What Is It

For thousands of years, garlic has been valued for its therapeutic potential. Egyptian pyramid builders took it for strength and endurance; Louis Pasteur investigated its antibacterial properties, and physicians in the two world wars used it to treat battle wounds. Garlic is related to the onion, scallion, and other plants in the genus Allium. The entire plant is odoriferous, but the strongest aroma is concentrated in the bulb, the site of garlic’s healing powers and flavor.

Most of garlic’s health benefits derive from the more than 100 sulfur compounds it contains. When the bulb is crushed or chewed, alliin, one of the sulfur compounds, becomes allicin, the chemical responsible for garlic’s odor and health effects. In turn, some of the allicin is rapidly broken down into other sulfur compounds, such as ajoene, which can also have medicinal properties. Cooking garlic inhibits the formation of allicin and eliminates some of the other therapeutic chemicals.

What Does It Do

Traditionally, garlic has been employed to treat everything from leprosy and parasites to hemorrhoids. Today, researchers are focusing on its potential to reduce the risk of heart disease and cancer.

Common Uses

  • May lower cholesterol levels.
  • Reduces blood clotting.
  • Fights infections.
  • Acts to boost immunity.
  • May prevent some cancers.
  • May produce a slight drop in blood pressure.
  • Combats fungal infections.


The liberal use of garlic in Italy and Spain may partly explain why these countries have such a low incidence of hardening of the arteries (atherosclerosis). Several studies suggest that garlic can prevent heart disease in various ways. For example, garlic makes platelets (the cells involved in blood clotting) less likely to clump and stick to artery walls, lessening the chance of heart attack. There’s evidence that the herb dissolves clot-forming proteins, which can affect plaque development. Garlic also lowers blood pressure slightly, mainly because of its ability to widen blood vessels and help blood circulate more freely.

Recent studies examined garlic’s effect on cholesterol. Though the results are not clear-cut, most nutritionally oriented doctors think that garlic, perhaps in combination with other cholesterol-lowering supplements, is worth a try. The herb may interfere with the metabolism of cholesterol in the liver; as a result, less cholesterol is released into the blood.

Additional Benefits

Garlic may have anticancer properties. It has been found to be particularly effective in preventing digestive cancers and possibly even breast and prostate cancers. Researchers aren’t sure how garlic produces these benefits. Several mechanisms may be involved. First, there’s the herb’s ability to increase the level of enzymes that can detoxify cancer triggers. Then, it blocks the formation of nitrites linked to stomach cancer, and it’s proficient at stimulating the immune system. Garlic’s antioxidant properties are important as well.

Garlic is often effective against infectious organisms (viruses, bacteria, and fungi) because allicin can block the enzymes that give the organisms their ability to invade the damage tissues. The herb has also been shown to inhibit the fungi responsible for athlete’s foot and swimmer’s ear.

How To Take It


Look for supplements that supply 4,000 mcg of allicin potential per pill, approximately the same amount of allicin potential found in one clove of fresh garlic. For general health or to help high cholesterol: Take a 400 to 600 mg garlic supplement each day. For colds and flu: Take a 400 to 600 mg garlic supplement four times a day. For topical benefits: Apply garlic oil two or three times a day. Some skin conditions, including warts and insect bites, may respond to garlic oil or a crushed raw garlic clove applied directly to the affected area.

Guidelines For Use:

Garlic can be taken indefinitely. However, if you are using the herb for cholesterol problems, have your levels checked in three months to see if they have changed; if you’ve derived no benefits, talk to your doctor about other remedies.

Possible Side Effects

Some people develop heartburn, intestinal gas, and diarrhea when taking high doses of garlic. Using enteric-coated supplements may reduce such side effects. Skin rashes have also been reported.

Latest Findings

  • In a recent laboratory study, researchers found that garlic extract was powerful enough to neutralize Helicobacter pylori, the bacterium that causes ulcers. The next step is to see whether garlic will do the same in the body.
  • Garlic may prevent stiffening of the aorta (the artery that carries blood from the heart to the rest of the body) which occurs naturally with age. In one study, some 200 people took either garlic supplements or a placebo daily for two years. At the end of the study, the aortas of the 70-year-olds in the garlic group were as supple as those of the 55-year-olds who didn’t take the supplement. A flexible aorta may help reduce age-related organ damage.

Shopping Hints

  • Most experts believe supplements made from garlic powder are the most effective.
  • Enteric-coating prevents garlic breath and allows the supplement to pass throughout the stomach undigested, which assures the formation of allicin.
  • Deodorized garlic preparations appear to have the same benefits as regular supplements.

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