"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 (130mg to 190mg 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.