Myths around staying hydrated washed away

Scientists at the universities of Stirling, Loughborough and Bangor have discovered that a variety of drinks can keep people as equally hydrated as water.

A trial investigating the effects of 13 commonly consumed drinks on urine output and fluid balance, revealed that several fluids are just as, or more, hydrating compared to water.

Participants consumed one litre of liquid over a 30 minute period and researchers collected urine output for the subsequent four hours to monitor body salt balance and establish which fluids were retained in the body for longest.

Liquids consumed included still water, fizzy water, whole milk, skimmed milk, cola, diet cola, hot tea, cold tea, coffee, lager, orange juice, an oral rehydration solution, and a sports drink.

One of the lead authors, Dr Stuart Galloway of the Health and Exercise Sciences Research Group at the University of Stirling, said: “We set out to establish how various fluids affect people’s hydration levels on a daily basis. Our investigation has uncovered that a variety of drinks – not just water – can keep us well hydrated.

“Many people believe that drinking items such as tea and coffee causes us to become dehydrated. However, we found that when ingested at a normal dose and volume these fluids do not stimulate any additional water loss.”

Researchers now believe these findings could pave the way for the creation of a beverage hydration index which could see drinks clearly labelled by their hydration potential to help consumers identify fluids that are retained by the body for longer.

Dr Galloway, explained: “In our trial we found participants drinking milk or an oral hydration solution retained a third of fluid consumed over a two hour follow-up period and remained hydrated for over four hours. However, when drinking water or any of the other fluids, they retained nothing at two hours and lost further fluid after four hours.

“This is potentially valuable for individuals who want to stay hydrated but are unable to take frequent toilet breaks, or do not have regular access to fluids throughout their day. While the composition of some of the fluids must be considered, for example calories, salt and sugar content, it’s important that people are aware of the hydration potential that a variety of different drinks can have.”


Media enquiries to Corrie Campbell, Communications Officer on 01786 466 169 or [email protected].

Notes for editors:

The full Hydration Index Trial can found in the American Society for Nutrition. The study was funded by a scholarship from the European Hydration Institute (EHI) which is a not for profit foundation established to increase knowledge and understanding of all matters related to human hydration and its effects on health, wellness and performance. Further information about the EHI can be found on its website (

University of Stirling

The University of Stirling is ranked fifth in Scotland and 40th in the UK for research intensity in the 2014 Research Excellence Framework. Stirling is committed to carrying out research which has a positive impact on communities across the globe – addressing real issues, providing solutions and helping to shape society.

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At almost 50-years-young, Stirling retains a pioneering spirit and a passion for innovation. Its scenic central Scotland campus – complete with a loch, castle and golf course – is home to more than 11,000 students and 1400 staff representing 115 nationalities. This includes an ever-expanding base for postgraduate study.