The Oxalate Situation: Kidney Stones and Your Diet

Kidney stones, particularly those made of calcium oxalate, are a common health concern. If you've experienced one, you know how painful they can be. When it comes to preventing future stones, many people are told to follow a low-oxalate diet. But is that always the right approach? Let's break it down.  

The Importance of a 24-Hour Urine Test

Before making any dietary changes, the American Urological Association (AUA) strongly recommends a 24-hour urine test. This test provides valuable insights into your individual kidney stone risk factors, including your oxalate levels.¹ Think of it as a personalized roadmap to prevention. This test helps your doctor determine the most effective strategies for you, rather than relying on a one-size-fits-all approach.

Why a Low-Oxalate Diet Isn't Always the Answer

Unfortunately, many sources, including well-meaning friends or online influencers, might suggest a low-oxalate diet without considering your unique situation. It's crucial to understand that calcium oxalate stones can form due to various factors, not just high oxalate intake.

Can Everyone Benefit from Cutting Out Oxalate?

The answer is a resounding no! If your 24-hour urine test reveals normal oxalate levels, a low-oxalate diet could actually be detrimental. Many foods rich in oxalate also offer significant health benefits and may even help prevent stone formation.² ³ ⁴ ⁵ ⁶ ⁷ Removing these foods unnecessarily could increase your risk.

What if My Oxalate Levels Are High?

Even with elevated oxalate levels, a strict low-oxalate diet isn't always necessary. There are many dietary and medical strategies to reduce oxalate without drastically changing your eating habits. For example, ensuring adequate calcium intake, especially when you eat oxalate-rich foods, can significantly decrease oxalate absorption. ² ⁸

When a Low-Oxalate Diet Might Be Necessary

In some cases, a low-oxalate diet may be recommended, particularly for individuals with specific hereditary conditions, gastrointestinal surgeries, or bowel diseases that lead to high urinary oxalate. ⁹ However, even in these situations, a moderate reduction in oxalate might be sufficient if the underlying cause is addressed.

Where Does Oxalate Come From?

Oxalate in your urine comes from two sources: your diet and your body's own production. Dietary oxalate may account for up to 50% of urinary oxalate, while the liver can contribute 50-80%. ¹⁰

Your body produces oxalate as a byproduct of protein, amino acid, and vitamin C metabolism. This means that excessive protein or vitamin C intake, particularly from supplements, can increase oxalate levels.¹¹ ¹²

Foods high in oxalate include certain beans, nuts, grains, vegetables, and herbal supplements. However, oxalate content can vary significantly, and lists found online are often inconsistent. The AUA recommends using Harvard's updated 2023 oxalate list as a reliable resource. Keep in mind that Harvard doctors themselves caution against use of a strict low oxalate diet unless absolutely needed. ¹³ ¹⁴

Seeking Professional Guidance

If a low-oxalate diet is necessary, working with a registered dietitian specializing in kidney stone prevention is essential. They can help you identify hidden sources of oxalate in your diet, plan balanced meals, and suggest low-oxalate alternatives. They'll also guide you on optimizing calcium intake and addressing any gastrointestinal issues that might contribute to oxalate absorption.

A kidney stone prevention physician is another vital member of your healthcare team. They can order and interpret the 24-hour urine test, prescribe medications if needed, and monitor your progress. Remember, not all kidney stones are diet-related, and a physician can help identify other potential causes.   

Taking Control of Your Kidney Stone Health

Understanding the role of oxalate in kidney stone formation is crucial for prevention. By working closely with your healthcare providers and utilizing resources like the 24-hour urine test and Harvard's oxalate list, you can take a proactive approach to managing your kidney stone risk.

If you are a Florida resident looking for a kidney stone prevention dietitian and physician team, book your complimentary discover call with us today!

Kidney Stone Clinic

References:

1.  Pearle MS, Goldfarb DS, Assimos DG et al. Medical Management of Kidney Stones: AUA Gluideline. J Urol 2014; 192:316.

2.  Wagner, CA, Mohebbi N. Urinary pH and stone formation. J Nephrol. 2010 Nov-Dec; Suppl 16:S165-9.

3.  Trinchieri A, Maletta A et al. Potential renal acid load and the risk of renal stone formation in a case-control study. Eur J Clin Nutr. 2013;67(10)1077-1080.

4.  Ryall, R.L. Urinary inhibitors of calcium oxalate crystallization and their potential role in stone formation. World J Urol 15, 155-164 (1997).

5.  Lui M, Devlin JC et al. Microbial genetic and transcriptional contributions to oxalate degradation by the gut microbiota in health and disease. Elife. 2021 Mar 26;10:e63642.

6.  Abate V, Vergatti A, et al. Low Potassium Intake: A Common Risk Factor for Nephrolithiasis in Patients with High Blood Pressure, High Blood Press Cardiovasc Prev. 2023 Jul;30(4): 343-350.

7.  Eisner B, Sheth S et al. High dietary magnesium intake decreases hyperoxaluria in patients with nephrolithiasis, Urology 2012 80(4)780-783.

8.  Sromicki J, Hess B. Simple dietary advice targeting five urinary parameters reduces urinary supersaturation in idiopathic calcium oxalate stone formers. Urolithiasis 2020, 48, 425-433.

9.  Ermer T, Nazzal L, Tio MC, et al. Oxalate Homeostasis. Nat Rev Nephrol. 2023; 19(2)L 123-138.

10.  Holmes RP, Goodman HO et al. Contribution of dietary oxalate to urinary oxalate excretion. Kidney Int. 2001, 59, 370-276.

11.  Knight J, Jiang J et al. Hydroxyproline ingestion and urinary oxalate and glycolate excretion. Kidney Int. 2006; 70(11)L 1929-1934.

12.  Traxer O, Huet B et al. Effect of ascorbic acid consumption on urinary stone risk factors. Urolithiasis 2016, 44, 289-297.

13.  Harvard T.H. Chan. (2023). Nutrient Data: Oxalate Table. Hsph.harvard. https://hsph.harvard.edu/department/nutrition/nutrition-questionnaire-service-center/#nutrient-data

14.  Lewine, H. (August 2023). The kidney stone diet: Not as restrictive as you may think. Harvard Health Publishing. https://www.health.harvard.edu/diseases-and-conditions/the-kidney-stone-diet-not-as-restrictive-as-you-may-think