Garlic's effectiveness as an antiseptic made the crushed herb a common poultice in ancient times. Treating wounds with garlic helped prevent infection. The herb found use in military field hospitals as recently as World War II, according to the Langone Medical Center. The chemicals in garlic that show antibacterial action last only about two days after crushing the herb. Aged garlic and other forms of processed garlic contain almost none of garlic's most potent ingredients.
Traditional Uses
Garlic originated in the grasslands of Asia and evolved chemical compounds to protect itself from attack by fungi and bacteria. The same compounds helped ancient humans preserve food. The antibacterial properties of garlic and other natural spices improved an individual's chances of survival, according to Professor Paul Sherman of Cornell University. Individuals who prospered passed along the preference for spices to their descendants. Many ancient cultures regarded garlic as a source of health and strength. Slave owners and military commanders ordered the consumption of garlic by the working classes to increase productivity. Garlic remedies treated diarrhea, parasitic infestations and fevers.
Allicin
The chemical that gives garlic its antibacterial action only activates when garlic cloves suffer damage. Alliin, the precursor compound, has no odor and no active properties. Damaged garlic cloves release an enzyme called alliinase that turns alliin into allicin, the active compound that kills bacteria and fungi. Allicin also creates the pungent odor of garlic. Crushing a garlic clove causes allicin formation within 10 to 60 seconds, according to the Linus Pauling Institute. Antimicrobial allicin lasts only 2.5 days in crushed garlic and breaks down much faster if eaten. Allicin metabolizes so quickly it never shows up in blood or urine samples.
Aged Garlic
Crushed garlic cloves fermented in an alcohol and water solution convert to aged garlic in about 20 months. During the fermentation, the allicin in the garlic breaks down into allyl sulfides. Some of the new sulfides evaporate and others become stable sulfur compounds. In laboratory tests, these sulfur compounds slow the growth of pathogens such as Helicobacter pylori, the infective agent responsible for many stomach ulcers. Allicin shows a stronger antibacterial effect than any of its byproducts, but scientific tests as of date of publication do not prove any garlic product's effect on bacteria within the human body, according to the Linus Pauling Institute.
Effectiveness
Compounds in aged garlic lack the antibacterial properties of raw crushed garlic, but could offer other important health benefits. Your body absorbs the water-soluble sulfur compounds in aged garlic more efficiently than the allicin in raw garlic. Some studies show that taking aged garlic supplements regularly reduces the size of colorectal adenomas, the lesions that form before cancerous tumors develop. Antioxidants in aged garlic could ease inflammation and slow the progress of atherosclerosis. In test studies, garlic supplements alone did not protect against gastric cancer, but diets high in raw or cooked garlic lowered cancer rates. No garlic product affects the incidence of stomach ulcers.
References
- New York University Langone Medical Center: Garlic
- "Cornell Chronicle"; Study: Antibacterial Spices Explain Why Some Like It Hot; Roger Segelken; March 1998
- Wilkes University; Medical Attributes of Allium sativum - Garlic; Jarrod Buzalewski, et al.; May 2009
- Linus Pauling Institute; Garlic and Organosulfur Compounds; Jane Higdon; July 2005
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