Background
Habitual water intake plays a fundamental role in maintaining homeostasis and health throughout ageing. Low habitual water intake may stimulate the secretion of arginine vasopressin (AVP), promoting water conservation mechanisms and maintaining water homeostasis through increased urine concentration. Prolonged exposure to these adaptive mechanisms has been associated with metabolic, renal, cardiovascular and neuroendocrine changes.
Older adults are particularly vulnerable to low water intake due to reduced thirst perception, changes in renal function, polypharmacy and mobility limitations. Despite growing observational evidence of associations between low water intake and various health indicators, intervention studies assessing the effects of increasing habitual water intake in older adults remain scarce.
Objectives
The overall aim of the DrinkAge project is to investigate the effects of increasing habitual water intake on hormonal regulation, hydration status, and physical and metabolic health in older adults with low habitual water intake.
The specific objectives are:
1. Hydration and endocrine regulation – To assess whether increasing habitual water intake reduces AVP concentrations and improves key objective markers of hydration status, such as plasma osmolality (POSM), urine osmolality (UOSM), salivary osmolality (SalOSM) and urine specific gravity (USG), as well as subjective markers, namely thirst and dry mouth.
2. Cardiometabolic health – To investigate the effects of increasing water intake on blood glucose, insulin resistance and circulating cortisol levels.
3. Body water distribution – To assess changes in total body water (TBW), intracellular water (ICW), extracellular water (ECW) and the ECW/ICW ratio using bioelectrical impedance analysis (BIA).
4. Neuromuscular function and functional capacity – To investigate potential changes in muscle strength, power, fatigue resistance and functional performance.
5. Well-being and quality of life – To assess potential changes in mood, physical activity and health-related quality of life.
Main Methods
1. Randomised controlled trial
A seven-day experimental study involving adults aged ≥60 years with low habitual water intake (≤35 mL/kg/day). Participants will be randomly allocated to an intervention group, which will increase habitual water intake to ≥45 mL/kg/day, or a control group, which will maintain its usual water intake habits.
2. Assessment of hydration and vasopressin
Blood, urine and salivary markers will be assessed, including AVP, POSM, UOSM, SalOSM and USG, alongside urine colour and perceived thirst. AVP is the primary study outcome.
3. Cardiometabolic and renal health
Glucose, insulin, HOMA-IR and cortisol will be analysed.
4. Body water and bioimpedance
Total body water and its compartments will be assessed using BIA, including TBW, ICW, ECW and the ECW/ICW ratio, together with raw resistance, reactance and impedance measurements, and phase angle.
5. Neuromuscular function and functional capacity
Handgrip strength will be assessed, alongside maximal lower-limb strength, power, work and fatigue resistance using force platforms. Functional capacity will be assessed using test batteries specifically validated for older adults.
6. Psychological status and quality of life
The study will include an assessment of mood using the Profile of Mood States (POMS) and health-related quality of life using the SF-36.
7. Physical activity and monitoring of water intake
Habitual water intake will be assessed using food and fluid diaries, including water from both beverages and foods. During the intervention, adherence will be monitored using daily records.
Expected Results
Increasing habitual water intake is expected to reduce activation of the AVP system and improve objective and subjective markers of hydration in older adults with low habitual water intake.
In addition, the project may help clarify whether increasing water intake is associated with favourable changes in cardiometabolic regulation, body water distribution, neuromuscular function, functional capacity, mood and quality of life.
The findings may contribute to a better understanding of the physiological mechanisms associated with low habitual water intake during ageing and provide evidence to inform simple, low-cost and potentially scalable strategies to promote healthy ageing. The study rationale is based on the hypothesis that increasing habitual water intake may attenuate some of the physiological adaptations associated with chronically low water intake.
Partner Institutions
- Águas do Vimeiro
- Clínica Germano de Sousa – Rio Maior
- Rio Maior Sports Centre – DESMOR
Scientific domain: Medical and Health Sciences
Scientific area: Health Sciences
Scientific sub-area: Sport Sciences
Start date: 2 November 2026
Duration: 12 months
Location: SPRINT (Sport Physical Activity and Health Research Innovation Center), Rio Maior, Portugal
Keywords
Older adults; Healthy ageing; Hydration; Water intake; Vasopressin; AVP; Cardiometabolic health; Neuromuscular function; Functional capacity; Body water; Bioimpedance; Quality of life.
Sustainable Development Goals
The DrinkAge project is particularly closely aligned with:
SDG 3 – Good Health and Well-being:** Promoting health and well-being throughout life by investigating a simple and potentially scalable strategy to improve hydration and reduce the potential physiological consequences of low habitual water intake.
SDG 10 – Reduced Inequalities:** Contributing to accessible, low-cost health promotion strategies, particularly relevant to older and potentially vulnerable populations.
SDG 11 – Sustainable Cities and Communities:** Contributing to healthier communities and active ageing by promoting simple and sustainable health behaviours.
SDG 17 – Partnerships for the Goals:** Promoting collaboration between national and international institutions and across different scientific disciplines, including sport sciences, physiology, health and clinical research.
Funding
The project is partially funded by Águas do Vimeiro as part of the collaboration between the company and SPRINT – Sport Physical Activity and Health Research Innovation Center.
