Take another look at the elixir of life

Apparently not, according to some scientists. A recent report found no evidence of any benefits from drinking the recommended amounts of water.

In fact, according to the report almost everything we think we know about water is wrong. There's no evidence that it stops you from gaining weight, or helps rid the body of toxins. No indication it plumps the skin, shines the hair or brightens the eyes. None whatsoever – or so we're told.

As part of their study. Dr Dan Negoianu and Dr Stanley Goldfarb from the Philadelphia's University of Pennsylvania reviewed every published clinical study into the subject.

While they found evidence that those in hot, dry climates have an increased need for water – as do athletes, and patients with certain diseases – this is not the case for the average, healthy individual. "Indeed, it is unclear where this recommendation came from," says a spokesman for the scientists added.

According to the scientists, while some previous studies revealed that water intake affects the rate that kidneys clear salt and urea from the body, they failed to show any real health benefits.

Furthermore, the study didn't show any benefit to organs from increased water intake, and while water has been touted as an elixir for improved skin tone, there were no clinical studies to back this up.

Their conclusions, published in the Journal of the American Society of Nephrology, state that "There is simply a lack of evidence in general," that water is good for our health.

Edinburgh doctor, Peter Copp, of GP-Plus, knows the recent findings all too well. While he admits the researchers made some valid points – for example, he agrees there is no evidence to support claims that water can reduce cancer – he stresses that water is vital for life. And lots of it.

"We definitely need water to stay healthy and it's an absolute essential," he says. "You can only maybe survive for a limited period of time without any water, which is something along the lines of 100 hours. Water is essential for life and required for normal cell function. We will die without it."

Emma Conroy of Edinburgh Nutrition agrees. "I agree that there's no benefit to drinking extra water if you're already well hydrated, but the problem is that despite not feeling thirsty, many of us are not well hydrated, and eat a diet high in salt without many fruit and vegetables."

"The body can last a lot longer without food than it can without water. Water can be regarded as an essential nutrient, and like any nutrient, how much you need depends on how much you are using up."

Peter continues: "I'm sure there are people out there who think there's very little, if any, evidence to support the current recommendations and they're based on well meaning people sitting round the table and coming up with what they think is sensible advice.

"Probably the cynic might suggest that the focus on water is driven by the bottled water industry and it's in their interest for people to carry bottles of water around. But in Scotland that's strange considering we have access to wonderful tap water.

"The difficulty is working out how much we do need. Generally speaking we need around 1ml to 1.5ml per calorie we consume in food energy. My recommendation for ordinary people who do sedentary jobs and eat a sensible diet is two litres of fluids for men, and 1.5 litres for women. This can be doubled if they do physical activity such as the gym, or breast-feeding mothers.

"Water requirements vary with where we are, what we're doing and even our jobs. People who are on a diet need even more fluids as they won't get enough fluids from the foods they eat."

So how do we gauge when to drink – and how much?

"Thirst isn't the best yardstick," explains Emma.

"You can already be dehydrated by the time you feel thirsty, and even if you never feel thirsty, it's quite possible to benefit from drinking more water.

"Symptoms like sluggish digestion, headaches, sore joints or back ache, bladder infections, poor concentration, fatigue, dry eyes and dry skin can all indicate lack of water.

"Check the colour of your urine – if it's dark yellow, you may need to drink more water. Note that if your urine is clear yet you experience strong thirst, you should be tested for diabetes.

"Your fluid requirements depend on a number of factors, including your salt intake, and the amount of water in your food. Someone eating a lot of fresh fruit and vegetables will need to drink far less water than someone eating a lot of salted peanuts."

Nutritionist Lou Johnston of Tonic Health Scotland in Leith points out: "Our systems are over 70 per cent water – right down to our cellular level. Our bodies constantly use water to process and rid our bodies of waste and as a solution to break down and absorb nutrients that we need for life on a daily basis. Without regular top-ups, our body's survival time is limited to a matter of hours or days."

The idea that those who don't drink enough water will suffer from health problems became widespread in the 1990s and, while our body certainly needs fluids to survive, it doesn't just have to be water. In fact, drinking three or more cups of tea a day is just as good for you as drinking plenty of water.

Ursula Arens, a spokesman for the British Dietetic Association, claims that the typical adult needs between two and three litres of fluids a day – but it can come from other foods and drink.

"Most people can rely on their thirst to tell them when they need to drink, although as we get older perception of thirst is not so good," she says.

"Tea and the sort of coffee you get in Britain are fine for re-hydrating – the diuretic effects of caffeine are massively outweighed by the fluids in those drinks. There are millions of people who get most of their fluids from tea without any ill effects."

Public health nutritionist Dr Carrie Ruxton and colleagues at the Kings College London also found that drinking up to four cups of tea can reduce the chances of a heart attack.

"Drinking tea is actually better for you than drinking water. Water is essentially replacing fluid. Tea replaces fluids and contains antioxidants so it's got two things going for it." So, drink up.

BOTTLED VERSUS TAP

WE all know the benefits of staying hydrated, but is bottled water the best way to do it? Should we spend nearly 2 billion a year on the stuff, when we have drinkable tap water at our finger?

According to Which? Online, 98.8 percent of tap water sampled passed drinking water inspectorate tests and drinking water available from our taps is perfectly adequate to replenish our fluid loss, undergoing a myriad of processes to bring it up to the standards set out in the Water Supply Regulations. And Scotland boasts some of the best water supplies in the country.

There are no proven health benefits either – so it comes down to personal taste.

There are two types of bottled water – spring water and mineral water. Spring water is collected directly from the spring where it arises from the ground and is bottled at the source. Mineral water emerges from under the ground, then flows over rocks before it's collected. Unlike spring water, it's not treated except to remove grit and dirt.