British Coffee Association - Fluid Intake
Fluid Intake

Fluid Intake

Young businessman drinking coffeeWater, as the principal constituent of the body, accounts for 50 to 70 per cent of total body weight and is essential to our well-being. It is generally recommended that we consume about 1.5 to 2 litres of fluid per day.

Coffee and Fluid Intake

Consumers of coffee are frequently being wrongly advised to cut down on their consumption because the caffeine in coffee is a diuretic and drinking coffee will result in dehydration. This is out of date information and is simply not true! Recent research has shown that caffeine, as commonly consumed in coffee, is no more a diuretic than water and concludes that ‘scientific evidence does not support the claim that caffeine-containing beverages promote dehydration' 1,2,3. In January 2014, a Birmingham University study made national headlines because research found no evidence of a link between moderate coffee consumption and dehydration.4 

The British Dietetic Association and other UK expert bodies such as the British Nutrition Foundation are in agreement that moderate coffee consumption (up to four to five cups per day) can contribute to daily fluid intake and will help to keep coffee consumers alert and hydrated.1,2,3 Similarly, proceedings from a conference in North America advised consumers that drinking a variety of caffeinated beverages, including coffee, can contribute to meeting the body’s requirement for fluids5 – not surprising when it is considered that a cup of black coffee contains more than 95% water.6

A diuretic is defined as any substance that increases the production of urine – put simply this means anything that makes you want to pass water. Although caffeine does have a mild diuretic effect, it is not true to say that drinking caffeine-containing drinks in moderation will result in dehydration. Coffee, along with other popular hot and cold drinks, is accepted as being an important source of fluid in the diet when consumed in moderation. Contrary to popular advice you DO NOT need to drink more water to compensate for consuming caffeinated drinks 7.

Summary

The diuretic effect of caffeine, as consumed in a cup of coffee, can be considered weak to negligible and certainly no greater than the effects seen when drinking plain water. For people following calorie-controlled diets, black coffee or coffee with skimmed milk and no sugar contains virtually no calories at all, so can be an important source of fluid that will not affect weight gain. Moderate coffee consumption, of four to five cups per day, can contribute to a healthy, balanced diet for the general population, and may confer health benefits. Pregnant women should however moderate their intake following the guidelines issued by the Food Standards Agency, to 200mg caffeine per day from all sources.



1. Kolasa K.M. et al. (2009) Hydration and health promotion. Nutr Today; 44, 190-203.
2. Goldstein E.R. et al. (2010) Caffeine enhances upper body strength in resistance trained athletes. J. Int Soc Sports Nut; 7.
3. Armstrong L.E. (2007) Exercise and Sports Science Reviews, Volume 35.
4. Killer, S.C. et al. (2014) No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population, PLOS ONE.
5. Kolasa, K.M. et al. (2009) Hydration and health promotion. Nutrition Today; 44, 190-203.
6. British Nutrition Foundation. (2014) http://www.foodafactoflife.org.uk/attachments/b5784ad9-550d-41fee2e7a4dd.pdf, accessed August 2014.
7. Armstrong L.E. (2005) International Journal of Sport Nutrition & Exercise Metabolism, Volume 14.