Despite intriguing laboratory studies hinting at garlic's potential to prevent arteriosclerosis, inconsistent results from dozens of clinical trials have left researchers confused. The main problem is lack of standardization of garlic extracts, according to experts at a National Institutes of Health workshop on herbs and heart disease.
"The most striking limitation in these trials is the overall lack of standardization or characterization of the garlic preparations used," said Christopher Gardner, PhD, director of the Stanford University Center for Research in Disease Prevention, who reviewed 30 clinical trials.
Vastag B. . . . But Lack of Standardized Extracts Foils Clinical Studies. JAMA. 2002;288(11):1342. doi:10.1001/jama.288.11.1342-JHA20009-2-1