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  • With Mayo Clinic nutritionist

    Katherine Zeratsky, R.D., L.D.

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Question

Caffeine: Is it dehydrating or not?

I've been seeing ads that say caffeinated drinks hydrate you as well as water does. Is this true?

Answer

from Katherine Zeratsky, R.D., L.D.

It is true that caffeinated fluids can contribute to your daily fluid requirement.

Drinking caffeine-containing beverages as part of a normal lifestyle doesn't cause fluid loss in excess of the volume ingested. While caffeinated drinks may have a mild diuretic effect — meaning that they may cause the need to urinate — they don't appear to increase the risk of dehydration.

Still, caffeinated drinks can cause headaches and insomnia in some people. Water is probably your best bet to stay hydrated. It's calorie-free, caffeine-free, inexpensive and readily available.

Next question
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References
  1. Armstrong LE, et al. Caffeine, fluid-electrolyte balance, temperature regulation, and exercise-heat tolerance. Exercise and Sport Sciences Review. 2007;35:135.
  2. Maughan RJ, et al. Caffeine ingestion and fluid balance: A review. Journal of Human Nutrition and Dietetics. 2003;16:411.
  3. Lopez RM, et al. The influence of nutritional ergogenic aids on exercise heat tolerance and hydration status. Current Sports Medicine Reports. 2009;8:192.
  4. Ruxton CH, et al. Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: Results from a randomized controlled trial. British Journal of Nutrition. 2011;106:588.
  5. Heneghan C, et al. Mythbusting sports and exercise products. BMJ. 2012;345:e4848.
  6. Caffeine. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed Aug. 13, 2013.
  7. Zeratsky KA (expert opinion). Mayo Clinic, Rochester, Minn. Aug. 13, 2013.
AN01661 Aug. 20, 2011

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