An interventional study of Water in Dehydrated, Water-Electrolyte Imbalance, Malnutrition and Dehydration (Physiology), sponsored by Polytechnic University of Santarém. Not yet recruiting. Open to participants aged 60 Years to 85 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-23.
Sponsored by Polytechnic University of Santarém · Not applicable, Interventional, and Basic science
DrinkAge is a randomized controlled trial investigating whether increasing daily water intake can improve hydration and health-related outcomes in adults aged 60 years or older who habitually drink relatively little water.
The study will include 38 participants who habitually consume 35 mL/kg/day or less of water. Participants will be randomly assigned to either increase their daily water intake to at least 45 mL/kg/day or maintain their usual water intake for 7 days.
Before and after the 7-day intervention, participants will undergo assessments of hydration, blood and urine markers, hormone levels, body water distribution, body composition, muscle and physical function, mood, physical activity, and health-related quality of life.
The main purpose of the study is to determine whether increasing habitual water intake changes levels of arginine vasopressin, a hormone involved in the regulation of body water balance. The study will also investigate whether increasing water intake is associated with changes in hydration status, cardiovascular and kidney-related markers, stress-related hormones, body water distribution, physical performance, mood, and quality of life.
The results may help clarify whether increasing habitual water intake is a feasible strategy to improve hydration and support healthy ageing in older adults who habitually drink relatively little water.
The DrinkAge study is a 7-day randomized controlled trial designed to investigate the effects of increasing habitual water intake on hormonal regulation of water balance, hydration status, body water distribution, cardiometabolic and renal biomarkers, neuromuscular function, physical performance, mood, physical activity, and health-related quality of life in community-dwelling older adults who habitually consume relatively low amounts of water.
Older adults may be particularly susceptible to low habitual water intake because of age-related reductions in thirst perception and changes in renal water conservation, as well as medication use, mobility limitations, and other factors that may make adequate fluid consumption more difficult. Individuals who habitually consume relatively little water can maintain total body water and plasma osmolality through physiological mechanisms that conserve water. One of these mechanisms is increased secretion of arginine vasopressin (AVP), a hormone involved in the regulation of water balance and kidney water conservation. Although this response helps maintain water homeostasis, persistent activation of AVP has been associated with several metabolic, renal, cardiovascular, and stress-related outcomes.
Previous intervention studies in younger and middle-aged adults have reported that increasing habitual water intake can reduce copeptin, a validated surrogate marker of AVP secretion, and may improve some hydration and metabolic markers. However, evidence from randomized intervention studies in older adults remains limited. In addition, it is not well established whether increasing habitual water intake affects body water distribution, muscle function, functional capacity, mood, or quality of life in older adults who habitually drink relatively little water.
The primary aim of the DrinkAge study is to determine whether increasing habitual water intake for 7 days changes circulating plasma AVP concentration in low-drinking older adults. The study will also investigate whether the intervention changes objective and subjective markers of hydration, cardiometabolic and renal biomarkers, cortisol, body water compartments, bioelectrical impedance parameters, neuromuscular function, functional capacity, mood, physical activity, and health-related quality of life.
A total of 38 adults aged 65 years or older will be recruited from the community of Rio Maior, Santarém, Portugal. Participants must have a habitual total water intake of 35 mL/kg/day or less, including water obtained from beverages and foods. Participants must be community-dwelling, able to attend the study visits at the research laboratories, and able to walk independently without assistive devices. Participants must have a stable clinical condition and be able to provide informed consent and comply with the study procedures.
Potential participants will undergo a screening process to confirm eligibility. The screening process will include collection of demographic and clinical information, assessment of body mass and height, dietary and fluid-intake assessment, and evaluation of hydration biomarkers. Habitual total water intake will be assessed using a three-day food and fluid diary, including one weekend day. Participants with a habitual total water intake of 35 mL/kg/day or less will be classified as low drinkers and will proceed with the remaining eligibility assessment.
Participants who meet all eligibility criteria will be randomly assigned in a 1:1 ratio to either an experimental group or a control group. Randomization will be performed using a computer-generated allocation scheme by a member of the research team who is not involved in data collection or intervention delivery. Permuted blocks and stratification by sex will be used.
