Editing Vitamin E (section)

=== Cancer ===
In a 2022 update of an earlier report, the [[United States Preventive Services Task Force]] recommended against the use of vitamin E supplements for the prevention of cardiovascular disease or cancer, concluding there was insufficient evidence to assess the balance of benefits and harms, yet also concluding with moderate certainty that there is no net benefit of supplementation.<ref name="Mangione2022">{{cite journal |vauthors=Mangione CM, Barry MJ, Nicholson WK, Cabana M, Chelmow D, Coker TR, Davis EM, Donahue KE, Doubeni CA, Jaén CR, Kubik M, Li L, Ogedegbe G, Pbert L, Ruiz JM, Stevermer J, Wong JB |title=Vitamin, mineral, and multivitamin supplementation to prevent cardiovascular disease and cancer: US preventive services task force recommendation statement |journal=JAMA |volume=327 |issue=23 |pages=2326–33 |date=June 2022 |pmid=35727271 |doi=10.1001/jama.2022.8970 |s2cid=249886842 |url=| doi-access = free | title-link = doi }}</ref>

As for literature on different types of cancer, an inverse relationship between dietary vitamin E and [[kidney cancer]] and [[bladder cancer]] is seen in observational studies.<ref>{{cite journal | vauthors = Shen C, Huang Y, Yi S, Fang Z, Li L | title = Association of vitamin E intake with reduced risk of kidney cancer: a meta-analysis of observational Studies | journal = Medical Science Monitor | volume = 21 | pages = 3420–6 | date = November 2015 | pmid = 26547129 | pmc = 4644018 | doi = 10.12659/MSM.896018 }}</ref><ref>{{cite journal | vauthors = Wang YY, Wang XL, Yu ZJ | title = Vitamin C and E intake and risk of bladder cancer: a meta-analysis of observational studies | journal = International Journal of Clinical and Experimental Medicine | volume = 7 | issue = 11 | pages = 4154–64 | date = 2014 | pmid = 25550926 | pmc = 4276184 }}</ref> A large clinical trial reported no difference in bladder cancer cases between treatment and placebo.<ref>{{cite journal | vauthors = Lotan Y, Goodman PJ, Youssef RF, Svatek RS, Shariat SF, Tangen CM, Thompson IM, Klein EA | title = Evaluation of vitamin E and selenium supplementation for the prevention of bladder cancer in SWOG coordinated SELECT | journal = The Journal of Urology | volume = 187 | issue = 6 | pages = 2005–10 | date = June 2012 | pmid = 22498220 | pmc = 4294531 | doi = 10.1016/j.juro.2012.01.117 }}</ref>

An inverse relationship between dietary vitamin E and [[lung cancer]] was reported in observational studies,<ref>{{cite journal |vauthors = Zhu YJ, Bo YC, Liu XX, Qiu CG | title = Association of dietary vitamin E intake with risk of lung cancer: a dose-response meta-analysis |journal = Asia Pacific Journal of Clinical Nutrition |volume = 26 |issue = 2 | pages = 271–7 |date = March 2017 |pmid = 28244705 |doi = 10.6133/apjcn.032016.04 }}</ref> but a large clinical trial in male tobacco smokers reported no impact on lung cancer between treatment and placebo,<ref>{{cite journal | title = The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers | journal = The New England Journal of Medicine | volume = 330 | issue = 15 | pages = 1029–35 | date = April 1994 | pmid = 8127329 | doi = 10.1056/NEJM199404143301501 | vauthors = ((Alpha-Tocopherol)), ((Beta Carotene Cancer Prevention Study Group)) | doi-access = free | title-link = doi }}</ref> and a trial which tracked people who chose to consume a vitamin E dietary supplement reported an increased risk of lung cancer for those consuming more than 215&nbsp;mg/day.<ref name="Slatore2008">{{cite journal | vauthors = Slatore CG, Littman AJ, Au DH, Satia JA, White E | title = Long-term use of supplemental multivitamins, vitamin C, vitamin E, and folate does not reduce the risk of lung cancer | journal = American Journal of Respiratory and Critical Care Medicine |volume = 177 |issue = 5 |pages = 524–30 |date = March 2008 |pmid = 17989343 |pmc = 2258445 |doi = 10.1164/rccm.200709-1398OC }}</ref>

