Bellizzi V, De Nicola L, Minutolo R, Russo D, Cianciaruso B, Andreucci M, Conte G, Andreucci V E
Division of Nephrology, School of Medicine, University Federico II, Naples, Italy.
Nephron. 1999;81 Suppl 1:66-70. doi: 10.1159/000046301.
Both amount and timing of dietary calcium intake influence the recurrence of renal calcium stones. We have evaluated whether the hardness of extra meal drinking water modifies the risk for calcium stones. The urinary levels of calcium, oxalate and citrate, i.e., the main urinary risk factors for calcium stones, were measured in 18 patients with idiopathic nephrolithiasis, maintained at fixed dietary intake of calcium (800 mg/day), after drinking for 1 week 2 liters per day, between meals, of tap water and at the end of 1 week of the same amount of bottled hard (Ca2+ 255 mg/l) or soft (Ca2+ 22 mg/l, Fiuggi water) water, in a double-blind randomized, crossover fashion. As compared with both tap and soft water, hard water was associated with a significant 50% increase of the urinary calcium concentration in the absence of changes of oxalate excretion; the calcium-citrate index revealed a significant threefold increase during ingestion of hard water as compared with respect to soft water (Fiuggi water), making the latter preferable even when compared with tap water. This study suggests that, in the preventive approach to calcium nephrolithiasis, the extra meal intake of soft water is preferable to hard water, since it is associated with a lower risk for recurrence of calcium stones.
膳食钙摄入量的多少和时间都会影响肾钙结石的复发。我们评估了餐外饮用水的硬度是否会改变钙结石的风险。在18例特发性肾结石患者中，保持固定的钙膳食摄入量（800毫克/天），以双盲随机交叉方式，在餐间每天饮用2升自来水1周后，以及饮用相同量的瓶装硬水（钙含量255毫克/升）或软水（钙含量22毫克/升，菲尤吉水）1周结束时，测量了尿液中钙、草酸盐和柠檬酸盐的水平，即钙结石的主要尿液风险因素。与自来水和软水相比，硬水在草酸盐排泄无变化的情况下，会使尿钙浓度显著增加50%；与软水（菲尤吉水）相比，饮用硬水期间钙-柠檬酸盐指数显著增加了两倍，这使得软水即使与自来水相比也更可取。这项研究表明，在预防钙肾结石方面，餐外摄入软水比硬水更可取，因为它与钙结石复发风险较低有关。