Participants assigned to the experimental group will increase their total daily water intake to at least 45 mL/kg/day for 7 days. The prescribed intake will be individualized according to body mass and the estimated contribution of food to total water intake. The intervention will consist of increasing fluid intake while participants maintain their habitual dietary patterns. The additional fluid provided during the intervention will be Vimeiro Original natural mineral water. Participants will receive pre-measured water bottles corresponding to their individualized daily prescription. The bottles will include graduated time markers to encourage the gradual distribution of water intake throughout the day.
Participants in the experimental group will also receive a hydration scorecard to record beverage type, volume, and time of consumption. Daily reminders will be provided during the intervention period to support adherence.
Participants assigned to the control group will be instructed to maintain their habitual water and fluid intake and usual dietary habits throughout the 7-day study period. Control participants will not receive the hydration tools or behavioral support provided to the experimental group.
Participants in both groups will be instructed to maintain their habitual dietary patterns, physical activity levels, caffeine consumption, and alcohol intake throughout the intervention. Any changes in medication, illness, unusual physical activity, or environmental conditions that could affect hydration status will be recorded.
Adherence to the intervention will be assessed using daily food and fluid records completed throughout the 7-day intervention. These records will be reviewed by a registered dietitian to estimate total daily water intake and determine whether participants achieved the prescribed water-intake target. Participants may also be asked to provide daily confirmations or photographs of beverage containers when necessary to improve the accuracy of intake reporting.
Assessments will be performed at baseline and immediately after the 7-day intervention under standardized laboratory conditions. Participants will undergo anthropometric, biochemical, hydration, body composition, neuromuscular, functional, psychological, and quality-of-life assessments.
The primary outcome is plasma arginine vasopressin concentration, measured at baseline and post-intervention.
Hydration status will be assessed using multiple physiological, biochemical, and perceptual measures. These will include serum, urine, and saliva osmolality; urine-specific gravity; urine color; and subjective measures of thirst and mouth dryness. Urine samples will be collected in the morning, and osmolality measurements will be performed using a freezing-point depression osmometer. Urine-specific gravity will be assessed using a digital refractometer. Thirst and mouth dryness will be assessed using 10-cm visual analogue scales.
Blood samples will be collected in the morning following an overnight fast of at least 10 hours. Blood analyses will include glucose, insulin, glycated hemoglobin, triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, sodium, creatinine, urea, uric acid, cortisol, high-sensitivity C-reactive protein, and arginine vasopressin. Insulin resistance will be estimated using the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Estimated glomerular filtration rate will also be calculated.
Body water distribution and bioelectrical properties will be assessed using whole-body and segmental bioelectrical impedance analysis. Measurements will include estimates of total body water, intracellular water, extracellular water, and the extracellular-to-intracellular water ratio. Raw bioelectrical impedance parameters, including resistance, reactance, impedance, and phase angle, will also be evaluated. Bioelectrical impedance vector analysis will be used to further characterize hydration status and soft tissue characteristics.
Neuromuscular function will be evaluated using handgrip strength and isokinetic knee testing. Handgrip strength will be measured using a portable hand dynamometer. Lower-limb neuromuscular function will be assessed using an isokinetic dynamometer. Outcomes from the isokinetic assessment will include maximum voluntary isometric contraction, rate of torque development, impulse, peak torque, peak power, total work, hamstrings-to-quadriceps strength ratios, and fatigue-related measures.
Functional capacity and fall-related physical performance will be assessed using the ViviFrail assessment protocol, including the Short Physical Performance Battery and the Timed Up and Go test. The Short Physical Performance Battery includes assessments of static balance, 4-meter gait speed, and repeated chair stands. The Timed Up and Go test measures the time required to stand from a chair, walk 3 meters, turn, return, and sit down.
Psychological outcomes will include mood state and health-related quality of life. Mood will be assessed using the Profile of Mood States questionnaire, which evaluates tension-anxiety, depression-dejection, anger-hostility, fatigue-inertia, vigor-activity, and confusion-bewilderment. Health-related quality of life will be assessed using the 36-Item Short Form Health Survey, which evaluates physical and mental health domains.
Habitual physical activity and dietary and fluid intake will be monitored during the study. Participants will complete food and fluid records during the intervention period, allowing the research team to quantify water intake from beverages and foods and to evaluate adherence to the intervention.
