Copyright © 1995 by Jack Challem, The Nutrition Reporter™
All rights reserved.

If garlic had been created in the laboratory instead of by nature, it would probably be a high-priced prescription drug.

That's just how good it really is.

Medical studies have shown that garlic - the aromatic seasoning people either love or hate - can lower cholesterol, prevent dangerous blood clots, reduce blood pressure, prevent cancer, and protect against bacterial and fungal infections.

Just what makes garlic so good? Known scientifically as Allium sativum, garlic contains more than 100 biologically useful chemicals, including substances with such strange names as alliin, alliinase, allicin, S-allylcysteine, diallyl sulfide, allyl methyl trisulfide.

In fact, garlic has been used medicinally for at least 3,000 years, but until relatively recently its benefits were considered little more than folklore. According to a report in the Journal of the American Medical Association (Nov. 28, 1990;264:2614), the therapeutic roles of garlic have been described in more than 1,000 scientific studies.

Garlic Benefits the Cardiovascular System

Adesh K. Jain, M.D., of the Clinical Research Center and Tulane University School of Medicine, New Orleans, reported last year that garlic can lower blood levels of "total" cholesterol and, particularly, of the dangerous low-density lipoprotein (LDL) form. Jain gave 20 men and women 900 milligrams of garlic powder tablets daily and compared them to 22 people getting just a placebo.

By the end of the 12-week study, total blood cholesterol levels dropped by an average of 6 percent among those taking the garlic tablets, compared with only a 1 percent drop among those taking a placebo. The garlic takers also benefited from an 11 percent decrease in the LDL form of cholesterol, compared with a 3 percent reduction in the placebo group.

"Garlic powder, given in the form of tablets in our study, was well tolerated and only one subject reported increased belching and a garlic odor," explained Jain in the American Journal of Medicine (June 1994;94:632-5).

Garlic is also an anticoagulant - a natural blood thinner. H. Kieswetter, M.D., of the University of Saarlandes, Hamburg, Germany, recently found that garlic could help patients suffering from peripheral arterial occlusive disease, characterized by blood clots in the legs.

Typically, patients with the condition are asked to walk, because increased blood flow reduces the number of clots. However, they are easily discouraged because peripheral arterial occlusive disease causes extreme pain after walking only a short distance.

Kieswetter gave 32 patients 800 milligrams of garlic powder tablets daily for 12 weeks, while another 32 patients received a placebo. He then measured their "pain-free walking distance." For the first several weeks, both groups of patients progressed about as they would in a typical walking program. As time went on however, patients taking garlic were able to walk about one-third farther without pain, according to Kieswetter's report in Clinical Investigator (May 1993;71:383-6). The researcher also noted that garlic's benefits, which included decreased blood pressure, could be detected after patients took a single garlic powder capsule.

Why does garlic lower blood pressure? Blood pressure increases in response to the body's production of angiotensen I-converting enzyme (ACE). Some prescription blood pressure drugs work as "ACE inhibitors," blocking formation of the chemical. Garlic contains gamma-glutamylcysteine, a natural ACE inhibitor, according to an article in Planta Medica (Sendl, A. Feb. 1992;58:1-7).

Garlic Protects Against Cancer

Garlic also protects against cancer. Benjamin Lau, M.D., Ph.D., noted in Molecular Biotherapy (June 1991;3:103-7), that garlic "is one of the most ancient of plants reputed to have an anticancer effect. As recorded around 1550 B.C., in the Ebers Papyrus, garlic was used externally for the treatment of tumors by ancient Egyptians and internally by Hippocrates and Indian physicians."

Lau, a researcher at the Loma Linda University School of Medicine, has identified three ways garlic protects against cancer: by directly inhibiting tumor cell metabolism, by preventing the initiation and reproduction of cancer cells, and by boosting a person's immune system to more efficiently fight cancer cells.

John Milner, Ph.D., of Pennsylvania State University, University Park, recently studied how aged garlic powder might protect against nitrosamine-induced cancers in laboratory mice. Nitrosamines are formed when processed meats, such as bacon and bologna are eaten.

Milner found that a diet consisting of 2 to 4 percent garlic delayed the growth of breast cancer and reduced the number of tumors. "The total tumor number was reduced by 56% in rats fed the 2% garlic-powder diet throughout the 20 weeks feeding period compared to control-fed rats," he explained in Carcinogenesis (Oct. 1992;13:1847-51).

