Wheat bran heated and shaped into short, crispy strips for a commercial breakfast cereal was more effective than raw wheat bran in reducing an indicator of colon cancer in laboratory rats, a new study shows. ARS and University of California at Davis School of Medicine researchers conducted the 6½ month test. Bran is the thin, fiber-rich outer layer of the wheat kernel. Scientists have known for more than a decade that feeding raw wheat bran to lab animals reduces the occurrence of aberrant crypt foci, or ACF, thought to be a colon cancer precursor in rats and humans. The California experiment, however, is apparently the first to show that processing the bran with a machine known as an extruder may boost bran's effectiveness in reducing ACF. Of the 120 white lab rats in the study, those fed a diet that included processed wheat bran had 33 percent fewer aberrant crypt foci in their colons than those fed raw wheat bran. The animals had been injected with a chemical that stimulates formation of ACF. Colorectal cancer is the second deadliest cancer in the U.S., killing nearly 55,000 Americans every year. Kellogg Co., Battle Creek, MI, funded part of the experiment under a cooperative research and development agreement with ARS.
Western Regional Research Center, Albany, CA
Wallace H. Yokoyama, (510) 559-5695, wally@pw.usda.gov

Women and girls battling severe eating disorders may suffer bone mineral loss. New evidence from ARS-funded research suggests that use of estrogen and progestin hormones may guard against this loss of calcium. The natural menstrual cycle circulates hormones that play a role in maintaining strong bones. But the risk of osteoporosis later in life increases if normal menstruation is interrupted because of an eating disorder. Scientists found that women suffering from these disorders maintain their spines and skeletons better with hormone therapy. They suspect that the treatment, by mimicking the hormonal activity of a normal menstrual cycle, could stem mineral loss until other medical care can restore the patients' general health—and natural menstrual cycle. The research was published in the American Journal of Obstetrics and Gynecology.
Children's Nutrition Research Center, Houston, TX
Kenneth J. Ellis, (713) 798-7025, kellis@bcm.tmc.edu;
Albert C. Hergenroeder, M.D., (713) 770-3658, alberth@bcm.tmc.edu

Two cardiovascular health indicators improved in six volunteers who ate foods enriched with a natural compound called DHA. The volunteers showed an increase in HDL-cholesterol—the kind known to protect against heart disease. And their blood fats, called triglycerides, decreased by about 26 percent. DHA, short for docosahexaenoic acid, occurs in fish and meats and belongs to the omega-3 family of fatty acids. Volunteers on the high-DHA regimen also showed an increase of about 69 percent in apoprotein-E, a compound that carries cholesterol to the liver for breakdown and excretion. An apo-E increase had not yet been noted in other DHA studies with humans. Ten healthy, non-smoking men age 20 to 39 lived at the ARS Western Human Nutrition Research Center in San Francisco for the four-month investigation, making it the longest DHA experiment yet reported with in-residence volunteers. For three months, about a teaspoon of DHA- rich oil was added to salad dressings or bean, salsa or guacamole dips served to six volunteers, substituting safflower oil in the servings for the four other men. Scientists designed the study to distinguish the effects of DHA from those of another omega-3 fatty acid, EPA. Both occur in fish oils thought to have cardiovascular benefits.
Western Human Nutrition Research Center, San Francisco, CA
Gary J. Nelson, (415) 556-0899, gnelson@whnrc.usda.gov

New findings suggest African-American women living in the northern latitudes may benefit from increasing their vitamin D intake. The vitamin is essential for absorbing calcium and thus integral to strong bones. Compared to Caucasian women, the African-American women in an ARS study had about half as much 25- hydroxyvitamin D—the most sensitive measure of D status—circulating in their blood throughout the year. The African-Americans also had smaller increases in circulating vitamin D during summer. Sunlight stimulates skin to make the vitamin, but pigmented skin makes less. What's more, in the winter when vitamin D levels are lowest, an important hormone called parathyroid hormone was elevated only in the African- American women. This hormone signals low blood calcium and can stimulate loss of calcium from the bones. Apparently, African-American women living in northern latitudes don't manufacture enough vitamin D during the summer to carry them through the winter months, the researchers concluded. The amounts of vitamin D and calcium in the diets of the two groups of women did not differ enough to explain the differences in their blood levels of the vitamin.
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA
Susan Harris, (617) 556-3064, harris_si@hnrc.tufts.edu
Bess Dawson-Hughes, (617) 556-3073, hughesb@hnrc.tufts.edu

Last Updated: November 13, 1998
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