Goldfarb D S, Asplin J R
Kidney Stone Prevention and Treatment Programs, New York Veterans Affairs Medical Center, New York, New York, USA.
J Urol. 2001 Jul;166(1):263-7.
An increased risk of nephrolithiasis has been associated with the ingestion of grapefruit juice in epidemiological studies. To our knowledge the basis of this effect of grapefruit juice has not been studied previously. We studied the effect of grapefruit juice consumption on urinary chemistry and measures of lithogenicity.
Ten healthy men and women between ages of 25 and 40 years participated. Each subject drank 240 ml. of tap water at least 3 times daily for 7 days during the control period. This period was followed by a second 7 days experimental period during which they drank 240 ml. of grapefruit juice 3 times daily. In each 7-day period urine was collected for 24 hours during the last 3 days. Urine chemical analysis was performed, supersaturations of calcium oxalate, calcium phosphate and uric acid were calculated and urinary lithogenicity was measured.
Urine volume and creatinine excretion were the same during the control and experimental periods. Grapefruit juice ingestion was associated with an increase in mean oxalate excretion plus or minus standard deviation of 41.1 +/- 9.2 to 51.9 +/- 12.0 mg. per 24 hours (p = 0.001) and in mean citrate excretion of 504.8 +/- 226.5 to 591.4 +/- 220.0 mg. per 24 hours (p = 0.01). There was no net change in the supersaturation or upper limit of metastability of calcium oxalate, calcium phosphate or uric acid. Crystal aggregation and growth inhibition by urinary macromolecules was not affected by grapefruit juice ingestion.
Offsetting changes in urine chemistry caused by the ingestion of grapefruit juice led to no net change in calculated supersaturation. No changes in lithogenicity were demonstrated. The results do not demonstrate an effect of grapefruit juice for increasing lithogenicity. The basis of the observations of epidemiological studies remain unexplained.
在流行病学研究中，肾结石风险增加与摄入葡萄柚汁有关。据我们所知，此前尚未对葡萄柚汁这种作用的基础进行研究。我们研究了饮用葡萄柚汁对尿液化学成分及结石形成倾向指标的影响。
10名年龄在25至40岁之间的健康男性和女性参与研究。在对照期，每位受试者每天至少饮用3次240毫升的自来水，持续7天。在此期间之后是第二个为期7天的实验期，在此期间他们每天饮用3次240毫升的葡萄柚汁。在每个7天周期的最后3天收集24小时尿液。进行尿液化学分析，计算草酸钙、磷酸钙和尿酸的过饱和度，并测量尿液结石形成倾向。
对照期和实验期的尿量和肌酐排泄量相同。摄入葡萄柚汁与平均草酸盐排泄量增加相关，从每24小时41.1±9.2毫克增加到51.9±12.0毫克（p = 0.001），平均柠檬酸盐排泄量从每24小时504.8±226.5毫克增加到591.4±220.0毫克（p = 0.01）。草酸钙、磷酸钙或尿酸的过饱和度或亚稳上限没有净变化。尿液中大分子对晶体聚集和生长的抑制作用不受摄入葡萄柚汁的影响。
摄入葡萄柚汁引起的尿液化学成分变化相互抵消，导致计算出的过饱和度没有净变化。未显示结石形成倾向有变化。结果未证明葡萄柚汁有增加结石形成倾向的作用。流行病学研究观察结果的基础仍未得到解释。
