"Drink at least eight glasses of water a day." Really? Is there scientific evidence for "8 x 8"?

@article{Valtin2002DrinkAL,
  title={"Drink at least eight glasses of water a day." Really? Is there scientific evidence for "8 x 8"?},
  author={Heinz Valtin},
  journal={American journal of physiology. Regulatory, integrative and comparative physiology},
  year={2002},
  volume={283 5},
  pages={
          R993-1004
        }
}
  • H. Valtin
  • Published 1 November 2002
  • Medicine
  • American journal of physiology. Regulatory, integrative and comparative physiology
Despite the seemingly ubiquitous admonition to "drink at least eight 8-oz glasses of water a day" (with an accompanying reminder that beverages containing caffeine and alcohol do not count), rigorous proof for this counsel appears to be lacking. This review sought to find the origin of this advice (called "8 x 8" for short) and to examine the scientific evidence, if any, that might support it. The search included not only electronic modes but also a cursory examination of the older literature… 

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References

SHOWING 1-10 OF 183 REFERENCES
Do elderly persons need to be encouraged to drink more fluids?
TLDR
Until the authors have more evidence-based documentation that fluid intake of eight glasses (2 liters) per day improves some aspect of an elderly person's health, encouraging a fluid intake above a level that is comfortable for the individual seems to serve little useful purpose.
Water: an essential but overlooked nutrient.
  • S. Kleiner
  • Medicine
    Journal of the American Dietetic Association
  • 1999
The diuretic effects of alcohol and caffeine and total water intake misclassification
  • J. Stookey
  • Medicine
    European Journal of Epidemiology
  • 2004
TLDR
Future studies of water–disease relationships, especially those intending to compare extremes of total water intake, should consider caffeine- and alcohol-related misclassification bias.
The Effect of Caffeinated, Non-Caffeinated, Caloric and Non-Caloric Beverages on Hydration
TLDR
The across-treatment weight loss observed suggests that optimal fluid intake may be higher than common recommendations, and advising people to disregard caffeinated beverages as part of the daily fluid intake is not substantiated by the results of this study.
Volume of food consumed affects satiety in men.
TLDR
The results indicate that the volume consumed is an important determinant of satiety after milk drinks under these conditions, and the best adjustment for the energy in the preloads was with the largest, least energy-dense drink.
Body fluid changes, thirst and drinking in man during free access to water
Water incorporated into a food but not served with a food decreases energy intake in lean women.
TLDR
Consuming foods with a high water content more effectively reduced subsequent energy intake than did drinking water with food.
Drinking water with a meal: a simple method of coping with feelings of hunger, satiety and desire to eat.
TLDR
The results show that drinking two glasses of water affects subjective feelings of hunger and satiety during the meal, but this effect is not maintained after the meal.
Water consumption in the United States in 1994-96 and implications for water fluoridation policy.
TLDR
It is suggested that water fluoridation policy requires further research regarding water consumption and climate, and no obvious strong or consistent association between water intake and month or season was apparent in these recent data.
Coffee consumption and total body water homeostasis as measured by fluid balance and bioelectrical impedance analysis.
TLDR
To investigate the impact of coffee consumption on fluid balance, 12 healthy volunteers were supplied with a standardized diet for 2 days after having abstained from consumption of methylxanthines for 5 days and urine excretion was elevated and urinary excretion of sodium and potassium was elevated.
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