Using Low-calorie Orange Juice as a Dietary Alternative to Alkali Therapy

Abstract

Purpose: The pursuit of a dietary source to increase urine pH and citrate in stone formers has been ongoing for more than 30 years. Early evidence showed that orange juice (OJ) contains alkali and citrate but high sugar and ascorbic acid content limited the use of OJ as a viable daily source of alkali. Recently, novel low calorie OJs have emerged and could potentially be a better option. Methods: Beverages with high concentrations of alkali citrate and malate were identified using ion chromatography. Two low calorie OJ beverages, in addition to Crystal Light Lemonade (CLLB) were chosen. Healthy volunteers (5 men, 5 women) drank 1L of OJ or CLLB with 1L water daily for 7 days and then completed a 24-hour urinalysis. A washout week was instituted between trial weeks. The study design is a prospective randomized cross over control trial. A paired analysis using comparison of means was used to evaluate low calorie OJ and CLLB. Volunteers had no prior history of kidney stones and maintained a journal with beverage compliance, side effect, and dietary consumption data. Results: Tropicana 50 (TRP50), Kroger low calorie OJ (KLCO) and CLLB were found to have a total alkali content of 56.60, 47.9, and 17.3 mEq/L, respectively, based on ion chromatography. Consumption of all three beverages raised urinary citrate (116.6 [-118 to 373, 177.9 [-3 to 359], 155.6 [-4 to 237] mg/d 95% CI) and urinary pH (0.25 [0.08-0.53], 0.74 [0.41-1.07 p<0.05], 0.25 [0.25-0.64]) respectively, compared to water phase. Based on volunteer journal entries , TRP50 had the most side effects (90% participants) felt to be a result of the artificial sweetener (Stevia ®). Conclusion: Low-calorie orange juice, and to a lesser extent CLLB, have alkali and citrate based on ion chromatography. Daily consumption, by healthy volunteers of KLCO can raise urinary pH.