H2 Woah! We bust 5 hydration myths...

Posted 14 July 2009

Water is essential to us. It transports nutrients, hormones and oxygen to our cells and removes waste products via the bloodstream, it regulates temperature, lubricates joints...the list is endless.

While we can go for several weeks without food we can only survive a few days without water. And we’re constantly losing it through our breath, sweat and urine.

But how much do we really need to drink to stay healthy?

Myth One: "You should drink two litres of water a day".

It's thought that the "two litre" figure can be traced back to a 1945 report from the US Food and Nutrition Board. But that same report goes on to explain that much of this water can be found in the food we eat: fruit and veg are around 80 per cent water while rice and pasta dishes are around 70 per cent water.

In a healthy diet it's estimated that food can provide up to one litre of water a day and in addition to this, the body also creates some water itself as a by-product of metabolism.

The official line from the UK Food Standards Agency is that we should drink six to eight glasses of fluid a day, about 1.2 litres in total, and more when it's hotter or we're exercising.

But the key word here is 'fluid' - not necessarily water.

Although water is an ideal drink (it's calorie-free, caffeine-free, sugar-free and fat-free!) fruit juice, squash, herbal tea, in fact almost any non-alcoholic drink, all count towards your daily fluid intake. Which brings us to myth two...

Myth Two: "Tea and coffee dehydrate you".

Tea and coffee also count towards your fluid intake. In fact a recent study in the Journal Of The American College Of Nutrition revealed that coffee drinkers had the same levels of hydration as those who stuck to water.

Caffeine does have a slight diuretic effect, but the amount of liquid in an average cup of coffee or tea more than cancels it out.

One exception to this is the espresso, so follow the Italian example and drink a glass of water alongside it.

Myth Three: "Feeling thirsty means you’re already seriously dehydrated."

The body's pretty good at regulating water. If you drink too much, you'll pass urine more often and it will be almost colourless, while if you don't drink enough, your urine will become darker and more concentrated and your brain will then tell you that you need more water by making you feel thirsty.

It's worth noting that vitamin supplements (particularly vitamin C) can also darken urine, so some experts say that volume is a better indicator than colour.

The medically accepted definition of dehydration is when a person has lost more than 3% of their body weight, while in most cases, thirst kicks in when less than 2% of body weight is lost.

So under normal circumstances most people can stay hydrated using thirst as an indicator.

Myth Four: "More water = better skin and hair"

According to the received wisdom, drinking more water will improve the look of your skin and hair, flush out additional toxins and even help you lose weight.

But a 2007 study by the University of Pennsylvania concluded that there was no solid evidence that an increased water intake improved skin tone, kept organs flush or helped avoid overeating.

Back in 2004 a researchers on BBC1's 'Should I Worry About Water?' studied two identical twins for a month.

The twins, Lesley Peal and Denise Braxton, both 38, from Kent, underwent hair and skin analysis before one began drinking two litres of water a day, while the other stuck to her normal half pint.

After a month, doctors repeated the tests and found no significant difference in the moisture content of their hair or skin, or their weight.

Myth five: "It's impossible to drink too much water."

In July 2008 a court awarded 52-year-old Dawn Page from Farringdon, Oxfordshire £810,000 after a "detox" diet involving six pints of water a day left her with severe brain damage.

There have also been a handful of incidents where amateur marathon runners have died through over-drinking water during an event. This can seriously deplete the body's sodium levels, causing a rare condition called 'Hyponatraemia.'

Symptoms include dizziness, muscle cramping, confusion, and stomach bloating. Severe cases can lead to seizure, coma, and even death. The above are extreme cases and there's no need to panic. As always, it's a question of listening to your body. Don't force yourself to drink more than you're thirsting for and drink at a comfortable, natural rate.

So what's the conclusion?

The most reliable way to know whether you're getting enough fluid is to keep an eye on the colour of your urine- if it's pale-coloured, you're probably drinking plenty. And despite what bottled water manufacturers might have you believe, there’s no 'right amount' to drink!