Vitamin DThe Sunshine “Vitamin”

History • Vitamin D was discovered as a cure for Rickets

in the early 20th century.• It was first understood to only come from the

skin of animals and was necessary for the body, and therefore it was named a vitamin.

• However, further research showed that humans are able to manufacture significant quantities of it in their skin, this technically means that it is not a vitamin.

Rickets • A bone disease brought on by a

Vitamin D deficiency.• Rickets causes weakening and

softening of the bones in children.• It afflicted many children in the

18th and 19th century, killing many due to a lack of understanding of the disease.

• The first cure for rickets came in the early 19th century in the form of cod liver oil; however, the reason why this worked was not know till the early 20th century.

Vitamin D• Vitamin D is a group of fat-soluble steroid molecules

that are derived from the parent structure cholesterol.• Vitamin D is based on the

cyclopentanoperhydrophenanthrene ring structure.• It is unique in that it is the only vitamin that is

produced inside the body.• It is technically classified as a seco steroid hormone

due to the fact that it is manufactured by the body and plays regulatory roles.

• There are two dominant forms of vitamin D, D2 and D3 .

• Vitamin D, when either ingested or created in the skin, is inactive and must be hydroxylated two times in order to become hormonally active and useful to the body.

• The first hydroxylation takes place in the liver where the number 25 carbon is hydroxylated.

• The second hydroxylation takes place in the kidney where the number 1 carbon is hydroxylated.

Vitamin D

Vitamin D3• Also known as cholecalciferol.• Produced photochemically in

the skin of animals and humans from the ultraviolet radiation of 7-dehydrocholesterol.

• Regulation of production is controlled by an equilibrium; meaning that when the concentration of D3 is high enough the ultraviolet radiation begins to break down the D3.

1,25- Dihydroxycholecalciferol

7-Dehydrocholesterol

Vitamin D3• Vitamin D3 is produced in the

epidermis of the skin.• The epidermis contains five strata.

– From outer to inner:• Stratum Corneum• Stratum Lucidum• Stratum Granulosum• Stratum Spinosum• Stratum Basale

• The stratum spinosum and basale is where the highest concentration of 7-dehydrocholesterol is found.

• The melanin concentration in the epidermis is a factor that must be considered.

UVB

Melanin

UVB

7-dehydrocholesterol

Vitamin D2

• Also known as ergocalciferol

• Produced photochemically by the ultraviolet radiation of ergosterol in plants.

• Functionally serves the same purpose as D3, however it is markedly less effective.

1,25- Dihydroxyergocalciferol

Ergosterol

Comparison1,25-Dihydroxycholecalciferol 1,25-Dihydroxyergocalciferol

Major Biological Role• Vitamin D is responsible for the regulation of calcium

and phosphorus in the serum. • Vitamin D can increase or decrease the small

intestine effectiveness of absorbing calcium and phosphorus.

• This is made possible by the vitamin D receptor (VDR) which conformationally changes when bound to 1,25-dihydroxy vitamin D, which allows absorption of calcium and phosphorus in the small intestine so that bone mineralization can occur.

Minor/Recently Discovered biological roles

• Recent studies have shown that vitamin D may be able to suppress some autoimmune diseases.

• Also a recent study showed that vitamin D plays some role in neurotransmitter synthesis, however the exact role is not known yet.

Daily intake

< 1 1-13 14-18 19-70 71<0

100

200

300

400

500

600

700

800

Vitamin D Daily Recommended Intake

years of age

IU / day

Still being debated…

Sources of vitamin D

1 Egg Yolk

4oz Beef Liver

4oz Tuna

4oz Cod

4oz Trout

1 table spoon Cod Liver Oil

0 200 400 600 800 1000 1200

25

53

140

140

520

1350

Naturally Occuring Vitamin D

IU

Conclusion• Vitamin D is absolutely essential for natural

function of the body.• We still do not understand all of the uses of

vitamin D in the body and therefore further research must be conducted.

References• Wolf, G. (2004). The Discovery of Vitamin D: The Contribution of Adolf Windaus. The Journal of Nutrition, 134, 1299-1302. Retrieved 13 Oct. 2010, from

http://jn.nutrition.org/cgi/content/full/134/6/1299.• University of California, Riverside. (1999). History of Vitamin D. About Vitamin D. Retrieved 13 Oct. 2010, from http://vitamind.ucr.edu/history.html.• National Academy of Sciences. (2009). Unraveling the Enigma of Vitamin D. Beyond Discovery: The path from research to human benefit. Retrieved 13 Oct. 2010, from

http://www.beyonddiscover.org/content/view.txt.asp?a=414.• Vitamin D – Vitamin D2, Vitamin D3, Vitamin D4, formerly, Vitamin D5, Vitamin D6. http://science.jrank.org/pages/44204/vitamin-D.html. • Vitamin D (calciferol). (2006). Vitamins & Health Supplements. Retrieved 13 Oct. 2010, from http://www.vitamins-supplements.org/vitamin-D.php.• What is Vitamin D? What are the Benefits of Vitamin D? (2009). Medical News Today. Retrieved 13 Oct. 2010, from http://www.medicalnewstoday.com/articles/161618.php.• University of California, Riverside. (1999). Chemistry of Vitamin D. About Vitamin D. Retrieved 13 Oct. 2010, from http://vitamind.ucr.edu/chem.html.• Ergocalciferol (vitamin D2, vitamin D, calciferol). (2006). Vitamins & Health Supplements. Retrieved 17 Nov. 2010, from http://www.vitamins-supplements.org/ergocalciferol.php.• Houghton, L. A., & Vieth, R. (2006). The Case Against Ergocalciferol (vitamin D2) as a Vitamin Supplement. American Journal of Clinical Nutrition, 84(4), 694-697. Retrieved 17 Nov.

2010, from http://www.ajcn.org/content/84/4/694.full.• Cholecalciferol (vitamin D3, vitamin D, calciferol). (2006). Vitamins & Health Supplements. Retrieved 17 Nov. 2010, from http://www.vitamins-supplements.org/cholecalciferol.php.• New Ideas on Vitamin D. (1973). The British Medical Journal, 1(5854), 629-630. JSTOR. Web 17 Nov. 2010.• Cooke, N.E., Murgia, A., & McLeod, J.F. (2006). Vitamin D-Binding Protein: Structure and Pattern of Expression. Annals of the New York Academy of Sciences, 538, 49-59. Retrieved 17

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• Haussler, M.R., Whitfield, G.K., Haussler, C.A., Hsieh, J., Thompson, P.D., Selznick, S.H., Dominguez, C.E., & Jurutka, P.W. (1998). The Nuclear Vitamin D Receptor: Biological and Molecular Regulatory Properties Revealed. Journal of Bone and Mineral Research, 13(3), 325-349. Retrieved 17 Nov. 2010, from http://onlinelibrary.wiley.com/doi/10.1359/jbmr.1998.13.3.325/full.

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• Garcion, E., Wion-Barbot, N., Montero-Menei, C.N., Berger, F., & Wion, D. (2002). New Clues About Vitamin D Functions in the Nervous System. Trends in Endocrinology and Metabolism, 13(3), 100-105. doi: 10.1016/S1043-2760(01)00547-1.

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