Three forms of garlicincluding raw garlic and two types of commercial garlic supplementsdid not significantly reduce low-density lipoprotein (LDL or "bad") cholesterol during a six-month trial, according to results published in the February 26 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
"Garlic supplements, many of which seek to package the benefits of raw garlic in more palatable forms, are promoted as cholesterol-lowering agents and are among the top-selling herbal supplements," the authors write as background information in the article. Crushing garlic triggers the formation of a compound known as allicin, which has been shown to prevent the formation of cholesterol in the laboratory. However, clinical trials on garlic as a cholesterol-lowering agent in humans have been inconsistent.
Christopher D. Gardner, Ph.D., Stanford University Medical School, Calif., and colleagues enrolled 192 adults age 30 to 65 who had moderately high LDL levels (130 to 190 milligrams per deciliter) beginning in November 2002. Forty-nine participants were randomly assigned to receive raw garlic, 47 to take a powdered garlic supplement, 48 to take an aged garlic supplement and 48 to take placebo. The amount of garlic consumed in the three garlic groups was the equivalent of an average-sized garlic clove each day, six days per week. Fasting blood cholesterol levels were assessed monthly, and the chemical composition of the supplements was checked regularly.
A total of 169 adults completed the study, which continued through June 2005. "Retention was 87 percent to 90 percent in all four treatment arms, and the chemical stability of study materials was high throughout the trial," the authors write. "There were no statistically significant effects of the three forms of garlic on LDL cholesterol concentrations." Levels of other types of cholesterolincluding high-density lipoprotein (HDL or "good" cholesterol), triglyceride
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