REPLY
Grapefruit Juice and Kidney Stones
Gary C. Curhan, MD, ScD, and
Meir J. Stampfer, MD, DrPH
1 December 1998 | Volume 129 Issue 11 Part 1 | Page 913
IN RESPONSE:
We agree with Dr. Ameer that it would be scientifically and clinically interesting to determine the mechanism by which drinking grapefruit juice may increase the risk for kidney stone formation. It is unlikely to be due to the oxalate content of grapefruit juice itself, which is relatively low. Perhaps grapefruit juice increases oxalate absorption from other dietary sources, but no data on this are available.
It is interesting to speculate about certain components of grapefruit juice, but it is unlikely that the proposed mechanism for naringin is responsible. Naringin is found in both oranges and grapefruits. We found no association between orange juice and risk for stone formation in women or men [1]. In addition, binding of calcium by naringin in the blood would not necessarily lead to an increase in the glomerular filtration of calcium. Unbound calcium is freely filtered at the glomerulus, so there is no need to have it delivered to the renal system. Furthermore, if naringin binds tightly to calcium, this may reduce the actual amount of calcium filtered and act as a natural inhibitor of crystal formation in the urine by interfering with the interaction between calcium and oxalate. Additional studies are needed to examine the effect of grapefruit juice on known urinary factors.
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Author and Article Information
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Brigham and Women's Hospital; Boston, MA 02115
1. Curhan GC, Willett WC, Rimm EB, Spiegelman D, Stampfer MJ. Prospective study of beverage use and the risk of kidney stones. Am J Epidemiol. 1996; 143:240-7.
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