For [[prostate cancer]], there are also conflicting results. A meta-analysis based on serum alpha-tocopherol content reported an inverse correlation in relative risk,<ref>{{cite journal | vauthors = Cui R, Liu ZQ, Xu Q | title = Blood α-tocopherol, γ-tocopherol levels and risk of prostate cancer: a meta-analysis of prospective studies | journal = PLOS ONE| volume = 9 | issue = 3 | pages = e93044 | date = 2014 | pmid = 24667740 | pmc = 3965522 | doi = 10.1371/journal.pone.0093044 | bibcode = 2014PLoSO...993044C | doi-access = free | title-link = doi }}</ref> but a second meta-analysis of observational studies reported no such relationship.<ref>{{cite journal | vauthors = Kim Y, Wei J, Citronberg J, Hartman T, Fedirko V, Goodman M | title = Relation of vitamin E and selenium exposure to prostate cancer risk by smoking Status: A Review and Meta-Analysis | journal = Anticancer Research | volume = 35 | issue = 9 | pages = 4983–96 | date = September 2015 | pmid = 26254398 }}</ref> A large clinical trial with male tobacco smokers and reported a 32% decrease in the incidence of prostate cancer,<ref>{{cite journal | vauthors = Heinonen OP, Albanes D, Virtamo J, Taylor PR, Huttunen JK, Hartman AM, Haapakoski J, Malila N, Rautalahti M, Ripatti S, Mäenpää H, Teerenhovi L, Koss L, Virolainen M, Edwards BK | title = Prostate cancer and supplementation with alpha-tocopherol and beta-carotene: incidence and mortality in a controlled trial | journal = Journal of the National Cancer Institute | volume = 90 | issue = 6 | pages = 440–6 | date = March 1998 | pmid = 9521168 | doi = 10.1093/jnci/90.6.440 | doi-access = free | title-link = doi }}</ref> but the SELECT trial of selenium or vitamin E for prostate cancer enrolled men ages 55 or older and reported relative risk 17% higher for the vitamin group.<ref>{{cite journal | vauthors = Klein EA, Thompson IM, Tangen CM, Crowley JJ, Lucia MS, Goodman PJ, Minasian LM, Ford LG, Parnes HL, Gaziano JM, Karp DD, Lieber MM, Walther PJ, Klotz L, Parsons JK, Chin JL, Darke AK, Lippman SM, Goodman GE, Meyskens FL, Baker LH | title = Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT) | journal = JAMA | volume = 306 | issue = 14 |pages = 1549–56 | date = October 2011 | pmid = 21990298 | pmc = 4169010 | doi = 10.1001/jama.2011.1437 }}</ref>

For [[colorectal cancer]], a systematic review of randomized clinical trials and the large SELECT trial reported no statistically significant change in relative risk.<ref>{{cite journal | vauthors = Arain MA, Abdul Qadeer A | title = Systematic review on "vitamin E and prevention of colorectal cancer" | journal = Pakistan Journal of Pharmaceutical Sciences | volume = 23 | issue = 2 | pages = 125–30 | date = April 2010 | pmid = 20363687 }}</ref><ref>{{cite journal | vauthors = Lance P, Alberts DS, Thompson PA, Fales L, Wang F, San Jose J, Jacobs ET, Goodman PJ, Darke AK, Yee M, Minasian L, Thompson IM, Roe DJ | title = Colorectal adenomas in participants of the SELECT randomized trial of selenium and vitamin E for prostate cancer prevention | journal = Cancer Prevention Research | volume = 10 | issue = 1 | pages = 45–54 | date = January 2017 | pmid = 27777235 | pmc = 5510661 | doi = 10.1158/1940-6207.CAPR-16-0104 }}</ref> The Women's Health Study reported no significant differences for incidences of all types of cancer, cancer deaths, or specifically for breast, lung or colon cancers.<ref name="ReferenceA">{{cite journal | vauthors = Lee IM, Cook NR, Gaziano JM, Gordon D, Ridker PM, Manson JE, Hennekens CH, Buring JE | title = Vitamin E in the primary prevention of cardiovascular disease and cancer: the Women's Health Study: a randomized controlled trial |journal = JAMA | volume = 294 |issue = 1 | pages = 56–65 |date = July 2005 | pmid = 15998891 | doi = 10.1001/jama.294.1.56 }}</ref>

