***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Patients with kidney stones are routinely advised to increase their fluid intake to decrease the risk of stone recurrence . However , there has been no detailed examination to determine whether the effect on recurrence varies by the type of beverage consumed . The authors conducted a prospect i ve study of the relation between the intake of 21 different beverages and the risk of symptomatic kidney stones in a cohort of 45,289 men , 40 - 75 years of age , who had no history of kidney stones .  Beverage use and other dietary information was measured by means of a semiquantitative food frequency question naire in 1986 . During 6 years of follow-up ( 242,100 person-years ) , 753 incident cases of kidney stones were documented . After adjusting simultaneously for age , dietary intake of calcium , animal protein and potassium , thiazide use , geographic region , profession , and total fluid intake , consumption of specific beverages significantly added to the prediction of kidney stone risk ( p < 0.001 ) . After mutually adjusting for the intake of other beverages , the risk of stone formation decreased by the following amount for each 240-ml ( 8-oz ) serving consumed daily : caffeinated coffee , 10 % ( 95 % confidence interval 4 - 15 % ) ; decaffeinated coffee , 10 % ( 3 - 16 % ) ; tea , 14 % ( 5 - 22 % ) ; beer , 21 % ( 12 - 30 % ) ; and wine , 39 % ( 10 - 58 % ) . For each 240-ml serving consumed daily , the risk of stone formation increased by 35 % ( 4 - 75 % ) for apple juice and 37 % ( 1 - 85 % ) for grapefruit juice . The authors conclude that beverage type may have an effect on stone formation that involves more than additional fluid intake alone Pomegranate juice ( PJ ; also known as pomegreat pure juice ) provides a rich and varied source of polyphenolic compounds that may offer cardioprotective , anti-atherogenic and antihypertensive effects . The aim of this study was to investigate the effect of PJ consumption on glucocorticoids levels , blood pressure ( BP ) and insulin resistance in volunteers at high CVD risk . Subjects ( twelve males and sixteen females ) participated in a r and omised , placebo-controlled cross-over study ( BMI : 26·77 ( sd 3·36 ) kg/m2 ; mean age : 50·4 ( sd 6·1 ) years ) . Volunteers were assessed at baseline , and at weeks 2 and 4 for anthropometry , BP and pulse wave velocity . Cortisol and cortisone levels in urine and saliva were determined by specific ELISA methods , and the cortisol/cortisone ratio was calculated . Fasting blood sample s were obtained to assess plasma lipids , glucose , insulin and insulin resistance ( homeostasis model assessment of insulin resistance ) . Volunteers consumed 500 ml of PJ or 500 ml of a placebo drink containing a similar amount of energy . Cortisol urinary output was reduced but not significant . However , cortisol/cortisone ratios in urine ( P = 0·009 ) and saliva ( P = 0·024 ) were significantly decreased . Systolic BP decreased from 136·4 ( sd 6·3 ) to 128·9 ( sd 5·1 ) mmHg ( P = 0·034 ) , and diastolic BP from 80·3 ( sd 4·29 ) to 75·5 ( sd 5·17 ) mmHg ( P = 0·031 ) after 4 weeks of fruit juice consumption . Pulse wave velocity decreased from 7·5 ( sd 0·86 ) to 7·44 ( sd 0·94 ) m/s ( P = 0·035 ) . There was also a significant reduction in fasting plasma insulin from 9·36 ( sd 5·8 ) to 7·53 ( sd 4·12 ) mIU/l ( P = 0·025 ) and of homeostasis model assessment of insulin resistance ( from 2·216 ( sd 1·43 ) to 1·82 ( sd 1·12 ) , P = 0·028 ) . No significant changes were seen in the placebo arm of the study . These results suggest that PJ consumption can alleviate key cardiovascular risk factors in overweight and obese subjects that might be due to a reduction in both systolic and diastolic BP , possibly through the inhibition of 11β-hydroxysteroid dehydrogenase type 1 enzyme activity as evidence d by the reduction in the cortisol/cortisone ratio . The reduction in insulin resistance might have therapeutic benefits for patients with non-insulin-dependent diabetes , obesity and the metabolic syndrome OBJECTIVE The objective of the present study was to evaluate the effects of drinking 2 additional litres of