dream
08-19-2005, 00:30
I keep seeing this all the time "caffeine is a diuretic!""Don't drink cokes/coffee it will dehydrate you" on whiteblaze .Thats just bad science (I was gonna say a flat out lie). It is just as much of a diuretic as water. These studies (around 9 so far) were done in 2002 there's no reason why this myth needs to be perpetuated 3 years later. I am providing full text of the articles and links to the pages. This is old news folks. Sorry to burst those bubbles. This isn't secret info and yes it has been published in tons of medical journals so it's not just " E-medicine ".
COFFEE AND KIDNEY FUNCTION
The effects of coffee or caffeine consumption on several aspects of kidney function have been studied including diuresis, detrusor instability and kidney stones.
Increased urine output over a 24 hour period was observed with high coffee intake (aprroximately 6 cups equating to 642mg caffeine) though such effects have not been confirmed at levels below 300mg (1).
Athletes and physically active people are often recommended to abstain from consuming caffeinated beverages. It is assumed that caffeine, which is a mild diuretic, will exaggerate the dehydration and electrolyte loss caused by exercise and lead to impaired athletic performance or health although no scientific evidence is offered in support of this assumption. Nine studies, which have looked at the effects of caffeine consumption on the volume of urine, have recently been reviewed (2). The author wrote in his abstract that “The scientific literature suggests that athletes and recreational enthusiasts will not incur detrimental fluid-electrolyte imbalances if they consume caffeinated beverages in moderation and eat a typical U.S. diet”.
Two of these nine studies are particularly informative. The first study was one to collect urine over a 24-hour period (3). It was found that there were no significant differences in the volume of urine produced in response to water, 114 mg caffeine or 253 mg caffeine. The second study was the only one to measure urine production during exercise (4). It was observed that a single dose of 8.7 mg caffeine per kg body weight led to a significant increase in urine production vs. placebo at rest but a non-significant reduction in urine production by comparison with placebo both at rest and during cycling exercise.
A recently published large cross sectional study of 27,936 Norwegian women found that coffee consumption was not significantly associated with urinary incontinence (5). This confirms the results of three earlier but smaller studies (6,7,8). Patients with symptoms of urgency and frequency due to detrusor muscle instability often complain that their symptoms are exacerbated by drinking coffee or tea. It has been shown that a single dose of 200 mg caffeine significantly increased detrusor pressure in 20 women with confirmed detrusor instability but not in 10 asymptomatic women (9). Although a study of 41 elderly women found that a decrease in the amount of caffeine consumed was associated with fewer episodes of involuntary urine loss, this association was not significant (10). In a case control study of 131 women with detrusor instability and 128 controls, caffeine intake was significantly higher in cases than in controls (11). Cohort studies and intervention trials are required to confirm these results.
A high fluid intake is the oldest existing treatment for kidney stones. However, recent research suggests that the composition of the fluid may also exert a beneficial influence. An early case control study was the first to show an inverse association between coffee consumption and a history of kidney stones (12). In a subsequent cohort study of 45,289 men in the USA, 753 new cases of kidney stones were diagnosed and the risk of developing a stone fell by 10% in response to 240 ml/day of caffeinated or decaffeinated coffee (13). In a cohort study of 81,093 women in the USA, 719 new cases of kidney stones were identified and the risk of developing a stone fell by 10% in response to 240 ml caffeinated and 9% in response to 240 ml decaffeinated coffee (14). The available evidence consistently demonstrates that coffee consumption lowers the risk of developing a kidney stone.
References:
1.Neuhauser-Berthold, M. et al. Annals of Nutrition & Metabolism,41, 29-36, 1997.
2. Armstrong, L.E. International Journal of Sport Nutrition and Exercise Metabolism, 12, 189-206, 2002.
3. Grandjean, A.C. et al. Journal of the American Collegeof Nutrition, 19, 591-600, 2000.
4. Wemple, R.D. et al. International Journal of Sports Medicine, 18, 40-46, 1997.
5. Hannestad, Y.S. et al. British Journal of Obstetrics and Gynaecology, 110, 247-254, 2003.
6. Burgio, K.L. et al. Journal of Urology, 146, 1255-1259, 1991.
7. Brown, J.S. et al. Obstetrics and Gynecology, 87, 715-721, 1996.
8. Roe, B. and Doll, H. Journal of Wound, Ostomy and Continence Nursing, 26, 312-319, 1999.
9. Creighton, S.M. and Stanton, S.L. British Journal of Urology, 66, 613-614, 1990.
10. Tomlinson, B.U. et al. International Urogynecology Journal, 10, 22-28, 1999.
11. Arya, L.A. et al. Obstetrics and Gynecology, 96, 85-89, 2000.
12. Shuster, J. et al. Journal of Chronic Disease, 38, 907-914, 1985.
13. Curhan, G.C. et al. American Journal of Epidemiology, 143, 240-247, 1996.
14. Curhan, G.C. et al. Annals of Internal Medicine, 128, 534-540, 1998.
Armstrong's Study Shows Caffeine Does Not Increase Dehydration
By Janice Palmer
Caffeine is not the diuretic demon people are often told to avoid during exercise or while working in extreme environmental conditions.
