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Garlic Relaxes Blood Vessels, Increases Blood Flow

Oct. 15, 2007 -- The health benefits of garlic have been touted for centuries, but now researchers may have pinpointed at least one reason why.

A new study shows red blood cells process compounds from digested garlic and turn them into the cell messenger hydrogen sulfide (H2S), which relaxes blood vessels and increases blood flow. Therefore, eating garlic may increase our natural supply of this vital chemical and play a role in reducing the risk of heart disease.

Previous studies on garlic’s health effects have produced mixed results. For example, some studies of garlic have found few benefits, but others have been shown to lower the risk of heart disease.

But researchers say if further studies confirm these findings, testing the ability to produce hydrogen sulfide may be used to standardize garlic supplements to produce greater health benefits.

Finding Garlic’s Effect

In the study, researcher Gloria Benavides, of the University of Alabama at Birmingham, and colleagues analyzed the effects of juice extracted from supermarket garlic on human red blood cells in the lab.

They found the red blood cells immediately began producing hydrogen sulfide after getting a tiny dose of garlic. The amount of garlic tested in the lab was roughly equal to two garlic cloves for a typical adult.

Further tests showed the key chemical reaction occurred at the membranes of the red blood cells, but a small amount of hydrogen sulfide was also produced inside the cells.

Few plants other than garlic contain the building blocks of hydrogen sulfide to provide these health benefits, and researchers say garlic is the only one commonly used in the human diet.

Their results appear in the Proceedings of the National Academy of Sciences.

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