Coffee consumption and bone mineral density in dialysis patients

The influence of ingested coffee on bone mineral density (BMD) and the related risk of pathologic fractures is controversial. We decided to check if dialysis patients drinking coffee may have a BMD different from that of non coffee drinkers. We studied 30 dialysis patients (26 on hemodialysis, 4 on peritoneal dialysis). Group I (n = 11, 5 women) included patients who regularly drank at least 1 cup of coffee daily [dialysis duration: 29.1 months (range: 8.7- 59.6 months); age: 56.0 +/- 14.6 years]. Group II (n = 19, 13 women) consisted of patients who said that they were nondrinkers of coffee [dialysis duration: 15.2 months (range: 6.3 - 45.4 months); age: 56.3 +/- 19.8 years]. We examined BMD in all subjects in two sites (femoral neck and L2 - L4 lumbar region) by dual-energy X-ray absorptiometry. Serum parathyroid hormone, calcium-phosphate balance parameters, blood pH, serum markers of inflammation, bioimpedance records of body composition, and markers of nutrition were simultaneously evaluated. Compared with group II, group I showed significantly lower L2 -L4 parameters: BMD (0.906 +/- 0.236 g/cm2 vs. 1.172 +/- 0.227 g/cm2, p = 0.005), percent of peak BMD (78.4% +/- 18.9% vs. 98.4% +/- 17.0%, p = 0.006), percent of age norm (82.7% +/- 18.2% vs. 105.9% +/- 17.7% p = 0.002), T-score [-2.07 (range: -3.95 to 2.02) vs. -0.51 (range: -2.29 to 4.07), p = 0.020], and Z-score [-1.25 (range: -4.41 to 1.90) vs. 0.26 (range: -1.48 to 4.49), p = 0.006]. Serum albumin concentration was higher in group I [4.0 g/dL (range: 3.1 - 4.3 g/dL) vs. 3.3 g/dL (range: 2.9 - 4.4 g/dL), p = 0.020]. Our results suggest that regular coffee consumption may contribute to BMD loss in dialysis patients.