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Europe PMC · 2026
Associations between dietary composition, water intake, urine pH, and cardiometabolic indicators among young Saudi women.
ALTamimi JZ, Aljabryn DH, Alnooh GS, Alhaji JH, Alamri E, Hendy A, AlFaris NA.
Background Cardiometabolic disorders continue to rise globally, yet limited evidence exists regarding the associations between dietary composition, hydration status, urine pH, and cardiometabolic risk indicators in young Saudi women. Aim To investigate the associations between dietary composition, water intake, urine pH, and cardiometabolic indicators among young Saudi women. Methods A cross-sectional analytical study was conducted among 135 Saudi women aged 19-30 years in Riyadh, Saudi Arabia. Data were collected remotely using a structured, self-administered electronic questionnaire under home-based conditions. Anthropometric measurements, blood pressure, water intake, dietary intake, and urine pH were assessed following standardized instructions provided to participants. Dietary intake was evaluated using repeated 24-hour dietary recalls and analyzed using Food Processor software (ESHA Research, Version 7). Statistical analyses included descriptive statistics, Pearson correlation analysis, and multiple linear regression models to examine associations between dietary intake, hydration status, and cardiometabolic risk indicators. Results Central adiposity was present in 26.6-35.5% depending on the index. Elevated diastolic blood pressure was observed in 72.6% of participants. Only 8.9% consumed ≥8 cups of water/day. Higher energy, sodium, and omega-6 intake were positively associated with systolic blood pressure, while carbohydrate and phosphorus intake showed inverse associations. Energy intake was positively associated with diastolic blood pressure, and urine pH showed weak positive correlations with soluble fiber and thiamin. Conclusion Dietary composition and hydration status were significantly associated with blood pressure and urine pH among young Saudi women. Higher energy and sodium intake were associated with higher blood pressure levels, while carbohydrate intake showed inverse associations with blood pressure outcomes. In addition, dietary fiber, selected micronutrients, and unsaturated fatty acids demonstrated variable associations with cardiometabolic risk indicators. Regarding urine pH, energy intake was inversely associated, whereas carbohydrate, omega-6, and magnesium intake showed significant associations. These findings highlight important diet-health relationships; however, they should be interpreted as exploratory associations rather than causal effects due to the cross-sectional design of the study.
Europe PMC · 2026
Comparing the Effects of Water, Sodium-Potassium, and Potassium-Rich Solutions on Fluid Balance and Thermal Strain Following Exercise in the Heat: A Randomized Triple-Blind Crossover Study.
Killick JA, Jenkins EJ, Benson J, Macciochi J, Corr L.
Exercise in the heat perturbs human physiology through elevated core temperature, fluid loss, and cardiovascular strain. While fluid intake can mitigate these effects, the electrolyte composition of hydration solutions may improve rehydration efficacy. This study evaluated whether hydration strategy modulates thermal strain, inflammation, and performance during and after exercise in a hot environment, comparing three different fluid solutions: water, sodium-potassium drink, and coconut water. Twelve participants (seven males) completed a randomized, triple-blind crossover trial. Measures included handgrip strength, countermovement jump, tympanic temperature, thermal sensation, discomfort, body mass, body water percentage, heart rate, and total leukocyte count. Participants were randomly assigned 300 ml of one of three solutions before cycling for 60 min at 1.5 W/kg in ∼33 °C conditions. Additional 300-ml doses were consumed postexercise at 0, 30, and 60 min; measures were taken at each time point before solution consumption and at 90-min postexercise. Following exercise in the heat, a significant main effect for time was observed for all outcomes: thermal responses, heart rate, body mass and body water (p < .001); fatigue (p < .001); and leukocyte count (p = .016), indicating a strong physiological response to heat stress. However, no significant differences were observed between hydration strategies (p ≥ .152) for all measures. In conclusion, exercise in the heat elicited significant thermal strain, fatigue, and inflammation, independent of hydration strategy. Electrolyte composition did not significantly alter responses when fluid intake was controlled, highlighting the need for further research.
Europe PMC · 2026
Hydration and Water Intake among Children and Parents.
Seal AD, Suh H, Emmanuel H, Colburn AT, Summers L, Bottin J, Zemdegs J, Vanhaecke T, Mauromoustakos A, Kavouras SA.
Background Studies show that 80% of children in the United States do not meet the dietary guidelines for water intake, and 65% have elevated urine osmolality (UOsm), indicative of underhydration. Objectives This study aims to examine the relationship between parental-child hydration habits and identify parental factors associated with children's water intake and hydration. Methods A cross-sectional study was conducted in 729 parent-child pairs (children aged 3-13 y) from Northwest Arkansas and Phoenix, Arizona. Participants completed a food and fluid diary and collected a 24-h urine sample for hydration assessment. Associations between parental and child hydration indicators, including total water intake (TWI), plain water intake (PWI), sugar-sweetened beverage (SSB) intake, and UOsm, were assessed using linear regression and multivariable models. Results Children's fluid intake habits were significantly associated with those of their parents. Positive associations were observed between parent and child TWI (β = 0.12, P 500 mmol/kg) had 1.54 times greater odds of also presenting with UOsm >500 mmol/kg (95% confidence interval: 1.05, 2.26, P = 0.03). Multivariable analysis revealed that higher parental PWI and water intake from food were associated with greater TWI in children. Child-specific factors, including older age, male sex, higher BMI, physical activity, and energy/protein intake, also predicted higher TWI. Conclusions Parental fluid intake habits are strongly associated with children's hydration status and habits. These findings underscore the importance of parental role modeling in promoting healthy hydration practices in children and highlight the need for family-centered interventions to improve hydration outcomes. This trial was registered at clinicaltrials.gov as NCT02937038.
