Low-Oxalate Diet for Kidney Stones

Recruiting in Palo Alto (17 mi)

Age: 18+

Sex: Any

Travel: May Be Covered

Time Reimbursement: Varies

Trial Phase: Academic

Recruiting

Sponsor: University of Chicago

Disqualifiers: Bowel surgery, Inflammatory bowel disease, others

No Placebo Group

Approved in 1 Jurisdiction

Trial Summary

What is the purpose of this trial?

This study aims to learn more about how oxalate, a compound found in many foods, may affect a person's chances of forming kidney stones. Active participation in this study will last for around one week. For the first two days, subjects will be asked to eat a special diet at home. From Days 3-5, they will eat special meals delivered to their home from a research clinic at the University of Chicago. They will also collect 24-hour urine samples at home on Days 4 and 5. On Day 6, they will come in to the research clinic at the University of Chicago in Hyde Park, where they will spend most of the day. They will receive a special liquid that contains oxalate, and we will have them eat a specially prepared breakfast that is low in oxalate and citrate.

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 data supports the effectiveness of the low-oxalate diet treatment for kidney stones?

Research suggests that a low-oxalate diet can reduce the amount of oxalate in urine, which is linked to kidney stone formation. For example, a study showed that patients on a low-oxalate, low-fat diet had decreased urinary oxalate levels, which can help prevent kidney stones. ^{1 2 3 4 5}

Is a low-oxalate diet safe for humans?

A low-oxalate diet has been studied in patients with high oxalate levels in their urine, and it was found to be manageable with proper dietary guidance, though it can be demanding. No specific safety concerns were reported in the studies, suggesting it is generally safe for humans. ^{2 5 6 7 8}

How does the low-oxalate diet treatment for kidney stones differ from other treatments?

The low-oxalate diet treatment for kidney stones is unique because it focuses on reducing oxalate intake, which can help lower urinary oxalate levels and potentially prevent stone formation. Unlike other treatments that may involve medication or surgery, this approach is dietary and requires careful management of food choices, often with guidance from a dietitian. ^{1 2 9 10 11}

Research Team

Eligibility Criteria

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.

I am aged 18-70, have a BMI of 30 or more, have had at least one calcium-based kidney stone, and my urine oxalate level is high.

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.

Trial Timeline

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

Treatment Details

Interventions

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

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.

Participant Groups

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.

Who Is Running the Clinical Trial?

University of Chicago

Lead Sponsor

Trials

1,086

Recruited

844,000+

Pete Salzmann

University of Chicago

Chief Executive Officer since 2018

MD from University of Chicago’s Pritzker School of Medicine, MBA from Stanford University’s Graduate School of Business

Anh Nguyen

University of Chicago

Chief Medical Officer

MD from Rutgers New Jersey Medical School, MBA from University of Chicago

University of Alabama at Birmingham

Collaborator

Trials

1,677

Recruited

2,458,000+

Kierstin Kennedy

University of Alabama at Birmingham

Chief Medical Officer since 2022

MD

S. Dawn Bulgarella

University of Alabama at Birmingham

Chief Executive Officer since 2023

BSc in Commerce and Business Administration from the University of Alabama, MS in Health Administration from the University of Alabama at Birmingham

Findings from Research

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]

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 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]

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]

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]

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]

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]

References

1. United States pubmed.ncbi.nlm.nih.gov

Diet to reduce mild hyperoxaluria in patients with idiopathic calcium oxalate stone formation: a pilot study. [2022]

2. Sweden pubmed.ncbi.nlm.nih.gov

Low-oxalate, low-fat dietary regimen in hyperoxaluria following jejunoileal bypass. [2013]

3. United States 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. [2019]

4. United States pubmed.ncbi.nlm.nih.gov

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

5. Switzerland pubmed.ncbi.nlm.nih.gov

Oral calcium supplement decreases urinary oxalate excretion in patients with enteric hyperoxaluria. [2017]

6. United States pubmed.ncbi.nlm.nih.gov

Empiric use of potassium citrate reduces kidney-stone incidence with the ketogenic diet. [2021]

7. United States pubmed.ncbi.nlm.nih.gov

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

8. United States pubmed.ncbi.nlm.nih.gov

Prospects for dietary therapy of recurrent nephrolithiasis. [2014]

9. Switzerland pubmed.ncbi.nlm.nih.gov

[Incidence of hyperoxaluria in idiopathic calcium nephrolithiasis]. [2013]

10. England pubmed.ncbi.nlm.nih.gov

Hyperoxaluria in patients with recurrent calcium oxalate calculi: dietary and other risk factors. [2022]

11. Switzerland pubmed.ncbi.nlm.nih.gov

Influence of the calcium content of the diet on the incidence of mild hyperoxaluria in idiopathic renal stone formers. [2018]