The primary statistical analysis will use linear mixed-effects models to evaluate the effects of the intervention. Models will include group, time, and the group-by-time interaction as fixed effects, with participant included as a random effect to account for repeated measurements within individuals. The group-by-time interaction will represent the primary effect of interest. Models may be adjusted for clinically relevant covariates, including age, sex, and baseline values of the dependent variable. Additional exploratory analyses may include other biologically relevant covariates.
The study is designed to determine whether a short-term increase in habitual water intake can modify AVP secretion and other physiological and functional measures in older adults who habitually consume relatively little water. By simultaneously evaluating endocrine, hydration, metabolic, renal, body water, neuromuscular, functional, psychological, and quality-of-life outcomes, the study will provide a comprehensive assessment of the potential physiological effects of increasing water intake in this population.
The intervention period is limited to 7 days to facilitate adherence and to evaluate early physiological responses to increased water intake. The study is not designed to determine the long-term effects of increased water intake on chronic disease, mortality, or long-term functional independence.
208 studies on the registry are indexed under Dehydration; 29 are open to participants now.
This study's planned enrollment of 38 is close to the median of 42 across 150 interventional studies indexed under Dehydration.
Browse Dehydration studies →Polytechnic University of Santarém is the lead sponsor of 2 studies on the registry; 2 are open to participants now.
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Inclusion Criteria:
Participants must meet all of the following criteria:
Exclusion Criteria:
Chronic use of medications known to substantially affect fluid and electrolyte balance, including:- Loop diuretics;
Participants will maintain their habitual total water intake and usual dietary and physical activity patterns throughout the 7-day study period. Participants will not receive the hydration tools or behavioral support provided to the experimental group.
Other: Water
Participants will maintain their habitual total water intake and usual dietary and physical activity patterns throughout the 7-day study period. No additional water, hydration tools, or behavioral support will be provided. Participants will complete daily food and fluid records to document their habitual intake during the intervention period.
Participants will be assigned at random to either the experimental group (EG) or the control group (CG). Over the 7-day intervention period, the EG will be asked to increase total daily water intake (WI) to at least 45 mL·kg-¹·day-¹, while the CG will continue their usual water consumption, corresponding to ≤35 mL·kg-¹·day-¹. Total WI will account for water obtained from both beverages and food. Participants allocated to the EG will be instructed to keep their usual dietary habits unchanged during the intervention so that the amount of water derived from food remains comparable to habitual intake. Accordingly, the intervention will involve an increase in fluid consumption only. The additional amount of water required to reach the target of ≥45 mL·kg-¹·day-¹ will be individually determined based on body mass and the estimated contribution of food to total WI. Vimeiro Original natural mineral water will be used as the additional source of fluid. This water has a total mineralization of
Change in Serum Arginine Vasopressin Concentration
Serum arginine vasopressin (AVP), will be assessed as a biomarker of the physiological regulation of water balance. Venous blood samples will be collected in the morning after an overnight fast. Serum AVP concentration will be determined using a radioimmunoassay (RIA) according to the standardized procedures of the clinical laboratory. The outcome will be expressed as the change in serum AVP concentration from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Serum Cortisol Concentration
Serum basal cortisol concentration will be assessed as an endocrine biomarker. Venous blood samples will be collected in the morning following an overnight fast, with the time of blood collection recorded to account for the circadian variation in cortisol concentrations. Serum cortisol concentration will be determined using a chemiluminescence assay according to the standardized procedures of the clinical laboratory. The outcome will be expressed as the change in serum cortisol concentration from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Fasting Serum Glucose Concentration
Fasting serum glucose concentration will be assessed as a biochemical marker of glucose metabolism. Venous blood samples will be collected in the morning following an overnight fast of 8-12 hours. Serum glucose concentration will be determined using the hexokinase-glucose-6-phosphate dehydrogenase enzymatic method according to the standardized procedures of the clinical laboratory. The outcome will be expressed as the change in fasting serum glucose concentration from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Fasting Serum Insulin Concentration
Fasting serum insulin concentration will be assessed as a biochemical marker of insulin metabolism. Venous blood samples will be collected in the morning following an overnight fast of 8-12 hours. Serum insulin concentration will be determined using a chemiluminescence immunoassay according to the standardized procedures of the clinical laboratory. The outcome will be expressed as the change in fasting serum insulin concentration from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Homeostatic Model Assessment of Insulin Resistance (HOMA-IR)
Insulin resistance will be estimated using the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), calculated from fasting serum glucose and fasting serum insulin concentrations. HOMA-IR will be calculated as: fasting insulin (μU/mL) × fasting glucose (mmol/L) / 22.5. The outcome will be expressed as the change in HOMA-IR from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in serum osmolality
Serum, osmolality (mOsm/kg) will be measured using a freezing-point depression osmometer (Mod OSMO1, Advanced Instruments, Canada). All osmolality measurements will be performed in duplicate.
