Association Between Plain-Water Intake Frequency and Self-Reported Grades Among High School Students Participating in the 2023 National Youth Risk Behavior Survey: A Cross-Sectional Analysis

BackgroundHydration has been associated with cognitive processes relevant to learning, but evidence linking plainwater intake frequency with academic performance in adolescents remains limited.We examined this association among participants in the 2023 National Youth Risk Behavior Survey (YRBS) with available study data. MethodsWe conducted a survey-weighted, cross-sectional complete-case analysis of 10,199 students.The primary analysis compared plain-water intake three or more versus less than three times/day in relation to selfreported mostly A/B grades.A secondary analysis used four intake categories: less than one, one to two, three, and more than four times/day.Models adjusted for age, sex, race/ethnicity, regular soda intake, physical activity, fruit/100% fruit juice intake, and vegetable intake and accounted for YRBS weights, strata, and primary sampling units. ResultsThe survey-weighted prevalence of mostly A/B grades was 75.6% among students reporting intake three or more times/day and 70.8% among those reporting less than three times/day, an absolute difference of 4.86 percentage points (95% confidence interval (CI), 2.34-7.38).After adjustment, intake three or more times/day was associated with higher odds of mostly A/B grades (adjusted odds ratio (aOR), 1.16; 95% CI, 1.01-1.32).Compared with intake less than one time/day, aORs were 1.53 (95% CI, 1.26-1.87)for one to two times/day, 1.42 (95% CI, 1.08-1.86)for three times/day, and 1.45 (95% CI, 1.23-1.71)for four or more times/day. ConclusionIn this complete-case analytic sample from the 2023 YRBS, students reporting plain-water intake three or more times/day had higher adjusted odds of reporting mostly A/B grades than those reporting intake less than three times/day.In the categorical analysis, each of the three higher-frequency groups had higher adjusted odds of reporting mostly A/B grades than the less than one time/day group, but the point estimates were similar in magnitude and did not increase monotonically across successive categories.The crosssectional design precludes causal inference; water-drinking frequency and grades were self-reported; frequency did not measure water volume or physiological hydration status; residual confounding remains possible; and 14 of 89 primary sampling units (PSUs) contributed no complete cases, which may limit national representativeness.Longitudinal and experimental studies using objective hydration measures and independently recorded academic outcomes could further clarify this association.