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.
Jul. 30, 2014
- Killer SC, et al. No evidence of dehydration with moderate daily coffee intake: A counterbalanced cross-over study in a free-living population. Plos One. 2014;9:e84154
- Caffeine. Micromedex 2.0 Healthcare Series. http://www.micromedexsolutions.com. Accessed June 4, 2014.
- Heneghan C, et al. Mythbusting sports and exercise products. BMJ. 2012;345:e4848.
- 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.
- Zeratsky KA (expert opinion). Mayo Clinic, Rochester, Minn. June 9, 2014.