Garlic

(And its “Sidekicks:” Scallions, Shallots, Leeks, Onions)

A Source of:

  • Organosulfur compounds (75 total, with allicin the most active)
  • Saponins
  • Polyphenols
  • Selenium
  • Arginine
  • Vitamin C
  • Potassium
Copyrighted Material*

Garlic, a small and humble-looking vegetable, plays a huge role in the major cuisines of the world. It’s hard to imagine Italian, French, or Asian cooking without garlic. The big news on garlic isn’t its ability to flavor a dish, but rather its considerable role as a health promoter. Indeed, recent findings on the power of garlic to fight cancer and cardiovascular disease, as well as its anti-inflammatory and antiviral properties, give garlic the bona fides to elevate it to SuperFood status.

Garlic, a member of the lily, or allium, family, traces its origin to Central Asia. Garlic is a major flavoring agent, particularly in Mediterranean cuisine, but as far back as 2600 B.C., it was used by the Sumerians as medicine. One of the oldest cultivated plants in the world, garlic was recognized by early civilizations as a source of strength and was mentioned in the Bible. Indeed, throughout the history of civilization, the medicinal properties of garlic have been prized, and it’s been used to treat ailments, including atherosclerosis, stroke, cancer, immune disorders, cerebral aging, arthritis, and cataract formation.

Garlic’s power as a health promoter comes from its rich variety of sulfur-containing compounds. Of the nearly one hundred nutrients in garlic, the most important in terms of health benefits seems to be the sulfur compound allicin—an amino acid. Allicin is not present in fresh garlic, but it is formed instantly when cloves are crushed, chewed, or cut. Allicin seems to be responsible for the superbiological activity of garlic as well as its odor. In addition to allicin, a single clove of garlic offers a stew of compounds with potential health benefits, including saponins, phosphorus, potassium, zinc, selenium, polyphenols, and arginine. In addition to these compounds, garlic is a good source of vitamin B6 and also of vitamin C. As with most  whole foods, garlic’s antioxidant and anti-inflammatory abilities are probably due to the sum of the whole rather than a single agent.

Garlic and Cardiovascular Disease

A number of studies have shown that garlic has an important impact on risk factors for cardiovascular disease. It has been demonstrated that those who make garlic a regular part of their diets enjoy lowered blood pressure and decreased platelet aggregation, as well as decreased triglycerides and LDL (“bad”) cholesterol. Garlic also may increase HDL (“good”) cholesterol. Consuming one half to one clove of garlic daily lowers LDL cholesterol levels by approximately 10 percent, partially by decreasing cholesterol absorption. Garlic extracts have also been shown to decrease blood pressure: In one study, a 5.5 percent decrease in systolic blood pressure and a slight decrease in diastolic pressure were noticed. While these are modest decreases, they cold still lead to a significant lessening of the risk for stroke and heart attack. The end result of all of these benefits is a lowered risk of atherosclerosis and heart disease as well as a reduced risk of heart attack and stroke. Garlic oil has been shown to decrease total and LDL cholesterol and triglyceride levels.

Garlic’s primary positive effect on cardiovascular disease comes from its sulfur compounds, but the effect of vitamin C, B6, selenium, and manganese cant’ be ignored. Garlic’s vitamin C—the body’s primary antioxidant defender—protects LDL cholesterol from oxidation. It’s the oxidation of LDL cholesterol that begins the process that damages blood vessel walls. Vitamin B6 lowers levels of homcysteine, a substance that can directly damage blood vessel walls. The selenium in garlic fights heart disease, while it’s also working to protect against cancer and heavy metal toxicity. Manganese works on a variety of antioxidant defenses, and studies have found that adults deficient in manganese have lowered their levels of the “good” or HDL, cholesterol.

Garlic and Cancer

A number of studies have reported on garlic’s ability to fight cancer, although further research is needed to clarify the precise role of garlic in this battle. Several population studies have shown a link between garlic in the diet and a decrease in the risk for colorectal and gastric cancer, and one clove of garlic daily may decrease the risk of developing prostate cancer. Recent reviews of more than 35 studies report some protective effect against cancer in about 75 percent of the published articles.

Garlic as Antibiotic

Two recent studies have shown that garlic can be a potent antibiotic. Particularly impressive was that garlic was effective against strains of pathogens that have become resistant to many drugs. One study showed that garlic juice showed significant antibacterial activity against a host of pathogens, even including antibiotic-resistant strains such as ciprofloxacin-resistant staphylococci. The second study, conducted on mice, found that garlic was able to inhibit a type of staph infection that’s become increasingly resistant to antibiotics and increasingly common in hospitals. This type of staph infection has become a potential danger for health care workers, as well as for people with weakened immune systems. Sixteen hours after the mice were infected with the pathogen, garlic extract was fed to them. After twenty-four hours, garlic was found to have been protective against the pathogen and to have significantly decreased the infection.

*This brief summary contains copyrighted material from SuperFoods HealthStyle by Steven G. Pratt, M.D. and Kathy Matthews. Copyright © 2006 by Steven G. Pratt, M.D. and Kathy Matthews Inc., published by HarperCollins; and from SuperFoods Rx For Pregnancy by Steven Pratt, M.D. Copyright © 2013 by SuperFoods Partners, LLC, published by Wiley. All rights reserved.