Editing Human nutrition (section)

=== Vitamins ===
{{Main|Vitamin}}

Except for [[vitamin D]], vitamins are essential nutrients,<ref name="Mitchell, Dakota and Haroun, Lee 2012 279" /> necessary in the diet for good health. Vitamin D can be synthesized in the skin in the presence of [[UVB radiation]]. (Many animal species can synthesize [[vitamin C]], but humans cannot.) Certain vitamin-like compounds that are recommended in the diet, such as [[carnitine]], are thought useful for survival and health, but these are not "essential" dietary nutrients because the human body has some capacity to produce them from other compounds. Moreover, thousands of different [[phytochemicals]] have recently been discovered in food (particularly in fresh vegetables), which may have desirable properties including [[antioxidant]] activity (see below); experimental demonstration has been suggestive but inconclusive. Other essential nutrients not classed as vitamins include [[essential amino acid]]s (see [[#Amino Acids|above]]), [[essential fatty acid]]s (see [[#Essential fatty acids|above]]), and the minerals discussed in the preceding section.{{medical citation needed|date=July 2015}}

Vitamin deficiencies may result in disease conditions: [[goiter]], [[scurvy]], [[osteoporosis]], impaired [[immune system]], disorders of cell [[metabolism]], certain forms of cancer, symptoms of premature [[aging]], and poor [[psychology|psychological health]] (including [[eating disorders]]), among many others.<ref>{{cite book | year=2005 | title=Modern Nutrition in Health and Disease | publisher=Lippincott Williams and Wilkins | isbn=978-0-7817-4133-0 | author=Shils}}</ref>

Excess levels of some vitamins are also dangerous to health. The Food and Nutrition Board of the Institute of Medicine has established Tolerable Upper Intake Levels (ULs) for seven vitamins.<ref>{{cite book | editor1=Institute of Medicine | editor-last2=Ross | editor-first2=A. Catharine | editor-last3=Taylor | editor-first3=Christine L. | editor-last4=Yaktine | editor-first4=Ann L. | editor-last5=Del Valle | editor-first5=Heather B. | date=30 March 2011 | title=Dietary reference intakes for calcium and vitamin D | publication-place=Washington, DC | publisher=National Academies Press | isbn=978-0-309-16394-1 | doi=10.17226/13050 | oclc=721907472 | pmid=21796828 | at=pp. [https://nap.nationalacademies.org/read/13050/chapter/24#1112 1112]-1113, Table: Dietary reference intakes (DRIs): Tolerable upper intake levels, vitamins | url=https://www.ncbi.nlm.nih.gov/books/NBK56068/table/summarytables.t7/?report=objectonly | archive-date=2022-06-29 | archive-url=https://web.archive.org/web/20220629190328/https://www.ncbi.nlm.nih.gov/books/NBK56068/table/summarytables.t7/?report=objectonly | url-status=live | author1=Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium | last2=Ross | first2=A. C. | last3=Taylor | first3=C. L. | last4=Yaktine | first4=A. L. | last5=Del Valle | first5=H. B. }}</ref>