Watermelon Juice: Nature’s Solution for Smashing Kidney Stones
Citrullus lanatus
📜Ancient Use
Watermelon’s history dates back over 5,000 years to Africa, where its drought-tolerant ancestor thrived. Initially bitter and hard, generations of selective breeding transformed it into the sweet, red fruit we enjoy today. By 400 B.C. to 500 A.D., writings indicate that watermelon had spread to the Mediterranean and the Middle East. In the Middle East, it was highly revered, and Islamic teachings attribute to Prophet Muhammad the belief that watermelon can "wash and purify the urinary bladder. (1)"
🧪Relevant Pathophysiology
Nephrolithiasis, commonly known as kidney stones, affects approximately 1 in 11 people in the United States. The pain can be severe, with some likening to the pain to childbirth. Obesity and diabetes are strongly linked to kidney stone formation, and white males are the most commonly affected group. Kidney stones can develop anywhere along the urinary tract, from the kidneys to the bladder (2).
Stone formation occurs due to an increased promotion of crystallization and reduced inhibition of stone formation. As shown in the illustration below, high substrate concentration (oxalate), slow urinary flow, and cell injury are major promoters or stone formation while citrate and magnesium can inhibit stone formation. Calcium oxalate make up about 70% of kidney stones. A study published in Nature highlights that we are still learning about the formation and treatment of calcium oxalate stones. Calcium oxalate forms when Ca²⁺ and C₂O₄²⁻ associate into stable complexes. Citrate can inhibit the early stages of calcium oxalate crystallization, thereby preventing stone formation (3). Although this is relatively new information in Western medicine, ancient societies may have indirectly recognized this through their use of watermelon for urinary health.
💊Current Medical Therapies
For hospitalized patients with kidney stones, IV hydration is the primary treatment, with a goal of achieving 2.5 L of urinary output per day. This helps dilate the ureters, relieve pain from obstructed stones, and promote their passage. Medications such as Tamsulosin can facilitate urinary flow, while Hydrochlorothiazide reduces calcium excretion to prevent stone formation. Potassium citrate is also commonly prescribed as it binds to calcium, forming a soluble salt that limits calcium-oxalate or calcium-phosphate stone formation (2). If these interventions fail and pain persists, a procedure called lithotripsy may be necessary to remove the stone.
🧬Major Phytochemicals
Watermelon contains citric acid, from which citrate is derived. Similar to potassium citrate, citrate from watermelon binds urinary calcium, preventing crystal aggregation and decreasing urine acidity, which reduces calcium oxalate stone formation (5). Though mildly acidic itself, watermelon has an alkaline-forming effect when digested, producing citrate as a key byproduct.
Another significant compound in watermelon is citrulline, a nonessential amino acid that converts into arginine, a precursor to nitric oxide. As discussed in my article on beetroot (link below if you haven’t checked it out yet),
Nitric oxide dilates blood vessels and lowers blood pressure. Nitric oxide is also able to relax the ureters—facilitating stone passage. Citrulline has also been shown in rat studies to protect kidneys from oxidative stress (6).
Interestingly, watermelon rind contains significantly higher concentrations of citrulline than its flesh (7). While commonly discarded, watermelon rind can be consumed in various forms, including kimchi, or in stir-fried, pickled, and juiced forms.
👩🏽🔬Scientific Studies
🍉A meta-analysis of seven randomized controlled trials involving 477 participants found that citrate therapy significantly reduced kidney stone size and the rate of new stone formation compared to placebo (8). This is particularly relevant for stones larger than 1 cm, which typically require urological intervention.
🍉An animal study confirmed the anti-urolithiatic properties of watermelon pulp extract. When male rats were given supersaturated calcium and oxalate solutions to induce kidney stones, subsequent administration of watermelon pulp extract significantly reduced calcium oxalate crystal counts in the kidneys and urine. The extract also promoted increased urinary flow, highlighting watermelon juice’s diuretic effects (9). This supports the claims of communities from both the Middle East and Russia who have used watermelon for its diuretic properties (10).
🍉Another animal study found that watermelon rind extract was as effective as potassium citrate in preventing calcium oxalate stones. The rind extract reduced oxalate, sodium, and calcium levels while increasing urinary citrate and volume. Notably, it also improved creatinine levels, a key marker of kidney function. Persian melon rind extract actually outperformed both watermelon rind and potassium citrate, warranting further study (11).
🍉A study in Iraq demonstrated the antilithiatic effect of watermelon juice on calcium oxalate kidney stones. After just 24 hours of submersion in fresh watermelon juice, stones dissolved and fragmented completely, losing their rigidity and crystallization. Images from the study are shown below. This rapid dissolution is likely due to watermelon’s citrate content, which alkalinizes urine and dissolves stones.
🔑🍉These studies suggest that watermelon juice may serve as a natural and effective remedy for alleviating kidney stone pain and reducing the need for invasive urological procedures (12).
💡Fun Fact
Contrary to intuition, a low-calcium diet does not prevent calcium containing kidney stones and can actually increase the risk. Calcium helps reduce oxalate absorption in the intestines, lowering urinary oxalate levels (13).
✅Recommendations
For those prone to kidney stones or seeking prevention, consider the following:
✅Stay well-hydrated (2-3L of fluids daily).
