Garlic May Not Lower Cholesterol, According to Study Meta-Analysis

ENGLAND--Garlic may be better than placebo in reducing total cholesterol levels, but its use in treating hypercholesterolemia may be questionable, according to a meta-analysis study published in the Sept. 19 issue of the Annals of Internal Medicine (133:420-429, 2000).

In a meta-analysis of randomized, double-blind, placebo-controlled trials that were conducted through November 1998, two reviewers independently extracted data and assessed methodological quality. The trials that were selected used garlic monopreparations and included subjects with mean total cholesterol levels of at least 200mg/dL.

Data was collected using keyword searches [using garlic, Allium sativum and Knoblauch] in databases such as MEDLINE, EMBASE, BIOSIS, Cochrane Library, AMED and CISCOM. Most trials were disqualified because data was missing for statistical pooling and important co-founding factors were not controlled [i.e., some patients were given dietary advice while other patients were instructed not to change their diet]. Therefore, of the 39 studies found, only 13 trials--involving a total of 796 subjects--met the researchers' inclusion criteria. It was found that, within these 13 studies, reduction of total cholesterol levels was -0.41 mmol/L for garlic compared to placebo--a modest difference, according to researchers.

The study added that an unnamed expert found that in vivo production of allicin from Lichtwer Pharma's Kwai (the garlic used in 10 of the 13 trials) may have negatively skewed data results.

According to Lichtwer Pharma, the "expert" the study used is a former employee for one of its competitors. Additionally, the company stated that the amount of allicin present in Kwai tablets fell within the acceptable variance range of 0.6 to 1.0 percent. "We've used the same formulation for years during these clinical trials," said David Illingworth, president and chief executive officer of Lichtwer Pharma in America. "The overall effect from allicin is what we're looking for. We know that it won't have the same effect as [cholesterol-lowering] statin drugs, but allicin also has fewer [adverse reactions compared to] statin drugs."

According to the researchers, none of the 13 trials directly addressed the clinical implications of lowering plasma lipid levels through administering garlic. Instead, the researchers noted, garlic may offer other protective effects in regard to cardiovascular disease [such as reduced blood pressure, platelet inhibition and increased blood flow] that are independent of cholesterol level changes. Illingworth added that because of disease claim guidelines in the United States, Kwai tablets are promoted as lipid- lowering. In Germany, where the company is based, Kwai tablets are more aptly sold as a way to keep arteries flexible to prevent arteriosclerosis.

The researchers concluded their analysis by suggesting that large-scale, long-term studies are needed to provide better data for garlic consumption. For more information, visit www.annals.org/issues/current/toc.html.