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  • The study of the effect of coffee, and caffeine in particular, on fluid balance can be split into two distinct areas: caffeine intake during exercise, and caffeine intake at rest in the general population.
  • The most recent studies and literature reviews on the effects of caffeine during normal life activities conclude that moderate caffeine consumption does not lead to dehydration.
  • During exercise, the best quality studies conclude that not only is moderate caffeine beneficial for endurance performance, they also conclude that it does not contribute to body dehydration.
  • Advice to abstain from drinking moderate amounts of caffeinated coffee, in order to maintain adequate fluid balance, is unfounded.
  • Coffee drinking in moderation contributes to our fluid intake and does not lead to dehydration, or significant loss of body fluid.
  • Whilst there is some indication of a mild, short-term diuretic effect of caffeine, this effect is not strong enough to counter-balance the benefits of fluid intake from coffee drinking.
  • Black coffee contains more than 95% water. The European Food Safety Authority (EFSA) recently concluded that a cause and effect relationship has been established between the dietary intake of water and the maintenance of normal and physical cognitive function.

The content in this Topic Overview was last edited in May 2015. Papers in the Latest Research section and further resources are added regularly.

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