An ingredient found in many curries may help prevent and treat colon cancer.

A small clinical trial showed the food chemicals reduced the size and number of precancerous growths in the intestinal tract. If left untreated, such growths commonly lead to colon cancer.

The experimental combination contained a chemical found in turmeric, the spice that gives curries a yellow color, and an antioxidant found in onions called quercetin.

Curry Spice May Fight Skin Cancer

Observational studies in people who eat large amounts of curries with these ingredients, as well as animal tests, have suggested that curcumin, the yellow pigment extracted from turmeric, may help prevent and treat colon cancer, say the researchers.

Curry Spice May Curb Breast Cancer’s Spread

Studies have also shown that quercetin, one of a group of antioxidants known as flavonoids and found in onions, green tea, and red wine, inhibits the growth of cancer cells in humans and rats.

Curry Cure for Colon Cancer?

In the study, published in the journal Clinical Gastroenterology and Hepatology, researchers evaluated the use of these curry ingredients as a potential colon cancer drug in five people with a rare genetic condition that causes the growth of precancerous polyps in the intestines.

The condition, Familial Adenomatous Polyposis (FAP), is usually inherited.

If the colon is not surgically removed, there is a 100 percent chance some of the polyps will develop into cancer, usually by age 40.

Cancer Prevention: What Really Works?

All participants in this study had had their colons removed, but still had remnants of their intestines. Internal exams were done before the start of treatment to record the baseline number and size of polyps present.

Each of the patients then received 480 milligrams of curcumin and 20 milligrams of quercetin three times a day for six months.

Pomegranates May Prevent Prostate Cancer

The results showed that treatment with the curry and onion compounds reduced the average number of polyps by 60 percent and decreased their size by 50 percent.

Although study participants received the two substances together, the researchers believe curcumin was the key ingredient.

"The amount of quercetin we administered was similar to what many people consume daily. However, the amount of curcumin is many times what a person might ingest in a typical diet, since turmeric only contains on average 3 percent to 5 percent curcumin by weight," researcher Dr. Francis M. Giardiello, of Johns Hopkins University School of Medicine, said in a news release.

Visit WebMD's Cancer Health Center

Because of this, Giardiello says simply eating curry and onions may not have the same effect as was seen in this study.

This study is the first to show curry ingredients reduce precancerous polyps in people at risk for colon cancer, the researchers say. Further studies are planned.

By Jennifer Warner, reviewed by Dr. Louise Chang

SOURCES: Cruz-Correa, M. Clinical Gastroenterology and Hepatology, August 2006; vol 4: pp 1035-1038. News release, Johns Hopkins Medicine.