You may have heard in the past that caffeinated drinks are not a good fluid source, as the diuretic effect will cause you to lose the fluid you have consumed (a diuretic causes an increase in fluid losses, this means an increase in urinary output).

A common ‘health tip’ has been to drink a glass of water for every cup of coffee or tea consumed, to balance the loss. This however is completely unnecessary.

The diuretic effect of caffeine is actually fairly insignificant, and the small effect that does exist is reduced in people that regularly consume caffeine. Basically, for every mg of caffeine you consume you may lose approx. 1.07mls of fluid.

What does this mean for the average coffee and tea drinker?

• A cup of instant coffee contains approx 57mg of caffeine (61mls lost approx)
• An espresso 77mg
• Drip coffee 145mg
• Black tea 47mg
• Green tea 25mg
• White tea 15mg

Caffeinated soft drinks have less than black tea, but energy drinks contain as much if not well more than drip coffee.

~ Caffeine amounts taken from an online database, you can read the complete list here ~

A cup of fluid is 250mls of water, so in a cup of strong coffee, you will still consume in fluid more than possible losses (155.15mls of water lost from drip coffee).

(Note: all values approximations)

There are of course exceptions to this, a short black is made with only a small amount of fluid and MAY dehydrate, and energy drinks with their potential high caffeine content could cause dehydration.

As a general rule though, you can feel reassured next time you sit down with a standard cup of tea or coffee that it is contributing to your daily fluid requirements.