While studies on caffeine pills have produced inconsistent results1, those on caffeinated drinks, at caffeine intakes of 114-420mg/d, have found no significant impact on hydration. However, there have been no randomised controlled trials on tea, as consumed.
The present trial aimed to assess the impact of 4 x 240ml mugs of black, i.e. regular tea, on blood and urine measures of hydration. The control condition was a similar volume of boiled water. Four mugs is slightly above average daily tea intakes in the UK.
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