Does Coffee Make You Dehydrated?

Have you been told that you need to drink an extra glass of water for every cup of coffee or tea that you drink?

For some time there has been a belief that drinking coffee and tea can make you dehydrated because the caffeine they contain has a diuretic effect (Causes your body to produce urine).

But is there any evidence to show that your morning cuppa needs to be offset with a big glass of water?

If you regularly enjoy a few cups of coffee or tea a day, then you can rest assured the moderate amount of caffeine they contain doesn't cause you to lose more fluid than you ingest.

Although there is evidence that caffeine in higher amounts acts as a diuretic in some people, moderate intake is actually not that significant.

A UK study of regular male coffee drinkers found no difference in hydration levels between those who drank four 200ml cups of coffee a day and those who drank the same amount of water.

Researchers measured the urine output of the men over a 24-hour period and other hydration markers in their blood, and concluded moderate coffee intake provides similar hydrating qualities to water.

While the study focused on the intake of coffee, those who drink tea can also take heart from the results as it contains similar amounts of caffeine to coffee.

How Caffeine Affects Hydration

One of the reasons that drinks containing caffeine, such as coffee, tea, chocolate, cola drinks and energy drinks, have been given such a bad rap over the years is because caffeine is actually a diuretic when consumed in large doses (more than 500mg).

Diuretics make your body produce more urine, so not only do they have you running to the toilet more often, they also cause you to lose sodium and water. When you lose too much sodium and water you become dehydrated, and this can have an effect on a range of bodily functions – from temperature control to even your absorption of food.

However, the amount of caffeine you get in a cuppa is unlikely to have these effects and it can actually contribute to your overall daily fluid intake.

If you have to have more than four cups of coffee a day you may see a diuretic effect from that, but if your intake is less, then from a dehydration view you would be totally going to be okay,

Men's bodies need around 2.6 litres and women's around 2.1 litres of water a day, but this can be gleaned from a range of food and drinks other than water, including coffee and tea.

The Good, The Bad and The Ugly

It's worth noting there are undesirable side effects associated with caffeinated drinks. Things such as rapid heart beat, restlessness, anxiety, irritability, trembling hands and sleeplessness can occur to those who are drinking a little to many cups of joe. .

However, drinking coffee can also have a range of positive health benefits, and has been linked to decreased risk of some cancers, heart disease and type 2 diabetes.

Like all things, moderation is key. Just make sure you're not relying too heavily on coffee or else you might just go overboard on your Monday morning meeting.