Not consuming sufficient water intensifies the physique’s stress response. Staying hydrated may cut back dangers linked to excessive cortisol.
Ingesting inadequate water might heighten susceptibility to stress-related well being issues, in accordance with new analysis from scientists at LJMU.
The research discovered that people who consumed lower than the really useful day by day quantity of fluids confirmed a stronger launch of cortisol, the physique’s important stress hormone. Elevated cortisol responses are linked to greater dangers of coronary heart illness, diabetes, and despair.
Printed within the Journal of Utilized Physiology, the analysis reported that folks consuming below 1.5 liters of fluid per day (roughly seven cups of tea) exhibited stress-induced cortisol ranges greater than 50% better than those that met really useful water consumption.
Examine lead Professor Neil Walsh, a physiologist in LJMU’s Faculty of Sport and Train Sciences, stated: “Cortisol is the physique’s major stress hormone and exaggerated cortisol reactivity to emphasize is related to an elevated danger of coronary heart illness, diabetes and despair.”
“If you already know you could have a looming deadline or a speech to make, preserving a water bottle shut might be an excellent behavior with potential advantages to your long-term well being.”
Poor long-term well being
Neil and his colleagues divided wholesome younger adults into two equal teams based mostly on their day by day fluid consumption, representing the bottom and highest 25% of consumption. The ‘low fluid’ group included members who usually drank lower than 1.5 liters of fluid every day (together with water, tea, and different drinks). The ‘excessive fluid’ group was made up of people who constantly met the really useful consumption of two liters for ladies and a pair of.5 liters for males. Each teams had been balanced for vital components that may have an effect on stress responses, similar to psychological traits and sleep patterns.
For one week, members continued with their regular consuming habits whereas their hydration standing was tracked by blood and urine exams. Afterward, they accomplished the Trier Social Stress Take a look at, a broadly used technique that recreates real-world stress by combining a mock job interview with a timed psychological arithmetic problem.
Dr Daniel Kashi, a member of the research crew, stated: “Each teams felt equally anxious and skilled related will increase in coronary heart charge throughout the stress take a look at. Nevertheless, solely the ‘low fluid’ group confirmed a major improve in saliva cortisol in response to the stress take a look at.”
He added: “Though the low fluid group didn’t report being thirstier than the excessive fluid group, they’d darker and extra concentrated urine, clear indicators of poor hydration. An vital remark was that poor hydration was related to better cortisol reactivity to the stress take a look at. Exaggerated cortisol reactivity to emphasize has been related to poor long-term well being.”
“When you have a traumatic schedule, preserving a bottle of water shut might be an excellent behavior,” says Dr Daniel Kashi, physiologist, LJMU.
Why is dehydration dangerous?
The reply lies within the physique’s water-regulation system, which is carefully related to the mind’s stress-response middle. When the physique senses dehydration, whether or not resulting from insufficient fluid consumption or extreme fluid loss, it triggers the discharge of a hormone known as vasopressin. Vasopressin acts totally on the kidneys, selling water reabsorption to keep up blood quantity and electrolyte stability. This conservation mechanism comes at a value. Sustained vasopressin launch locations further pressure on the kidneys, which should work more durable to pay attention urine and handle electrolyte stability.
Vasopressin additionally acts on the mind’s stress-response middle, the hypothalamus, the place it will possibly affect the discharge of cortisol. This twin function for vasopressin helps preserve blood quantity and electrolyte stability but additionally will increase cortisol.
The researchers say that whereas additional long-term research are wanted, the findings reinforce present water consumption suggestions — roughly 2 liters of fluid every day for ladies and a pair of.5 liters for males.
Hydration helps us handle stress
“Being hydrated might assist your physique handle stress extra successfully,” added Dr Kashi. A sensible approach to test your hydration standing is to observe your urine shade — gentle yellow sometimes signifies good hydration.
“If you already know, for instance, that you’ve a traumatic schedule, perhaps a looming deadline or a speech to make, preserving a water bottle shut might be an excellent behavior with potential advantages to your long-term well being.”
Reference: “Routine fluid consumption and hydration standing affect cortisol reactivity to acute psychosocial stress” by Daniel S. Kashi, Marianne Hunter, Jason P. Edwards, Juliane Zemdegs, Jennifer Lourenço, Anne-Cécile Mille, Erica T. Perrier, Alberto Dolci and Neil P. Walsh, 3 September 2025, Journal of Utilized Psychology.
DOI: 10.1152/japplphysiol.00408.2025
Funding: Danone Analysis & Innovation
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