Study Crushes Garlic's Claim to Lower Cholesterol

Neither the fresh or pill-packaged varieties brought LDL levels down

MONDAY, Feb. 26, 2007 (HealthDay News) -- For those enduring bad breath for the sake of good cardiovascular health, a new study brings bad news: Garlic does not lower LDL, the so-called "bad cholesterol."

The finding, reported in the Feb. 26 issue of the Archives of Internal Medicine, applies to both fresh garlic and popular garlic supplements.

"We did a bigger and better trial than has ever been done before and with NIH (National Institutes of Health) funding, not with supplement-manufacturer funding. And as far as lowering cholesterol, garlic didn't work," said Christopher D. Gardner, study lead author and nutrition scientist and assistant professor with the Stanford Prevention Research Center in Stanford, Calif.

Too much low-density lipoprotein (LDL) cholesterol in arteries is known to elevate risks for stroke or heart attack. Typically, patients with LDL levels below 130 mg/dl are considered to be in the healthy range.

The notion that garlic is one of nature's answers to all sorts of serious ills stretches as far back as Egypt, circa 1500 B.C., experts say.

More recent interest in garlic's specific potential as an LDL-lowering agent stems from lab work and animal testing done over the past few years. That data suggested that crushing garlic produces a sulfur-containing compound, allicin, that might block cholesterol synthesis.

To test that theory, Gardner's team analyzed the impact of garlic and garlic supplements on LDL blood levels in 192 men and women between the ages of 30 and 65. All of the study participants had moderately high LDL cholesterol readings that averaged out at about 140 mg/dl.

The researchers focused on this moderate-level group, because they assumed that those with more severely elevated LDL would be taking prescription drugs, such as statins, that could confound the results. By contrast, patients with moderate elevations were more likely to combat the problem with supplements alone.

Pregnant women, smokers, those with heart disease, cancer, or diabetes, and current users of high blood pressure or lipid-lowering medications were excluded from the study.

Six days a week for six months, all the participants ingested the equivalent of a four-gram clove of garlic in one of three forms: either mixed into a sandwich in raw form or as one of two popular commercially-available supplements, Garlicin and Kyolic-100.

The authors pointed out that the two chosen supplements are manufactured differently, with Garlicin being a powdered option that is the only brand so far to have demonstrated an ability in lab studies to produce a consumable amount of allicin equivalent to raw crushed garlic.

By contrast, Kyolic is an aged-garlic extract specifically designed to reduce bad breath side-effects in users. This option was described by the authors as "one of the most popular brands on the market" and is the only supplement to have been previously tested for cholesterol-lowering abilities in more than one clinical trial.

Gardner and his team noted that in order to match the properties found in four grams of fresh garlic, patients in the two supplement groups actually consumed slightly more than the daily-recommended dosage printed on either supplement's label.

The results: Blood tests revealed that none of the garlic options had any "clinically relevant effect" on LDL concentrations over the course of the study, either in the short run or the long run.

They concluded that neither dietary garlic nor supplements are likely to offer any such benefit to most patients seeking to lower their LDL levels.

Nevertheless, future research might identify certain sub-groups of people who might still derive LDL-lowering benefit from garlic (such as those with more severe LDL elevations) or that higher daily doses of garlic consumption might prove at least somewhat effective.

"We are actually very disappointed with the results we do have," admitted Gardner. "We really thought garlic was going to work. Now, maybe you could say the supplements didn't work because they're not the same as fresh garlic. But then, fresh garlic should've worked, if anything was going to work. And it didn't."

"So, I'd say you really ought to just enjoy your hummus with whole wheat bread and your Asian vegetable stir-fry with garlic, which, of course, makes it so much more enjoyable," joked Gardner. "But if you're going to take a garlic supplement, it should be for something other than cholesterol lowering, because in real life it doesn't work."

Ruth Kava, director of nutrition at the American Council on Science and Health in New York City, expressed little surprise at the study findings.

"I think that what's happened over the last 10 to 12 years in this country is that supplements have gotten a much better rep than many deserve," she said. "The garlic claim has been out there for quite a while, but manufacturers have been making all sorts of qualified claims that aren't really backed up with substantial clinical evidence."

While Kava called for more research to confirm the latest finding, she encouraged patients looking to lower their cholesterol in other ways to take advantage of proven methods.

"The tried and true things that are going to lower LDL cholesterol are statins, which, although they can't be taken by everyone, are really very effective; and lifestyle changes such eating a diet with less saturated fat, getting exercise, and losing weight," she advised. "Unfortunately, there is no magic pill."

More information

For additional information on LDL, visit the American Heart Association.

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