Potential confounding factors are the form of vitamin E used in prospective studies and the amounts. Synthetic, racemic mixtures of vitamin E isomers are not bioequivalent to natural, non-racemic mixtures, yet are widely used in clinical trials and as dietary supplement ingredients.<ref>{{cite book | vauthors = Jensen SK, Lauridsen C | title = Alpha-tocopherol stereoisomers | volume = 76 | pages = 281–308 |year = 2007 |pmid = 17628178 | doi = 10.1016/S0083-6729(07)76010-7 |isbn = 978-0-12-373592-8 |series = Vitamins & Hormones |chapter = Α-Tocopherol Stereoisomers }}</ref> One review reported a modest increase in cancer risk with vitamin E supplementation while stating that more than 90% of the cited clinical trials used the synthetic, racemic form dl-alpha-tocopherol.<ref name="Slatore2008" />

==== Cancer health claims ====
The U.S. Food and Drug Administration initiated a process of reviewing and approving food and dietary supplement health claims in 1993. Reviews of petitions results in proposed claims being rejected or approved. If approved, specific wording is allowed on package labels. In 1999, a second process for claims review was created. If there is not a scientific consensus on the totality of the evidence, a Qualified Health Claim (QHC) may be established. The FDA does not "approve" qualified health claim petitions. Instead, it issues a Letter of Enforcement Discretion that includes very specific claim language and the restrictions on using that wording.<ref>{{cite web |url=https://www.fda.gov/Food/LabelingNutrition/ucm2006877.htm |title=Qualified health claims |website=Overview from the US Food & Drug Administration |access-date=24 August 2018 |archive-date=7 September 2018 |archive-url=https://web.archive.org/web/20180907203827/https://www.fda.gov/Food/LabelingNutrition/ucm2006877.htm |url-status=live }}</ref> The first QHCs relevant to vitamin E were issued in 2003: "Some scientific evidence suggests that consumption of antioxidant vitamins may reduce the risk of certain forms of cancer." In 2009, the claims became more specific, allowing that vitamin E might reduce the risk of renal, bladder and colorectal cancers, but with required mention that the evidence was deemed weak and the claimed benefits highly unlikely. A petition to add brain, cervical, gastric and lung cancers was rejected. A further revision, May 2012, allowed that vitamin E may reduce risk of renal, bladder and colorectal cancers, with a more concise qualifier sentence added: "FDA has concluded that there is very little scientific evidence for this claim." Any company product label making the cancer claims has to include a qualifier sentence.<ref>{{cite web |url=https://www.fda.gov/Food/IngredientsPackagingLabeling/LabelingNutrition/ucm306866.htm |archive-url=https://wayback.archive-it.org/7993/20171114183722/https://www.fda.gov/Food/IngredientsPackagingLabeling/LabelingNutrition/ucm306866.htm |url-status=dead |archive-date=14 November 2017 |title=Alliance for Natural Health v. Sebelius, Case No. 09-1546 (D.D.C.) | date=2012 |website=US Food & Drug Administration |access-date=24 August 2018}}</ref>