Mind & Body, May 2007

Study Shows Garlic Ineffective in Lowering "Bad Cholesterol"

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 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," says Christopher D. Gardner, Ph.D., study lead author and nutrition scientist at the Stanford Prevention Research Center.

“And as far as lowering cholesterol, garlic didn't work," he says.

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.

Fresh Garlic, Supplements Tested

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.

Findings suggest that crushing garlic produces a sulfur-containing compound called allicin that might block cholesterol synthesis.

To test that theory, Dr. 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 milligrams per deciliter (mg/dl).

The researchers focused on this moderate-level group, because they assumed that those with more severely elevated LDL would be taking prescription medications, such as statins, that could affect 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®.

Not All Supplements Are the Same

The authors pointed out that the two chosen supplements are manufactured differently.

Garlicin is 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.

Dr. Gardner notes 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 authors also state that only one dosage level was studied and that further investigation with higher doses might yield beneficial effects.

Always consult your physician for more information.

Online Resources

(These links are provided for the education and convenience of our Neighbors. AAMC is not responsible for the content of Internet sites.)

American Heart Association

Archives of Internal Medicine - Coffee, Cirrhosis, and Transaminase Enzymes

Centers for Disease Control and Prevention (CDC)

National Heart, Lung, and Blood Institute (NHLBI)

National Institutes of Health (NIH)

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Cholesterol Defined

Cholesterol is a waxy substance that can be found in all parts of your body. It aids in the production of cell membranes, some hormones, and vitamin D.

The cholesterol in your blood comes from two sources: the foods you eat and your liver.

However, your liver makes all of the cholesterol your body needs.

Cholesterol and other fats are transported in your blood stream in the form of spherical particles called lipoproteins.

The two most commonly known lipoproteins are low-density lipoproteins (LDL) and high-density lipoproteins (HDL).

LDL (low-density lipoprotein) cholesterol is commonly called the "bad" cholesterol, and is a type of fat in the blood that contains the most cholesterol.

It can contribute to the formation of plaque buildup in the arteries, known as atherosclerosis.

You want your LDL to be low. To help lower it:

• avoid foods high in saturated fat, dietary cholesterol, and excess calories
• exercise
• maintain a healthy weight
• stop smoking

HDL (high-density lipoprotein) cholesterol is known as the "good" cholesterol, and is a type of fat in the blood that helps to remove cholesterol from the blood, preventing the fatty buildup and formation of plaque.

You want your HDL to be as high as possible. Some people can raise HDL by:

• exercising for at least 20 minutes three times a week
• kicking the cigarette habit
• avoiding saturated fat intake
• decreasing body weight

For others, medicine may be needed. Because raising HDL is complicated, you should work with your physician on a therapeutic plan.

Always consult your physician for more information.