title: [Drinking in different periods of a day of primary and middle school students in four cities of China].
abstract: OBJECTIVE
  To investigate intake of water in different periods of a day of primary and middle school students in Beijing, Shanghai, Guangzhou and Chengdu of China.
  
  
  METHODS
  A total of 5914 primary and middle school students from Beijing, Shanghai, Guangzhou and Chengdu were recruited using multiple-stage random sampling method from September to October 2011. Among them, 5868 students completed the survey. The information of amounts and types of drinking in 8 time periods, morning, afternoon, night as well as in meal and non-meal time in 24 hours of a day was recorded by subjects for seven consecutive days using a quantitative measurement. This information was analyzed by different periods.
  
  
  RESULTS
  The amount of drinking water among 8 periods of a day was (99 ± 101), (130 ± 106), (191 ± 155), (96 ± 107), (246 ± 172), (90 ± 101), (188 ± 135) and (50 ± 81) ml, respectively for before breakfast, during breakfast, after breakfast, during lunch, after lunch, during dinner, after dinner, and midnight (F = 1679.77, P < 0.01). Based on three periods of a day, the amount of drinking water in the morning (420 ± 242) ml was the statistically significantly most, followed by afternoon (341 ± 199) ml, and the least in the evening (327 ± 195) ml (F = 325.23, P < 0.01). The distribution trend of plain water in three periods was the same as total drinking water, with (270 ± 209), (250 ± 179) and (224 ± 177) ml, respectively (F = 84.89, P < 0.01) ; but beverage consumption was the most in the morning(151 ± 133) ml, then in the evening (103 ± 122) ml, and the least in the afternoon (91 ± 199) ml (F = 373.56, P < 0.01). The daily plain water consumption in meal time was (316 ± 247) ml, while it in non-meal time was (773 ± 445) ml with statistically significant difference (Z = 65.2, P < 0.01). There was no significant difference in meal time between plain water (165 ± 194) ml and beverage (151 ± 152) ml (Z = 0.59, P = 0.56) whilst plain water (579 ± 408) ml in non-meal time was significantly higher than beverages (194 ± 204) ml (Z = 64.5, P < 0.01).
  
  
  CONCLUSIONS
  The amount of drinking water of primary and middle school students in different periods of a day was different in four cities of China.
authors.affiliation: Institute for Nutrition and Food Safety, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xiao-qi
authors.initials: XQ
authors.lastname: Hu
authors.forename: Song-ming
authors.initials: SM
authors.lastname: DU
authors.forename: Hui
authors.initials: H
authors.lastname: Pan
authors.forename: Xiao-jun
authors.initials: XJ
authors.lastname: Wang
authors.forename: Dong
authors.initials: D
authors.lastname: Zhang
authors.forename: Zhen-ni
authors.initials: ZN
authors.lastname: Zhu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Luo
authors.forename: Yong
authors.initials: Y
authors.lastname: Ju
authors.forename: Guan-sheng
authors.initials: GS
authors.lastname: Ma
mesh_terms: D000293:Adolescent; D001628:Beverages; D002648:Child; D002681:China; D004034:Diet Surveys; D004327:Drinking Behavior; D060766:Drinking Water; D005260:Female; D006801:Humans; D008297:Male; D013334:Students; D011795:Surveys and Questionnaires; D013997:Time Factors; D014505:Urban Population
chemical_list: D060766:Drinking Water