Compounds found in garlic, cauliflower and soy sauce have been found to prevent cancer in rodents, according to reports at the American Chemical Society meeting in Washington.
The anti-cancer potential of these foods in humans is not yet known, the researchers say. But one scientist who studied garlic and vegetables such as cauliflower, brussels sprouts and cabbage said that eating these foods probably has a beneficial effect.
In one study to be presented today, researchers at the American Health Foundation in Valhalla, N.Y., found that a compound derived from garlic, called diallyl sulfide, can prevent almost 80 percent of colon-cancer tumors in rats.
The rodents were injected with a cancer-causing substance; half were fed a diet that included the garlic compound, while the other half did not receive the compound. After one year, those who got the garlic compound had significantly fewer tumors, according to researcher Bandaru Reddy.
Another study found that a compound found in cauliflower, brussels sprouts and cabbage also prevented about 80 percent of colon tumors, Mr. Reddy said.
People should not start taking garlic pills based on these findings, because the effects of high doses of the pills are unknown, Mr. Reddy said. But eating cauliflower and using natural garlic in cooking, "if they can stand the smell," can be beneficial, he said.
Mr. Reddy said studies are needed to determine whether garlic pills can benefit people who have non-cancerous colon polyps, who are at high risk of developing colon cancer.
In a separate study, the garlic compound also has been found to reduce lung cancer in mice, according to C.S. Yang at the Laboratory for Cancer Research at Rutgers University's College of Pharmacy in Piscataway, N.J.
Mice were injected with a substance called NNK, found in cigarette smoke. Those who were pretreated with an oral dose of the garlic compound had a greatly reduced incidence of lung cancer compared with the mice who did not receive the compound, Mr. Yang said.
And in another report to be given at today's meeting, a major flavoring compound in soy sauce has been found to reduce the risk of esophagus cancer in mice. The compound, HEMF, is naturally produced during the fermentation of soy sauce, said Michael W. Pariza, director of the Food Research Institute at the University of Wisconsin-Madison.
"We can't say you can eat soy sauce to prevent cancer, but we know there are anti-carcinogens in it," he said. "Once we find out how the compound prevents cancer, then it will give us a strong clue as to whether it will work in humans."
Mr. Pariza noted that several studies have found a number of anti-cancer compounds in soybean products, and that scientists have linked those compounds with a decreased risk of several types of cancer in Japan, where soy products are eaten in large amounts compared with the United States.