1 Department of Clinical Nutrition, Chinese Academy of Medical Sciences-Peking Union Medical College, Peking Union Medical College Hospital, Beijing 100730, China; National Key Clinical Specialty Capacity Improvement Project, Beijing 100730, China.
2 Department of Clinical Nutrition, Chinese Academy of Medical Sciences-Peking Union Medical College, Peking Union Medical College Hospital, Beijing 100730, China; National Key Clinical Specialty Capacity Improvement Project, Beijing 100730, China. Electronic address: txchenwei@sina.com.