Low-Oxalate Diet for Kidney Stones

Overseen By Elaine Worcester, MD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of Chicago

Disqualifiers: Bowel surgery, Inflammatory bowel disease, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Approved in 1 Jurisdiction This treatment is already approved in other countries

Compensation: Varies

Number of Visits: 1

30 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to determine how a low-oxalate diet affects kidney stone formation, which often occurs when oxalate, a compound in many foods, accumulates in the body. Participants will follow a special low-oxalate diet for a week and visit the University of Chicago research clinic on the final day. The trial suits individuals who have had at least one calcium-based kidney stone and meet specific health criteria, such as having undergone Roux-en-Y gastric bypass surgery or having a body mass index (BMI) of 30 or more. As an unphased trial, it offers participants the chance to contribute to valuable research that could improve dietary recommendations for preventing kidney stones.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications. It's best to discuss this with the study coordinators or your doctor.

What prior data suggests that this low-oxalate diet is safe for participants?

Research has shown that a low-oxalate diet is generally safe and can help people with kidney stones. Studies indicate that this diet can significantly lower the risk of developing new stones. For example, individuals who follow a low-oxalate diet often experience fewer kidney stone issues because they consume less oxalate, a substance in many foods that can lead to stone formation.

One study highlighted that a low-oxalate diet benefits those with kidney stones, also known as nephrolithiasis. This finding suggests the diet not only helps prevent stones but is also easy for those who have had stones before to follow.

Overall, the low-oxalate diet is considered safe for most people, with no major side effects reported. It involves eating foods with less oxalate, which is found in many healthy foods. While certain foods might need to be avoided, the diet itself is safe and could be helpful for those prone to kidney stones. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the low-oxalate diet for kidney stones because it offers a unique, non-invasive approach to managing stone formation. Unlike traditional treatments that often rely on medications to alter urine chemistry or surgical procedures to remove stones, this diet focuses on reducing the intake of oxalate-rich foods, potentially lowering the risk of stone formation naturally. This dietary approach is particularly appealing because it empowers individuals to manage their condition through lifestyle changes, potentially reducing the need for more invasive interventions.

What evidence suggests that a low-oxalate diet is effective for kidney stones?

Studies have shown that a low-oxalate diet can help reduce the risk of kidney stones. Research indicates that even a small increase in oxalate (a substance found in many foods) can significantly raise the chance of developing stones. A low-oxalate diet benefits patients with kidney stones by reducing the likelihood of recurrence. This trial will evaluate the effectiveness of a special low-oxalate diet, which participants will follow before visiting the University of Chicago research clinic. By limiting oxalate intake, this diet lowers the amount in urine, thus decreasing the risk of stones. Overall, following a low-oxalate diet effectively manages and prevents kidney stones. ^{1 2 4 6 7}

Are You a Good Fit for This Trial?

This trial is for adults aged 18-70 who have had bariatric surgery or are obese, with a history of calcium-based kidney stones and high urine oxalate levels. It's not for those with certain bowel surgeries, inflammatory bowel disease, or non-calcium based kidney stones.

Inclusion Criteria

I am 18-70, had Roux-en-Y surgery, and developed calcium kidney stones with high urine oxalate levels after.

I am 18-70 years old, not obese, and have had at least one calcium kidney stone.

Exclusion Criteria

I have had bowel surgery or have a history of specific types of kidney stones or inflammatory bowel disease.

I have had gastric bypass and specific types of bowel surgery or stones.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Diet Preparation

Participants follow a special low-oxalate diet at home for the first two days

2 days

No visits

Controlled Diet and Sample Collection

Participants receive special meals from the research clinic and collect 24-hour urine samples at home

3 days

No visits

Clinic Visit and Testing

Participants visit the research clinic for administration of a special liquid containing oxalate and a low-oxalate breakfast

1 day

1 visit (in-person)

Follow-up

Participants are monitored for changes in urine oxalate and sucralose levels after the intervention

1 week

What Are the Treatments Tested in This Trial?

Interventions

• Special low-oxalate diet followed by all-day visit to University of Chicago research clinic

Trial Overview

Participants will follow a special low-oxalate diet at home and then eat meals provided by the University of Chicago research clinic. They'll also provide urine samples and consume a liquid containing oxalate during an all-day clinic visit to study its effects on kidney stone formation.

How Is the Trial Designed?

Group I: Subjects who will follow low-oxalate diet followed by visit to research clinic Experimental Treatment 1 Intervention

30 stone-forming participants will be recruited to this study.

Special low-oxalate diet followed by all-day visit to University of Chicago research clinic is already approved in United States for the following indications:

Approved in United States as Low-Oxalate Diet for:

• Prevention of Kidney Stones
• Management of Hyperoxaluria

Who Is Running the Clinical Trial?

University of Chicago

Lead Sponsor

Trials

1,086

Recruited

844,000+

University of Alabama at Birmingham

Collaborator

Trials

1,677

Recruited

2,458,000+

Published Research Related to This Trial

In a study of 79 patients with idiopathic calcium nephrolithiasis, only 14% showed mild hyperoxaluria on a free diet, indicating that the incidence of elevated oxalate levels among these patients is relatively low.

Patients with absorptive-type idiopathic hypercalciuria (IHC) are particularly susceptible to developing hyperoxaluria on a low calcium diet, suggesting that such a diet may not be beneficial for them unless oxalate intake is also reduced.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Incidence of hyperoxaluria in idiopathic calcium nephrolithiasis]. Jaeger, P., Portmann, L., Bugnon, JM., et al.[2013]

A proposed randomized controlled trial aims to test whether dietary changes, particularly increasing calcium intake to 1,200 mg/day while reducing animal protein, salt, and oxalate, can effectively prevent recurrent kidney stones, building on previous successful trials.

