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).
Conclusion: The amount of drinking water of primary and middle school students in different periods of a day was different in four cities of China.