Editing Multivitamin (section)

=== Cohort studies ===
[[File:Wyeth Centrum.jpg|thumb|right|250px|Centrum multivitamins produced by [[Pfizer]], which were used in Physicians' Health Study II]]
In February 2009, a study conducted in 161,808 [[postmenopausal]] women from the Women's Health Initiative clinical trials concluded that after eight years of follow-up "multivitamin use has little or no influence on the risk of common cancers, cardiovascular disease, or total mortality".<ref name="Neuhouser ML 2008" /> Another 2010 study in the ''[[Journal of Clinical Oncology]]'' suggested that multivitamin use during [[chemotherapy]] for stage III colon cancer had no effect on the outcomes of treatment.<ref>{{cite journal | vauthors = Ng K, Meyerhardt JA, Chan JA, Niedzwiecki D, Hollis DR, Saltz LB, Mayer RJ, Benson AB, Schaefer PL, Whittom R, Hantel A, Goldberg RM, Fuchs CS | title = Multivitamin use is not associated with cancer recurrence or survival in patients with stage III colon cancer: findings from CALGB 89803 | journal = Journal of Clinical Oncology | volume = 28 | issue = 28 | pages = 4354–4363 | date = October 2010 | pmid = 20805450 | pmc = 2954134 | doi = 10.1200/JCO.2010.28.0362 | author-link1 = Kimmie Ng }}</ref> A very large prospective cohort study published in 2011, including more than 180,000 participants, found no significant association between multivitamin use and mortality from all causes. The study also found no impact of multivitamin use on the risk of cardiovascular disease or cancer.<ref>{{cite journal | vauthors = Park SY, Murphy SP, Wilkens LR, Henderson BE, Kolonel LN | title = Multivitamin use and the risk of mortality and cancer incidence: the multiethnic cohort study | journal = American Journal of Epidemiology | volume = 173 | issue = 8 | pages = 906–914 | date = April 2011 | pmid = 21343248 | pmc = 3105257 | doi = 10.1093/aje/kwq447 }}</ref>

A cohort study that received widespread media attention<ref name="NYT-20121017">{{cite news | vauthors = Rabin RC |title=Daily Multivitamin May Reduce Cancer Risk, Clinical Trial Finds |url=https://www.nytimes.com/2012/10/18/health/daily-multivitamin-may-reduce-cancer-risk-clinical-trial-finds.html |date=October 17, 2012 |newspaper=[[New York Times]] |access-date=October 17, 2012 |archive-date=October 18, 2012 |archive-url=https://web.archive.org/web/20121018151130/http://www.nytimes.com/2012/10/18/health/daily-multivitamin-may-reduce-cancer-risk-clinical-trial-finds.html |url-status=live }}</ref><ref name=Winslow>{{cite news| vauthors = Winslow R |title=Multivitamin Cuts Cancer Risk, Large Study Finds|url=https://www.wsj.com/articles/SB10000872396390444868204578062463819724232|access-date=13 December 2012|newspaper=[[The Wall Street Journal]]|date=18 October 2012|archive-date=22 December 2015|archive-url=https://web.archive.org/web/20151222230112/http://www.wsj.com/articles/SB10000872396390444868204578062463819724232|url-status=live}}</ref> is the Physicians' Health Study II (PHS-II).<ref name="JAMA-20121017">{{cite journal | vauthors = Gaziano JM, Sesso HD, Christen WG, Bubes V, Smith JP, MacFadyen J, Schvartz M, Manson JE, Glynn RJ, Buring JE | title = Multivitamins in the prevention of cancer in men: the Physicians' Health Study II randomized controlled trial | journal = JAMA | volume = 308 | issue = 18 | pages = 1871–1880 | date = November 2012 | pmid = 23162860 | pmc = 3517179 | doi = 10.1001/jama.2012.14641 }}</ref> PHS-II was a double-blind study of 14,641 male U.S. physicians initially aged 50 years or older (mean age of 64.3) that ran from 1997 to June 1, 2011. The mean time that the men were followed was 11 years. The study compared total cancer (excluding non-melanoma skin cancer) for participants taking a daily multivitamin ([[Centrum (multivitamin)|Centrum]] Silver by [[Pfizer]]) versus a [[placebo]]. Compared with the placebo, men taking a daily multivitamin had a small but [[statistically significant]] reduction in their total incidence of cancer. In absolute terms, the difference was just 1.3 cancer diagnoses per 1000 years of life. The [[hazard ratio]] for cancer diagnosis was 0.92 with a 95% [[confidence interval]] spanning 0.86–0.998 (P = .04); this implies a benefit of between 14% and .2% over placebo in the confidence interval. No statistically significant effects were found for any specific cancers or for cancer mortality. As pointed out in an editorial in the same issue of the ''[[Journal of the American Medical Association]]'', the investigators observed no difference in the effect whether the study participants were or were not adherent to the multivitamin intervention, which diminishes the [[dose–response relationship]].<ref name="Bach">{{cite journal | vauthors = Bach PB, Lewis RJ | title = Multiplicities in the assessment of multiple vitamins: is it too soon to tell men that vitamins prevent cancer? | journal = JAMA | volume = 308 | issue = 18 | pages = 1916–1917 | date = November 2012 | pmid = 23150011 | doi = 10.1001/jama.2012.53273 }}</ref> The same editorial argued that the study did not properly address the [[multiple comparisons problem]], in that the authors neglected to fully analyze all 28 possible associations in the study—they argue if this had been done, the statistical significance of the results would be lost.<ref name=Bach />

Using the same PHS-II study, researchers concluded that taking a daily multivitamin did not have any effect in reducing [[heart attack]]s and other major cardiovascular events, MI, stroke, and CVD mortality.<ref name="JAMA-20121107">{{cite journal | vauthors = Sesso HD, Christen WG, Bubes V, Smith JP, MacFadyen J, Schvartz M, Manson JE, Glynn RJ, Buring JE, Gaziano JM | title = Multivitamins in the prevention of cardiovascular disease in men: the Physicians' Health Study II randomized controlled trial | journal = JAMA | volume = 308 | issue = 17 | pages = 1751–1760 | date = November 2012 | pmid = 23117775 | pmc = 3501249 | doi = 10.1001/jama.2012.14805 }}</ref>