Used medicinally for thousands of years, more recently garlic has been studied for treating health problems such as atherosclerosis and high blood pressure. Current studies of garlic's effects on gallstones show promising results, but more research is necessary. If you're considering taking garlic for gallstones, or any other health condition, it's best to talk to your doctor first.
Your liver makes bile, which helps to digest fats in the small intestine. It flows from the liver into the gallbladder for storage until needed. When that bile solidifies, the result is gallstones. Solidification occurs when concentrations of cholesterol or bilirubin in the bile become too high, and they precipitate out of solution and form crystals. This supersaturation can happen if the gallbladder doesn't empty regularly, among other causes. Cholesterol gallstones are yellow and more common, while dark gallstones are related to bilirubin.
A 2010 study in the journal "Metabolism: Clinical and Experimental" found that a combination of garlic and onions fed to mice reduced the incidence of cholesterol gallstones and helped shrink existing gallstones. Garlic and onion appeared to work by reducing the concentration of cholesterol in bile. A 2009 study in the "British Journal of Nutrition" found similar results, showing mice fed garlic and onion produced less biliary cholesterol and more bile. This mechanism helped reduce cholesterol gallstone formation.
Garlic contains a sulfur-containing compound called alliin that's converted to allicin when garlic is crushed. This compound gives garlic its distinctive odor and may be key to its medicinal benefits. Allicin isn't absorbed well by the body, however. Fermenting aged garlic transforms some of the allicin into more bioavailable sulfur compounds. Together, these sulfur-containing compounds may be responsible for garlic's beneficial effects on heart health and cancer, reports the University of Maryland Medical Center. However, in the gallstone studies cited above, raw or heat-processed, not aged garlic, was used.
Garlic is available fresh, dried, freeze-dried, as an oil or as an extract of aged garlic. Amounts of the active ingredients in garlic depend on how it's grown and later processed and prepared. As a food supplement, the University of Maryland Medical Center recommends adults consume 2 to 4 grams of fresh, minced garlic per day. One clove of garlic equals about 1 gram. If you prefer freeze-dried tablets, take two 200-milligram tablets three times per day, standardized to 1.3 percent alliin or 0.6 percent allicin. Garlic is considered generally safe, but it may interact with blood thinning medications, such as warfarin/Coumadin, clopidogrel/Plavix and aspirin, isoniazid, prescribed to treat tuberculosis, birth control pills, cyclosporine, taken after organ transplants, medications used to treat HIV/AIDS and NSAIDs like Advil, Motrin and Aleve. Garlic and can cause upset stomach and bad breath. Before taking garlic for any health condition, it's best to talk to your doctor first.