Coconut Water: An Unexpected Source of Urinary Citrate

Abstract

Purpose Coconut water has long been touted for its medicinal qualities including natural hydration. We sought to determine whether its consumption would induce changes to urinary lithogenic factors beyond changes in urine volume. Materials and Methods After Institutional Review Board approval, volunteers with no prior history of nephrolithiasis were recruited. Each participant was randomized initially to either the coconut water or the water phase of the study. Participants kept meticulous food and fluid intake logs during the first phase of the study and were asked to replicate that diet for the second phase. For each phase the participant consumed 2L of either Taste of Nirvana® pure coconut water or tap water daily for four days. Participants were not restricted to consume additional fluid of their choice during their assigned study phase. During days 3 and 4 of each phase the participant collected a 24-hour urine specimen. Coconut water citrate and malate content were measured and were used along with the beverage pH to calculate the total alkali content of the coconut water. Supersaturation levels were calculated using Equil2. Nonparametric paired analysis using the Wilcoxon test was performed for statistical analysis. Results There were 4 adult male and 4 adult female participants. Each individual's 24-hour urine collection had a creatinine excretion within 20% of the mean for each subject's four samples corroborating that all samples were collected properly. The two samples from each phase for each individual were averaged. The coconut water itself was also analyzed and it was calculated to have a total alkali content of 13.8 mEq/L. Consumption of coconut water significantly increased urinary citrate (29%, p=0.02), urinary potassium (130%, p=0.01), and urinary chloride (37%, p=0.03), without affecting urine pH (p=0.16) or volume beyond that of tap water (p=1.00). Conclusions Coconut water consumption increases urinary potassium, chloride, and citrate in nonstone forming individuals.

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

“…18,19 Aside from lemon-and orange-based beverages, other drinks, including grapefruit juice and coconut water, have shown similar changes in urinary citrate and pH after controlled consumption in healthy volunteers. 11,12 Compared with controls, after 4-7 days of grapefruit juice or coconut water consumption, urinary pH and citrate did increase, but these changes were all nonsignificant except for the increase in urinary citrate concentration after coconut water consumption (Table 4). By comparison, all beverage trials that used OJ (including this study for pH) showed statistical increases in urinary pH and citrate after 7 days of consumption (Tables 3 and 4).…”

“…6 In addition, lemon-based beverages have been evaluated extensively in both bench 7 and clinical settings. [8][9][10] Changing urinary citrate and pH levels with concentrated lemon extract, lemonade, grapefruit, 11 raspberry, and coconut juice 12 have had mixed results. Despite early evidence that OJ harbored excellent alkali potential, valid concerns over the sugar content in OJ, in combination with the promising bench results of concentrated lemon juice, led to a focused effort evaluating the efficacy of lemon-based beverages on urinary citrate and pH modulation.…”

Nutrition and Kidney Stone Disease

“…Overall, the relative risk of calcium oxalate stone formation was unaffected [70,72] or reduced [71] in healthy volunteers but increased in stone patients after the intake of cranberry juice [72]. Finally, a study of healthy subjects showed that the consumption of 1.9 L/day of coconut water compared to tap water significantly raised urinary citrate, potassium, and chloride excretion, without affecting urine pH [73]. Although fruit and vegetable juices could be useful in the dietary therapy of kidney stone disease, the oxalate concentration has to be taken into account.…”

Alkalinizing Agents: A Review of Prescription, Over-the-Counter, and Medical Food Supplements

“…16,17 Coconut water, due to a large malate as alkali component, can also increase urinary citrate if ingested in large quantities. 18 In addition, some citrus-flavored carbonated beverages also contain large portions of alkali due to citrate and malate content, however, substantial volumes of these beverages would need to be ingested to match the alkali content of prescribed potassium citrate. 19…”