading coach Sue Sylvester attracted praise, as did the staging of the musical mash-ups. However, Aly Semigran of MTV and Mandi Bierly of Entertainment Weekly both noted critically that dramatic storylines in the episode dominated over the musical performances.

Vitamin D usually refers to Vitamin D, the group of fat-soluble prohormones.

It may also refer to:

• Ergocalciferol, also known as vitamin D
• Cholecalciferol, also known as vitamin D
• 22-Dihydroergocalciferol, also known as vitamin D
• Vitamin D
• Calcifediol, also known as calcidiol: 25-hydroxycholecalciferol, or 25-hydroxyvitamin D (abbreviated 25(OH)D). Blood concentration of calcifediol is considered the best indicator of vitamin D status.
• vitamin D-related concepts, including:
  • Vitamin D and respiratory tract infections
  • Vitamin D and neurology
  • Hypervitaminosis D, toxicity caused by the ingestion of large doses of vitamin D
  • Hypovitaminosis D, a deficiency of vitamin D
  • Vitamin D-binding protein, encoded by the GC gene
  • calcitriol receptor, also known as VDR, a receptor for vitamin D
  • Vitamin D-dependent calcium-binding protein
  • X-linked hypophosphatemia, also known as vitamin D-resistant rickets, a form of rickets for which ingestion of vitamin D is relatively ineffective
• "Vitamin D" (Glee), an episode of the American musical comedy-drama television series Glee
• Dextromethorphan, or DXM, a street name for over-the-counter cough suppressants containing DXM.

Vitamin D is the first studio album by Canadian dubstep producer and artist Datsik, released on April 10, 2012 in US. The album was co-produced by various electronic music producers such as fellow Canadian dubstep producer Downlink, Israeli psytrance and electronica production duo Infected Mushroom and American DJ Z-Trip. The first official single from the album is "Fully Blown" (featuring Snak the Ripper), which was released on January 31st. The second single, "Evilution", which was co-produced by Infected Mushroom and features vocals from Jonathan Davis of the nu metal band Korn, was released on March 13.

"Light the Fuse" was released as a single (with remixes by Terravita and Sub Antix) over a year after the album's release.

Vitamin D refers to a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. In humans, the most important compounds in this group are vitamin D (also known as cholecalciferol) and vitamin D ( ergocalciferol). Cholecalciferol and ergocalciferol can be ingested from the diet and from supplements. Very few foods contain vitamin D; synthesis of vitamin D (specifically cholecalciferol) in the skin is the major natural source of the vitamin. Dermal synthesis of vitamin D from cholesterol is dependent on sun exposure (specifically UVB radiation).

Vitamin D from the diet or dermal synthesis from sunlight is biologically inactive; activation requires enzymatic conversion ( hydroxylation) in the liver and kidney. Evidence indicates the synthesis of vitamin D from sun exposure is regulated by a negative feedback loop that prevents toxicity, but because of uncertainty about the cancer risk from sunlight, no recommendations are issued by the Institute of Medicine (US) for the amount of sun exposure required to meet vitamin D requirements. Accordingly, the Dietary Reference Intake for vitamin D assumes no synthesis occurs and all of a person's vitamin D is from food intake, although that will rarely occur in practice. As vitamin D is synthesized in adequate amounts by most mammals exposed to sunlight, it is not strictly a vitamin, and may be considered a hormone as its synthesis and activity occur in different locations. Vitamin D has a significant role in calcium homeostasis and metabolism. Its discovery was due to effort to find the dietary substance lacking in rickets (the childhood form of osteomalacia).

Beyond its use to prevent osteomalacia or rickets, the evidence for other health effects of 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 decrease in mortality in elderly people, and another concluding no clear justification exists for recommending vitamin D.

In the liver, cholecalciferol (vitamin D) is converted to calcidiol, which is also known as calcifediol (INN), 25-hydroxycholecalciferol (aka 25-hydroxyvitamin D — abbreviated 25(OH)D). Ergocalciferol (vitamin D) is converted in the liver to 25-hydroxyergocalciferol (aka 25-hydroxyvitamin D — abbreviated 25(OH)D). These two specific vitamin D metabolites are measured in serum to determine a person's vitamin D status. Part of the calcidiol is converted by the kidneys to calcitriol, the biologically active form of vitamin D. Calcitriol circulates as a hormone in the blood, regulating the concentration of calcium and phosphate in the bloodstream and promoting the healthy growth and remodeling of bone. Calcitriol also affects neuromuscular and immune function.