Quantitative assessment of citric acid in lemon juice, lime juice, and commercially-available fruit juice products.
OBJECTIVE
Knowledge of the citric acid content of beverages may be useful in nutrition therapy for calcium urolithiasis, especially among patients with hypocitraturia. Citrate is a naturally-occurring inhibitor of urinary crystallization; achieving therapeutic urinary citrate concentration is one clinical target in the medical management of calcium urolithiasis. When provided as fluids, beverages containing citric acid add to the total volume of urine, reducing its saturation of calcium and other crystals, and may enhance urinary citrate excretion. Information on the citric acid content of fruit juices and commercially-available formulations is not widely known. We evaluated the citric acid concentration of various fruit juices.


METHODS
The citric acid content of 21 commercially-available juices and juice concentrates and the juice of three types of fruits was analyzed using ion chromatography.


RESULTS
Lemon juice and lime juice are rich sources of citric acid, containing 1.44 and 1.38 g/oz, respectively. Lemon and lime juice concentrates contain 1.10 and 1.06 g/oz, respectively. The citric acid content of commercially available lemonade and other juice products varies widely, ranging from 0.03 to 0.22 g/oz.


CONCLUSIONS
Lemon and lime juice, both from the fresh fruit and from juice concentrates, provide more citric acid per liter than ready-to-consume grapefruit juice, ready-to-consume orange juice, and orange juice squeezed from the fruit. Ready-to-consume lemonade formulations and those requiring mixing with water contain < or =6 times the citric acid, on an ounce-for-ounce basis, of lemon and lime juice.
Penniston
Kristina L
KL
Department of Surgery, Division of Urology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792-3236, USA. penn@surgery.wisc.edu
Nakada
Stephen Y
SY
Holmes
Ross P
RP
Assimos
Dean G
DG
D001628:Beverages / Q000032:analysis*; D019343:Citric Acid / Q000032:analysis*; D002957:Citrus / Q000737:chemistry*; D006801:Humans; D052878:Urolithiasis / Q000517:prevention & control
D019343:Citric Acid