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GARLIC: Research into health benefits continue

Garlic ma Garlic y ward off more than vampires, according to anincreasing body of research on the disease-fighting properties of this pungent herb. Garlic contains many elements and compounds including vitamins A and C, potassium, phosphorus, sulfur (including 75 different sulfur compounds), selenium and a number of amino acids. Among the most important of the compounds seems to be allicin, a sulfur-containing compound (formed when garlic is cut or crushed). It's allicin that gives garlic its characteristic pungent aroma and flavor. Garlic's close relatives, onions and leeks, contain similar sulfur compounds and are also being studied for possible health benefits.

Cardiovascular effects

The most convincing research thus far suggests that garlic may reduce some risks of heart disease. "Studies, including one published in 1993 in Annals of Internal Medicine, have shown that garlic lowers serum cholesterol by as much as 9 percent."

Researchers from Penn State University have found that garlic reduces the production of triglycerides and cholesterol in the livers and blood of rats. High levels of triglycerides and cholesterol increase the risk for coronary heart disease. Researchers are currently performing similar studies on humans.

Another potentially beneficial cardiovascular effect attributed to garlic is an ability to "thin" the blood and make clotting less likely. Researchers have discovered that similar sulfur compounds in onions make platelets slippery, less likely to stick together and form clots that can block blood flow and lead to heart attack and stroke."

Garlic also may help prevent and even reverse arteriosclerosis (the buildup of fatty deposits on and in artery walls). One study found less aortic stiffening among older adults taking standardized garlic powder for at least 2 years.

Wiping out Microbes

During World War I, garlic was used to treat typhus and dysentery and to clean wounds. Today researchers are finding that garlic Garlic does indeed appear to possess some antimicrobial properties. A study from the Weizmann Institute of Science in Israel (published in Antimicrobial Agents & Chemotherapy, October 1997) reported that garlic blocks the action of certain enzymes that help infectious microbes survive in host tissue. Such enzymes are produced by many bacteria and fungi, so garlic shows promise as a broad-spectrum antibiotic.

Garlic as cancer fighter

A study from the Penn State University College of Health and Human Development has found that garlic blocks the formation of nitrosamines in the test tube. Nitrosamines are carcinogens absorbed from food and water. According to the Penn State researchers, this nitrosamine-blocking ability is consistent with evidence that higher intake of garlic and onions may reduce the risks of some types of cancer.

Epidemiological studies have found that in areas of the world where people eat a lot of garlic and onions, there is decreased incidence of cancer. Compounds in garlic have antioxidant properties which may play a role in inhibiting cancer by protecting against cellular damage from free radicals. The Iowa Women's Health Study found that of all foods evaluated, garlic showed the strongest association with decreased risk for colon cancer.

Intriguing possibilities but few solid answers

The claims made for garlic don't go unchallenged. In the view of some researchers, many of the more than 1,000 studies on garlic's effects that have been performed over the past two decades were flawed in design or execution. The studies mentioned above and others now underway examine the findings of earlier studies or test new hypotheses. The results are intriguing, but so far little has been proven concerning garlic's health benefits.

While researchers are reasonably certain of garlic's ability to lower cholesterol and reduce clotting, they don't yet have definite proof of some of the other potential benefits. But as the quality of studies improves, they should begin to get some clearer answers.

What form is best?

For those who have decided to increase their garlic consumption, the best way to do that isn't clear either. Questions remain about what's a safe and effective "dose" and in what form the garlic should be consumed. Eating garlic as a food may reduce its effectiveness because it appears that the stomach breaks down allicin. Fresh garlic also may lose its effectiveness quickly after cutting or crushing, and cooking may either decrease or increase the potency of various compounds in garlic. Taking very large amounts of garlic also causes anemia and irritation of the intestinal tract for some people. For many, garlic's odor is offensive. A possible solution is to use enteric-coated garlic tablets; the coating allows the tablet to pass through the stomach intact so that the garlic can be absorbed by the small intestine. Such tablets are odorless. Some researchers use aged garlic extract (AGE) which contains a possibly more effective sulfur compound than does fresh garlic.

Despite the questions that remain about the health benefits of garlic, there is still nothing wrong with enjoying a meal with this versatile herb.