Editing Rickets (section)

===Sunlight===
Sunlight, especially ultraviolet light, lets human skin cells convert vitamin D from an inactive to active state. In the absence of vitamin D, dietary calcium is not properly absorbed, resulting in [[hypocalcaemia]], leading to skeletal and dental deformities and [[neuromuscular]] symptoms, e.g. hyperexcitability. Foods that contain vitamin D include butter, eggs, fish liver oils, margarine, fortified milk and juice, [[Agaricus bisporus|portabella]] and [[shiitake]] mushrooms, and [[oily fish]]es such as [[tuna]], [[herring]], and [[salmon]]. A rare [[X-linked dominant]] form exists called vitamin D-resistant rickets or X-linked hypophosphatemia.<ref>{{cite journal | vauthors = Wacker M, Holick MF | title = Sunlight and Vitamin D: A global perspective for health | journal = Dermato-Endocrinology | volume = 5 | issue = 1 | pages = 51–108 | date = January 2013 | pmid = 24494042 | pmc = 3897598 | doi = 10.4161/derm.24494 }}</ref>

Cases have been reported in Britain in recent years<ref>''[[Daily Telegraph]]'', page 4, Wednesday 19 January 2011</ref> of rickets in children of many social backgrounds caused by insufficient production in the body of vitamin D because the sun's ultraviolet light was not reaching the skin due to use of strong [[sunblock]], too much "covering up" in sunlight, or not getting out into the sun. Other cases have been reported among the children of some ethnic groups in which mothers avoid exposure to the sun for religious or cultural reasons, leading to a maternal shortage of vitamin D, and people with darker skin need more sunlight to maintain vitamin D levels.<ref>{{cite web | url = https://www.independent.co.uk/life-style/health-and-families/health-news/rise-in-rickets-linked-to-ethnic-groups-that-shun-the-sun-2319920.html | title = Rise in rickets linked to ethnic groups that shun the sun | work = [[The Independent]] | date = 25 July 2011 | access-date = 25 July 2011 }}</ref><ref>{{cite web | url = http://news.bbc.co.uk/1/hi/health/7161458.stm | title = Doctors fear rickets resurgence | work = [[BBC]] | date = 28 December 2007 | access-date = 25 July 2011 }}</ref>

Rickets had historically been a problem in [[London]], especially during the [[Industrial Revolution]]. Persistent thick fog and heavy industrial smog permeating the city blocked out significant amounts of sunlight to such an extent that up to 80 percent of children at one time had varying degrees of rickets in one form or the other.<ref>{{cite journal | vauthors = Holick MF | title = Resurrection of vitamin D deficiency and rickets | journal = The Journal of Clinical Investigation | volume = 116 | issue = 8 | pages = 2062–2072 | date = August 2006 | pmid = 16886050 | pmc = 1523417 | doi = 10.1172/JCI29449 }}</ref> It is sometimes known "the English Disease" in some foreign languages (e.g. German: {{Lang|de|Die englische Krankheit}}, Dutch: {{Lang|nl|Engelse ziekte}}, Hungarian: {{Lang|hu|angolkór}}, Swedish: {{Lang|sv|engelska sjukan}}).<ref>{{cite journal | vauthors = Bivins R | title = "The English disease" or "Asian rickets"? Medical responses to postcolonial immigration | journal = Bulletin of the History of Medicine | volume = 81 | issue = 3 | pages = 533–568 | date = 2007 | pmid = 17873451 | pmc = 2630160 | doi = 10.1353/bhm.2007.0062 }}</ref>