Editing Vitamin C (section)

===Common cold===
[[File:Linus Pauling.jpg|alt=1955 black-and-white photo of Nobel Prize winner, Linus Pauling.|thumb|upright|The Nobel Prize winner [[Linus Pauling]] advocated taking vitamin C for the [[common cold]] in [[Vitamin C and the Common Cold (book)|a 1970 book]].]]

Research on vitamin{{nbsp}}C in the common cold has been divided into effects on prevention, duration, and severity. Oral intakes of more than 200&nbsp;mg/day taken on a regular basis was not effective in prevention of the common cold. Restricting analysis to trials that used at least 1000&nbsp;mg/day also saw no prevention benefit. However, taking a vitamin{{nbsp}}C supplement on a regular basis did reduce the average duration of the illness by 8% in adults and 14% in children, and also reduced the severity of colds.<ref name=Hem2013>{{cite journal |vauthors = Hemilä H, Chalker E |title = Vitamin C for preventing and treating the common cold |journal = The Cochrane Database of Systematic Reviews |issue = 1 |pages = CD000980 |date = January 2013 |volume = 2013 |pmid = 23440782 |doi = 10.1002/14651858.CD000980.pub4 |pmc = 1160577}}</ref> Vitamin C taken on a regular basis reduced the duration of severe symptoms but had no effect on the duration of mild symptoms.<ref name=Hem2023>{{cite journal |vauthors=Hemilä H, Chalker E |title=Vitamin C reduces the severity of common colds: a meta-analysis |journal=BMC Public Health |volume=23 |issue=1 |pages=2468 |date=December 2023 |pmid=38082300 |pmc=10712193 |doi=10.1186/s12889-023-17229-8 |url= | doi-access = free | title-link = doi }}</ref> Therapeutic use, meaning that the vitamin was not started unless people started to feel the beginnings of a cold, had no effect on the duration or severity of the illness.<ref name="Hem2013" />

Vitamin C distributes readily in high concentrations into [[immune system|immune cells]], promotes [[natural killer cell]] activities, promotes [[lymphocyte]] proliferation, and is depleted quickly during infections, effects suggesting a prominent role in immune system function.<ref name="Wintergerst-2006">{{cite journal | vauthors = Wintergerst ES, Maggini S, Hornig DH | s2cid = 21756498 | title = Immune-enhancing role of vitamin C and zinc and effect on clinical conditions | journal = Annals of Nutrition & Metabolism | volume = 50 | issue = 2 | pages = 85–94 | year = 2006 | pmid = 16373990 | doi = 10.1159/000090495 | url = http://doc.rero.ch/record/303675/files/S0029665108006927.pdf | access-date = August 25, 2019 | archive-date = July 22, 2018 | archive-url = https://web.archive.org/web/20180722160530/http://doc.rero.ch/record/303675/files/S0029665108006927.pdf | url-status = live }}</ref> The [[European Food Safety Authority]] concluded there is a [[causality|cause and effect relationship]] between the dietary intake of vitamin C and functioning of a normal immune system in adults and in children under three years of age.<ref name="efsa09">{{cite journal |author=EFSA Panel on Dietetic Products, Nutrition and Allergies |title=Scientific Opinion on the substantiation of health claims related to vitamin C and protection of DNA, proteins and lipids from oxidative damage (ID 129, 138, 143, 148), antioxidant function of lutein (ID 146), maintenance of vision (ID 141, 142), collagen formation (ID 130, 131, 136, 137, 149), function of the nervous system (ID 133), function of the immune system (ID 134), function of the immune system during and after extreme physical exercise (ID 144), non-haem iron absorption (ID 132, 147), energy-yielding metabolism (ID 135), and relief in case of irritation in the upper respiratory tract (ID 1714, 1715) pursuant to Article 13(1) of Regulation (EC) No 1924/2006 |journal=EFSA Journal |volume=7 |issue=9 |year=2009 |page=1226 |doi=10.2903/j.efsa.2009.1226| doi-access = free | title-link = doi }}</ref><ref name="efsa15">{{cite journal |author=EFSA Panel on Dietetic Products, Nutrition and Allergies |title=Vitamin C and contribution to the normal function of the immune system: evaluation of a health claim pursuant to Article 14 of Regulation (EC) No 1924/2006 |journal=EFSA Journal |year=2015 |volume=13 |issue=11 |page=4298 |doi=10.2903/j.efsa.2015.4298| doi-access = free | title-link = doi |hdl=11380/1296052 |hdl-access=free }}</ref>