BACKGROUND: Previous studies have demonstrated that dietary intake of citrate in the form of citrus juices (e.g. lemonade, orange juice) will enhance urinary citrate excretion, a valuable benefit for patients with hypocitraturic calcium oxalate nephrolithiasis. While information on citrate concentrations in select citrus juices are available, data on citrate concentrations of commercially available beverages (juice and otherwise) is limited. Using nuclear magnetic resonance spectroscopy (1H NMR), we report citrate concentrations of several beverages to help guide dietary recommendations aimed at increasing urinary citrate excretion and correcting hypocitraturia.
METHODS: Citrate concentrations of a squeezed lemon, several fruit juices and common beverages were measured using 1H NMR. Spectra for each sample were obtained in duplicate; citrate peak identified, measured, quantified and compared the citrate concentration in the juice of 1 medium lemon.
RESULTS: Quantitative analysis revealed the highest concentration of citrate in grapefruit juice (197.5 mEq/L) followed in decreasing concentrations by lemon juice (145.48 mEq/L), orange juice (144.57 mEq/L), pineapple juice (126.89 mEq/L), reconstituted lemonade (117.97 mEq/L), lemonade flavored ‘Crystal Light’ (117.18 mEq/L), ready to consume not from concentrate lemonade (116.73 mEq/L), cranberry juice (60.65 mEq/L), lemon flavored Gatorade (60.5 mEq/L), home made lemonade (53.17 mEq/L), Mountain Dew (26.98 mEq/L), and Diet 7Up (24.36 mEq/L) respectively. Number of 8 oz servings of each tested beverage required to reach common loads of medically administered citrate are shown in table 1.
CONCLUSIONS: According to 1H NMR assessments, several citrus juices have high concentrations of citrate. In patients with mild-moderate hypocitraturia, dietary supplementation with citrus-based juices may be an effective alternative to medical management, while not requiring large volumes of fluid being consumed. There are, however, concerns of high carbohydrate, sodium & calorie content for some fruit juices which pose potentially confounding factors when considering dietary citrate therapy. Lemonade-flavored ‘Crystal Light^® provides a significant amount of citrate in the form of citric acid, potassium citrate and sodium citrate, without the associated carbohydrates, sodium, and calories found in other drinks. While this beverage may show significant promise for dietary citrate supplementation in patients with mild to moderate hypocitraturia, the formation of a clinical multi-arm study is warranted to evaluate urinary biochemical stone forming parameters, when compared to traditional therapies.

Table 1: 8oz Glasses of Tested Beverage to Administer Specific Citrate Loads

	10 mEq Citrate	40 mEq Citrate	60 mEq Citrate
Ruby Red Grapefruit Juice	0.2	0.9	1.3
Juice from Lemon	0.3	1.2	1.7
Orange Juice	0.3	1.2	1.7
Pinapple Juice	0.3	1.3	2.0
Reconstiuted Lemonade	0.4	1.4	2.1
Crystal Light Lemonade	0.4	1.4	2.2
Not From Concentrate Lemonade	0.4	1.4	2.2
Cranberry Juice	0.7	2.8	4.2
Lemon flavored Gatorade	0.7	2.8	4.2