1. Gastrointestinal Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
2. Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
3. Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA
4. Cancer Epidemiology Program, Dana‐Farber/Harvard Cancer Center, Boston, MA, USA
5. Department of Nutrition, Harvard School of Public Health, Boston, MA, USA
6. Department of Medical Oncology, Dana‐Farber Cancer Institute, Boston, MA, USA