1. U.S. Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Methods and Application of Food Composition Laboratory, Beltsville, Maryland 20705, United States
2. Department of Chemistry and Biochemistry, Clippinger Laboratories, Ohio University, Athens, Ohio 45701, United States
3. U.S. Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Food Components and Health Laboratory, Beltsville, Maryland 20705, United States
4. National Institutes of Health, National Cancer Institute, Division of Cancer Prevention, Rockville, Maryland 20852, United States