In fact, caffeine is no more a diuretic than water, according to a research review article by Larry Armstrong, a professor of exercise and environmental physiology at the Neag School of Education.
http://www.advance.uconn.edu/images/javacup.jpg
For decades, health and exercise experts have warned that consuming caffeine and caffeinated beverages can lead to dehydration. But Armstrong, an avid runner and a well respected scientist in the fields of thermo-regulation and human performance, observed evidence to the contrary, so he investigated whether abstaining from caffeinated beverages was scientifically and physiologically justifiable.
"While there have been several studies done that show caffeine is a mild diuretic, there is no evidence that exercise, when combined with the consumption of caffeine or caffeinated beverages, will result in chronic dehydration, and this is contrary to the advice of most exercise physiologists, physicians and dieticians," explains Armstrong, who has been conducting fluid balance research since 1980.
"Therefore, the health and performance of athletes and recreational enthusiasts will not be impaired if they consume caffeine and caffeinated beverages in moderation and eat a well-balanced diet," he says. The National Coffee Association funded his study.
Among his findings:
When caffeine or a caffeinated beverage is consumed, the body retains some of the fluid;
Caffeine consumption causes a mild diuresis very similar to that of water (water, when consumed in large volume, increases urine output);
There is no evidence that consumption of caffeinated beverages causes a fluid-electrolyte imbalance that is detrimental to health or exercise performance;
A person who regularly consumes caffeine has a higher tolerance to the diuretic effect;
The determination of safety or risk of consuming caffeine and caffeinated beverages depends on several factors, including the amount consumed and tolerance to caffeine.
For decades, caffeine has been a favorite stimulant for athletes trying to make weight or enhance muscle definition before competition. Both the National Collegiate Athletic Association (NCAA) and the International Olympic Committee classify caffeine as a banned substance, because of its ergogenic properties. But while there are instances of abnormal and unhealthy diuretic use by athletes, Armstrong reports that "these examples should not be interpreted to mean that the average person who participates in exercise several times a week would be jeopardizing his or her health by consuming one or two caffeinated products each day."
Because the scientific literature analyzed by Armstrong focused on moderate amounts of caffeine (one to four cups of coffee a day), he advises that further research be conducted to determine if chronic, high-dose caffeine consumed over several days results in fluid-electrolyte imbalances.
His findings were published in the June issue of the International Journal of Sport Nutrition and Exercise Metabolism and were recently presented at the American College of Sports Medicine conference in St. Louis, Missouri.
Links : http://www.advance.uconn.edu/2002/020722/02072207.htm
http://www.cosic.org/coffee-and-health/kidney-function
COFFEE AND KIDNEY FUNCTION
The effects of coffee or caffeine consumption on several aspects of kidney function have been studied including diuresis, detrusor instability and kidney stones.
Increased urine output over a 24 hour period was observed with high coffee intake (aprroximately 6 cups equating to 642mg caffeine) though such effects have not been confirmed at levels below 300mg (1).
Athletes and physically active people are often recommended to abstain from consuming caffeinated beverages. It is assumed that caffeine, which is a mild diuretic, will exaggerate the dehydration and electrolyte loss caused by exercise and lead to impaired athletic performance or health although no scientific evidence is offered in support of this assumption. Nine studies, which have looked at the effects of caffeine consumption on the volume of urine, have recently been reviewed (2). The author wrote in his abstract that “The scientific literature suggests that athletes and recreational enthusiasts will not incur detrimental fluid-electrolyte imbalances if they consume caffeinated beverages in moderation and eat a typical U.S. diet”.
Two of these nine studies are particularly informative. The first study was one to collect urine over a 24-hour period (3). It was found that there were no significant differences in the volume of urine produced in response to water, 114 mg caffeine or 253 mg caffeine. The second study was the only one to measure urine production during exercise (4). It was observed that a single dose of 8.7 mg caffeine per kg body weight led to a significant increase in urine production vs. placebo at rest but a non-significant reduction in urine production by comparison with placebo both at rest and during cycling exercise.
A recently published large cross sectional study of 27,936 Norwegian women found that coffee consumption was not significantly associated with urinary incontinence (5). This confirms the results of three earlier but smaller studies (6,7,8). Patients with symptoms of urgency and frequency due to detrusor muscle instability often complain that their symptoms are exacerbated by drinking coffee or tea. It has been shown that a single dose of 200 mg caffeine significantly increased detrusor pressure in 20 women with confirmed detrusor instability but not in 10 asymptomatic women (9). Although a study of 41 elderly women found that a decrease in the amount of caffeine consumed was associated with fewer episodes of involuntary urine loss, this association was not significant (10). In a case control study of 131 women with detrusor instability and 128 controls, caffeine intake was significantly higher in cases than in controls (11). Cohort studies and intervention trials are required to confirm these results.
