Garlic has a long history as a culinary and medicinal herb that people either love or hate. Its pungent aroma and warming flavor captivates or repels, but its wealth of natural chemicals does great things for your heart.

Garlic (Allium sativum), a member of the onion family, is native to Siberia but, in modern times, has become a treasured naturalized citizen grown all over the world. Garlic's use in folk medicine dates back about 7,000 years, making it one of the oldest known medicinal foods or herbs.

In modern times, garlic is generally used as a condiment lending a unique, pungent flavor to dishes, but in medieval times, garlic was cooked and eaten as a vegetable in its own right. Today you can revel in a wealth of garlic choices, consuming garlic raw, cooked in various recipes, as a dried concentrated powder, as a fresh liquid extract or as aged garlic powder.

Powerhouse Herb

Each little clove of garlic is a powerhouse of good-for-you natural compounds, vitamins and minerals. The biologically active constituents of garlic include allyl sulfur compounds as well as the minerals germanium and selenium.

When you chop up raw garlic and allowed it to stand for about 10 minutes or more, the herb's fragments release an enzyme that converts its compounds from allyl sulfur to another natural chemical called allicin.

Although some allicin is found in garlic before it is cut apart, the yield multiplies considerably when the garlic clove is chopped or pressed and exposed to water (Garlic Conference, Newport Beach, 11/15/98; Penn State).

Many researchers believe that the more allicin produced, the better the health benefits. (Although this is still being debated among the garlic cognoscenti.)

But garlic's benefits don't end meekly on the kitchen counter with its allicin content rising.

Cooked garlic and aged garlic contain other helpful chemicals called diallyl sulphides. Consequently, in any form, garlic produces beneficial health effects.

Fortunately, since raw garlic juice or oil can often irritate the stomach lining, especially in people with sensitive stomachs and delicate digestive systems, garlic supplements and cooked garlic are both helpful for heart health.

Aged Garlic Extract

Aging garlic significantly reduces its irritating compounds and makes it easier on the stomach.

In the aged form, all of garlic's healthy sulfur-containing compounds are converted to water- soluble compounds that retain garlic's natural health benefits. In addition, the pungent odor of the garlic is greatly reduced, an outcome many people desire.

When a group of researchers at Brown University studied the effects of aged garlic extract on people's cholesterol levels, they found that after six months, cholesterol dropped about 6% (Am J Clin Nutr 1996; 64:866-70).

In another study from Brown, researchers found that aged garlic extract reduced platelet adhesion, a sticky blood problem that can cause vessel blockages (New Drug Clin 45(3):456-66). When platelets are less sticky, they are less likely to form blood clots that can cause heart attacks.

Garlic and Heart Disease

A growing body of research shows that a clove of garlic a day can significantly reduce your risk of heart disease.

A four-year study of 280 people who took dried garlic powder three times a day found a striking reduction in the types of arterial plaque blockages that threaten the blood supply to your heart. Interestingly, in this particular study, women displayed a greater reduction in plaque than men (Atherosclerosis 2000; 150:437-8).

Another study found that garlic may also keep important blood vessels more supple and less likely to spasm. Arterial spasms have been linked to heart attacks and other cardiovascular problems in women.

Aortic Complications

As you age, the aorta, one of the main arteries that carries blood, may harden, reducing blood flow from the heart and placing damaging stress on a number of other bodily organs. In research at Ohio State University, people who took garlic supplements had 15% less aortic stiffness than people who avoided garlic (Circulation).

In this study, scientists found that the older people enjoyed the greatest cardiovascular benefits from daily garlic use.

Researchers believe this extra benefit is linked to the fact that as you age, the endothelial tissue in the linings of the aorta and other blood vessels become less responsive to the need to dilate (expand). As a result, when more blood flow is required, and the heart pumps faster, these vessels take more of a beating from the friction of blood passing through them.

That restriction in dilation has two damaging consequences: In one instance, vessel walls can be injured. In response to these injuries, cholesterol collects on artery walls, plaque forms and the blood supply to the heart muscle can be restricted, leading to a heart attack. In other cases, arteries can restrict blood flow to the heart simply because of the inability to expand sufficiently.

The Ohio State researchers found that arteries in folks aged 70 to 80 benefited the most from taking garlic. But those in their 60s also benefited significantly.

Garlic's natural antioxidant properties can also help protect the heart from damage after surgery (BMC Pharmacology 9/02).

In a study performed on lab animals, researchers found that oxidative stress, a source of cell damage that takes place after surgery, dropped when the animals ate a diet that included garlic.

Oxidative stress can seriously reduce cardiac function, limit the amount of blood the heart can pump and cause permanent damage to the heart muscle.

Garlic Against Blood Clots

Under normal circumstances, blood clots serve a useful purpose: Cut yourself and a blood clot stops the bleeding. Without this clotting ability, you might bleed to death. But if your blood is too prone to clotting, these clumps can cut off blood supply to your heart and other organs, endangering your life.

In a study of apparently healthy individuals whose relatives had already suffered from heart disease, researchers found that their blood formed thick, tangled blood clots, increasing their risk of heart problems (Circulation rapid access 9/23/02). These blood clots are made of a substance called fibrin, a protein in the plasma that can form elastic threads that cut off blood flow.

While these researchers recommended aspirin as an anti-clotting measure for people at risk of heart disease, garlic can also help break up fibrin and possibly lower your chance of heart problems (Pharmatherapy 5(2): 83).

The fibrin that forms clots is produced by blood cells called platelets. Other scientists who have looked into garlic's benefits believe that one of its natural chemicals called ajoene may keep platelets from producing excessive fibrin and gumming up the flow of blood through arteries.

If you've rarely indulged in garlic, you may need a period of adjustment in growing accustomed to its unique taste and aroma. But its heart benefits confirm the long-ago observation by Pliny, an ancient Roman naturalist, that "garlic has powerful properties."