✅Avoid excessive diuretics, caffeine, and energy drinks.
✅Maintain an optimal calcium intake (1,000-1,200 mg/day).
✅Keep sodium levels balanced, as too much or too little can increase kidney stone risk.
✅Incorporate watermelon juice and rind into your diet.
If you develop a kidney stone, undergo a 24-hour litholink analysis to determine its type. While watermelon juice is particularly effective for calcium stones, its effectiveness for other types may vary. Consult your nephrologist, PCP, or urologist before making dietary changes.
🔭Future Research
Given that citrate—a key treatment for kidney stones—is naturally abundant in watermelon, and considering watermelon’s historical use for urinary health, large-scale studies should further investigate its efficacy in kidney stone prevention and treatment.
🙌🏼Acknowledgments
Special thanks to Dr. Melby Abraham, MD, for her invaluable insights from a nephrologist’s perspective, which enriched this article with biochemical mechanisms and current treatment modalities.
References:
Marwat, S. K., Khan, M. A., & Fazal-ur-Rehman. (2008). Ethnomedicinal study of vegetables mentioned in the Holy Qura’n and Ahadith. Ethnobotanical Leaflets, 12(12), 1254–1269.
Shastri S, Patel J, Sambandam KK, Lederer ED. Kidney Stone Pathophysiology, Evaluation and Management: Core Curriculum 2023. Am J Kidney Dis. 2023 Nov;82(5):617-634. doi: 10.1053/j.ajkd.2023.03.017. Epub 2023 Aug 9. PMID: 37565942; PMCID: PMC11370273.
Ruiz-Agudo, E., Burgos-Cara, A., Ruiz-Agudo, C. et al. A non-classical view on calcium oxalate precipitation and the role of citrate. Nat Commun 8, 768 (2017). https://doi.org/10.1038/s41467-017-00756-5
Halbritter J, Seidel A, Müller L, Schönauer R, Hoppe B. Update on Hereditary Kidney Stone Disease and Introduction of a New Clinical Patient Registry in Germany. Front Pediatr. 2018 Mar 7;6:47. doi: 10.3389/fped.2018.00047. PMID: 29564324; PMCID: PMC5850730.
Ettinger B, Pak CY, Citron JT, Thomas C, Adams-Huet B, Vangessel A. Potassium-magnesium citrate is an effective prophylaxis against recurrent calcium oxalate nephrolithiasis. J Urol. 1997 Dec;158(6):2069-73. doi: 10.1016/s0022-5347(01)68155-2. PMID: 9366314.
Liu Y, Fu X, Gou L, Li S, Lan N, Zheng Y, Yin X. L-citrulline protects against glycerol-induced acute renal failure in rats. Ren Fail. 2013;35(3):367-73. doi: 10.3109/0886022X.2012.760408. Epub 2013 Jan 31. PMID: 23362955.
Gu, I., Balogun, O., Brownmiller, C., Kang, H. W., & Lee, S.-O. (2023). Bioavailability of Citrulline in Watermelon Flesh, Rind, and Skin Using a Human Intestinal Epithelial Caco-2 Cell Model. Applied Sciences, 13(8), 4882. https://doi.org/10.3390/app13084882
Phillips R, Hanchanale VS, Myatt A, Somani B, Nabi G, Biyani CS. Citrate salts for preventing and treating calcium containing kidney stones in adults. Cochrane Database Syst Rev. 2015 Oct 6;2015(10):CD010057. doi: 10.1002/14651858.CD010057.pub2. PMID: 26439475; PMCID: PMC9578669.
Siddiqui WA, Shahzad M, Shabbir A, Ahmad A. Evaluation of anti-urolithiatic and diuretic activities of watermelon (Citrullus lanatus) using in vivo and in vitro experiments. Biomed Pharmacother. 2018 Jan;97:1212-1221. doi: 10.1016/j.biopha.2017.10.162. Epub 2017 Nov 12. PMID: 29145146.
Pieroni A, Gray C. Herbal and food folk medicines of the Russlanddeutschen living in Künzelsau/Taläcker, South-Western Germany. Phytother Res. 2008 Jul;22(7):889-901. doi: 10.1002/ptr.2410. PMID: 18384192.
Nia, Leila & Dehkordi, Saba & Shirani, Majid & Hassanpour Dehkordi, Ali. (2021). The effects of hydroalcoholic extracts of watermelon and Persian melon rind on kidney stone prevention in male Wistar rats: Alternative medicine and the role of physician and nurse. Journal of Renal Injury Prevention. 10. e27-e27. 10.34172/jrip.2021.27.
Haleem, Azhar & Al-Hiyaly, Sedik & Haleem, Salah & Ahemd, Asala. (2021). Antilithiatic effect of watermellon (Citrullus lanatus) juice on Calcium Oxalate kidney stones. Veterinary Medicine and Public Health Journal. 2. 25-30. 10.31559/vmph2021.2.1.5.
Borghi L, Schianchi T, Mecschi T, et al. Comparison of two diets for the prevention of recurrent stones in idiopathic hypercalciuria. N Engl J Med 2002;346:77-84
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This was a huge help! Great for my senior parents trying to make some better lifestyle choices.
You rarely find information such as this these days.
Great read! Kidney stones particularly calcium oxalate are common in patients with Crohn’s disease! I will definitely be incorporating this into practice!