Aug. 25, 1998 BOSTON, Mass.--Processing wheat bran in cereals by a method called extrusion processing increased the bran's cancer-fighting potential, when compared to raw wheat bran and flaked cereals in a study with laboratory rats conducted by the U.S. Department of Agriculture and the University of California. The findings were presented here today at the national meeting of the American Chemical Society, the world's largest scientific society. Prior animal and human studies have demonstrated the value of wheat bran in the diet in reducing the risk of colon cancer.
The six-month study showed up to a 40 percent reduction in the number of aberrant crypt cells in the colons of laboratory rats fed a controlled diet of extrusion-processed wheat bran, according to principal investigators Wallace Yokoyama, Ph.D., of the USDA's Western Regional Research Center in Albany, Calif., and Paul Davis, Ph.D., Division of Clinical Nutrition and Metabolism, Department of Internal Medicine, UC-Davis, who termed the reduction "significant."
Colon cancer is expected to kill more than 47,000 people in the U.S. this year and is the third leading cause of cancer death for men and women, according to the American Institute for Cancer Research and the American Cancer Society.
Previous research has demonstrated that people with colon cancer have a higher number of aberrant crypt cells, found in the lining of the colon. Raw wheat bran is known to reduce the number of "crypts," says Yokoyama. However, he noted, since most people typically do not have raw wheat bran in their diet, "there was an interest in determining if cereals containing processed wheat bran performed as well as raw wheat bran." Not only did it perform as well, claims Yokoyama, "processing of wheat bran actually improves its health-promoting properties."
It's still unclear to researchers how the wheat bran, raw or processed, reduces the number of aberrant crypt cells, although it appears to involve microbial action, according to Yokoyama.
Most cereals, whether wheat bran or another type, undergo processing. Extrusion processing involves squeezing, stirring and applying high shear forces, causing changes to the wheat bran, which Yokoyama believes increases the colon's absorption of the bran's healthy properties. The other primary method of cereal processing is flake processing, a much gentler process that causes less change to the wheat bran.
The test results are applicable only to processed wheat bran in cereals. "You would not get the same results from processed wheat bran in bread, for example, because there is very little shear involved in that processing," says Yokoyama.
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