1. Department of Epidemiology and Preventive Medicine, University of Maryland Medical School, Baltimore, MD 21201
2. Division of Cancer Epidemiology and Genetics, NCI, Bethesda, MD 20892
3. Department of Medical Microbiology, University of Groningen, Groningen, The Netherlands
4. Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108
5. Beltsville Human Nutrition Research Center, U.S. Department of Agriculture, Beltsville, MD 20705