Time frame: Baseline and after 7 days of intervention
Change in saliva osmolality
Saliva osmolality (mOsm/kg) will be measured using a freezing-point depression osmometer (Mod OSMO1, Advanced Instruments, Canada). All osmolality measurements will be performed in duplicate. Unstimulated saliva samples will be collected with participants seated comfortably after resting quietly for 2 min, allowing saliva to accumulate passively in the mouth. Participants will then provide approximately 3-4 mL of saliva into Salivette collection tubes or until no additional saliva can be comfortably produced.
Time frame: Baseline and after 7 days of intervention
Change in urine osmolality
Urine osmolality (mOsm/kg) will be measured using a freezing-point depression osmometer (Mod OSMO1, Advanced Instruments, Canada). Urine samples will be collected in sterile urine collection cups at the specified assessment time point. Participants will be instructed to provide a midstream urine sample after discarding the initial urine stream. All osmolality measurements will be performed in duplicate.
Time frame: Baseline and after 7 days of intervention
Change in Urine Specific Gravity
Urine specific gravity (USG) will be assessed as a urinary marker of hydration status. A urine sample will be collected at the specified assessment time point, and USG will be determined using a digital refractometer (KERN ORM 1CO, KERN \& Sohn GmbH, Germany). The outcome will be expressed as the change in urine specific gravity from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Urine Color
Urine color will be assessed as a subjective urinary marker of hydration status. Urine color will be evaluated from a urine sample collected at the specified assessment time point using a standardized urine color scale. The outcome will be expressed as the change in urine color from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Total Water Intake
Total water intake (WI), including water obtained from beverages and foods, will be assessed using three-day food diaries. A certified dietitian will provide standardized instructions regarding portion sizes and food and beverage recording. Food Processor Plus® software will be used to estimate daily total water intake. The outcome will be expressed as the change in average daily total water intake from the screening/baseline assessment to the intervention period.
Time frame: Baseline and during the intervention
Change in Body Mass Index
Body mass index (BMI) will be calculated as body mass in kilograms divided by height in meters squared (kg/m²). Body mass and height will be assessed under standardized conditions. The outcome will be expressed as the change in BMI from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Handgrip strength
Handgrip strength will be assessed using a portable hand dynamometer (Jamar Plus+). Participants will perform three maximal voluntary isometric contractions with each hand alternately. A 60-second rest period will be provided between attempts. The highest recorded value will be used for analysis. The outcome will be expressed as the change in handgrip strength from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Short Physical Performance Battery Score
Functional performance will be assessed using the Short Physical Performance Battery (SPPB), comprising static balance, 4-meter gait speed, and repeated chair stand tests. The SPPB score will be calculated according to the standardized scoring procedure. The outcome will be expressed as the change in SPPB score from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Timed Up and Go Test Performance
The Timed Up and Go (TUG) test will assess functional mobility and fall risk. Participants will stand from a chair, walk 3 meters, turn around a reference point, return to the chair, and sit down. The time required to complete the test will be recorded. The outcome will be expressed as the change in TUG completion time from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Total Body Water
Total body water (TBW) will be estimated using whole-body and segmental bioelectrical impedance analysis (BIA) using a phase-sensitive single-frequency analyzer (AKERN BIA 101/BIVA PRO; Akern Srl, Florence, Italy). Participants will rest in the supine position for 10 minutes before assessment. The outcome will be expressed as the change in estimated total body water from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Intracellular Water
Intracellular water (ICW) will be estimated using whole-body and segmental bioelectrical impedance analysis. The outcome will be expressed as the change in estimated intracellular water from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Extracellular Water
Extracellular water (ECW) will be estimated using whole-body and segmental bioelectrical impedance analysis. The outcome will be expressed as the change in estimated extracellular water from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Extracellular-to-Intracellular Water Ratio
The extracellular-to-intracellular water ratio (ECW/ICW) will be calculated from bioelectrical impedance-derived estimates of extracellular and intracellular water. The outcome will be expressed as the change in the ECW/ICW ratio from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Bioelectrical Impedance Phase Angle
