Funding for this research was provided by:
National Natural Science Foundation of China (71774173)
Text and Data Mining valid from 2018-07-11
Received: 11 March 2018
Accepted: 26 June 2018
First Online: 11 July 2018
Ethics approval and consent to participate
: Data of this study was from the China Health and Nutrition Survey (CHNS). CHNS was approved by the Institutional Review Committees of the University of North Carolina at Chapel Hill and the National Institute of Nutrition and Food Safety, Chinese Center for Disease Control and Prevention.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.