Editing Vitamin (section)

==Classification==
Vitamins are classified as either [[Hydrophilicity|water-soluble]] or [[lipophilicity|fat-soluble]]. In humans there are 13 vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C). Water-soluble vitamins dissolve easily in water and, in general, are readily excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption.<ref name="pmid18635909">{{cite journal | vauthors = Fukuwatari T, Shibata K | title = Urinary water-soluble vitamins and their metabolite contents as nutritional markers for evaluating vitamin intakes in young Japanese women | journal = Journal of Nutritional Science and Vitaminology | volume = 54 | issue = 3 | pages = 223–229 | date = June 2008 | pmid = 18635909 | doi = 10.3177/jnsv.54.223 | doi-access = free }}</ref> Because they are not as readily stored, more consistent intake is important.<ref name="urlWater-Soluble Vitamins">{{cite web|url=http://www.ext.colostate.edu/PUBS/FOODNUT/09312.html|vauthors=Bellows L, Moore R|work=Colorado State University|title=Water-Soluble Vitamins|access-date=7 December 2008|archive-date=25 September 2015|archive-url=https://web.archive.org/web/20150925060831/http://www.ext.colostate.edu/pubs/foodnut/09312.html|url-status=dead}}</ref> Fat-soluble vitamins are absorbed through the [[gastrointestinal tract]] with the help of [[lipid]]s (fats). Vitamins A and D can accumulate in the body, which can result in dangerous [[hypervitaminosis]]. Fat-soluble vitamin deficiency due to malabsorption is of particular significance in [[cystic fibrosis]].<ref name="pmid18812835">{{cite journal | vauthors = Maqbool A, Stallings VA | title = Update on fat-soluble vitamins in cystic fibrosis | journal = Current Opinion in Pulmonary Medicine | volume = 14 | issue = 6 | pages = 574–581 | date = November 2008 | pmid = 18812835 | doi = 10.1097/MCP.0b013e3283136787 | s2cid = 37143703 }}</ref>