Garlic is considered a safe herb but it can cause skin irritation in sensitive people. Used as a food source it is safe even in pregnancy but used in medicinal amounts it may be unsafe during pregnancy, especially during the first trimester, and lactation. (1) Two studies used garlic during the third trimester with no adverse events. Garlic lowered hypertension but preeclampsia was not affected.(2)
Ancient tradition says that garlic can ward off evil spirits. I guess it works for illness due to the smell. Think about it wearing garlic around the neck would keep a lot of people away and that would keep away the germs too.
However, garlic can do a lot more than keep people away. Studies have shown garlic can inhibit plaque formation that leads to arteriosclerosis. (3) Another arterial issue that garlic can address is elasticity. With age the aorta can become stiff. Picture a rubber gasket like the ones you can find on airtight kitchen jars. After a while they become too stiff to work. They have lost their elasticity. Garlic appears to protect this aortic elasticity. (4, 5)
Herbs often work although it can take several weeks before any results will show.
Garlic has been shown to help reduce the risk of certain cancers, but not all. Eating more garlic may reduce your risk of colorectal and gastric cancers. (6)
Hypertension is another area that garlic is effective. Garlic can cause a modest reduction in blood pressure. Interestingly this does not work in people with normal blood pressure – which is a good thing. (7)
One other use for garlic could be as an insect repellant. A unique study reported less tick bites from people who had been taking garlic for several weeks. (8)
Garlic has been used for several other illnesses but with little or no positive results. Remember that in all of these claims there is usually some controversy. One issue is the brand and dose used in each study. One study may show no effect and another may show just the opposite. I have chosen to list studies that seemed well designed or ones that reviewed many other studies. I did not discuss negative studies. This is why it is important that you really do your research/homework before you decide to start an herbal regimen.
Remember to speak to your primary care physician.
- Farnsworth N, Bingel A, Cordell G, et al. Potential value of plants as sources of new antifertility agents I. J Pharm Sci 1975;64:535-98.
- Soltani PR. Preecampisia [sic] is an important complication of pregnancy which can result in morbidity and mortality in mother, fetus and the neonate. Journal of Medical Council of Islamic Republic of Iran (J MED COUNC ISLAMIC REPUB IRAN) 2005;23(3):319
- Siegel G1, Michel F, Ploch M, Rodríguez M, Malmsten M. Inhibition of arteriosclerotic plaque development by garlic. Wien Med Wochenschr. 2004 Nov;154(21-22):515-22.
- Breithaupt-Grogler K, Ling M, Boudoulas H, Belz GG. Protective effect of chronic garlic intake on elastic properties of aorta in the elderly. Circulation 1997;96:2649-55.
- Koscielny J, Klussendorf D, Latza R, et al. The antiatherosclerotic effect of Allium sativum. Atherosclerosis 1999;144:237-49..
- Fleischauer AT, Poole C, Arab L. Garlic consumption and cancer prevention: meta-analyses of colorectal and stomach cancers. Am J Clin Nutr 2000;72:1047-52.
- Ried K, Frank OR, Stocks NP, et al. Effect of garlic on blood pressure: A systematic review and meta-analysis. BMC Cardiovasc Disord 2008;8:13.
- Stjernberg L, Berglund J. Garlic as an Insect Repellant. JAMA 2000;284:831