A high fluid intake is the oldest existing treatment for kidney stones. However, recent research suggests that the composition of the fluid may also exert a beneficial influence. An early case control study was the first to show an inverse association between coffee consumption and a history of kidney stones (12). In a subsequent cohort study of 45,289 men in the USA, 753 new cases of kidney stones were diagnosed and the risk of developing a stone fell by 10% in response to 240 ml/day of caffeinated or decaffeinated coffee (13). In a cohort study of 81,093 women in the USA, 719 new cases of kidney stones were identified and the risk of developing a stone fell by 10% in response to 240 ml caffeinated and 9% in response to 240 ml decaffeinated coffee (14). The available evidence consistently demonstrates that coffee consumption lowers the risk of developing a kidney stone.
References:
1.Neuhauser-Berthold, M. et al. Annals of Nutrition & Metabolism,41, 29-36, 1997.
2. Armstrong, L.E. International Journal of Sport Nutrition and Exercise Metabolism, 12, 189-206, 2002.
3. Grandjean, A.C. et al. Journal of the American Collegeof Nutrition, 19, 591-600, 2000.
4. Wemple, R.D. et al. International Journal of Sports Medicine, 18, 40-46, 1997.
5. Hannestad, Y.S. et al. British Journal of Obstetrics and Gynaecology, 110, 247-254, 2003.
6. Burgio, K.L. et al. Journal of Urology, 146, 1255-1259, 1991.
7. Brown, J.S. et al. Obstetrics and Gynecology, 87, 715-721, 1996.
8. Roe, B. and Doll, H. Journal of Wound, Ostomy and Continence Nursing, 26, 312-319, 1999.
9. Creighton, S.M. and Stanton, S.L. British Journal of Urology, 66, 613-614, 1990.
10. Tomlinson, B.U. et al. International Urogynecology Journal, 10, 22-28, 1999.
11. Arya, L.A. et al. Obstetrics and Gynecology, 96, 85-89, 2000.
12. Shuster, J. et al. Journal of Chronic Disease, 38, 907-914, 1985.
13. Curhan, G.C. et al. American Journal of Epidemiology, 143, 240-247, 1996.
14. Curhan, G.C. et al. Annals of Internal Medicine, 128, 534-540, 1998.
Armstrong's Study Shows Caffeine Does Not Increase Dehydration
By Janice Palmer
Caffeine is not the diuretic demon people are often told to avoid during exercise or while working in extreme environmental conditions.
In fact, caffeine is no more a diuretic than water, according to a research review article by Larry Armstrong, a professor of exercise and environmental physiology at the Neag School of Education.
http://www.advance.uconn.edu/images/javacup.jpg
For decades, health and exercise experts have warned that consuming caffeine and caffeinated beverages can lead to dehydration. But Armstrong, an avid runner and a well respected scientist in the fields of thermo-regulation and human performance, observed evidence to the contrary, so he investigated whether abstaining from caffeinated beverages was scientifically and physiologically justifiable.
"While there have been several studies done that show caffeine is a mild diuretic, there is no evidence that exercise, when combined with the consumption of caffeine or caffeinated beverages, will result in chronic dehydration, and this is contrary to the advice of most exercise physiologists, physicians and dieticians," explains Armstrong, who has been conducting fluid balance research since 1980.
"Therefore, the health and performance of athletes and recreational enthusiasts will not be impaired if they consume caffeine and caffeinated beverages in moderation and eat a well-balanced diet," he says. The National Coffee Association funded his study.
Among his findings:
When caffeine or a caffeinated beverage is consumed, the body retains some of the fluid;
Caffeine consumption causes a mild diuresis very similar to that of water (water, when consumed in large volume, increases urine output);
There is no evidence that consumption of caffeinated beverages causes a fluid-electrolyte imbalance that is detrimental to health or exercise performance;
A person who regularly consumes caffeine has a higher tolerance to the diuretic effect;
The determination of safety or risk of consuming caffeine and caffeinated beverages depends on several factors, including the amount consumed and tolerance to caffeine.
For decades, caffeine has been a favorite stimulant for athletes trying to make weight or enhance muscle definition before competition. Both the National Collegiate Athletic Association (NCAA) and the International Olympic Committee classify caffeine as a banned substance, because of its ergogenic properties. But while there are instances of abnormal and unhealthy diuretic use by athletes, Armstrong reports that "these examples should not be interpreted to mean that the average person who participates in exercise several times a week would be jeopardizing his or her health by consuming one or two caffeinated products each day."
Because the scientific literature analyzed by Armstrong focused on moderate amounts of caffeine (one to four cups of coffee a day), he advises that further research be conducted to determine if chronic, high-dose caffeine consumed over several days results in fluid-electrolyte imbalances.
His findings were published in the June issue of the International Journal of Sport Nutrition and Exercise Metabolism and were recently presented at the American College of Sports Medicine conference in St. Louis, Missouri.
Links : http://www.advance.uconn.edu/2002/020722/02072207.htm
http://www.cosic.org/coffee-and-health/kidney-function