Study on Water Turnover of the Chinese Population Based on Deuterium Dilution Method

Overview

Water is essential for sustaining life and maintaining health. The human body relies on water to transport nutrients and waste products, lubricate joints, regulate body temperature, and preserve tissue structure. International research has shown that losing just 2% of body weight through water loss can impair physiological functions and reduce response capacity. Adequate water intake plays a crucial protective role in health: it helps regulate body weight, lowers the risk of chronic diseases such as cardiovascular and cerebrovascular conditions, and supports cognitive function. However, the common recommendation to drink eight cups of water per day lacks strong scientific evidence. Most national hydration guidelines are based on average population intake, and personalized water intake recommendations have yet to be fully developed. In this study, the investigators will use the deuterium dilution technique to measure water turnover in volunteers. Body composition will be assessed using the TANITA MC-780, while a seven-day fluid intake diary will track daily water consumption. Physical activity levels will be monitored using GT3 devices, and environmental data-including altitude, temperature, and humidity-will be collected based on participants' locations. The goal of this study is to collect comprehensive data on the physiological traits, environmental influences, and hydration needs of the Chinese population. This will allow for refinement and optimization of current prediction equations for water requirements. Ultimately, the investigators aim to develop a new, individualized water intake algorithm tailored to the Chinese population by quantifying the proportion of water intake relative to total water requirements.

The following assessments will be conducted with the volunteers: Height Measurement: Height will be measured using a Seca 217 stable stadiometer. Participants will be asked to remove their shoes for the measurement. Body Composition Measurement: Body composition will be assessed using the TANITA MC-780 device. This provides individual segmental weight measurements for the right arm, left arm, trunk, right leg, and left leg. A comprehensive report will also be generated, including body weight (BW), body fat percentage (fat%), fat mass (FM), body mass index (BMI), and fat-free mass (FFM). Body Water Measurement: Total body water will be measured using the deuterium dilution technique. Participants will arrive at the laboratory after an overnight fast and provide a baseline urine sample. They will then ingest a dose of deuterated water calculated based on their body weight. Additional urine samples will be collected three and four hours after dosing. The increase in deuterium concentration compared to baseline will be used to calculate total body water. Physical Activity Measurement: Physical activity will be monitored using a GT3 accelerometer, worn near the hip for seven consecutive days. The device should be removed during bathing or swimming. The first day of data will be excluded, as well as any day with less than 12 hours of wear time. Valid data must include at least two weekdays and two weekend days. Water Intake Measurement: Water intake will be tracked using a seven-day liquid intake diary. Participants will be provided with a form to record the type, time, and amount of liquid consumed across eight specific time intervals each day. Detailed instructions will be provided. Continuous recording for the full seven-day period is required. Environmental Data Collection: Environmental temperature and relative humidity will be recorded using an iButton device. The average altitude of each participant's city of residence will be determined using GPS-based altitude software.