Europe PMC · 2026
Effect of intentional daily liter of plain water on total fluid and caloric intake among free-living adults.
Zhao X, Atkins WC, McDermott BP.
While previous studies have examined short-term water consumption and corresponding energy intake, few have investigated the effects of a longitudinal intervention in non-obese, young adults. We aimed to evaluate the effect of a 6-week daily liter of plain water consumption on fluid and caloric intake among free-living healthy adults. Thirty-eight young healthy adults (25 ± 6 y, 1.67 ± 0.09 m, 73.0 ± 16.7 kg, 25.8 ± 4.2 of body mass index) were provided two 500mL bottles of water per day and asked to consume them for six weeks. They were provided no further direction on fluid consumption during the study. Participants recorded 24-hour total food and fluids consumed and collected urine across three time points of baseline, 3-week (mid), and 6-week (post). Twenty-four-hour total fluid, plain water, sugar-sweetened beverages, caloric intake, urine specific gravity (USG), urine osmolality (Uosm), and urine volume were measured at all three time points. Hydration status was assessed via 24-hour USG and Uosm. Twenty-four-hour total fluid intake was significantly increased at mid (p = .040) but not post (p = .426). Twenty-four-hour total plain water intake was significantly increased at mid (p = .028) and post (p = .049) time points. No significant differences were observed in 24-hour total sugar-sweetened beverage intake across time points (p = .210). Twenty-four-hour total caloric intake was significant reduced at the post (p = .048) but not at mid (p = .257). Twenty-four-hour total caloric intake was not associated with 24-hour total fluid intake (r = .052, p = .618), total plain water intake (r = -.049, p = .636), and total sugar-sweetened beverages intake (r = .143, p = .170). No significant differences were found in 24-hour USG (p = .075) and total urine volume (p = .491) among time points, but Uosm significantly decreased at mid (p = .001). In conclusion, a moderate increase in plain water intake may prompt a decrease in daily caloric intake and thus facilitate weight management.
Europe PMC · 2026
Effect of a Theory-Informed, Six-Week Gamified Educational Intervention on Hydration Knowledge, Behavior, and Status in School Children: A Randomized Controlled Trial.
Kacem S, Trabelsi K, Ceylan Hİ, Khacharem A, Ammar A, Clark CCT, Abed KE, Jahrami H, Muntean RI, Dergaa İ, Bragazzi NL, Aziz AR.
Aim: This study assessed the effects of a six-week educational intervention using an adapted "Snakes and Ladders" board game on hydration knowledge, behavior, and status among Tunisian elementary school children during physical education (PE) lessons. Method : A randomized controlled trial involving 207 children was conducted, with participants assigned to either the educational group (EG, n = 99) or the control group (CG, n = 108). The EG participated in six weekly 30-min board game sessions, while the CG continued regular activities. Knowledge of hydration was assessed using a validated questionnaire. Hydration status was monitored indirectly by the percentage change in body mass from pre- to post-PE session. Perceived thirst was evaluated using a 9-point scale, and hydration behavior was evaluated based on water consumption during PE lessons. Results : Following the intervention, the EG demonstrated a significant improvement in overall hydration knowledge (ΔMean = +0.30 ± 0.11 vs. -0.05 ± 0.08 in CG; p p p Conclusions . The six-week board-game intervention appeared effective in increasing hydration knowledge, promoting healthier drinking behaviors during PE, and improving indirect indicators of hydration status. These findings provide preliminary evidence for the feasibility and educational value of a gamified, low-cost approach to hydration promotion in schools. Further research should examine long-term retention, include objective hydration biomarkers, and evaluate applicability across diverse school settings and environmental conditions.
Europe PMC · 2026
Multimodal MRI local metrics and cognitive performance following water intake in 12-h water-restricted adults: a randomized controlled trial.
Zhang Y, He H, Zhang N, Zhang J, Ma G.
