Editing Carotene (section)

==β-Carotene and physiology==

===β-Carotene and cancer===
An article on the [[American Cancer Society]] says that [[The Cancer Research Campaign]] has called for warning labels on β-carotene supplements to caution smokers that such supplements may increase the risk of lung cancer.<ref>{{cite web|url=http://www.cancer.org/docroot/NWS/content/NWS_1_1x_Warning_Labels_on_Beta_Carotene_Called_For.asp |title=British Cancer Organization Calls for Warning Labels on Beta-Carotene |date=2000-07-31 |access-date=2007-03-15 |archive-url=https://web.archive.org/web/20061204074724/http://www.cancer.org/docroot/NWS/content/NWS_1_1x_Warning_Labels_on_Beta_Carotene_Called_For.asp |archive-date=2006-12-04 |url-status=dead }}</ref>

[[The New England Journal of Medicine]] published an article<ref>{{cite journal |author=The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group |title=The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers |journal=N Engl J Med |volume=330 |issue=15 |pages=1029–35 |year=1994 |pmid=8127329 |doi=10.1056/NEJM199404143301501 |doi-access=free }}</ref> in 1994 about a trial which examined the relationship between daily supplementation of β-carotene and [[vitamin E]] (α-[[tocopherol]]) and the incidence of lung cancer. The study was done using supplements and researchers were aware of the epidemiological correlation between carotenoid-rich fruits and vegetables and lower lung cancer rates. The research concluded that no reduction in lung cancer was found in the participants using these supplements, and furthermore, these supplements may, in fact, have harmful effects.

The Journal of the [[National Cancer Institute]] and The New England Journal of Medicine published articles in 1996<ref>{{cite journal |vauthors=Omenn GS, Goodman GE, Thornquist MD |title=Risk factors for lung cancer and for intervention effects in CARET, the Beta-Carotene and Retinol Efficacy Trial |journal=J Natl Cancer Inst |volume=88 |issue=21 |pages=1550–9 |year=1996 |pmid=8901853 |doi=10.1093/jnci/88.21.1550 |display-authors=etal|url=https://escholarship.org/content/qt8qk8w9zw/qt8qk8w9zw.pdf?t=ol280z |doi-access=free }}</ref><ref name=fn1>{{cite journal |vauthors=Omenn GS, Goodman GE, Thornquist MD |title=Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease|journal=N Engl J Med |volume=334 |issue=18 |pages=1150–5 |year=1996 |pmid=8602180 |doi=10.1056/NEJM199605023341802 |display-authors=etal|url=https://escholarship.org/content/qt0mr2057n/qt0mr2057n.pdf?t=ngzuwv }}</ref> about a trial with a goal to determine if vitamin A (in the form of [[retinyl palmitate]]) and β-carotene (at about 30&nbsp;mg/day, which is 10 times the [[Reference Daily Intake]]) supplements had any beneficial effects to prevent cancer. The results indicated an ''increased'' risk of lung and prostate cancers for the participants who consumed the β-carotene supplement and who had lung irritation from [[tobacco smoking|smoking]] or [[asbestos]] exposure, causing the trial to be stopped early.<ref name=fn1 />

A review of all randomized controlled trials in the scientific literature by the [[Cochrane Collaboration]] published in ''[[Journal of the American Medical Association|JAMA]]'' in 2007 found that synthetic β-carotene ''increased'' mortality by 1–8% (Relative Risk 1.05, 95% confidence interval 1.01–1.08).<ref>{{cite journal |vauthors=Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C |title=Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis|journal=JAMA |volume=297 |issue=8 |pages=842–57 |year=2007 |pmid=17327526 |doi=10.1001/jama.297.8.842}}
</ref> However, this meta-analysis included two large studies of smokers, so it is not clear that the results apply to the general population.<ref>
See the [http://jama.ama-assn.org/cgi/content/extract/298/4/401-a letter] to [[Journal of the American Medical Association|JAMA]] by Philip Taylor and [[Sanford Dawsey]] and the [http://jama.ama-assn.org/cgi/content/extract/298/4/402 reply] by the authors of the original paper.
</ref> The review only studied the influence of synthetic antioxidants and the results should not be translated to potential effects of fruits and vegetables.

===β-Carotene and photosensitivity===
Oral β-carotene is prescribed to people suffering from [[erythropoietic protoporphyria]]. It provides them some relief from photosensitivity.<ref>{{cite journal|last1=Mathews-Ross|first1=Michelene|title=Beta Carotene Therapy for Erythropoietic Protoporphyria and Other Photosensitivity Diseases|journal=Archives of Dermatology|date=1977|volume=113|issue=9|pages=1229–1232|doi=10.1001/archderm.1977.01640090077011|pmid=900968}}</ref>

===Carotenemia===
{{Main|Carotenodermia}}
Carotenemia or hypercarotenemia is excess carotene, but unlike excess vitamin A, carotene is non-toxic. Although hypercarotenemia is not particularly dangerous, it can lead to an oranging of the skin (carotenodermia), but not the [[conjunctiva]] of eyes (thus easily distinguishing it visually from [[jaundice]]). It is most commonly associated with consumption of an abundance of [[carrot]]s, but it also can be a [[medical sign]] of more dangerous conditions.