Researchers demonstrate the mechanism behind garlic's incredible antibiotic powers and its cardiovascular and cholesterol lowering benefits

Biologists from the University of Alabama in Birmingham, USA, have shown how garlic can be so effective in lowering cholesterol, lessening blood pressure and protecting your heart, as well as beating infections and boosting your immune system.

Garlic (Allium sativum) has been known as a universal savory ingredient, even a food in its own right, ever since the ancient Egyptians, Greeks and Romans ate the pungent bulb in large quantities. The slaves and free men building the Egyptian Pyramids were fed garlic, onions and leeks, and garlic was an essential part of the rations for Roman legions. Equally important, these ancient civilizations recognized garlic's important health protecting powers, attributes that 21 century science is just starting to recognize.

Garlic's Health Benefits

In the past couple of decades, garlic has been touted as an excellent source of Vitamin C, and more recently as a natural antibiotic, a stimulus to the immune system, and a possible treatment for lowering high blood pressure.

Garlic might also prevent the development of atherosclerosis, which hardens arteries and is the first step in the development of heart disease, by discouraging 'bad' LDL cholesterol & increasing 'good' HDL cholesterol. According to the U.S. National Center for Complementary and Alternative Medicine, garlic is also used to prevent certain types of cancer, including stomach and colon cancers, but there is no scientific evidence to support this theory.

Hydrogen Sulfide Is the Key

Garlic contains a compound called allicin, which the researchers showed stimulates the release of hydrogen sulfide (H2S ), better known as "rotten egg gas", from our red blood cells. Hydrogen sulfide is lethal in large doses, for humans and animals as well as to bacteria and viruses. However, in minute doses it relaxes the blood vessels and promotes smooth flow of blood, thus lowering blood pressure and protecting the heart.

The lead researcher, Dr David Kraus told listeners to Australian National Radio that hydrogen sulfide is a toxic gas. "Sometimes it's called sewer gas. It's got a number of different names like that because it is very potent to our olfactory system and it is very toxic. It is a naturally occurring toxic gas, and if we smell a lot of it, if we get a large whiff of it, it can paralyze your olfactory system and you can succumb to it.

"So it is lethal, under high concentration."

Fortunately for us, at low doses it is highly beneficial.

To start with, the University of Alabama researchers took mice blood vessels and bathed them in the juice of crushed garlic cloves. Measuring the tension within these garlicky blood vessels they found it was reduced by a dramatic 72 percent.

Then they found that garlic juice was able to stimulate red blood cells to release hydrogen sulfide. Hydrogen sulfide at low concentrations is also useful in cell-cell communication. It also relaxes the blood vessels promoting easier blood flow within them. This in turn brings down the blood pressure and lowers the load on the heart.

"What we think our research shows is that if the benefits of garlic are related to the release of H2S when it's in the body, then this would be a way to standardize the variety of garlic supplements that are used for clinical trials, to make sure that the patients are all getting the same amount of the compounds that will produce H2S in the body," Dr Kraus said.

He said other research is already showing that sulfide can protect from cardiovascular damage during a heart attack. "It can alleviate various sorts of inflammation, it can reduce platelet aggregation that would cause a clot to form. So sulfide is known to do many of these things already.

"So if we can show that garlic produces sulfide from these compounds, then it's a very small logical step to say that sulfide that's produced from garlic is providing these additional benefits."

The findings appear in the journal Proceedings of the National Academy of Sciences (PNAS).

Taking Garlic: Supplements or Fresh Cloves?

So, should we all take garlic supplements to maintain healthy hearts and perfect blood pressure, as well as to protect us against colds and flu’s?

Not necessarily, says Dr Kraus. Earlier studies into garlic's health benefits had failed to produce uniform results mainly because of the way garlic was prepared . "If you prepare it in certain ways, you can lose the compounds that cause it to release hydrogen sulfide," he says. In fact, 'odorless garlic' supplements are probably a complete waste of money, since the odor is a key to the herb's efficacy.

Dr Krause suggests we take our garlic the way the ancients did - as a food. Cooked garlic retains much of it's efficacy, but naturally raw is better.

How much raw garlic should we eat ? How about five or six cloves a day? Dr Krause told the radio listeners that he and his fellow researchers had a dinner club and came up with all sorts of ideas for eating that much garlic. For example?

"We take a small tub of hummus, and you can take an entire bulb of garlic and chop it up and put it in there and then spread that on bread; you can put it on vegetables, or in vegetable dips, you can use it on pasta, you can use it in a number of different ways. And in one bulb of garlic there's probably 15 or 20 cloves present."

If you plan on following Dr Krause's culinary advice, don't forget the parsley afterwards. A few springs of parsley (Petroselinum sativum) chewed after eating garlic takes most of the smell away. Be sure your friends and family enjoy the smell of garlic, before you incorporate it too enthusiastically in your diet.

Warning: Garlic Is a Powerful Blood Thinner

Garlic must be used with caution by people who have a bleeding disorder, or are on blood thinning medication such as aspirin or warfarin, because it is a powerful blood thinner. Other side effects include bad breath, body odor, heartburn, upset stomach, and allergic reactions.

See also: Turmeric Spice Benefits the Heart

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