Another benefit was that levels of glutathione-S-transferase were 42 percent higher among the animals eating high-garlic diets. Glutathione-S-transferase is an enzyme that helps the liver detoxify carcinogens and other dangerous chemicals.

In a separate study, Milner found that garlic could dramatically reduce the number of "adducts" in deoxyribonucleic acid (DNA). Adducts are chemicals that attach nitrosamines to DNA, setting the stage for cancerous changes.

Milner exposed a group of laboratory rats to nitrosamines, but some of the animals were also given large amounts of aged garlic powder - again, 2 to 4 percent of the diet. Depending on the amount of garlic they ate, the rats had a 40 to 80 percent reduction in the adducts in the liver. In addition, garlic-eating rats benefited from 55 to 69 percent fewer mammary gland adducts, according to Milner's article in Carcinogenesis (Feb. 1994;15:349-52).

Several studies have also shown that garlic reduces the risk of stomach cancer. One study, conducted in China, found that garlic consumption was inversely related to the incidence of stomach cancer, according to a report in Preventive Medicine (Han, J., Sept. 1993;22:712-22). Other experiments, such as the one described in Cancer Letters (Nagabhushan, M., Oct. 21, 1992;66:207-16), noted that diallyl sulfide significantly reduced stomach tumors in hamsters.

In still another experiment, Professor M. M. El-Mofty of Alexandria University, Egypt, fed Egyptian toads either freshly minced garlic, garlic oil, or corn oil (placebo) for four months, then exposed them to aflatoxin B1 (AFB1), a food contaminant that can cause liver cancer.

Only 3 percent of the toads fed fresh garlic and only 9 percent of the 65 animals fed garlic oil developed tumors. In contrast, 19 percent of those fed corn oil developed liver and kidney tumors.

"Our results show that feeding toads minced garlic or garlic oil resulted in a marked reduction in the incidence of tumors induced by AFB1," El-Mofty wrote in Nutrition and Cancer, 1994;21:95-100). "The fresh garlic showed a greater inhibitory effect...This suggests that there are additional highly active components in fresh garlic."

Fights Microbial and Fungal Infections

Scientific research has also confirmed garlic's role as a natural antibiotic. Back in 1983, Lau noted in Medical Hypotheses (12:227-37) that "garlic extract has broad-spectrum antimicrobial activity against many genera of bacteria and fungi...Because many of the microorganisms susceptible to garlic extract are medically significant, garlic holds a promising position as a broad-spectrum therapeutic agent."

One way garlic works is by promoting phagocytosis, the ability of white blood cells to fight infections. Another is by stimulating other immune cells, such as macrophages and T-cells to fight bacterial and viral infections and to scavenge for cancer cells. One report, in Deutsche Zeitschrift für Onkologie (April 1989;21:52-3), described how garlic enhanced the body's "killer cell" activity against the AIDS virus.

Lau has also noted that garlic can combat Candida infections. In one study, he injected an aged garlic extract into mice with Candida infections. After a day, the Candida colonies numbered 400, compared with 3,500 among the mice given only a salt-water solution. After two days, the garlic-treated mice were free of Candida.

Active Ingredients

In one of the great ironies of nature, raw garlic has very little biological activity. But when you "damage" garlic cloves - by slicing, cooking, or chewing - the enzyme alliinase immediately converts alliin into allicin, which gives garlic its characteristic odor.

Allicin was once thought to be garlic's principal active ingredient. However, researchers now know that allicin is rapidly oxidized. More than 100 biologically active sulfur-containing compounds, proteins, and saponins are created as a result of this oxidation. While allicin may still serve as a general marker of garlic's potency, research increasingly points to S-allylcysteine and other compounds as the most therapeutically active ingredients in garlic.

So how should you take garlic? Most scientific studies have, for consistency, used a standardized garlic extract in capsule or liquid form. However, just about any form offers some benefits. If you enjoy the taste of garlic, use it liberally in your food. If the taste and odor turn you off, opt for deodorized garlic capsules. Either way, garlic is good for your health.

This article originally appeared in Let's Live magazine. The information provided by Jack Challem and The Nutrition Reporter™ newsletter is strictly educational and not intended as medical advice. For diagnosis and treatment, consult your physician.