title: An umbrella review of garlic intake and risk of cardiovascular disease.
abstract: OBJECTIVE
  To gain further insight into the strength of evidence and extent of possible biases in the scope of studies investigating the impact of garlic and garlic supplement intake on biomarkers of cardiovascular disease, we performed an umbrella review of all published meta-analyses synthesizing data from both observational studies and randomized controlled trials.
  
  
  METHODS
  Electronic database PubMed (between 1966 and June 2015) was searched for systematic reviews and meta-analyses using following search terms: ("garlic" OR "allium sativum" OR "allicin" OR "organosulfur") AND ("cardiovascular" OR "coronary" OR "cholesterol" OR "triglyceride" OR "atherosclerosis" OR "blood pressure" OR "hypertension" OR "blood glucose") AND ("systematic review" OR "meta-analysis"), with no restriction to calendar data and language. Hand-search of reference lists and relevant clinical guidelines was performed as well.
  
  
  RESULTS
  Nine systematic reviews investigated the effects of garlic on lipid parameters and eight systematic reviews analyzed the effects on blood pressure parameters were identified. Eight of nine meta-analyses synthesizing the effect of garlic on blood lipids reported significantly decreased total cholesterol levels. Inconsistent results could be detected for HDL-cholestrol, LDL-cholesterol, and triacylglycerols. The effect of garlic on systolic blood pressure showed consistent results across publications with 7 out of 8 meta-analyses demonstrating a substantial decrease in systolic blood pressure. Similar results could be reported regarding the effect of garlic on diastolic blood pressure, i.e. 6 out of 8 meta-analyses detected significant reductions in diastolic blood pressure levels following interventions with garlic.
  
  
  CONCLUSIONS
  According to the data summarized in the present umbrella review, garlic preparations as well as garlic exerted some positive effects on indicators and biomarkers of cardiovascular disease, typically without causing any serious side effects. However, with regard to the substantial heterogeneities between the different trials enrolled in the various meta-analyses of this review, a conservative interpretation of the outcome seems to be appropriate.
authors.affiliation: Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, Althanstraße 14 (UZAII), A-1090 Vienna, Austria; German Institute of Human Nutrition, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany. Electronic address: lukas.schwingshackl@dife.de.
authors.forename: Lukas
authors.initials: L
authors.lastname: Schwingshackl
authors.affiliation: Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, Althanstraße 14 (UZAII), A-1090 Vienna, Austria.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Missbach
authors.affiliation: Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, Althanstraße 14 (UZAII), A-1090 Vienna, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Hoffmann
mesh_terms: D001794:Blood Pressure / Q000187:drug effects; D002318:Cardiovascular Diseases / Q000178:diet therapy / Q000378:metabolism / Q000517:prevention & control*; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D019587:Dietary Supplements / Q000009:adverse effects; D005737:Garlic; D006801:Humans; D006973:Hypertension / Q000178:diet therapy / Q000188:drug therapy; D008055:Lipids / Q000097:blood; D015201:Meta-Analysis as Topic; D016032:Randomized Controlled Trials as Topic; D014280:Triglycerides / Q000097:blood
chemical_list: D008078:Cholesterol, LDL; D008055:Lipids; D014280:Triglycerides; D002784:Cholesterol
keywords: Blood lipids; Blood pressure; Cardiovascular disease; Garlic; Umbrella review