Hydration Status

Hydration status during exercise is often determined by measuring body mass change, fluid intake and urine output. However, obtaining these measurements can be an invasive, time-consuming process. Hydration status may be detectable by analyzing blood flow patterns of the superficial (just under the skin) blood vessels. Wearable devices are now abundant among the general population, and despite attempts from several groups, a hydration status metric based on noninvasive wearable device metrics has not been developed. With wearables, a light source connected to an optical sensor transmits and reflects light through the body. The light sensor detects absorption of the light based on wavelength measurements of the detected light. Absorption of specific wavelengths of light energy is dependent upon the amount of oxygenated blood in the vessels. When the vessels expand and relax, the amount of blood volume in the observed tissue increases and decreases potentially causing a shift in the photoplethysmography (PPG) wave detected by the wearable. The shift in the shape of the PPG wave may be detected in a way that indicates the relative change in tissue hydration levels. However, to our knowledge, no wrist worn device that utilizes PPG has been successfully able to predict hydration status. Therefore, this study aims to utilize photoplethysmography (PPG) technology in a wearable device to accomplish this approach to hydration monitoring.

Over half of the adult population in Europe, Asia and Latin America fail to meet adequate water intake guidelines as advised by the European Food Safety Authority (EFSA; 2.5 and 2 litres/day for men and women, respectively coming from both food and drinks). Increasing epidemiological evidence suggests that chronic low fluid intake may be associated with an increased risk of cardiovascular, metabolic, and renal diseases. The association between chronic low fluid intake and increased morbidity risk may be underpinned by elevations in key water-regulating hormones, such as arginine vasopressin (AVP) and its surrogate copeptin, which influence glucose regulation and renal function. For example, AVP stimulates the hypothalamic-pituitary adrenal (HPA) axis to release the stress hormone cortisol with potentially far-reaching effects on metabolism, immunity and inflammation. Prospective cohort studies have demonstrated that exaggerated cortisol responses to acute stress are associated with poor health outcomes. A recent cross-sectional study (NCT05491122) from our group found that individuals with a low habitual fluid intake experienced greater cortisol reactivity to acute stress than those with a high habitual intake. The findings of this study may provide a potential explanation for why poor hydration and low fluid intake have negative effects on long-term health. We now aim to explore whether altering fluid intake influences cortisol reactivity to acute stress.

The primary goal of this 12-week randomized controlled study is to evaluate whether daily use of Hydrate Heroes results in measurable improvements in brain activity, mental health, and performance on cognitive tasks. By analyzing brainwave data, physical response metrics, and patient-reported outcomes, the study will demonstrate whether the supplement produces meaningful effects on mental and neurological health.

This study will examine how hydration status (drinking a large amount of water or avoiding water for a short period of time) affects the eye. Healthy adult volunteers will participate in two sessions: one after mild dehydration (no water for 12 hours) and one after drinking 2 liters of water within 4 hours. At each session, detailed eye measurements will be taken, including scans of the retina and optic nerve using optical coherence tomography (OCT), corneal imaging with Pentacam, and eye length measurements with an optical biometer. The results from the two conditions will be compared within the same participants. The main goal is to determine whether hydration influences the thickness of the retina (macula). Secondary goals include assessing changes in the optic nerve, cornea, and other biometric eye parameters. The study involves only non-invasive tests and minimal risk. Findings may help improve understanding of how hydration affects the eye and may be important for clinical practice, such as planning cataract or refractive surgery.

This randomized controlled trial aims to evaluate the impact of a mobile-friendly, web-based hydration tracking application (named "SIVI") on hydration-related knowledge, attitudes, and behaviors in older adults. Inadequate fluid intake is a common and modifiable risk factor for dehydration in the elderly, leading to increased morbidity, hospitalizations, and functional decline. However, many older individuals forget to drink fluids or face barriers such as fear of incontinence, mobility limitations, or cognitive challenges. This study will include 70 community-dwelling older adults aged 65-84 years, recruited from a Family Health Center. Participants will be randomly assigned to either the intervention or control group. The intervention group will use the SIVI application for two months. The app is specially designed for older adults and includes features such as personalized fluid goals, reminders, hydration education modules, feedback, and a user-friendly interface with large fonts and high contrast. Participants will log their daily fluid intake, receive motivational messages, and access videos and information about healthy hydration habits. A water bottle will be provided to standardize measurement across groups. The control group will receive only routine care. Both groups will complete questionnaires measuring demographics, hydration knowledge, attitudes, behaviors, and fluid consumption habits at baseline, one month, and two months. Data collection will be conducted face-to-face by the researcher, and analysis will be performed using SPSS 22.0. Statistical tests will include descriptive statistics, Shapiro-Wilk for normality, chi-square for categorical data, and t-tests and ANOVA for comparisons over time. The results are expected to show that the SIVI application improves older adults' hydration knowledge, fosters positive attitudes, and promotes healthy fluid intake behaviors, thus supporting self-management of hydration and potentially reducing dehydration-related health risks.