A type of soybean oil high in oleic acid--a heart- friendly mono-unsaturated fatty acid--may find its way to the breakfast table in a new margarine being developed by ARS scientists. The new table spread uses oil from soybean varieties specially bred to produce higher levels of oleic acid, which has been shown to reduce cholesterol levels in some humans. ARS scientists are examining new ways to use these oils using a process called interesterification, a process which rearranges the fatty esters on the glycerol molecule. This process changes the chemistry of the oil and makes it a better component of margarine. Without interesterification, the oils would separate and the margarine would become soft and unspreadable. Interesterification also discourages the formation of trans-fatty acids, which some studies show may slightly raise cholesterol levels in humans.
National Center for Agricultural Utilization Research, Peoria, IL
Gary R. List, (309) 681-6388, listgr@mail.ncaur.usda.gov

A reliable and painless early warning system for colorectal cancer may soon be available. That's in large part because an ARS chemist developed a method for isolating live colon cells from stool samples. Colon cancer causes about 14 percent of all cancer-related deaths in the U.S. It begins as abnormal growths, or polyps, 3 to 5 years before a malignancy appears. The current noninvasive screening method checks for blood in fecal smears. But it is plagued with false positives and false negatives. And a true positive reading means the tumor is fairly advanced. A technique that detects the polyp stage would give physicians ample time to remove growths before they turn cancerous. This would also give patients an opportunity to correct dietary habits that may contribute to cancer risk. Working with a physician at Sinai Hospital of Baltimore, the ARS chemist found that CD44--the tell-tale marker reported on other types of cancer cells--also appears on the surface of isolated colon cells. Recently, Japanese researchers reported that variants of CD44 appear on isolated colon cells of colorectal cancer patients far more frequently than on cells from people without tumors or on patients' cells after surgery. As more such markers and gene mutations signaling abnormal cell changes emerge, screening of isolated colon cells may become routine in as few as 5 years, the ARS and Sinai scientists suggest. It is already one of the first molecular biology assays to be evaluated in a clinical setting.
Beltsville Human Nutrition Research Center, Beltsville, MD
Padmanabhan P. Nair, (301) 504-8145, nair@bhnrc.arsusda.gov

An expectant mother's water-weight gain--vital to fetal growth and delivery of a healthy, normal-weight infant--might be easier to monitor with a safe, fast and painless technique called bioimpedance spectroscopy. Scientists with ARS, the University of California at Berkeley and Xitron Technologies, Inc., found that bioimpedance measurements of 10 women taken before, during and after pregnancy correlated significantly with infant birth weight. Low-birth-weight babies--those weighing less than 5-1/2 pounds at birth-- have a higher risk of early health problems. The study is apparently the first to indicate that the impedance technique may offer a convenient, inexpensive way for physicians to detect subnormal water-weight gains in time to help expectant mothers take corrective action. The technique requires sending a current--a harmless range of consecutive electrical frequencies--between electrodes placed on the hand and foot, then using a computer to calculate water content or "total body water."
Western Human Nutrition Research Center, San Francisco, CA
Marta D. Van Loan, (415) 556-5729, mvanloan@whnrc.usda.gov

A popular belief--that dietary fat increases people's calorie intake--lost credibility in an ARS study of identical twins. On average, the seven sets of male twins chose about the same number of calories from either of the two diets they were offered. One diet contained 20 percent fat calories; the other, 40 percent fat. Both diets had about the same palatability, fiber content and number of calories per ounce of food-- factors that may affect total calorie intake. Four sets of twins ate more calories from the high-fat menu. The other three pairs preferred the low-fat diet. This suggests fat content is not the dominant influence on calorie intake; calories per ounce of food may be more important. This supports some earlier, short-term studies. The findings also suggest that genes exert some control over a person's preference for a high- or low-fat diet. The research may help explain why the U.S. population has added weight during a time when fat intake has dropped and thousands of low-fat and fat-free products have hit the market. Designed to taste good, many such products are high in calories.
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA
Edward Saltzman/Susan Roberts, (617) 556- 3245/3237, saltzman_em@hnrc.tufts.edu, roberts_em@hnrc.tufts.edu.

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