A Systematic Review of Water Intake Assessment Across Populations and the Development of a Population-Specific Prediction Model for Japanese Adults
1
Graduate School of Informatics, Kyoto University, Sakyo-ku, Kyoto, Japan
2
Research Institute, Suntory Global Innovation Center Limited, Seika-cho, Soraku-gun, Kyoto, Japan
3
Center for Innovative Research and Education in Data Science, Institute for Liberal Arts and Sciences, Kyoto University., Sakyo-ku, Kyoto, Japan
4
Division of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
5
Institute for Water Science, Suntory Global Innovation Center Limited, Seika-cho, Soraku-gun, Kyoto, Japan
6
Department of Preventive Medicine and Public Health, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan
Popul. Med. 2026;8(Supplement Supplement 1):
ABSTRACT
BACKGROUND:
Accurate assessment of water intake is essential for public health and nutritional research. Although many studies have examined hydration and water intake, substantial heterogeneity exists in assessment methods, definitions of intake sources, and target populations. Evidence from East Asian populations remains limited despite their distinct dietary patterns compared to Western populations. This study aimed to systematically review literature on water intake by source, identify research gaps, and develop a simple population-specific water intake prediction model for Japanese adults to support surveys in broader Asian populations.
METHODS:
A systematic review was conducted to identify studies assessing total water intake and its sources. Data on study populations, assessment methods, and reported indicators were extracted and synthesized (PROSPERO; CRD4202510042331). Based on identified gaps, prediction models for total daily water intake and water intake by source were developed using demographic, anthropometric, lifestyle, and dietary variables. Models were constructed and validated using Japanese cohort data and then applied to assess water intake patterns among Japanese adults.
RESULTS:
The review showed that most water intake studies were conducted in Western populations and that assessment methods and definitions varied widely. It also indicated that water intake patterns in East Asia differ from those in other regions and highlighted the scarcity of available data. The developed prediction model demonstrated acceptable performance in estimating total daily water intake among Japanese adults. Application of the model revealed substantial inter-individual variability and a relatively high contribution of water from foods, consistent with the systematic review findings.
CONCLUSIONS:
By integrating a systematic review with a population-specific prediction model, this study contributes to improving hydration assessment in East Asia. The findings highlight the importance of context-appropriate assessment tools, provide new insights into water intake patterns among Japanese adults, and may inform public health strategies in the region.
Accurate assessment of water intake is essential for public health and nutritional research. Although many studies have examined hydration and water intake, substantial heterogeneity exists in assessment methods, definitions of intake sources, and target populations. Evidence from East Asian populations remains limited despite their distinct dietary patterns compared to Western populations. This study aimed to systematically review literature on water intake by source, identify research gaps, and develop a simple population-specific water intake prediction model for Japanese adults to support surveys in broader Asian populations.
METHODS:
A systematic review was conducted to identify studies assessing total water intake and its sources. Data on study populations, assessment methods, and reported indicators were extracted and synthesized (PROSPERO; CRD4202510042331). Based on identified gaps, prediction models for total daily water intake and water intake by source were developed using demographic, anthropometric, lifestyle, and dietary variables. Models were constructed and validated using Japanese cohort data and then applied to assess water intake patterns among Japanese adults.
RESULTS:
The review showed that most water intake studies were conducted in Western populations and that assessment methods and definitions varied widely. It also indicated that water intake patterns in East Asia differ from those in other regions and highlighted the scarcity of available data. The developed prediction model demonstrated acceptable performance in estimating total daily water intake among Japanese adults. Application of the model revealed substantial inter-individual variability and a relatively high contribution of water from foods, consistent with the systematic review findings.
CONCLUSIONS:
By integrating a systematic review with a population-specific prediction model, this study contributes to improving hydration assessment in East Asia. The findings highlight the importance of context-appropriate assessment tools, provide new insights into water intake patterns among Japanese adults, and may inform public health strategies in the region.
| eISSN: | 2654-1459 |
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