1. Cancer Prevention Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
2. Department of Family and Preventive Medicine, University of California, San Diego, La Jolla, CA 92093
3. Nutrition Science Institute, Procter & Gamble Company, Cincinnati, OH 45224
4. Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, MN 55454
5. Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, MD 21224