Coffee with High but Not Low Caffeine Content Augments Fluid and Electrolyte Excretion at Rest.

Background: Low levels of caffeine ingestion do not induce dehydration at rest, while it is not clear if larger doses do have an acute diuretic effect. The aim of the present investigation was to examine the acute effect of low and high levels of caffeine, coffee, on fluid balance in habitual coffee drinkers (at least one per day) at rest.

Methods: Ten healthy adults (eight males and two females; age: 27 ± 5 years, weight: 89.