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Interactions of commonly used dietary supplements with cardiovascular drugs: a systematic review

Salmaan Kanji1, Dugald Seely12, Fatemeh Yazdi3, Jennifer Tetzlaff3, Kavita Singh3, Alexander Tsertsvadze3, Andrea C Tricco4, Margaret E Sears35, Teik C Ooi6, Michele A Turek7, Becky Skidmore7 and Mohammed T Ansari3*

Author Affiliations

1 Clinical Epidemiology, The Ottawa Hospital Research Institute and the Department of Pharmacy, The Ottawa Hospital, Ottawa, ON, Canada

2 Department of Research & Clinical Epidemiology, The Canadian College of Naturopathic Medicine, Toronto, ON, Canada

3 Ottawa Methods Centre, Clinical Epidemiology Program, Ottawa Hospital Research Institute, University of Ottawa Evidence-based Practice Center, Ottawa, ON, Canada

4 Li Ka Shing Knowledge Institute, St Michael’s Hospital, Toronto, ON, Canada

5 Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada

6 Division of Endocrinology and Metabolism, The Ottawa Hospital, University of Ottawa, Ottawa, ON, Canada

7 Division of Cardiology, The Ottawa Hospital, University of Ottawa, Ottawa, ON, Canada

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Systematic Reviews 2012, 1:26  doi:10.1186/2046-4053-1-26

Published: 31 May 2012

Abstract

Background

The objective of this systematic review was to examine the benefits, harms and pharmacokinetic interactions arising from the co-administration of commonly used dietary supplements with cardiovascular drugs. Many patients on cardiovascular drugs take dietary supplements for presumed benefits and may be at risk for adverse supplement-drug interactions.

Methods

The Allied and Complementary Medicine Database, the Cochrane Library, EMBASE, International Bibliographic Information on Dietary Supplements and MEDLINE were searched from the inception of the review to October 2011. Grey literature was also reviewed.

Two reviewers independently screened records to identify studies comparing a supplement plus cardiovascular drug(s) with the drug(s) alone. Reviewers extracted data using standardized forms, assessed the study risk of bias, graded the strength of evidence and reported applicability.

Results

Evidence was obtained from 65 randomized clinical trials, 2 controlled clinical trials and 1 observational study. With only a few small studies available per supplement, evidence was insufficient for all predefined gradable clinical efficacy and harms outcomes, such as mortality and serious adverse events. One long-term pragmatic trial showed no benefit from co-administering vitamin E with aspirin on a composite cardiovascular outcome. Evidence for most intermediate outcomes was insufficient or of low strength, suggesting no effect. Incremental benefits were noted for triglyceridemia with omega-3 fatty acid added to statins; and there was an improvement in levels of high-density lipoprotein cholesterol with garlic supplementation when people also consumed nitrates

Conclusions

Evidence of low-strength indicates benefits of omega-3 fatty acids (plus statin, or calcium channel blockers and antiplatelets) and garlic (plus nitrates or warfarin) on triglycerides and HDL-C, respectively. Safety concerns, however, persist.

Keywords:
Cardiovascular drugs; Dietary supplements; Harms; Systematic review