Department of Internal Medicine, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD, USA. Fatty Acid Research Institute, Sioux Falls, SD, USA. Department of Mathematics and Statistics, Dordt College, Sioux Center, IA, USA. Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, USA. Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Canada. Department of Epidemiology, College of Public Health, Iowa City, IA, USA. Department of Internal Medicine, College of Medicine, University of Iowa, Iowa City, IA, USA.