Infection Benefits From Garlic

Garlic's potential to combat heart disease has received a lot of attention, but it should receive even more acclaim for its antimicrobial properties. Fresh, raw garlic has proven itself since ancient times as an effective killer of bacteria and viruses. Once again, we can thank allicin.

Garlic can prevent infection inside or outside the body.
Garlic can prevent infection inside or outside the body.

Laboratory studies confirm that raw garlic has antibacterial and antiviral properties. Not only does it knock out many common cold and flu viruses but its effectiveness also spans a broad range of both gram-positive and gram-negative bacteria (two major classifications of bacteria), fungus, intestinal parasites, and yeast. Cooking garlic, however, destroys the allicin, so you'll need to use raw garlic to prevent or fight infections.

Antimicrobial Activity

Garlic's infection-fighting capability was confirmed in a study conducted by researchers at the University of Ottawa that was published in the April 2005 issue of Phytotherapy Research. Researchers tested 19 natural health products that contain garlic and five fresh garlic extracts for active compounds and antimicrobial activity.

They tested the effectiveness of these substances against three types of common bacteria: E. faecalis, which causes urinary tract infections; N. gonorrhoeae, which causes the sexually transmitted disease gonorrhea; and S. aureus, which is responsible for many types of infections that are common in hospitals. The products most successful at eradicating these bacteria were the ones with the highest allicin content.

Now garlic is being investigated to see whether it can help us battle microbes that are resistant to antibiotics. Can garlic go where current antibiotics cannot and knock out the resistant bacteria? Perhaps.

One simple but meaningful demonstration of garlic's antibacterial power can be found in a study conducted at the University of California, Irvine. Garlic juice was tested in the laboratory against a wide spectrum of potential pathogens, including several antibiotic-resistant strains of bacteria. It showed significant activity against the pathogens. Even more exciting was the fact that garlic juice still retained significant antimicrobial activity even in dilutions ranging up to 1:128 of the original juice.

Garlic and Your Gums
Garlic may even help your gums stay healthy. In a study published in the July 2005 issue of Archives of Oral Biology, researchers concluded that garlic extract inhibits disease-causing bacteria in the mouth and may be valuable in fighting periodontitis, a serious gum disease. (Untreated gingivitis often leads to periodontisis, a condition in which the ligaments and bones supporting the teeth become infected and inflamed, ultimately resulting in tooth loss.)

This is exciting news because oral health can impact the rest of your body. For instance, disease-causing bacteria in your mouth can get into the bloodstream via bleeding gums, travel to your heart valve, and damage it.

Is it possible that garlic can work alongside prescription medications to reduce side effects or to help the drugs work better? Results from several studies say yes.

In a Rutgers University study that used bacteria in lab dishes, garlic and two common antibiotics were pitted against certain antibiotic-resistant strains of S. aureus (a gram-positive bacteria) and E. coli (a gram-negative bacteria). Garlic was able to significantly increase the effectiveness of the two antibiotic medications in killing the bacteria.

Research done in Mexico City at a facility supported by the National Institutes of Health of Mexico also showed some interesting results. It extended previous research in rats that used aged garlic extract and various sulfur-containing compounds from garlic along with gentamicin, a powerful antibiotic that can cause kidney damage. When any of the garlic compounds was ingested along with gentamicin, kidney damage was diminished.

Next, researchers set about to determine whether garlic weakened the effectiveness of gentamicin. As it turns out, the exact opposite happened: Garlic actually enhanced the effect of gentamicin. These findings indicate that with the use of garlic, perhaps less gentamicin would be needed, and kidney damage could be minimized.

Judging by research conducted in lab dishes and animals, it appears that garlic is a strong defender against microbes, even against those that have developed a resistance to common antibiotics. It also appears that garlic enhances the effects of some traditional antibiotics. But does it stand up to the test in humans?

Battling the Bugs Within

Eating raw garlic may help combat the sickness-causing bugs that get loose inside our bodies. Garlic has been used internally as a folk remedy for years, but now the plant is being put to the test scientifically for such uses. So far, its grades are quite good as researchers pit it against a variety of bacteria.

For eons, herbalists loaded soups and other foods with garlic and placed garlic compresses on people's chests to provide relief from colds and chest congestion. Now the Mayo Clinic has stated, "preliminary reports suggest that garlic may reduce the severity of upper respiratory tract infection." The findings have not yet passed the scrutiny of numerous, large, well-designed human studies, so current results are classified as "unclear."

