Table 1.

Summary of the main experimental studies of orange, grapefruit, and lemon juice intake and urinary stone formation.

Author.	Year	Study Type	Orange/Grapefruit/Lemon	Sample Size	Assessment	Study Goal	Conclusion
Curhan [10]	1996	Prospective cohort study	Orange, Grapefruit	45,289	Questionnaire	The relation between intake of 21 different beverages and the risk of symptomatic kidney stones in men.	Grapefruit juice was directly associated with risk of stone formation. No increased risk for orange juice consumption.
Curhan [11]	1998	Prospective cohort study	Orange, Grapefruit	81,093	Questionnaire	The association between the intake of 17 beverages and risk for kidney stones in women.	Grapefruit juice was directly associated with risk of stone formation. No increased risk for orange juice consumption.
Ferraro [12]	2013	Prospective cohort study	Orange, Grapefruit	217,883	Questionnaire	The association between intake of several types of beverages and incidence of kidney stones.	Protective effect for the consumption of orange juice. Risk of grapefruit juice not significant.
Baia [13]	2012	Prospective clinical study	Orange, Lime	30 hypocitraturic stone forming patients	Urine analyses	To compare the acute effects of a non-citrus fruit (melon) vs. citrus fruits (orange and lime) on citraturia and other lithogenic parameters.	Significant and comparable increases of mean urinary citrate were observed in all groups. Mean urinary pH significantly increased after orange juice but not after lime juice consumption.
Hönow [14]	2003	Prospective clinical study	Orange, Grapefruit	9 non-stone formers	Urine analyses	To evaluate the influence of grapefruit and apple juice consumption on urinary variables and crystallization, in comparison with orange juice.	Both grapefruit juice and apple juice reduce the risk of CaOx stone formation at a magnitude comparable with the effects obtained from orange juice.
Odvina [15]	2006	Prospective randomized study	Orange, Lemonade	13 volunteers (9 healthy and 4 stone formers)	Blood and urine analyses	To compare the effects of orange juice with those of lemonade on acid–base profile and urinary stone risks under controlled metabolic conditions.	Orange juice has greater alkalinizing and citraturic effects than lemonade. Orange juice is associated with lower calcium-oxalate supersaturation and lower uric acid.
Seltzer [16]	1996	Prospective clinical study	Lemonade	12 hypocitraturic stone formers	Urine analyses	To evaluate the urinary biochemical effects of dietary citrate supplementation (lemonade).	Lemonade results in elevated urinary citrate levels and can be a possible treatment in hypocitraturic calcium stone formers.
Wabner [17]	1993	Prospective clinical study	Orange	13 volunteers (8 healthy and 3 hypocitraturic stone formers)	Urine analyses	To evaluate the urinary biochemical effects of orange juice compared to potassium citrate.	Compared to potassium citrate, orange juice caused a similar increase in urinary pH and urinary citrate but increased urinary oxalate and did not reduce calcium excretion.
Large [18]	2020	Prospective randomized study	Orange, Artificial lemonade	10 non-stone formers	Urine analyses	To evaluate urinary citrate and pH changes with consumption of low-calorie orange juice and artificial lemonade.	Daily consumption of orange juice can raise urinary pH.
Goldfarb [19]	2001	Prospective clinical study	Grapefruit	10 non-stone formers	Urine analyses	To study the basis of the lithogenic effect of grapefruit juice demonstrated in epidemiologic studies.	Grapefruit juice associated with an increase in mean oxalate and citrate excretion. However, no net change in calculated supersaturation or lithogenicity.
Trinchieri [20]	2002	Prospective clinical study	Grapefruit	7 non-stone formers	Urine analyses	To investigate changes in urinary stone risk factors after consumption of grapefruit juice.	Grapefruit juice significantly increases urinary excretion of citrate, calcium, and magnesium.
Penniston [21]	2007	Retrospective analysis	Lemonade	100 CaOx stone formers	Urine analyses	To evaluate the urinary biochemical effects of lemonade compared to K-citrate + lemonade.	Lemonade raised urinary citrate and total urine volume but was less effective than K-citrate + lemonade.
Koff [22]	2007	Prospective clinical trial	Lemonade	21 stone formers	Urine analyses	To evaluate the urinary biochemical effects of lemonade compared to potassium citrate.	Lemonade did not increase urinary citrate or pH levels.