Today, the Division of Nutritional Sciences is a truly interdisciplinary graduate program that includes faculty from the Colleges of Agriculture, Engineering, Applied Life Studies, Liberal Arts and Sciences, Medicine, Veterinary Medicine, and Associated Health Professions (Chicago campus). Forty-seven faculty from thirteen departments have joined forces under the auspices of the Division to facilitate teaching, research, and public service activities in nutrition. Just five years ago, the Division joined hands with the Department of Nutrition and Medical Dietetics at our sister cam-pus, the University of Illinois at Chicago, to develop a joint Ph.D. program.
Our research strengths can be classified into five broad theme areas in which our faculty and students are most active: 1) nutritional requirements for optimal growth and well being of man and animals; 2) impact of nutrition on health and risk of chronic noninfectious disease; 3) relation of nutrients to gene expression; 4) nutrient composition of foods and feeds and the impact of agricultural practices, handling, and processing on food safety and quality; and 5) factors determining food preferences and habits and techniques for guiding consumers in selection of nutritionally adequate diets. These themes best reflect the areas of nutrition research for which the Division is recognized both nationally and internationally.
Most of the research in nutritional science in the Agricultural Experiment Station is covered by projects in the individual departments. However, not all projects fall under the aegis of the departments, so this report provides a "home" for reporting work outside the traditional units.
Soy Protein and Serum Cholesterol. The Division coordinated the formation of a research team and the solicitation of funds to carry out a human feeding study at the Danville Veterans Administration Hospital to evaluate the potential lipid lowering effects of soy protein and soy fiber.
Hypercholesterolemic men were fed diets in a four-week crossover design that provided 50 grams daily of soy protein or nonfat dry milk in baked foods. It was determined that this level of soy (50% of the daily protein intake) significantly reduced total and LDL cholesterol by an average of 11%. In a follow-up out-patient study, the research team found that 25 grams daily of soy protein was only effective in reducing serum cholesterol in those men with the highest initial serum cholesterol.
Diet and Cancer. Ammonia is known to destroy cells and stimulate cell proliferation which increases cancer risk. This is especially true in the gastrointestinal tract where the major uncontrolled source of ammonia is from the hydrolysis of endogenously synthesized urea by microbial urease. Urea is water-soluble and enters the alimentary tract with the secretions. Recently, extracts of Yucca plants which grow in the southern United States, Mexico, and Central America have been shown by others to contain a potent urease-inhibiting substance yet to be identified. Yucca extracts, generally recognized as safe by the U.S. Food and Drug Administration, have been used as flavoring and foaming agents in food and beverage manufacturing. Extracts from Y. shidigera known to contain urease-inhibiting activity are being fractionated by HPLC. These fractions will be analyzed by ultraviolet spectroscopy and mass spectrometry to determine their identity and chemical structure. Such information will make it possible to seek homologues or congeners for possible value as food additives for cancer prevention.
Energy Metabolism. Although all life processes require energy, the accurate measurement of energy balance in humans is a problem which has plagued nutritionists for over two hundred years. Indirect and direct calorimetry are two principal methods for assessing energy expenditure in humans. Direct calorimetry measures the total rate of body heat losses: the sum of radiant heat exchange, and convective, evaporative, and conductive heat transfer. Measurements obtained through this method, although widely accepted, are costly, complex, and not readily available for use outside a university environment. Indirect calorimetry estimates heat loss indirectly by measuring oxygen consumption and relating it to caloric expenditure. Due to inherent problems with both the direct and indirect calorimetry methods, the development of a simple and direct method of assessing heat loss would be of immense value. A new and viable method may be infrared thermography which uses a lightweight, portable, and direct imaging radiometer. One of our faculty members has shown that mean skin temperature and, ultimately, total heat loss can be determined when infrared thermography is used in conjunction with heat loss equations and specialized computer software. This technique has been validated for use in adults and infants against indirect calorimetry. During the past two years, studies have concentrated on human subjects with varying problems ranging from critical illnesses such as cancer to use in infants in intensive care. Available data obtained from these subjects indicate that infrared thermography is a valid, sensitive, and reliable method for measuring energy expenditure. The use of this technique to quantitate heat loss will be of considerable interest to the medical and nutrition communities because it is noninvasive, nonconfining, poses no risk to subjects, and can potentially deliver immediate results.