Funding for this research was provided by:
China Medical Board (15-277, 16-262)
National Natural Science Foundation of China (71874137)
Shaanxi Social Science Foundation (2017S024)
Research Program of Shaanxi Soft Science (2015KRM117)
Received: 26 November 2018
Accepted: 23 June 2019
First Online: 1 July 2019
Ethics approval and consent to participate
: The ethics approval was obtained by the review board from the University of North Carolina at Chapel Hill, National Institute for Nutrition and Food Safety, China Center for Disease Control and Prevention and China-Japan Friendship Hospital. Informed consent was obtained, and data were anonymized for the analysis.
: Not applicable.
: The authors declare that they have no competing interests. We declare that Prof. Zhongliang Zhou is a member of the editorial board (Associate Editor) of this journal.