1. Department of Gastroenterology, Renji Hospital, Shanghai Institute of Gastrointestinal Diseases, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China.
2. Division of nutrition, Zhongshan Hospital, Fudan University School of Medicine, Shanghai, People's Republic of China.
3. Faculty of Medical Laboratory Science, Shanghai Jiaotong University School of Medicine, Shanghai, People's Republic of China.