X-Message-Number: 27877 From: "Hare, Tim R" <> Subject: RE: [CN] Antioxidant Selenium Offers No Heart-disease Date: Fri, 28 Apr 2006 11:26:03 -0400 "Despite the documented antioxidant and chemopreventive properties of Selenium..." I find this statement a bit troubling, in that selenium is a transition metal, with no inherent REDOX bias (putting aside the lack of meaning of any such bias within different body compartments, and associated REDOX microenvironment). As well, metals have a complex role as enzyme active site components, and selenium is no exception, being associated with GSH-peroxidase, and the transferase family of enzymes involved in xenobiotic metabolism in the liver. The net of all this is that for an author to refer to selenium as an "antioxidant" begs the question of the author's knowledge base, and the journals peer review process. Such gaffs only confound and misinform, extending debunking process of "antioxidants" via confusion over terms and roles. As a chemopreventative, even, it's role is unclear, given that low dietary doses (not to mention different forms with attendant differences in bioavailability, clearance, and metabolic fate) have not been clearly implicated as chemopreventative, and higher doses found effective are close to the toxic dose (again, depending on form) and are clearly pharmacological in action, rather than dietary. The statistics may be sound, but the discussion and the conclusions are muddled. To crow about knocking down another "antioxidant" is simply rhetoric that misrepresents the science, and misrepresents the positions of all parties on both sides of the issue, and helps no one. Timothy R. Hare Automated Biotechnology (952) Bld NW-2, 503 Louise Lane, North Wales, PA 19454 Merck E-mail: <mailto:> Voice: (267) 305-3235 Mobile (267) 984-7136 FAX: (267) 305-0182 -----Original Message----- From: CryoNet F [mailto:] On Behalf Of Doug Skrecky Sent: Friday, April 28, 2006 12:20 AM To: CryoNet F Subject: [CN] Antioxidant Selenium Offers No Heart-disease Protection [More of the same. Free radicals do not drive atherosclerosis.] Selenium does not protect against cardiovascular disease, despite its documented antioxidant and chemopreventive properties, analysis of a randomized placebo-controlled clinical trial covering 13 years has shown. The selenium-CVD association was a secondary endpoint in the Nutritional Prevention of Cancer Trial, which was designed primarily to determine if selenium supplementation could prevent the recurrence of non-melanoma skin cancer. Results of the trial, the only large randomized clinical trial to date to examine selenium supplementation alone in the prevention of CVD, appear in the April 15 issue of the American Journal of Epidemiology. Saverio Stranges, M.D., Ph.D., assistant professor of social and preventive medicine in the School of Public Health and Health Professions, University at Buffalo, is first author. "Our results extend previous research based on smaller intervention trials focusing on cardiovascular risk factors," said Stranges. "Our findings are consistent with those from previous studies that have shown no beneficial effect of selenium supplementation in combination with other antioxidants on the primary prevention of cardiovascular disease." Several antioxidants, vitamins C and E in particular, that were thought to play a role in preventing heart disease based on observational studies have turned out not to be protective in randomized clinical trials, and selenium now has joined this group. The main findings of this report focus on the 1,004 participants in the study, conducted from 1983-96, who were free of cardiovascular disease when they were recruited. Participants came from seven dermatology clinics in low selenium areas of the eastern United States: Augusta and Macon, Ga.; Columbia, S.C.; Miami, Fla.; Wilson and Greenville, N. C.; and Newington, Conn. Enrollees were assigned randomly to take a tablet containing 200 micrograms of selenium daily or a placebo. Information on sociodemographics, health habits, education and body mass index also was collected. Participants provided blood samples at their respective clinics twice a year and reported any new illnesses or medications. Individuals were followed for an average of 7.6 years. Results showed no association between selenium supplementation on any of the endpoints studied: coronary heart disease, stroke or deaths from cardiovascular disease, Stranges said. There also was no difference in the endpoints based on the level of selenium at baseline. In addition, the lack of significant association with CVD endpoints was confirmed even in the 246 participants who had CVD at baseline. (This data does not appear in the published manuscript.) "These results must be interpreted cautiously," said Stranges, "because they result from exploratory analyses, although from the largest randomized clinical trial available that has selenium only as the intervention. However, this report adds important information to our knowledge on the role of selenium in cardiovascular-disease prevention, indicating no overall benefit of supplementation by selenium alone in prevention of cardiovascular disease." Am J Epidemiol. 2006 Apr 15;163(8):694-9. Epub 2006 Feb 22. Effects of selenium supplementation on cardiovascular disease incidence and mortality: secondary analyses in a randomized clinical trial. Despite the documented antioxidant and chemopreventive properties of selenium, studies of selenium intake and supplementation and cardiovascular disease have yielded inconsistent findings. The authors examined the effect of selenium supplementation (200 microg daily) on cardiovascular disease incidence and mortality through the entire blinded phase of the Nutritional Prevention of Cancer Trial (1983-1996) among participants who were free of cardiovascular disease at baseline (randomized to selenium: n = 504; randomized to placebo: n = 500). Selenium supplementation was not significantly associated with any of the cardiovascular disease endpoints during 7.6 years of follow-up (all cardiovascular disease: hazard ratio (HR) = 1.03, 95% confidence interval (CI): 0.78, 1.37; myocardial infarction: HR = 0.94, 95% CI: 0.61, 1.44; stroke: HR = 1.02, 95% CI: 0.63, 1.65; all cardiovascular disease mortality: HR = 1.22, 95% CI: 0.76, 1.95). The lack of significant association with cardiovascular disease endpoints was also confirmed when analyses were further stratified by tertiles of baseline plasma selenium concentrations. These findings indicate no overall effect of selenium supplementation on the primary prevention of cardiovascular disease in this population. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=27875 ############################################################# This message is sent to you because you are subscribed to the mailing list <>. To unsubscribe, E-mail to: <> To switch to the DIGEST mode, E-mail to <> To switch to the INDEX mode, E-mail to <> Send administrative queries to <> Notice: This e-mail message, together with any attachments, contains information of Merck & Co., Inc. 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