Garlic: the hope and the current studies

Garlic is known to have been used for 7,000 years in cooking and as a medicine.  It is one of the first plants cultivated by humans.  Garlic has a long history of medicinal uses – including its use by grave diggers during the terrible episodes of bubonic plague in the 14^th and 15^th centuries that killed half of human populations in areas where it struck.   Grave diggers drank wine with crushed garlic to prevent catching the plague – perhaps their skin odor repelled the fleas that transmitted plague from infected rats.  Perhaps this was hype, and hope.  However, there are numerous current studies on the medicinal properties of garlic that are promising,

Garlic as an antioxidant: Studies from the National Research Council of Canada have shown that allicin, which gives garlic its aroma and flavor, acts as an extremely powerful antioxidant.   Garlic does not have a substantial amount of the compounds responsible for antioxidant activity in green tea or grapes.  The researchers found that a decomposition product of allicin, called sulfenic acid, acts rapidly when in contact with free radicals.  The author wrote ‘The reaction between the sulfenic acid and radicals is as fast as it can get, limited only by the time it takes for the two molecules to come in contact.  No one has ever seen compounds, natural or synthetic, react this quickly as antioxidants.’  While onions, leeks and shallots have a compound similar to allicin, they do not have the same medicinal properties, due to a slower rate of decomposition of allicin.

Cystic Fibrosis: this is an inherited lung disease that causes lung infections and limits the ability to breath. It is usually diagnosed in childhood and may be fatal. A group of infectious bacteria in cystic fibrosis are resistant to most antibiotics.  The chemical known as allicin produced by garlic bulbs may be helpful in the future to kill resistant bacteria.  Research is being done at the University of Edinburgh’s School of Chemistry.  Research on garlic’s antibiotic actions is also going on at the University of Copenhagen and many other centers. More effective antibiotics are desperately needed.

Brain protection:  Researchers at the University of Missouri have found a nutrient in garlic that protects brain cells against the kind of cell damage that promotes  cognitive problems, Parkinson’s disease and stroke.  This garlic nutrient, which they call FruArg,,  promotes the production of antioxidants which offer protective and healing benefits to brain cells,  Research is ongoing.

Reduction of “soft plaque” in arteries: Research at UCLA Medical Center has shown that patients at risk of heart attack benefited from using aged garlic extract.  ‘Soft plaque’ in the linings of arteries is composed mainly of white blood cells, which when released promote blood clotting.  Researchers studied 55 patients who had been diagnosed with ‘metabolic syndrome’ (obesity, high blood pressure, and other cardiac risk factors). After a workup that measured the plaque in their coronary arteries, they were given either a placebo or a dose of 2,400 mg of Aged Garlic Extract daily.  A year later those who had taken the garlic extract showed slowed total plaque accumulation by 80%. 

Cancer protection: Several population studies show an association between increased intake of garlic and reduced risk of certain cancers, including cancers of the stomach, colon, esophagus, pancreas, and breast. An analysis of data from seven population studies showed that the higher the amount of raw and cooked garlic consumed, the lower the risk of stomach and colorectal cancer.  These studies are from Europe, the U.S. and China.  Chinese studies also show a decreased risk of prostate cancer with greater intake of garlic and scallions.

Garlic as a ‘blood thinner’:  Garlic has an anticoagulant effect.  Many doctors advise stopping high doses of garlic 10 days before surgery.  If you are on an anticoagulant medicine, discuss this with your doctor.   Usual doses of garlic in cooking should not be a problem.

There is a restaurant in San Francisco called The Stinking Rose, which features garlic in every course.  If any reader wants to organize a trip there, count me in!

Sadja Greenwood MD, MPH  past issues on this blog