WASHINGTON--A consumer advocacy group petitioned the government to ban the use of cholesterol-lowering claims for garlic supplements after a new report showed that the herb has short-term but not long-term effects on reducing cholesterol levels.

On Dec. 5, the Center for Science in the Public Interest (CSPI) filed petitions against the Food and Drug Administration (FDA) and Federal Trade Commission (FTC) to cease the use of cholesterol-lowering claims for garlic supplements. The report, "Garlic: Effects on Cardiovascular Risks and Disease, Protective Effects Against Cancer and Clinical Adverse Effects," was conducted by the Agency for Healthcare Research and Quality (AHRQ) at the U.S. Department of Health and Human Services.

In the report, researchers evaluated 37 randomized trials that noted the effects of garlic consumption on blood cholesterol levels. Participants taking the supplement experienced reduced levels for one to three months; however, researchers found that six months or more of garlic consumption did not further reduce either triglycerides or LDL ("bad" cholesterol). This led researchers to conclude that garlic supplements may not lower cholesterol over the long haul.

"Since prolonged elevation of blood cholesterol levels promotes cardiovascular disease, a product that lowers levels for only a few months is virtually useless," said David Schardt, a CSPI nutritionist on the AHRQ advisory panel.

This report yields similar results found in a Sept.19 Annals of Internal Medicine meta-analysis of garlic clinical trials. In that analysis, researchers from the University of Exeter in England found that garlic may be superior to placebo in reducing total cholesterol levels; however, ".the size of the effect is modest, and the robustness of the effect is debatable."

"In studies that went beyond three months, there was no change [in cholesterol levels] from when the studies started," said Schardt. "If there was a small change initially, it disappeared." Schardt added that the body may have adjusted itself to the effects of the garlic. He also suggested that people, who may have begun to diet and exercise at the same time as taking the supplement, fell out of the habit after a few months, effectively raising their cholesterol levels again.

Schardt also suggested that current testing methods for short-term studies may be inappropriate for longer studies; the longest study in the meta-analysis lasted 24 months. "It's conceivable that there is something different about the way you do a longer term study than a shorter term study that might lead to different conclusions. You can't rule that out."

In fact, in the Nov. Journal of Nutrition (130:11 2662-5, 2000), researchers from John Moores University in England found that subjects ingesting 5 milliliters of aged garlic extract (kyolic) per day for 13 weeks experienced reduced platelet aggregation, leading to fewer blood clots and heart attacks.

The authors for the AHRQ report concluded that more studies needed to be conducted on different garlic preparations (raw, cooked or supplement form).

"Based on previous research that we have looked at, garlic's cholesterol-lowering effect is present," said Wayne Silverman, chief administrative officer at the American Botanical Council. "We definitely do not think that people should stop taking garlic."

"There may be other ways in which garlic affects heart disease, but in terms of lowering cholesterol, the research shows more and more that it doesn't have much of an effect," Schardt said. "What companies need to do is emphasize cardiovascular health or other benefits affecting heart disease other than cholesterol-lowering effects. Some people need to lower their cholesterol levels, and if those people go off to take garlic, thinking that that's going to lower their cholesterol levels because it says so on the box, they'll be hurting themselves in the long run."

FDA stated that it will make CSPI's docket public and respond to the center within 180 days. Additional information about the petition was not disclosed. For a copy of the AHRQ report, visit www.ahrq.gov/research/oct00/1000ra.pdf.