Overhydration Risks: How Much Water Is Too Much?

There has been enough emphasis on adequate water consumption and staying hydrated, but the causes and effects of overhydration are not well understood, often remaining undiscussed. Out of health consciousness, the habit of sipping water at regular intervals has become a new norm. While it is essential for maintaining vital functions and overall health, it is crucial to understand the requirements of the body and drink as and when needed.

Normal Water Regulation Mechanism

Water processed inside the body depends on a variety of factors like dietary intake, metabolic activity, medical conditions, and environmental stresses, and this regulation differs from person to person. Normally, our bodies try to maintain a balance between water intake/excretion and the level of electrolytes (e.g., sodium, chloride, potassium, etc.) present in the blood.

The brain plays a key role in triggering feelings of thirst when hydration levels drop and in releasing hormones responsible for water excretion when hydration reaches an optimal level in the body. Plasma osmolarity is the concentration of solutes (electrolytes) in the blood, the measure which indicates dehydration or overhydration. When there is dehydration, plasma osmolarity is high, signaling the brain to develop a sensation of thirst in order to increase water consumption. In case of increased hydration, plasma osmolarity levels drop, stimulating the kidneys to excrete more water. The ADH hormone (anti-diuretic hormone) that helps conserve water in the body is shut off and the kidneys begin to release excessive water.

Any imbalance in this balancing mechanism, either due to dehydration or overhydration can have mild to serious effects on the body.

Factors Influencing Water Intake

As mentioned earlier, water consumption is influenced by numerous factors like activity level, temperature/humidity of the environment, medications, pre-existing medical and psychological conditions. The type of food, whether dry or soupy, and the amount of water taken along with a meal can also make a significant difference in hydration. Consuming dry foods can result in increased water intake to overcome mouth dryness and this does not necessarily interfere with the thirst-excretion mechanism.

Some people are more vulnerable to overhydration or effects of overhydration than others because of their pre-existing medical conditions or medications. Antidepressants, water pills (diuretics), certain antihypertensive, cancer and antipsychotic medications can increase the risk of overhydration. Psychological conditions like stress and psychogenic polydipsia (a condition characterized by an excessive and compulsive thirst that leads to excessive fluid intake) may also contribute to water poisoning. Athletic activities where there are chances of increased thirst and excessive water consumption can also lead to overhydration, especially when the intake of water is more than the water lost through sweat. Overly health-conscious people with the intent of staying hydrated or persons taking part in competitions or events involving excess fluid consumption are also at a higher risk of water intoxication.

Effects of Water Poisoning

Common symptoms of excess hydration are nausea, headache, vomiting, and confusion. Although rare, water intoxication can lead to life threatening consequences if left unnoticed/untreated. Mostly, excess water is removed by the kidneys, but in persons with specific health conditions like heart failure or kidney disease, excess water intake can pose a severe problem. Research based on a urine flow cytometry test indicated that causes of overhydration may sometimes be hospital induced, for the purpose of an investigation or study.

Usually, the color of urine can indicate the extent of hydration in one’s body – pale yellow or amber shows appropriate hydration, whereas clear urine suggests increased hydration. Serious adverse effects of water poisoning can lead to headache, confusion, high blood pressure, seizures, or even coma. The brain cells or neurons take up excess water and swell, which may cause increased pressure within the head resulting in a splitting headache.

How Much Should You Drink

There is no scientific evidence to support the consumption of a specified amount of water to maintain healthy hydration. A person who does mild physical activity and lives in temperate climatic conditions may not need as much water as someone who does strenuous physical activity. One size fits all approach can be dangerous when it comes to hydration, leading to unintended consequences. It is always advisable to listen to your body and drink in moderation and be wary of any individual health conditions or medications prior to activities involving increased fluid consumption.

References

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3.       Su, M., & Woo, H. H. (2012). Severe hyponatremia from water intoxication associated with preparation for urine flow study. Su | Journal of Medical Cases. https://doi.org/10.4021/jmc.v3i2.498

4.       Ballantyne, C. (2024, February 20). Strange but true: Drinking too much water can kill. Scientific American. https://www.scientificamerican.com/article/strange-but-true-drinking-too-much-water-can-kill/

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7.       Wong, L. L., & Verbalis, J. G. (2002). Systemic diseases associated with disorders of water homeostasis. Endocrinology and Metabolism Clinics of North America, 31(1), 121–140. https://doi.org/10.1016/s0889-8529(01)00007-x

8.       Klees, L., & Borkowska, A. (n.d.). 11.17 – Regulation of Water Balance. Nutrition 100 Nutritional Applications for a Healthy Lifestyle. https://psu.pb.unizin.org/nutr100/chapter/11-17-regulation-of-water-balance/

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