This document summarizes 4 studies that examined the effects of caffeine consumption on hydration status. The studies involved randomized controlled trials with participants consuming moderate amounts of caffeine from sources like coffee or caffeinated beverages. The studies found no significant effects of caffeine intake on hydration as assessed by measures of total body water, body weight changes, and biochemical markers. The document concludes that caffeine consumption does not appear to have adverse effects on hydration status.

1. Introduction Results, continued Results, continued
Methods
References
Primary research regarding caffeine and hydration status was obtained from 4 scholarly
journals. Eligible articles had participants ages 18-60, were community dwelling, and had
no previous nutritional related problems. The primary research studies had to be an
experimental study design, study population of at least 10 persons, and a drop out rate of
no less than 50%. Research must have been published after the year 2000 and have
been peer-reviewed. Key terms used for the eligible papers were “coffee”, “hydration
status” and “caffeine.” Research articles were extracted from multiple databases. We
used a search engine which utilized the following databases: Academic Search
Complete, SPORTDiscussion, Environment Complete, and Business source complete,
revealing 26 eligible articles. We excluded a studies that had participants with signs of
acute or chronic illness and studies with an observational design. Majority of articles
were excluded due to titles and descriptions that match the search criteria4 articles were
identified that matched our criteria and are summarized in our conclusion.
During 11 days of controlled caffeine consumption including 59 males ages 18-34,
subjects were given nutritional education by an RD on how to properly record fluid
consumption3. Design involved 3 randomized caffeine dose groups that were based on
% body fat and age. Day 1-6 subjects consumed 3mg/kg of caffeine via capsules. Days
7-11 each subject consumed either a placebo or 226mg-452mg of caffeine. There was no
significant influence on hydration status3.
Everyday 54% of Americans over the age of 18 drink coffee5. Coffee is a tropical green
shrub (genus, Coffee) that grows in warm climates7. Approximately 50 countries in
Central and South America, Africa, and Asia grow coffee on a commercial basis5.
Roast or ground coffee contains about 85mg of caffeine per cup, this can range from
60-135mg and is about 95% water6. Approximately 55mg of caffeine is in 30 ml of
expresso and about 35 mg of caffeine in a cola can or cup of tea. Caffeine can be
found in expresso, tea, chocolate, soft drinks, and energy drinks. Caffeine takes about
45 minutes to be absorbed by body tissues. Caffeine has a half-life of about 4 hours
and is metabolized through the liver6.
Discussion
Results
A counterbalanced cross-over study in a free-living population including 52, non-
smoking males ages 18-46 were randomly allocated to a treatment group1.
Intervention and control trial consumed 200mL of black coffee or water per day
(4mg/kg of body weight of caffeine) respectively. Results showed no significant
differences in the hydrating properties of coffee or water across a wide range of
hydration assessment indices. Additionally, there were no significant differences
between other characteristics that were measured (hematological markers, BUN,
serum creatinine, urinary data, and total body weight)1.
.
1. Snetselaar LGKiller SC, Blannin AK, Jeukendrup AE. No Evidence of Dehydration with Moderate Daily Coffee Intake: A Counterbalanced Cross-Over
Study in a Free Living Population.
2. Fiala KA, Casa DJ, Roti MW. Rehydration with a Caffeinated Beverage During the Nonexercise Periods of 3 Concsecutive Days of a 2-a-Day
Practices.Int J of Sport Nutr and Exc Metab. 2004 (14)419-429.
3. Armstrong L, Pumerantz A, Roti M, Judelson D, Watson G, Dias J, Sokmen B, Casa D, Maresh C, Lieberman H, Kellogg M. Fluid, electrolyte, and
renal indices of hydration during 11 days of controlled caffeine consumption. Int J Sport Nutr & Exc Metab. 2005:252-265.
4. Silva A, Juice P, Matias C, Santos D, Magalhaes J, St-Onge MP, Goncalves E, Armada-da-Silva P, Sardinha L. Total body water and its
compartments are not affected by ingesting a moderate dose of caffeine in healthy young adult males. Appl Psysiology Nutr. & Metab. 2013; 38(6): 626-
633.
5. Coffee by the Numbers. Harvard School of Public Health. http://www.hsph.harvard.edu/news/multimedia-article/facts/. Published in 2016. Accessed
February 22, 2016.
6.Coffee, caffeine & hydration in the general population. Coffee and health: from the institute of scientific information on coffee.
http://coffeeandhealth.org/topic-overview/coffee-caffeine-hydration-in-the-general-population/. Published 2016. Accessed January 28th, 2016.
7.History of Coffee. National Coffee Association. Ncausa.org. Accessed March 3rd 2016.
A strength of this review is the reliability of study designs from the chosen articles
(randomized controlled trials). Limitations of the review includes the lack of
descriptions for handing of withdrawals for 3 out of the 4 reviewed articles. In
relation to health care, practitioners should not discourage clients from
consuming caffeine on the basis that caffeine will have adverse effects on
hydration status.
ACKNOWLEDGEMENT: The authors would like to thank Dr. Brenda Marques,
for guidance with project design and implementation.
Table 1
Total body water and its compartments are not affected by ingesting a moderate
dose of caffeine in the target population of 30 healthy non-smoking males 20-39
years of age4. The study design was a double-blind crossover including a
caffeine intervention. Caffeine capsules were given in 5 mg/kg of body mass.
Results indicate that there were no changes in hydration with caffeine intake4.
Rehydration with a caffeinated beverage during non-exercise period of 3
consecutive days of 2-a-day practices included10 subjects with a median age of
242. Participants were generally of healthy weight, and habitual coffee
consumers. Each subject completed 2 double-blind, random, cross-over design
trails, each 3 days in duration. On days 1-3 the intervention group received
caffeine rehydrated Coca Cola (250 mg/day) and the control group received
caffeine free rehydrated Coca Cola. Results showed no significant changes in
body weight or in lab values (hematocrit, hemoglobin, plasma osmolality, urine
color, urine osmolality, or thirst)2.