The Institute of Human Nutrition, College of Public Health, Qingdao University, Qingdao, PR China. Qingdao Fuwai Cardiovascular Disease Hospital, Qingdao, PR China. Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden. The Department of health statistics, College of Public Health, Tai Shan Medical University, Tai'an, PR China. The basic medical college of Qingdao University, Qingdao, PR China. Qingdao Zhong Ren Health Management Company, Jiao Zhou, PR China. Qingdao Community Health Center of Lao Shan Qingdao, PR China. The Institute of Human Nutrition, College of Public Health, Qingdao University, Qingdao, PR China. Email: qdlianghui@126.com.