Effect of raw garlic vs commercial garlic supplements on plasma lipid concentrations in adults with moderate hypercholesterolemia: a randomized clinical trial.
BACKGROUND
Garlic is widely promoted as a cholesterol-lowering agent, but efficacy studies have produced conflicting results. Garlic supplements differ in bioavailability of key phytochemicals. We evaluated the effect of raw garlic and 2 commonly used garlic supplements on cholesterol concentrations in adults with moderate hypercholesterolemia.


METHODS
In this parallel-design trial, 192 adults with low-density lipoprotein cholesterol (LDL-C) concentrations of 130 to 190 mg/dL (3.36-4.91 mmol/L) were randomly assigned to 1 of the following 4 treatment arms: raw garlic, powdered garlic supplement, aged garlic extract supplement, or placebo. Garlic product doses equivalent to an average-sized garlic clove were consumed 6 d/wk for 6 months. The primary study outcome was LDL-C concentration. Fasting plasma lipid concentrations were assessed monthly. Extensive chemical characterization of study materials was conducted throughout the trial.


RESULTS
Retention was 87% to 90% in all 4 treatment arms, and chemical stability of study materials was high throughout the trial. There were no statistically significant effects of the 3 forms of garlic on LDL-C concentrations. The 6-month mean (SD) changes in LDL-C concentrations were +0.4 (19.3) mg/dL (+0.01 [0.50] mmol/L), +3.2 (17.2) mg/dL (+0.08 [0.44] mmol/L), +0.2 (17.8) mg/dL (+0.005 [0.46] mmol/L), and -3.9 (16.5) mg/dL (-0.10 [0.43] mmol/L) for raw garlic, powdered supplement, aged extract supplement, and placebo, respectively. There were no statistically significant effects on high-density lipoprotein cholesterol, triglyceride levels, or total cholesterol-high-density lipoprotein cholesterol ratio.


CONCLUSIONS
None of the forms of garlic used in this study, including raw garlic, when given at an approximate dose of a 4-g clove per day, 6 d/wk for 6 months, had statistically or clinically significant effects on LDL-C or other plasma lipid concentrations in adults with moderate hypercholesterolemia.
Gardner
Christopher D
CD
Stanford Prevention Research Center and Department of Medicine, Stanford University Medical School, Stanford, Calif 94305, USA. cgardner@stanford.edu
Lawson
Larry D
LD
Block
Eric
E
Chatterjee
Lorraine M
LM
Kiazand
Alexandre
A
Balise
Raymond R
RR
Kraemer
Helena C
HC
D000498:Allyl Compounds / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use; D008078:Cholesterol, LDL / Q000097:blood* / Q000187:drug effects; D019587:Dietary Supplements; D004220:Disulfides / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D005737:Garlic; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D008517:Phytotherapy / Q000379:methods*; D028321:Plant Preparations / Q000627:therapeutic use*; D012189:Retrospective Studies; D016896:Treatment Outcome
D000498:Allyl Compounds; D000959:Antihypertensive Agents; D008078:Cholesterol, LDL; D004220:Disulfides; D028321:Plant Preparations; C028009:diallyl disulfide