Member International Society for Research on Human Milk and Lactation, American Society Nutritional Sciences, American Society Clinical Nutrition (councilor 1991-1994, chairman residency education and subspecialty training committee since 1995), American Society Parenteral and Enteral Nutrition, American College Nutrition, American Public Health Association, Society Pediatric Research.
Assistant in medicine Children's Hospital, Boston, 1980-1981. Assistant professor pathology and pediatrics Boston University School Medicine, 1982—1990, associate professor, 1987-1990, professor, 1990. Professor department pediatrics University North Carolina, Chapel Hill, since 1990, professor department nutrition, since 1990, chair department nutrition, 1990—2005.
Chair medical education committee American Society Clinical Nutrition, 1995—1997. Chair joint membership committee AIN/ASCN, 1992-1994. Chairman advisory board General Clinical Research Center, University North Carolina, 1990-2000.
Member Institute of Medicine panel on folate and B Vitamins, 1997-1999. Member science advisory board Monsanto Corporation, 1998-2000. Member science council Dannon Institute.
Board directors Interactive Info. Director University North Carolina Clinical Nutrition Research Unit.