Garlic, an herb long used medicinally and in cooking, may help boost your defense against several types of cancer. Preliminary research suggests that certain compounds in garlic might act as anti-cancer agents and help thwart the growth of tumors. Often touted as a natural remedy for the common cold and high blood pressure, garlic also appears to stimulate the immune system and curb inflammation. Here's a look at the science behind garlic and cancer prevention.
Research on Garlic and Cancer
Although garlic has not been proven to fight any form of cancer, it shows promise as a natural prevention approach for the following cancer types:
1) Colorectal Cancer
Garlic is "possibly effective" for prevention of colon cancer and rectal cancer, according to the National Institutes of Health (NIH). Indeed, a 2007 research review from the Journal of Nutrition found "consistent scientific evidence" that garlic may play a role in prevention of colorectal cancer. In an earlier report (published in the American Journal of Clinical Nutrition in 2000), scientists looked at 18 studies and concluded that high intake of both raw and cooked garlic may protect against colorectal and stomach cancers.
The NIH notes that while eating garlic seems to reduce risk of colon, rectal, and stomach cancers, taking garlic supplements doesn't seem to have the same benefit.
Garlic shows promise for breast cancer prevention, suggests preliminary research published in Anti-Cancer Agents in Medicinal Chemistry in 2011. Analyzing data from animal studies and test-tube research, the study's authors determined that garlic may suppress the growth of breast cancer. However, most available clinical studies indicate that taking garlic does not lower breast cancer risk, according to the NIH.
In a population-based study published in the Journal of the National Cancer Institute in 2002, scientists discovered that men who ate about a clove of garlic daily had a 50 percent reduced risk of developing prostate cancer. (The study included 238 prostate cancer patients and 417 healthy men, all of whom lived in China.) Additionally, a 2007 lab study from Clinical Cancer Research demonstrated that S-allylmercaptocysteine (a compound found in garlic) may fight prostate cancer by inhibiting tumor growth.
Should You Use for Garlic for Cancer Prevention?
It's too soon to recommend garlic for prevention of any type of cancer. However, boosting your garlic intake may offer a number of health benefits (including protection against high blood pressure and hardening of the arteries). While consuming garlic as a food is generally considered safe, some people may experience heartburn, upset stomach, or bad breath.
It should be noted that using garlic supplements in combination with certain medications and natural remedies (such as anticoagulants and fish oil) might increase your risk of bleeding. If you're considering the use of garlic supplements for prevention of cancer (or any other condition), consult your physician before starting your supplement regimen.
Fleischauer AT, Poole C, Arab L. "Garlic consumption and cancer prevention: meta-analyses of colorectal and stomach cancers." Am J Clin Nutr. 2000 Oct;72(4):1047-52.
Howard EW, Ling MT, Chua CW, Cheung HW, Wang X, Wong YC. "Garlic-derived S-allylmercaptocysteine is a novel in vivo antimetastatic agent for androgen-independent prostate cancer." Clin Cancer Res. 2007 Mar 15;13(6):1847-56.
Hsing AW, Chokkalingam AP, Gao YT, Madigan MP, Deng J, Gridley G, Fraumeni JF Jr. "Allium vegetables and risk of prostate cancer: a population-based study." J Natl Cancer Inst. 2002 Nov 6;94(21):1648-51.
Milner JA. "A historical perspective on garlic and cancer." J Nutr. 2001 Mar;131(3s):1027S-31S.
Milner JA. "Preclinical perspectives on garlic and cancer." J Nutr. 2006 Mar;136(3 Suppl):827S-831S.
National Institutes of Health. "Garlic: MedlinePlus Supplements". November 2010.
Ngo SN, Williams DB, Cobiac L, Head RJ. "Does garlic reduce risk of colorectal cancer? A systematic review." J Nutr. 2007 Oct;137(10):2264-9.
Tsubura A, Lai YC, Kuwata M, Uehara N, Yoshizawa K. "Anticancer Effects of Garlic and Garlic-derived Compounds for Breast Cancer Control." Anticancer Agents Med Chem. 2011 Jan 26.