Phenotype X said:
I've heard of a study that relates caffeine consumption to water depletion in the body of the vertebrae? is that true Anthrax?
yes, caffeine is diuretic:
Diuretic Effects of Caffeine
Depending on several factors, the diuretic effects caused by caffeine can be considered weak to negligible under normal caffeine consumption and for people without urinary tract problems. However, it is difficult to measure the effects, even in a laboratory situation. A study by Nussberger et al. (1) does not show a significant increase of urine excretion when comparing intake of drinks containing caffeine to the water control intake. Transitory effects have been reported by Neuhäuser-Berthold et al. (2) when passing from abstinence to an elevated dose or when a chronic intake is followed by massive absorption. Such transitory imbalances disappear after less than an hour. A study by Martof and Knox (3) concluded that there is no evidence to recommend that xanthines should be omitted when forcing fluids. Even in a recent epidemiological study attempting to classify alcohol and caffeine as diuretic substances (4) , the author admits that there are no estimates of the chronic effect of caffeine on diuresis under variable free-living conditions. Caffeine also causes smooth muscle relaxation particularly in relation to the function of lungs and the blood vessels. Its effect on the detrusor muscle, which is involved in bladder function, has been studied. A control study (5) showed that consumption of caffeine led to a rise in pressure on the detrusor muscle upon bladder filling but not to a diuretic effect as such. Women with normal bladder function were not significantly affected by caffeine. A more recent study (6) confirmed an association between high caffeine intake and detrusor instability in a population of women with symptoms of urinary incontinence.
The beneficial effects of caffeine on endurance exercise performance were discussed in an earlier section. However, there has been concern that use of caffeine during exercise might exacerbate dehydration induced by exercise. Consequently, it has usually been accepted that beverages containing caffeine should not be used to promote fluid replacement during prolonged exercise. Wemple and collaborators (7) , however, demonstrated that the presence of caffeine in drinks, taken before moderate endurance exercise, did not compromise hydration of the body, even though it did cause weak diuresis during rest. In a study aimed at assessing the effects of caffeine on endurance Graham and collaborators (8) did not observe differences among their trials in the volume of urine produced during preexercise and postexercise when comparing different fluids, decaffeinated coffee, placebo capsules, decaffeinated coffee with caffeine added, regular coffee and caffeine capsules.
Patients with kidney stones are routinely advised to increase their fluid intake. Questions arise such as: is the type of beverage important and will the presence of caffeine, which may cause weak diuresis, pose a problem for such patients? In two prospective studies Curhan et al (9,10) , found that greater intakes of regular and decaffeinated coffee, tea, beer and wine were associated with a decreased risk of stone formation, whereas greater intakes of apple and grapefruit juices were related to increased risk. Leitzmann et al (11) using the same mass of data suggested that decaffeinated coffee was not associated with decreased risk, but agreed with Curhan and concluded that the adjusted relative risk for those who regularly drank caffeinated coffee decreased very significantly.
Nussberger, J. et al. Journal of cardiovascular Pharmacology, 15, 685-691, 1990.
Neuhäuser-Berthold, M. et al. Annals of Nutrition & Metabolism, 41, 29-36, 1997.
Martof, M.T. and Knox, D.K., Clinical Nursing Research, 6, 186-196, 1997.
Stookey, J.D., European Journal of Epidemiology, 15, 181-188, 1999
Creighton, S.M. and Stanton, S.L. British Journal of Urology, 66, 613-614, 1990.
Arya, L.A. et al. Obstetrics & Gynecology, 96, 85-89, 2000.
Wemple, R.D. et al. International Journal of Sports Medicine, 18, 40-46, 1997.
Graham, T.E. et al. Journal of Applied Physiology, 85, 883-889, 1998.
Curhan, G.C. et al. American Journal of Epidemiology, 143, 240-247, 1996.
Curhan, G.C. et al. Annals of Internal Medicine, 128, 534-540, 1998.
Leitzmann, M.F. et al. Journal of American Medical Association, 281, 2106-2112, 1999.
Please Scroll Down to See Forums Below 