The article highlights the need for further research on dietary oxalate's role in stone formation and suggests that weight loss through low-fat or low-calorie diets may also help reduce kidney stone recurrence.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Prospects for dietary therapy of recurrent nephrolithiasis. Goldfarb, DS.[2014]

A normal-calcium, low-animal protein, low-salt diet significantly reduced oxalate excretion in patients with idiopathic calcium oxalate nephrolithiasis, decreasing mean oxaluria from 50.2 to 35.5 mg/d over 3 months.

In comparison, a traditional low-oxalate diet only reduced oxaluria from 45.9 to 40.2 mg/d, indicating that the new diet may be more effective in managing hyperoxaluria.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Diet to reduce mild hyperoxaluria in patients with idiopathic calcium oxalate stone formation: a pilot study. Nouvenne, A., Meschi, T., Guerra, A., et al.[2022]

In a study of 207 patients with recurrent kidney stones, 19% were found to have mild hyperoxaluria, and 45% of these patients benefited from a low oxalate diet, normalizing their urinary oxalate levels.

Patients with persistent hyperoxaluria showed some improvement with dietary restrictions, while those with intermittent hyperoxaluria did not, indicating that dietary management may be effective for some but not all individuals with hyperoxaluria.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Hyperoxaluria in patients with recurrent calcium oxalate calculi: dietary and other risk factors. Laminski, NA., Meyers, AM., Kruger, M., et al.[2022]

A low-oxalate, low-fat diet significantly reduced urinary oxalate excretion in 10 patients with hyperoxaluria, from an average of 1.1 to 0.7 mmol/24 h, indicating its efficacy in managing this condition.

The study suggests that while the diet is challenging, it is manageable for patients, and emphasizes the importance of regular dietary guidance from a dietitian for successful implementation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Low-oxalate, low-fat dietary regimen in hyperoxaluria following jejunoileal bypass. Nordenvall, B., Backman, L., Burman, P., et al.[2013]

In a study of 101 male calcium stone formers, urinary oxalate excretion was similar between normocalciuric and hypercalciuric patients on free-choice and calcium-enriched diets, with hyperoxaluria occurring in 11-22% of participants.

However, on a low-calcium diet, hypercalciuric patients showed a significant increase in oxalate excretion and a higher incidence of hyperoxaluria (33%), suggesting that low-calcium diets may not be advisable without also reducing oxalate intake, especially for those with high intestinal calcium absorption.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Influence of the calcium content of the diet on the incidence of mild hyperoxaluria in idiopathic renal stone formers. Jaeger, P., Portmann, L., Jacquet, AF., et al.[2018]

In a study of 99 patients with a history of calcium oxalate stones, those following a low animal protein, high fiber diet experienced a significantly higher recurrence rate of kidney stones (7.1 per 100 person-years) compared to those who only increased fluid intake (1.2 per 100 person-years).

The relative risk of recurrent stones for those on the low protein diet was 5.6 times higher than the control group, suggesting that this dietary intervention does not provide any benefit over simply increasing fluid intake.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Randomized controlled trial of a low animal protein, high fiber diet in the prevention of recurrent calcium oxalate kidney stones. Hiatt, RA., Ettinger, B., Caan, B., et al.[2019]

High protein intake is a significant factor contributing to the rise of kidney stones (nephrolithiasis) in developed countries, as it may increase urinary calcium excretion in susceptible individuals.

Dietary modifications, including increased fluid intake, can help reduce the risk of recurrent kidney stones by lowering urinary calcium and oxalate levels while increasing urinary citrate, suggesting that lifestyle changes may be more beneficial than long-term medication use.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The role of diet in the pathogenesis and therapy of nephrolithiasis. Goldfarb, S.[2013]

In a study of 313 children on the ketogenic diet for epilepsy, those who received potassium citrate (Polycitra K) had a significantly lower incidence of kidney stones (2.0%) compared to those who did not receive the supplement (10.5%).

Starting potassium citrate supplementation at the onset of the ketogenic diet resulted in an even lower kidney stone incidence of 0.9%, demonstrating its effectiveness in preventing kidney stones by alkalinizing urine without reported adverse effects.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Empiric use of potassium citrate reduces kidney-stone incidence with the ketogenic diet. McNally, MA., Pyzik, PL., Rubenstein, JE., et al.[2021]

Oral calcium supplementation effectively reduced urinary oxalate excretion to normal levels in patients with enteric hyperoxaluria, as observed in a study of three patients with a history of renal stones after ileal resection.

When two patients reduced their calcium intake on their own, they experienced a return of hyperoxaluria and developed renal stones again, suggesting that maintaining an adequate dose of calcium is crucial for preventing stone formation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Oral calcium supplement decreases urinary oxalate excretion in patients with enteric hyperoxaluria. Takei, K., Ito, H., Masai, M., et al.[2017]

Recent studies indicate that increasing calcium intake may actually lower the risk of forming calcium oxalate stones, contrary to previous beliefs that recommended limiting calcium.

A large randomized trial found that individuals with normal calcium intake, along with lower protein and salt consumption, experienced significantly fewer recurrences of calcium oxalate stones, suggesting that dietary changes can effectively reduce stone risk.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Calcium oxalate kidney stones: another reason to encourage moderate calcium intakes and other dietary changes. Moyad, MA.[2013]

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He also highlighted data from studies showing that a low-oxalate diet can reduce kidney stone recurrence, though the efficacy depends on the ...

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