water/day on several urinary risk factors for lithiasis in healthy subjects , through measurement of crystallization risk indices ( Tiselius CRI ) . MATERIAL S AND METHODS 48 healthy subjects , aged 25 to 50 were studied for urinary parameters including CRI in the laboratory ward , for 24 hours . After this first period , they were r and omized either to a 2L/d additional water intake ( treated group ) or usual fluid consumption ( control group ) for a 6 days period , which ended by a second measurement period in the laboratory ward for 24 hours . RESULTS Total additional water intake was actually 1.3L/d on average in treated subjects , because subjects decreased other usual sources of fluid intake . In 24 hour urine , Tiselius CRI varied differently among treated subjects and controls between the 2 periods ; male controls subjects experienced much higher values ( above 2 in average in first morning urine sample ) in the second period ( p = 0.05 ) . Of interest , in a transversal analysis , we observed a positive relation between BMI or waist circumference on the one h and , and with 24 hour urea excretion or osmotic load on the other h and . CONCLUSION These results show a beneficial effect of a final 1.3L additional water intake on Tiselius CRI in healthy subjects BACKGROUND A high dietary calcium intake is strongly suspected of increasing the risk of kidney stones . However , a high intake of calcium can reduce the urinary excretion of oxalate , which is thought to lower the risk . The concept that a higher dietary calcium intake increases the risk of kidney stones therefore requires examination . METHODS We conducted a prospect i ve study of the relation between dietary calcium intake and the risk of symptomatic kidney stones in a cohort of 45,619 men , 40 to 75 years of age , who had no history of kidney stones .  Dietary calcium was measured by means of a semiquantitative food-frequency question naire in 1986 . During four years of follow-up , 505 cases of kidney stones were documented . RESULTS After adjustment for age , dietary calcium intake was inversely associated with the risk of kidney stones ; the relative risk of kidney stones for men in the highest as compared with the lowest quintile group for calcium intake was 0.56 ( 95 percent confidence interval , 0.43 to 0.73 ; P for trend , < 0.001 ) . This reduction in risk decreased only slightly ( relative risk , 0.66 ; 95 percent confidence interval , 0.49 to 0.90 ) after further adjustment for other potential risk factors , including alcohol consumption and dietary intake of animal protein , potassium , and fluid . Intake of animal protein was directly associated with the risk of stone formation ( relative risk for men with the highest intake as compared with those with the lowest , 1.33 ; 95 percent confidence interval , 1.00 to 1.77 ) ; potassium intake ( relative risk , 0.49 ; 95 percent confidence interval , 0.35 to 0.68 ) and fluid intake ( relative risk , 0.71 ; 95 percent confidence interval , 0.52 to 0.97 ) were inversely related to the risk of kidney stones . CONCLUSIONS A high dietary calcium intake decreases the risk of symptomatic kidney stones We evaluated the possible effects of a calcium entry blocking agent “ verapamil ” on new stone formation and /or regrowth of residual fragments  after shock wave lithotripsy ( SWL )  during long-term follow-up ( > 30 months ) and compared the results with the success rates of adequate fluid intake . A total of 70 patients treated with SWL  were r and omly divided into three different groups , in the first two of which the patients received different preventive measures with respect to stone recurrence and /or regrowth . While 25 patients received a calcium channel blocking agent , verapamil hydrochloride , beginning 3 days before SWL and continued 4 weeks after the procedure , an additional 25 patients were put in an enforced fluid intake program and the remaining 20 patients received no specific medication and /or measure apart from close follow-up . Patients were followed regularly with respect to the clearance/regrowth of the residual fragments and that of new stone formation during long-term follow-up ( within