Background and objective Hydration fluctuations affect brain structure, function, and cognition, but underlying neurobiological mechanisms remain unclear. This RCT investigated dose-dependent effects of water intake on multimodal MRI metrics and cognitive performance in young adults after 12-h water restriction. Methods 64 healthy university students (18-23 years) underwent 12-h water restriction and were randomized to high (500 mL), medium (200 mL), low (100 mL) water intake, or control (no water). Urine osmolality was measured pre- and post-intervention. Multimodal neuroimaging included resting-state functional MRI (fALFF, ReHo) and structural MRI (VBM), plus cognitive assessments. Results Baseline measures post-restriction showed no group differences in hydration status, with 57.8% dehydrated. Post-intervention, the control group had highest urine osmolality, with significant differences among groups. The high-intake group showed most notable fALFF changes across multiple gyri vs. all groups, and higher ReHo signals in right orbitofrontal gyrus vs. low-intake/control groups. This group also had lower cerebrospinal fluid density in limbic lobe vs. medium-intake/control groups. The medium-intake group demonstrated higher gray matter VBM values in hippocampus, superior frontal gyrus, and putamen vs. high-/low-intake groups. No significant between-group cognitive differences emerged. However, within-group comparisons revealed improved symbol search across all intake groups, increased mental arithmetic span for high-/medium-intake groups, and enhanced mental arithmetic scores specifically in the high-intake group. Conclusions This study preliminarily demonstrates that water intake following 12-h water restriction may improve hydration status to some extent in young adults, with observed changes in localized multimodal MRI metrics in specific brain regions and in select cognitive test scores compared with pre-intervention values; however, the correlations among these changes require further analytical validation. Clinical trial registration https://www.chictr.org.cn/showproj.html?proj=19279, identifier: ChiCTR-IOR-17011568.
Europe PMC · 2026
Nutrition and Hydration Strategies for Heatwave Adaptation: A Narrative Review.
D'Angelo S.
Climate change is increasing the frequency, intensity, and duration of heatwaves, making extreme heat a recurrent public health challenge with important nutritional implications. High ambient temperatures affect human health through thermoregulatory strain, sweating, dehydration, electrolyte imbalance, cardiovascular and renal stress, impaired cognitive and physical performance, and exacerbation of chronic diseases. Diet and hydration may therefore represent modifiable, although still underinvestigated, components of heat-health prevention. This narrative review synthesizes evidence on hydration, electrolyte balance, meal composition, dietary quality, vulnerable populations, Mediterranean dietary patterns, seasonality, environmental sustainability, and public health strategies for reducing heat-related health risks. Evidence from climate-health research, physiology, nutrition science, occupational and sports medicine, geriatrics, pediatrics, and public health guidance was integrated. Particular attention was given to distinguishing direct heat-health evidence from recommendations based on indirect evidence, physiological plausibility, or expert consensus. Regular water intake, water-rich foods, avoidance of alcohol, moderation of sugar-sweetened beverages, and individualized electrolyte replacement during prolonged or intense sweating are supported by physiological rationale and public health guidance, although direct heatwave-specific intervention studies remain limited. Dietary recommendations should prioritize smaller, digestible, nutrient-dense meals that preserve nutritional adequacy while reducing unnecessary digestive and metabolic burden. However, evidence on meal size, macronutrient composition, and heat-related outcomes remains largely indirect. Vulnerable groups, including older adults, children, pregnant women, individuals with chronic diseases, outdoor workers, athletes, and socioeconomically disadvantaged populations, require tailored strategies. The Mediterranean diet may provide a useful regional model because it emphasizes seasonal plant foods, fruits and vegetables with high water content, legumes, whole grains, olive oil, culinary simplicity, and environmental sustainability; however, its specific role in heat adaptation requires further study. Integrating nutrition and hydration into heat-health action plans may improve preparedness and support climate-resilient food systems. Future studies should evaluate hydration protocols, meal patterns, Mediterranean diet adherence, biomarkers of nutritional heat resilience, and nutrition-sensitive interventions in real-world heat exposure settings.
Europe PMC · 2026
Factors influencing renal shear wave elastography: effects of probe orientation, respiration, corticomedullary differentiation, and hydration.
Materniak A, Jędrzejewski G, Wieczorek AP, Woźniak M.
Aim To assess how probe orientation, respiratory phase, hydration, and corticomedullary differentiation affect renal two-dimensional shear wave elastography. Material and methods Prospective single-center study with four independent sub-studies: (1) probe orientation (long vs. short axis; children, n = 35), (2) respiration (quiet breathing vs. brief mid-expiratory breath-hold; children, n = 20), (3) hydration (adults, n = 12; 700 mL water intake; stiffness at baseline, +20, +40 min), and (4) corticomedullary differentiation with depth assessment (children, n = 29). Shear wave elastography was acquired as five-frame series using 5-mm regions of interest. Sub-studies 1-3 sampled the cortex, whereas sub-study 4 sampled the cortex and renal pyramids at matched depths. Outcomes included per-subject median stiffness (kPa) and interquartile-range-to-median ratio (IQR/M). A quality filter (IQR/M ≤0.30) was applied to all sub-studies except the orientation sub-study. Statistical analysis included the Wilcoxon signed-rank test, Friedman test (hydration), and Spearman's ρ (depth). Results Long-axis orientation reduced variability within measurement series (lower IQR/M) compared with short-axis orientation ( p p p p ≥0.19). Conclusions Among the four evaluated factors, probe orientation and hydration influenced renal shear wave elastography, whereas respiratory phase within the tested range did not. Corticomedullary differences should be explicitly reported when standardizing pediatric renal shear wave elastography.
