No problem with for profit supplement manufacturers

Department of Epidemiology Welch Center for Prevention, Epidemiology, and Clinical Research

What Have We Learned from Meta-analyses Evaluating Dietary Supplements? Eliseo Guallar, MD, DrPH [email protected]

Disclosures  No economic conflicts of interest  No problem with for profit supplement

manufacturers Presenter’s Namepopulation-wide use of safe  No problem with

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and efficacious supplements

Objectives  Understand the advantages and limitations of meta-analysis for summarizing the evidence on the health effects of dietary supplements  Review the main meta-analysis summarizing the effects of vitamin and mineral Presenter’s Name supplements for preventing chronic diseases Date  Discuss potential alternative to metaanalyses for evidence-based decision for dietary supplements

Focus  Chronic disease prevention  All cause mortality

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Evidence Based Medicine – Pyramid of evidence

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Steps in conducting a meta-analysis        

Define research question Identify relevant studies Select studies (inclusion / exclusion criteria) Evaluate individual studies Abstract data Qualitative synthesis Statistical meta-analysis (if appropriate) Discussion and conclusions

http://www.cochrane-handbook.org/

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Vitamin E supplements and mortality – Dose-response MA

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Miller ER III, et al. Ann Intern Med. 2005;142:37–46

Vitamin E supplements and mortality – Dose-response MA

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Miller ER III, et al. Ann Intern Med. 2005;142:37–46

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Vitamin E supplements and total mortality – Meta-analysis

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Bjelakovic G, et al. JAMA 2007;297:842–57

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Miller ER III, et al. Clin Trials 2009;6:47–9

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Bjelakovic G, et al. JAMA 2013;310:1178–9

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Intake of ß-carotene and CVD

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Egger M, et al. BMJ 1998;316:140-4

β-carotene supplements and mortality – ATBC Trial

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The Alpha-Tocopherol Beta Carotene Cancer Prevention Study Group. N Engl J Med 1994;330:1029–35

β-carotene supplements and CVD mortality – Meta-analysis

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Vivekananthan DP. Lancet 2003;361:2017–23

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Bjelakovic G, et al. JAMA 2013;310:1178–9

Vitamin C supplements and SBP – Meta-analysis

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Juraschek SP, et al. Am J Clin Nutr 2012;95:1079–88

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Rayman MP, et al. Ann Intern Med 2011;154:656–56

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Fortman SP, et al. Ann Intern Med 2013;159:824–34

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Fortman SP, et al. Ann Intern Med 2013;159:824–34

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Fortman SP, et al. Ann Intern Med 2013;159:824–34

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Fortman SP, et al. Ann Intern Med 2013;159:824–34

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Moyer VA, USPSTF. Ann Intern Med 2014;160:558–64

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Moyer VA, USPSTF. Ann Intern Med 2014;160:558–64

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Moyer VA, USPSTF. Ann Intern Med 2014;160:558–64

Conclusions  No clear evidence of benefit or harm for prevention of all cause mortality, CVD or cancer

 Evidence of harm  β-carotene, vitamin E Presenter’s Name Date

 Questionable use of observational studies  Mechanism of action  Effect size

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