EFFECT OF A GARLIC OIL PREPARATION ON SERUM-LIPOPROTEINS AND CHOLESTEROL-METABOLISM - A RANDOMIZED CONTROLLED TRIAL

Context.-Garlic-containing drugs have been used in the treatment of hy percholesterolemia even though their efficacy is not generally establi shed. Little is known about the mechanisms of action of the possible e ffects on cholesterol in humans. Objective.-To estimate the hypocholes terolemic effect of garlic oil and to investigate the possible mechani sm of action. Design-Double-blind, randomized, placebo-controlled tria l. Setting.-Outpatient lipid clinic. Patients.-We investigated 25 pati ents (mean age, 58 years) with moderate hypercholesterolemia. Interven tion.-Steam-distilled garlic oil preparation (5 mg twice a day) vs pla cebo each for 12 weeks with wash-out periods of 4 weeks. Main Outcome Measures.-Serum lipoprotein concentrations, cholesterol absorption, an d cholesterol synthesis. Results.-Baseline lipoprotein profiles were ( mean [SD]):total cholesterol, 7.53 (0.75) mmol/L (291 [29] mg/dL); low -density lipoprotein cholesterol (LDL-C), 5.35 (0.78) mmol/L (207 [30] mg/dL); high-density lipoprotein cholesterol (HDL-C), 1.50 (0.41) mmo l/L (58 [16] mg/dL); and triglycerides, 1.45 (0.73) mmol/L (127 [64] m g/dL). Lipoprotein levels were virtually unchanged at the end of both treatment periods (mean difference [95% confidence interval]): total c holesterol, 0.085 (-0.201 to 0.372) mmol/L (3.3 [-7.8 to 14.4] mg/dL), P=.54; LDL-C, 0.001 (-0.242 to 0.245) mmol/L (0.04 [-9.4 to 9.5] mg/d L), P=.99; HDL-C, 0.050 (-0.028 to 0.128) mmol/L (1.9 [-1.1 to 4.9] mg /dL), P=.20; triclycerides, 0.047 (-0.229 to 0.135) mmol/L (4.2 [-20.3 to 12.0]) mg/dL, P=.60. Cholesterol absorption (37.5% [10.5%] vs 38.3 % [10.7%], P=.58), cholesterol synthesis (12.7 [6.5] vs 13.4 [6.6] mg/ kg of body weight per day, P=.64), mevalonic acid excretion (192 [66] vs 187 [66] mu g/d, P=.78), and changes in the ratio of lathosterol to cholesterol in serum (4.4% [24.3%] vs 10.6% [21.1%], P=.62) were not different in garlic and placebo treatment. Conclusions.-The commercial garlic oil preparation investigated had no influence on serum lipopro teins, cholesterol absorption, or cholesterol synthesis. Garlic therap y for treatment of hypercholesterolemia cannot be recommended on the b asis of this study.