Can a garlic clove help stop your sniffles? A study published in the July/August 2001 issue of Advances in Therapy examined the stinking rose's ability to fight the common cold. The study involved 146 volunteers divided into two groups. One group took a garlic supplement for 12 weeks during the winter months, while the other group received a placebo. The group that received garlic had significantly fewer colds -- and the colds that they did get went away faster -- than the placebo group.
Garlic also may help rid the intestinal tract of Giardia lamblia, a parasite that commonly lives in stream water and causes giardiasis, an infection of the small intestine. Hikers and campers run the risk of this infection whenever they drink untreated stream or lake water.

Herbalists prescribe a solution of one or more crushed garlic cloves stirred into one-third of a cup of water taken three times a day to eradicate Giardia. If you're fighting giardiasis, be sure to consult your health-care provider, because it's a nasty infection, and ask if you can try garlic as part of your treatment.

Finally, in the January 2005 issue of Antimicrobial Agents and Chemotherapy, researchers reported the results of an investigation into whether fresh garlic extract would inhibit C. albicans, a cause of yeast infections. The extract was very effective in the first hour of exposure to C. albicans, but the effectiveness decreased during the 48-hour period it was measured. However, traditional antifungal medications also have the same declining effectiveness as time passes.

A solution of raw garlic and water may stop wounds from becoming infected.
A solution of raw garlic and water may stop
wounds from becoming infected.

External Treatments

Garlic has many uses on the outside of the body, too. Applying a topical solution of raw garlic and water may stop wounds from getting infected. (Simply crush one clove of garlic and mix it with one-third of a cup of clean water. Use the solution within three hours because it will lose its potency over time.) A garlic solution used as a footbath several times a day is traditionally believed to improve athlete's foot.

A study conducted at Bastyr University, a natural health sciences school and research center near Seattle, showed that a garlic oil extract cured all warts it was applied to within two weeks. A water extract of garlic was much less effective. In the same study, the garlic oil extract also proved useful in dissolving corns.

Using garlic oil extract appears to work better than the old folk remedy of tying or taping a slice of garlic to a wart. If the slice of garlic is bigger than the wart or moves just a bit, it blisters the healthy surrounding skin (of course, you have the same risk when using wart-removing products that contain acid).

Garlic's phytochemical compounds are strong enough to create chemical burns, so always apply externally with caution and do not use on young children. One way you can protect the surrounding healthy skin is to smear petroleum jelly on it before you apply the garlic.

Viruses are a relatively small foe compared with cancer. On the next page you'll learn about research into the use of garlic to prevent this dreaded disease.

Flu Fighter: Garlic vs. the Common Cold
Herbalists recommend chewing garlic and holding it in your mouth for a while before swallowing it to obtain the best dose of bacteria-fighting allicin. This may be rather difficult for children or for those who find garlic to be too spicy. As an alternative, mince a clove, let it sit for 10 to 15 minutes so the allicin can form, then stuff it into empty gelatin capsules (which you can purchase in the herb section of a natural foods store).

Taking three cloves a day when you have a cold may help you feel better. If the raw garlic bothers your stomach, take the capsules with food that contains a little bit of canola oil or, better yet, olive oil.

Other folk remedies battle colds and chest congestion with a garlic poultice or plaster. To make one, put some chopped garlic in a clean cloth, thin washcloth, or paper towel. Fold it over to enclose the garlic. Pour very warm (but not hot) water over the wrapped garlic, let it sit for a few seconds, and then lightly wring it out. Place the wrapped garlic on the chest for several minutes. Reheat with very warm water and place on the back, over the lung area, for several minutes. Some herbalists also recommend placing the poultice on the soles of the feet.

Caution: Be careful not to let garlic come into direct contact with the skin. Cut garlic is so powerful that prolonged exposure to the skin may result in a burn.


Want more information about garlic? Try:
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  • Nutrition: Find out how garlic fits in with your overall nutrition plans.
  • Vegetable Gardens: Grow a full harvest of great vegetables this year.
  • Gardening: We answer your questions about all things that come from the garden.

This information is solely for informational purposes. IT IS NOT INTENDED TO PROVIDE MEDICAL ADVICE. Neither the Editors of Consumer Guide (R), Publications International, Ltd., the author nor publisher take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading or following the information contained in this information. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Before undertaking any course of treatment, the reader must seek the advice of their physician or other health care provider.