Complementary and alternative medicine for lowering blood lipid levels: A systematic review of systematic reviews.

Background: The aim of this article is to summarize and critically evaluate the evidence from systematic reviews (SRs) of complementary and alternative medicine (CAM) for lowering blood lipid levels (BLL).

Methods: Eight electronic databases were searched until March 2016. Additionally, all the retrieved references were inspected manually for further relevant papers. Systematic reviews were considered eligible, if they included patients of any age and/or gender with elevated blood lipid levels using any type of CAM. We used the Oxman and AMSTAR criteria to critically appraise the methodological quality of the included SRs.

Results: Twenty-seven SRs were included in the analyses. The majority of the SRs were of high methodological quality (mean Oxman score=4.81, SD=4.88; and the mean AMSTAR score=7.22, SD=3.38). The majority of SRs (56%) arrived at equivocal conclusions (of these 8 were of high quality); 7 SRs (37%) arrived at positive conclusions (of these 6 were of high quality), and 2 (7%) arrived at negative conclusions (both were of high quality). There was conflicting evidence regarding the effectiveness of garlic; and promising evidence for yoga.

Conclusions: To conclude, the evidence from SRs evaluating the effectiveness of CAM in lowering BLL is predominantly equivocal and confusing. Several limitations exist, such as variety of doses and preparations, confounding effects of diets and lifestyle factors, or heterogeneity of the primary trials among others.