The article highlights the dangers of dehydration, emphasizing that even mild dehydration can impact physical and cognitive function. It emphasizes that the recommended daily water intake is often unmet. Dehydration is linked to several chronic conditions, including hypertension, diabetes, and dementia.
The article emphasizes the importance of maintaining hydration to mitigate these health risks, particularly among older adults who are more susceptible to dehydration and its consequences.
When did you last have a decent drink of water? We all know we should down more H₂O, yet the average Briton sips less than half the recommended six to eight glasses a day, shows recent research by PureGym. This doesn’t just leave us feeling parched, it can put us at risk of dehydration and long-term health issues.
“Water is essential for life and plays a vital role in nearly every body process,” says Stavros A. Kavouras, a professor of nutrition and director of the Hydration Science Lab at Arizona State University. “It helps regulate your temperature, transport nutrients, remove waste and lubricate your joints. Proper hydration aids digestion, supports kidney and heart health, and enhances physical performance.”
The human body is around 60 per cent water, but we constantly lose fluid – about 2 to 2.5 litres a day – through our sweat, urine, stools and breath. Replacing that fluid regularly is crucial.
“Many of us are mildly dehydrated or ‘under-hydrated’ without realising it,” says Prof Kavouras. “This can subtly, yet significantly, impact how we feel and function. More importantly, it’s linked to chronic health conditions such as hypertension, diabetes and dementia, which in turn means a reduced life expectancy.”
In hot weather, dehydration can escalate quickly, potentially leading to collapse or even death. The risk rises if you’re older, taking multiple medications or have sickness and diarrhoea. Dehydration is one of the most common reasons for A&E admissions in the elderly.
Here are the telltale symptoms to watch out for:
Feeling parched? You’re already mildly dehydrated. “Thirst is the first stage of dehydration,” says Dileep Lobo, a professor of gastrointestinal surgery at University of Nottingham, who researches fluid and electrolyte balance.
“Once you’ve lost two per cent of your body weight in fluid (1.4 litres for a 70kg person), it triggers receptors in the brain which make you feel thirsty. Mild dehydration can happen easily if you’re out in the sun or working in a warm office and not drinking much. You lose quite a lot of water through your sweat, especially if you’re not acclimatised.” At this point, dehydration is easily reversed by drinking fluids.
“If you replace the water you’ve lost, you’ll feel better immediately,” says Prof Lobo. “The fluid enters your bloodstream and corrects the imbalance.” Our sense of thirst declines with age, so sip water throughout the day.
Check the colour of your urine. If it’s honey coloured, you need to drink more. If it’s darker brown, you may be seriously dehydrated. “Once thirst occurs, your body starts holding on to water,” explains Prof Lobo. “Your kidneys send less water to the bladder, making your urine more concentrated.” This is a major risk factor for kidney stones.
“If you don’t drink enough, your kidneys have to work really hard and this raises your risk of certain diseases, including urinary tract infections, especially if you’re a woman,” adds Dr Lewis James, a reader in human nutrition at Loughborough University. Kidney function declines with age, making dehydration more likely, so keep an eye on your urine output. Ideally, you’ll be passing urine about seven times a day, and it should be transparent yellow.
The brain is 73 per cent water so your brain cells can struggle to function once you’re dehydrated. “Even a low level of dehydration can reduce cognitive skills such as memory, attention and motor coordination,” says Dr James. “This may affect your performance whether you’re working in an office, driving your car or deciding if it’s safe to cross the road.”
A study in the Journal of Clinical Nutrition found 45 per cent of doctors and nurses were dehydrated by the end of their shifts, and their short-term memory was impaired. Just drinking a 300ml glass of water has been shown to improve memory recall. As dehydration progresses, you can become confused and disorientated.
Dehydration is a common trigger for headaches. As fluid leaves your brain, it can put pressure on the pain receptors and nerves in the brain’s lining. The pain can worsen when you bend and turn your head or move around. Most dehydration headaches improve within an hour or two, once you’ve rehydrated and rested. Stay out of the sun and try putting a cool compress on your forehead.
A dehydration headache can turn into migraine, so try to drink fluids even if you feel nauseous – small sips are best. “Drinking enough water can help reduce risk of a migraine attack through dehydration,” says Pippa Coulter, health information manager for The Migraine Trust. A study in the Journal of Clinical Neuroscience found migraine pain, duration and frequency was significantly lower in patients who drank more water.
Dehydration is behind one in ten GP consultations for fatigue, according to a study of 300 GPs by the Natural Source Water Association. Regularly sipping water keeps your body and brain energised, especially if you’re active. During hot weather, you can lose 1.5 to 2 litres of water an hour through sweat whether you’re hiking or playing a round of golf. “If you don’t replace these fluids, your blood thickens, and your heart has to work harder to maintain your blood pressure and oxygen levels,” warns Prof Lobo.
As we age, dehydration can make daily life exhausting. “An 80-year-old who weighs 40kg (88 lb) and loses bodyweight through fluids is more likely to feel the effects,” says Prof Lobo. “Our research shows that older adults, admitted to hospital with dehydration, stay in for longer and have a 6 per cent higher mortality rate.”
“Once you’ve lost four per cent of your bodyweight in fluid, sweating becomes difficult and your temperature rises, putting you at risk of overheating,” says Prof Lobo. “Blood pressure drops, and you can become dizzy or faint.” This is “moderate dehydration” and you should seek medical advice. Oral electrolyte solutions can help but sometimes an IV drip is needed. Without treatment, dehydration can progress to “severe” (a 7 per cent loss of bodyweight) within 24 hours. It’s now a medical emergency. “The body reduces blood flow to non-vital organs, like your kidneys,” says Prof Lobo. “Cellular waste builds up, organ damage can occur and, without intervention, you may eventually suffer seizures or collapse.” Multi-organ failure, coma and even death can follow. Hot weather can accelerate the process, so always carry water and seek shade if you feel tired or light-headed.
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