Effects of Lactobacillus casei and Bifidobacterium breve on urinary oxalate excretion in nephrolithiasis patients.

It had been suggested that lactic acid bacteria (LAB) may degrade oxalate in the intestinal lumen, reducing urinary oxalate excretion. We aimed to evaluate the effect of a LAB mixture containing Lactobacillus casei (LC) and Bifidobacterium breve (BB) (LC + BB) upon urinary oxalate reduction in stone-forming (SF) patients without hyperoxaluria under conditions of an oxalate-rich diet. After an oxalate restriction period (7 days washout), 14 SF patients consumed an oxalate-rich diet during 4 weeks (200 mg/day) and a lyophilized LC + BB preparation was given t.i.d. after meals during the last 2 weeks. Twenty-four-hour urine samples were collected for determination of oxalate, calcium, magnesium, citrate, sodium, potassium and creatinine at baseline, after 2 weeks (DIET) and 4 weeks (DIET + LC + BB). The mean urinary oxalate excretion was significantly higher after DIET versus baseline (27 +/- 8 vs. 35 +/- 11 mg/24 h), but the mean decrease was not significant between DIET + LC + BB and DIET periods (35 +/- 11 vs. 33 +/- 10 mg/24 h). Seven out of 14 patients presented a reduction in oxaluria after LC + BB versus DIET, being the reduction higher than 25% in 4, and up to 50% in 2 of them. The latter two patients were those who had presented the greatest increase in oxaluria in response to dietary oxalate. In conclusion, this mixture of L. casei and B. breve was shown to possess a variable lowering effect upon urinary oxalate excretion that may be dependent on dietary oxalate intake.

Influence of muscle mass and physical activity on serum and urinary creatinine and serum cystatin C.

BACKGROUND AND OBJECTIVES: For addressing the influence of muscle mass on serum and urinary creatinine and serum cystatin C, body composition was assessed by skinfold thickness measurement and bioelectrical impedance analyses. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A total of 170 healthy individuals (92 women, 78 men) were classified as sedentary or with mild or moderate/intense physical activity. Blood, 24-h urine samples, and 24-h food recall were obtained from all individuals. RESULTS: Serum and urinary creatinine correlated significantly with body weight, but the level of correlation with lean mass was even greater. There was no significant correlation between body weight and lean mass with cystatin C. Individuals with moderate/intense physical activity presented significantly lower mean body mass index (23.1 +/- 2.5 versus 25.7 +/- 3.9 kg/m(2)) and higher lean mass (55.3 +/- 10.0 versus 48.5 +/- 10.4%), serum creatinine (1.04 +/- 0.12 versus 0.95 +/- 0.17 mg/dl), urinary creatinine (1437 +/- 471 versus 1231 +/- 430 mg/24 h), protein intake (1.4 +/- 0.6 versus 1.1 +/- 0.6 g/kg per d), and meat intake (0.7 +/- 0.3 versus 0.5 +/- 0.4 g/kg per d) than the sedentary individuals. Conversely, mean serum cystatin did not differ between these two groups. A multivariate analysis of covariance showed that lean mass was significantly related to serum and urinary creatinine but not with cystatin, even after adjustment for protein/meat intake and physical activity. CONCLUSIONS: Cystatin C may represent a more adequate alternative to assess renal function in individuals with higher muscle mass when mild kidney impairment is suspected.