National Institute for Nutrition and Health;
Chinese Center for Disease Control and Prevention;
Beijing 100050;
China;
Yanqing Center for Disease Control and Prevention;
Beijing 102100;
China;
Wanzhou Center for Disease Control and Prevention;
Chongqing 404000;
China;
Beijing Center for Disease Prevention and Control;
Beijing 100013;
China;
Chongqing Center for Disease Control and Prevention;
Chongqing 400042;
China;
Reliability; Validity; Food; frequency; questionnaire; Chinese; children;