London - From flushing out toxins to digestion, we need water for almost every bodily function. Feeling thirsty and passing dark coloured, strong-smelling urine are signs that you could be dehydrated.
Why drinking water is important
More than two-thirds of the human body consists of water. We require water for almost every function within our bodies, from flushing out toxins to digestion.
But knowing how much water to drink can be a challenge, particularly when it’s warm or you’re doing more exercise than usual. Drink too little and you could suffer potentially serious health problems. But, to complicate matters, drinking too much also carries health risks.
How much should you drink every day?
In normal circumstances, the amount of water in the body is controlled by the thirst response and urine production: you’re thirsty, you drink, you go to the toilet – the water cycle restarts.
In 2010, a report from The European Food Safety Authority suggested the minimum levels of water consumption should be two litres for men and 1.6 litres for women (between eight and 10 glasses). A standard soft drink can contains 330ml of fluid and the average bottle of water 500ml (a man would need to drink the equivalent of four bottles and a woman just over three).
However, much depends on your level of activity, physical health, size and weight and whether it’s a hot day.
I would recommend that drinking a little water often is the best way to stay hydrated.
What you drink is important too. While alcohol might quench your thirst, it’s actually a diuretic. This means it could make you pass urine more often, potentially leading to dehydration.
When people experience a hangover, a key component of this is dehydration. The typical hangover headache is a symptom of this. A good tip is to alternate every alcoholic drink with a glass of water.
Drinking milk, water and fruit juice is a good way to maintain hydration. However, always bear in mind the amount of sugar that might be contained in any sweetened drink.
Tea and coffee could help, but try to keep track of how much caffeine you are consuming.
How do you know if you are dehydrated?
Feeling thirsty and passing dark-coloured, strong-smelling urine are some signs that you could be dehydrated.
Other symptoms can include feeling sluggish, feeling light-headed and or having a dry mouth.
People at the extremes of age, such as children and the elderly, are at greater risk of becoming dehydrated.
Signs that might give your doctor cause for concern are children becoming drowsy, having fewer wet nappies or breathing more quickly.
Older people often do not realise they are dehydrated – confusion is a common presentation of dehydration in the elderly.
Patients experiencing vomiting, diarrhoea or sweats as a result of a fever can become dehydrated quickly unless they are able to replace the extra water lost from the body.
Is it possible to be over-hydrated?
It is possible to drink too much, although a person with healthy kidneys is normally able to deal with that by visiting the toilet more often.
Over-hydration occurs when the body retains or collects too much water. This can lead to water intoxication and sodium levels that are dangerously low – referred to as hyponatraemia.
Some athletes who participate in endurance events, especially marathon runners, can be prone to taking on too much fluid and suffering hyponatraemia.
A study in the Clinical Journal of Sports Medicine looked at the replacement of fluids in athletes, with the concluding advice that those taking part in sport should drink according to their thirst levels.
In some cases, there are medical reasons the body is unable to cope with excess water.
The water retention tends to affect people with kidney and heart conditions. Swollen ankles is a common sign of water retention.
To help the body to relieve itself of excess water, and to relieve pressure on the heart and other organs, doctors use diuretics or water tablets that promote the production of urine.
Time to see the doctor?
There are certain circumstances in which people should seek urgent medical attention. They include not passing urine for more than eight hours, feeling light-headed or lethargic, confusion or a pulse that feels rapid.
Constantly feeling thirsty can also be a symptom of other chronic conditions, including diabetes.
For most healthy people, drinking little and often throughout the day is the best approach. Drink a little more, but not too much, when it’s hot or you are exercising.
Listen to your body and it will let you know whether you are drinking too much or too little. But don’t be afraid to seek medical advice if anything seems out of the ordinary.
The Independent
* Dr Alexandra Phelan is an NHS GP