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March 2013

Garlic Intake May Not Affect Colorectal Cancer Risk

Increased garlic intake may not reduce the risk of colorectal cancer as previous research has suggested, according to a study.

Garlic is a culinary herb that is widely used for the treatment and prevention of heart disease and cancer. It has also been studied for possible benefits in colorectal cancer.

Colon cancer is cancer of the large intestine (colon), which is the lower part of the digestive system. Rectal cancer occurs on the last eight to ten inches of the colon. They are often referred to together as colorectal cancers, and are the second-leading cause of cancer-related deaths in the United States.

In the current study, scientists collected data from 76,208 women who had participated in the Nurses' Health Study and from 45,592 men in the Health Professionals Follow-up Study. They followed subjects for up to 24 years and collected information on garlic intake and the use of garlic supplements with regard to risk of colorectal cancer.

A total of 2,368 cases of colorectal cancer developed among the subjects. The researchers found a lack of association between daily garlic intake (one clove or four shakes of powder per serving) and colorectal cancer risk. Likewise, they found that garlic supplement use and colorectal cancer risk lacked correlation.

The scientists concluded that their results do not support garlic intake or garlic supplementation for purposes of reducing colorectal cancer risk. However, more research is needed in this area.

The incidence of colorectal cancer is slightly higher in men than women, and is highest in African American men. The incidence of colorectal cancer is highest in developed countries such as the United States and Japan, and lowest in developing countries such as Africa and Asia. Greater celandine, psychotherapy, and meditation have been studied as potential treatments and methods of improving quality of life in people with cancer. There is good scientific evidence supporting the effectiveness of these integrative therapies for these purposes.

For more information about colorectal cancer, please visit Natural Standard's Medical Conditions Database.


  1. Meng S, Zhang X, Giovannucci EL, et al. No association between garlic intake and risk of colorectal cancer. Cancer Epidemiol. 2013 Apr;37(2):152-5. doi: 10.1016/j.canep.2012.11.002. Epub 2012 Dec 21. 
  2. Natural Standard: The Authority on Integrative Medicine. 

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