Staying well hydrated is vital to the health of young and old. By Jennifer Bowden.
Whether you're older or younger, summer presents the same risk – dehydration thanks to the escalating heat and less-than-optimal fluid intake. More than half of older adults are either dehydrated or very close to dehydration, studies have shown, and one global study found about 60 per cent of children aren't meeting water and fluid intake guidelines.
Our body needs water to function correctly. When we lose more fluids than we consume, it places our health at risk. In older adults in particular, dehydration is associated with a high risk of adverse health outcomes and is a significant contributor to morbidity and death. This includes "falls, fractures, heart disease, confusion, delirium, heat stress, constipation, kidney failure, pressure ulcers, poor wound healing, suboptimal rehabilitation outcomes, infections, seizures, drug toxicity and reduced quality of life", according to a 2015 Cochrane Review.
Sports scientists have led the way in studying the impact of dehydration on sports performance, noting that a 2 per cent loss of body weight through sweat has a significant effect on physical and mental performance. Among elite cricketers, performance declines when they don't stay well hydrated with drinks at the sideline. One study of top Sri Lankan cricketers found that 85 per cent of the fielders and bowlers were unable to maintain levels of speed and accuracy when dehydrated. Fielders suffered a sizeable reduction in throwing speed and accuracy for overarm and sidearm throws – sidearm-throw accuracy dropped by 22 per cent – while bowlers' speeds dropped and their accuracy decreased by 20 per cent. Batsmen were mildly affected, running 2 per cent slower when completing three runs, which could be the difference between a run-out and a run.
But even those sitting at home watching cricket on television can be significantly affected by dehydration, with recent studies finding that even a relatively small loss of 0.6 per cent of body fluid affects mood and memory. Children are particularly susceptible to dehydration because they often rely on adults to supply them with drinks. In one study, when 9- to 11-year-old children drank more water for four days, they had faster reaction times on a task-switching test and an increased ability to multitask.
Older adults are at greater risk of dehydration because their "thirst response", which guides their fluid intake, declines with age. In addition, their ability to retain salt and fluid reduces as kidney function declines. On top of that, many medications can also increase dehydration risk.
Unfortunately, there are no simple tests to determine dehydration in older adults – even possible symptoms such as loss of elasticity of skin or dry mouth are unreliable. Instead, researchers have found that merely asking an older adult whether they've been drinking fluids between meals or are feeling fatigued is likely to more accurately gauge their hydration status.
Having fresh water handy is a significant first step in ensuring children and older adults stay hydrated. For instance, when water dispensers were installed in New York school cafeterias, the students drank three times as much water. Similarly, US Army employees more than doubled their intake when a water jug was placed on their dining table instead of 6m away.
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Parents, too, are important role models when it comes to water consumption. And it's not so much what they say but what they do that has the most significant impact. Hence, parents who make a habit of regularly drinking water and encouraging water consumption over other drinks are more likely to instil similar habits in their children.
It's a good idea to keep a water bottle handy in the car, on the bus or at your desk – make water so convenient that it's easy to say yes to more. Another tip is to keep a jug of chilled water in the fridge and place it on the dining table at breakfast, lunch and dinner – while remembering to drink between meals. The goal is to drink regularly throughout the day, not just one big glass with medications in the morning.