I'm amazed by what I have learned about the quirky antimicrobial nature of garlic (Allium sativum). Its organosulfuric constituents are largely responsible for its antibacterial, antifungal, and antiviral nature. Garlic has been used topically on wounds and fungal conditions like ringworm since the Middle Ages or earlier. In 1858, Louis Pasteur observed that bacteria died when it came into contact with this pungent allium.
An exciting trait of herbs like garlic is their ability to kill gastrointestinal pathogens while preserving—or even enhancing!—beneficial gut flora. Given the measures one should take when using prescription antibiotics, such as eating fermented foods and/or probiotic capsules to help mitigate damage to gastrointestinal flora, this fact is notable. Furthermore, garlic is digestion-stimulating and a cholagogue, prompting the flow of bile from the gallbladder and aiding in the digestion of fats.
But how effective is garlic as an antimicrobial, really?
Researchers at Washington State found the diallyl sulfide in garlic was as effective as 100 times the amount of the antibiotics erythromycin and ciprofloxacin. Garlic also tends to work more rapidly. Research published in Applied and Environmental Microbiology and Analytical Chemistry demonstrated that diallyl sulfide and other organosulfur compounds effectively kill Listeria monocytogenes and E. coli O157:H7—prevalent food-borne pathogens.
When I had a cold last winter, I experienced significant pressure in my ears that hinted at an ear infection. I read in Dawn Combs’ Healing Local that using prescription antibiotics can instigate chronic ear infections in children, and may not be the best treatment. I asked a friend in medical school why this might be. She explained that antibiotics destroy the easy-to-kill bacteria at the surface of an infection, but often do not touch bacteria protected by slimy “biofilm.” According to Washington State researchers, bacteria found in biofilms are 1000 times more resistant to antibiotics than freewheeling bacterial cells. These scientists found that the diallyl sulfide in garlic can “easily penetrate the protective biofilm and kill bacterial cells.” When this compound combines with a sulfur-containing enzyme in pathogens, the enzyme’s activity is altered and cell metabolism shuts down. So, the garlic oil I hesitantly dropped into my ears may have been the best choice. I noticed relief and a release of pressure surprisingly quickly—within an hour.
Like thyme, the antimicrobial volatile oils in garlic are largely excreted through lungs. This makes it a desirable companion when experiencing recurrent colds, chronic bronchitis, and the flu.
Garlic is also a preventative ally for the cardiovascular system. One clove a day is enough to
lower serum cholesterol, triglycerides and blood pressure over time, while raising “good” HDL cholesterol. Its antioxidant constituents can also help to prevent heart disease by preventing peroxidation of fats.
Using it: Garlic is most effective when eaten fresh. Active component allicin is only formed when the clove is crushed or chopped; it is recommended to do so and wait 10 minutes before eating. Allicin can be destroyed by heat, so I add garlic to my dish after cooking is complete.
*Note garlic's strong anticoagulant nature. Tell your doctor if you've had garlic before an emergency situation, or if you are taking blood thinners. Avoid garlic before surgery.
RECIPE: Speaking of alliums, check out this tasty recipe for wild onion (aka wild chive) vinegar.
Combs, Dawn. Heal Local. 2015.
Hoffman, David. Medical Herbalism. 2003.
Tilgner, Dr. Sharol. 2009.