Whole-body and segmental phase angle (PhA) will be obtained from resistance and reactance measurements using a phase-sensitive single-frequency bioelectrical impedance analyzer. The outcome will be expressed as the change in phase angle from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Resistance-to-Height Ratio
The resistance-to-height ratio (R/H) will be calculated from raw bioelectrical impedance resistance measurements normalized for participant height. The outcome will be expressed as the change in R/H from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Reactance-to-Height Ratio
The reactance-to-height ratio (Xc/H) will be calculated from raw bioelectrical impedance reactance measurements normalized for participant height. The outcome will be expressed as the change in Xc/H from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Impedance-to-Height Ratio
The Impedance-to-height ratio (Z/H) will be calculated from raw bioelectrical impedance reactance measurements normalized for participant height. The outcome will be expressed as the change in Z/H from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Perceived Thirst
Perceived thirst will be assessed using a 10-cm visual analogue scale (VAS). Participants will indicate their subjective level of thirst by placing a mark along the scale according to their perceived sensation. The outcome will be expressed as the change in thirst VAS score from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Profile of Mood States Score
Psychological state will be assessed using the Profile of Mood States (POMS), a 65-item self-administered questionnaire assessing six mood dimensions: tension-anxiety, depression-dejection, anger-hostility, fatigue-inertia, vigor-activity, and confusion-bewilderment. The outcome will be expressed as the change in POMS scores from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Change in Health-Related Quality of Life
Health-related quality of life will be assessed using the 36-Item Short Form Health Survey (SF-36). The questionnaire assesses eight domains of physical and mental health and provides physical and mental component summary scores. The outcome will be expressed as the change in SF-36 scores from baseline to the post-intervention assessment.
Time frame: Baseline and after 7 days of intervention
Absolute and Relative Ankle Plantar-Flexion Peak Force
Absolute peak force (N) and relative peak force (N·kg-¹) during a seated maximal voluntary isometric plantar-flexion contraction of the dominant limb. The highest force value recorded across four trials will be used for analysis.
Time frame: Baseline and after 7 days of intervention
Rate of Force Development During Isometric Ankle Plantar-Flexion
Rate of force development (RFD; N·s-¹) during maximal voluntary isometric plantar-flexion of the dominant limb, calculated over consecutive 50-ms intervals from contraction onset: 0-50, 50-100, 100-150, and 150-200 ms.
Time frame: Baseline and after 7 days of intervention
Explosive Isometric Ankle Plantar-Flexion Force
Explosive force, expressed as the percentage of peak force (%F) attained at 50, 100, 150, and 200 ms following contraction onset during maximal voluntary isometric plantar-flexion of the dominant limb.
Time frame: Baseline and after 7 days of intervention
Rate of Force Development During Dynamic Ankle Plantar-Flexion
Rate of force development (N·s-¹) during a standing bilateral rapid calf-raise task, calculated as peak force (N) divided by time to peak force (s).
Time frame: Baseline and after 7 days of intervention
Functional Lower-Limb Performance
Number of completed repetitions during the 30-second sit-to-stand test (30-s STS), performed from a 43-cm armless chair.
Time frame: Baseline and after 7 days of intervention
Mean Power During the 30-Second Sit-to-Stand Test
Mean lower-limb muscle power during the 30-s STS, estimated using a previously validated equation.
Time frame: Baseline and after 7 days of intervention
Peak Force During the 30-Second Sit-to-Stand Test
Peak vertical ground reaction force (N) recorded during the concentric phase of each sit-to-stand repetition. The participant-level summary measure will be defined a priori.
Time frame: Baseline and after 7 days of intervention
Fatigue Index During the 30-Second Sit-to-Stand Test
Fatigue index calculated to quantify the decline in performance across successive sit-to-stand repetitions during the 30-s STS. The calculation method will be specified a priori.
Time frame: Baseline and after 7 days of intervention
No study locations are listed for this record.
Plan to share: No — Individual participant data will not be made publicly available because of participant privacy and data protection considerations. The study data will be handled confidentially and access to identifiable information will be restricted to authorized members of the research team. De-identified data may be made available upon reasonable request, subject to approval by the research team, applicable ethical requirements, and institutional and data protection regulations.
No publications or documents are linked to this record.
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Polytechnic University of Santarém