Water and hydration: Physiological basis in Adults - Conclusion
IntroductionWater in the bodyI. Water in the body: content and distributionI.1. Water content of the human bodyI.1.1.Total body waterI.1.2. Water content of different organsI.1.3. Distribution among body compartmentsI.2. Water absorption and distribution in the bodyBody water balanceII. Body water balanceII.1. Body fluid lossesII.1.1. Insensible water lossesII.1.2. Fecal water lossesII.1.3. Sweat productionII.1.4. Urinary water lossesII.2. Body water inputsII.2.1. Metabolic water productionII.2.2. Dietary intakesII.3. The regulation and maintenance of body water balanceII.3.1.Regulation of fluid intake: physiological thirst, social and environmental factorsII.3.2.Regulation of water excretion by the kidneysII.3.3. Body water balance impairments: dehydration and hyponatremiaRecommendationsIII. Recommendations for daily water intakeConclusionReferences
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Water is the largest component of the human body, and is distributed throughout all tissues. The regulation of body water balance is therefore critical for maintaining homeostasis. Despite constant losses, the human body regulates efficiently its water balance, thanks to a fine control of urine volume and concentration.
This explains the broad range of fluid intakes observed in healthy individuals. However, the long-term health consequences of low or high fluid intake have been poorly investigated. Preliminary evidence seems to indicate that chronic low fluid intake may impact kidney health, as it may be associated with a more rapid decline of kidney function and higher risk of chronic kidney disease.
Additional research is therefore needed to evaluate the optimal daily fluid intake to prevent diseases or improve health, and to issue precise water intake guidelines for adults, but also for other demographic groups, such as children, pregnant and breastfeeding women, senior adults, and residents of hot climates.