2004 Annual Report 4.What were the most significant accomplishments this past year? D. Progress Report: This report serves to document research conducted under a General Assistance Type Cooperative Agreement between ARS and the Department of Food Science at Cornell University entitled "Bioavailability of Fe and Zn in Biofortified Crops". Additional details of research can be found in the report for the parent project 1907-42520-003-00D, "Understanding Soil-Plant-Human/Animal Food Systems and Nutrient Bioavailability." The commercial GOYA bean lines studied were chosen for use in a pilot study to test for the effect of inhibitory compounds in bean seed hulls on Fe bioavailability using an in vitro Caco-2 cell model. These studies suggest that the Fe uptake inhibitory compounds may be related to seed coat color possibly associated with certain polyphenolic compounds in the hull. Interestingly, the removal of the hull from the white bean decreased Caco-2 ferritin formation, indicating the possible presence of an Fe uptake promoter in the white hull. Overall, these experiments indicate that whole colored beans contain Fe absorption inhibitors in the hulls that are little affected by the addition of the Fe bioavailability promoter substance, ascorbic acid. Comparison of Fe bioavailability in 19 genotypes of Columbian bean samples indicated that all bean genotypes tested contain very little bioavailable Fe. This result reaffirmed the association of bean color with very low Fe bioavailability. Nevertheless, several varieties studied contained more bioavailable Fe than the others tested as indicated by their abilities to induce ferritin levels above the baseline of ferritin formation in cells. White beans genotypes had significantly more bioavailable Fe compared to the colored bean genotypes tested. This difference is not due to bean phytate levels but most likely the result of the presence of certain colored polyphenolic compounds in the hulls. Efforts to identify and characterize the nature of these compounds should be vigorously pursued. Furthermore, further studies should investigate the possibility that white seed coats contain promoters of Fe bioavailability.