Does coffee dehydrate me?

Does coffee dehydrate me?

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Historically, it has been thought that caffeine consumption resulted in a diuretic effect, and thus could not be contributed to hydration status. I remember when I went to uni it was recommended to consume an extra 1.5 cups of water for every cup of coffee!

A recent study has debunked these thoughts. A group of 50 men who habitually consumed between 3-6 cups of coffee per day were assessed for hydration status when consuming either coffee or water each over a period of 3 days. Hydration was measured using total body water and urinary hydration markers, whilst plasma was analysed for caffeine to confirm compliance; each person was provided with 4mg/kg of caffeine in 200mL water to consume per day for the caffeine consumption arm of the trial. This was replaced with just water for the other arm.

What were the findings? No significant difference in body mass or hydration status.

What does this mean? The key finding of the study was that there was no significant difference between hydration status when caffeine had or had not been consumed, thus consumption of caffeinated beverages can be counted towards fluid intake in males who regularly consume moderate amounts of coffee. Research specific to women is still required.

Of course, excessive amounts of caffeine can have other side effects, such as sleep disturbance, nervousness and anxiety, thus, this does not mean to drink large quantities of coffee instead of water. Moderate amounts of consumption only are recommended.

How much coffee do you drink?

Chloe McLeod is a dietitian at BJC Health.
This blog focuses on diet & nutrition generally and diet & nutrition in relation to the treatment of arthritis and arthritis-related diseases. Contact us if you'd like our help in managing diet-related health issues.

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