A BOWL OF BRAN A DAY MAY KEEP CANCER AT BAY.

Byline: Theresa Tamkins Medical Tribune News Service

Eating a bowl of wheat bran cereal every morning may reduce your risk of colorectal cancer, a new study suggests.

The reason: the bran lowers intestinal levels of toxic substances thought to cause the cancer, the researchers said.

But if you skip the cereal, try a calcium supplement: It can lower levels of the toxic substances as well, said Dr. David Alberts, director of cancer prevention and control at the Arizona Cancer Center in Tucson.

In the new study, people who ate two-thirds of a cup of wheat fiber cereal every day for nine months cut their concentration of potentially cancer-causing bile acids by 73 percent.

Bile acids are produced by the liver, stored in the gall bladder and travel into the intestines after you eat a fatty meal.

The bile acids are crucial for digesting fat, but high levels of some bile acids - particularly one type called deoxycholic acid - have been linked toan increased risk of colon cancer.

In the study, some of the 95 participants ate low-fiber diets, but took 1,500 milligrams a day of calcium, which is thought to decrease bile acid. Those people had about a 43 percent reduction in bile acids after nine months, according to the study, published Wednesday in the Journal of the National Cancer Institute.

However, a combination of a high-fiber diet and calcium supplements is not better than either alone. People in the study who ate 13.5 grams of fiber and 1,500 milligrams of calcium had no greater decrease in bile acids than those who had either one alone, the researchers reported.

All the study participants were between 50 and 75 years of age and were considered at high risk of colon cancer, having undergone previous surgery in the past to remove precancerous polyps in the colon.

The amount of wheat bran fiber used in the study could easily be found in one serving of breakfast cereal, according to lead study author Alberts.

"That is what is so exciting about the study," he said. "We used a common dose of fiber where so many other studies used huge doses that no one could sustain over a period of time."

Although some breakfast bars do contain wheat bran, they also tend to be high in fat as well, according to Alberts.

Deoxycholic acid is the best known and most studied bile acid when it comes to cancer-causing ability, according to the Arizona researcher.

Depending on the acid-base balance of the colon, such bile acids may increase the risk of cancer by damaging intestinal cells, according to Michael Wargovich, an associate professor of medicine at M.D. Anderson Cancer Center in Houston.

"In a basic environment, bile acids can act like detergents, becoming irritants and causing cell death," he said. "The colon is sensitive so you get a hyperproliferation of cells that puts more cells at risk for becoming tumors."

The fermentation of fiber in the colon may alter the acid-base balance, preventing bile acids from causing harm, he said.