07/18/2011 12:18 pm ET | Updated Sep 12, 2011

Breaking Down Water Science

Water or H2O is essential to humans and other lifeforms. I believe that Hydration Council UK is a very useful organisation, providing the latest research and advice on water. Their healthy hydration fact sheets are clear, concise and useful for people in all walks of life. Recently howoever, The Guardian published an article that expressed some controversial views about water intake:

We should all raise our glasses to Dr. Margaret McCartney, a GP from Glasgow, writing in the BMJ, who has revealed what most doctors already know: there is no scientific evidence that we need so much water. None. At all.

That is a pretty radical statement to make for the BMJ. The Hydration Council has this to say:

The opinion of one GP seems to be dismissing the years of research by scientists in this country and across Europe. This kind of article is misleading and unhelpful. The average Briton drinks just 200ml of water a day -- equivalent of less than one glass[1]. Last year, the leading European authority of food safety advised that we should be drinking 1.5 - 2.0 litres of water per day.

A 1 to 2 percent reduction in body weight over the day can signal mild dehydration and reduce our ability to concentrate. Dehydration can leave us feeling tired, dizzy and suffering from headaches [2].

Water is the only fluid you need to hydrate as part of a healthy lifestyle and contains zero sugar, calories, preservatives or additives. Children aged 4-10 get about one-fifth of their sugar intake from soft and sugar sweetened drinks and those aged 11-18 get about one-third of their sugar intake from soft and sugar sweetened drinks[3] , so when the country is facing an obesity crisis it's not helpful to denigrate water.

Science Daily has a different take on this and states that there is no robust scientific evidence supporting the health benefits of 8 glasses of water. This does not necessarily mean there are no advantages. It simply means that scientists as yet have been unable to prove the myths.

Professional athletes were studied and this was the conclusion:

Professional indoor sports persons sweat profusely when playing their sports (1.4 litres/hour on average), but their rehydration habits prevent them from reaching levels of dehydration that would affect their sporting performance," the research underlined. The authors insist how important it is to recover body fluids and sodium after training sessions.

Essentially, the quantity of water required depends upon individual requirements, level of activity, weather, underlying illnesses and age. Nothing is ever crystal clear in the world of science. If in doubt, discuss your water requirements with your doctor and don't just take a research paper as gospel.