a mean follow-up of 30.4 months ) . The overall stone recurrence rate was 14 % ( 10/70 ) . Of the patients who became stone free ( 12/25 , 48 % ) in group I , only one patient ( 1/12 , 8.3 % ) showed a new stone formation during long-term follow-up . The figure was 40 % ( 4/10 ) in group II patients and 55 % ( 5/9 ) in group III patients receiving no specific medication . Regarding the residual stone fragments ( < 5 mm ) after SWL , again high fluid intake was found to be the most effective on stone regrowth rates ( 2/13 , 15.3 % ) . Patients treated with verapamil also had acceptable regrowth rates ( 3/15 , 20 % ) . Finally , verapamil treatment significantly improved the clearance of residual fragments ; while 7 out of 15 patients with residual fragments passed these particles successfully , ( 46.5 % ) in this group ; these figures were 46 % ( 6/13 ) and 18 % ( 2/13 ) in the remaining groups . Residual fragments located in lower calyces demonstrated a poor clearance rate with higher regrowth rates .  Verapamil administration was found to be effective enough to limit the regrowth of residual fragments and also to facilitate residual fragment clearance after SWL . Patients receiving this medication seemed to pass the retained fragments easily in a shorter time than the others Diet plays an important role in the pathogenesis of kidney stones . Because the metabolism of many dietary factors , such as calcium , may change with age , the relation between diet and kidney stones may be different in older adults . Uncertainty also remains about the association between many dietary factors , such as vitamin C , magnesium , and animal protein , and the risk of kidney stone formation . To examine the association between dietary factors and the risk of incident , symptomatic kidney stones in men and to determine whether these associations vary with age , a prospect i ve cohort study was conducted of 45,619 men without a history of nephrolithiasis .  Self-administered food frequency question naires were used to assess diet every 4 yr . A total of 1473 incident symptomatic kidney stones  were documented during 477,700 person-years of follow-up . For men aged < 60 yr , the multivariate relative risk ( RR ) for stone formation in the highest quintile of dietary calcium as compared with the lowest quintile was 0.69 ( 95 % confidence interval [ CI ] , 0.56 to 0.87 ; P = 0.01 for trend ) . By contrast , there was no association between dietary calcium and stone formation in men aged 60 yr or older . The multivariate RR for men who consumed 1000 mg or greater of vitamin C per day compared with those who consumed less than the recommended dietary allowance of 90 mg/d was 1.41 ( 95 % CI , 1.11 to 1.80 ; P = 0.01 for trend ) . Other dietary factors showed the following multivariate RR among men in the highest quintile of intake compared with those in the lowest : magnesium , 0.71 ( 95 % CI , 0.56 to 0.89 ; P = 0.01 for trend ) ; potassium , 0.54 ( 95 % CI , 0.42 to 0.68 ; P < 0.001 for trend ) ; and fluid , 0.71 ( 95 % CI , 0.59 to 0.85 ; P < 0.001 for trend ) . Animal protein  was associated with risk only in men with a body mass index < 25 kg/m(2 ) ( RR , 1.38 ; 95 % CI , 1.05 to 1.81 ; P = 0.03 for trend ) . Sodium , phosphorus , sucrose , phytate , vitamin B(6 ) , vitamin D , and supplemental calcium were not independently associated with risk . In conclusion , the association between calcium intake and kidney stone formation varies with age . Magnesium intake decreases and total vitamin C intake seems to increase the risk of symptomatic nephrolithiasis . Because age and body size affect the relation between diet and kidney stones , dietary recommendations for stone prevention should be tailored to the individual patient PURPOSE We define the role of urine volume as a stone risk factor in idiopathic calcium 
    Output:
    
The evidence from only one study indicates that increased water intake reduces the risk of recurrence of urinary stones and prolongs the average interval for recurrences .
Due to the lack of appropriate RCTs , no conclusions can be drawn on increased water intake for the primary and secondary prevention of urinary stones