Does Garlic Really Add More Than Just Flavor?

Garlic has been the subject of centuries of mythology and folklore, from warding off vampires and evil spirits to providing courage to the fearful, strength to the weak and healing to the sick.

It was fed to the slaves who built the pyramids and also was used to embalm the pharaohs, who were entombed there. At one time it even served as a negative marker for social status. Roman soldiers and workers were fed garlic, but the nobles, who had no reason to be strong or brave, never touched the stuff. Historically, garlic has at one time or another been credited with healing broken bones, curing tuberculosis, the common cold and countless other ailments, even just by being worn around the neck.

Any plant that has been so heavily touted for medicinal properties was bound to end up as a supplement. Ever since garlic hit the health food stores, it has been discussed as a possible weapon in the war against heart disease and cancer. Because of the heightened interest in the healing powers of garlic and the amount of scientific investigation that has been carried out on this subject, the National Cancer Institute put garlic on a list of possible cancer preventives they are studying.

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So with all of this focus on garlic and the amount of money being spent on it as a nutritional supplement, what do we know at this point?

Here are some questions and answers.

* Does garlic lower blood cholesterol?

About five years ago, two well-publicized meta-analyses concluded that eating a clove of garlic a day (or its equivalent) would lower blood cholesterol by 9% to 12%. (A meta-analysis is an analysis in which the data from a number of previous studies are combined and reanalyzed.)

Unfortunately the meta-analyses were poorly done (they did not include any of the studies that contained negative results), and the studies they included were often seriously flawed.

More recently, in 1998, two well-designed studies were published and neither one could find any cholesterol-lowering effect of garlic supplements. This is particularly interesting since one of these studies used garlic oil and the other one used the popular garlic powder tablet (Kwai), two supplements that have different chemical compositions.

* Does it lower blood pressure?

Like the research concerning cholesterol, these studies have been contradictory and thus largely inconclusive.

* Does garlic prevent cancer?

There have been some studies showing that people who eat garlic regularly (not as supplements) have a reduced risk of stomach and colon cancer and possibly breast and prostate cancer. However, a large, well-designed study in the Netherlands failed to show a reduction in breast cancer risk among 2,100 women or lung cancer among 3,600 men who took garlic supplements. So, while this is an area that is under investigation, nothing much can be concluded.

* Does it strengthen the immune system?

Again, while it is certainly possible that it does, at the moment there isn’t enough evidence one way or the other.

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Because there are so many unanswered questions about garlic, it is hard to give advice. For instance, if there are significant health benefits to garlic, does it matter whether the garlic is raw or cooked? Even though there is no evidence that garlic supplements are more or less effective than garlic as food, does it matter which kind you take? Are supplements with allicin better than those without it?

* So what is the bottom line here?

We cannot see any reason to take garlic as a supplement or to eat it in the huge quantities that would probably be needed to get a medicinal level of any of garlic’s many compounds. However, unlike some other supplements that don’t do any good, this one isn’t likely to do any harm.

* What about garlic as a food?

Even if garlic had no redeeming health benefits at all, which is possible, it is still a great flavoring agent for all kinds of food, especially low-fat vegetarian dishes, which often need a flavor boost. If possible, buy loose garlic and choose a bulb that is plump and compact with no soft spots. The outer skin should not be broken, and the bulb should feel heavy for its size. If it feels very light or if the skin gives way, it has probably dried out.

Garlic stores well in a cool dark place, in a container that allows some air to circulate. Depending on how old it was when you bought it, you can probably keep garlic for a few weeks or even months.

Don’t worry if garlic sprouts. It is still usable, but since it will have lost much of its pungency, you may have to use a lot more to get the desired flavor. Garlic sprouts are delicious and can be cut up and used like scallions or chives. They are especially good in stir-fry.

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Dr. Sheldon Margen is professor of public health at UC Berkeley; Dale A. Ogar is managing editor of the UC Berkeley Wellness Letter. They are the authors of several books, including “The Wellness Encyclopedia of Food and Nutrition.”