Dietary Oxalate Impact on Kidney Stones

Overseen By Tanecia Mitchell, PhD

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of Alabama at Birmingham

Must not be taking: Medications, Supplements

Disqualifiers: Kidney stones, Active medical problems, others

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

Compensation: Varies

Number of Visits: 24

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to examine how dietary oxalate affects urinary crystal formation and the immune system. Participants will follow two different diets: a High Oxalate Diet and a Low Oxalate Diet, each for four days, with a break in between. It is ideal for healthy individuals without a history of kidney stones who can adhere to strict eating plans and avoid intense exercise. As an unphased trial, this study allows participants to contribute to valuable research on diet and health without the risks linked to new treatments.

Will I have to stop taking my current medications?

Yes, you will need to stop taking any medications or dietary supplements to participate in this study.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research has shown that consuming foods high in oxalate may harm kidney health. Studies suggest that excessive oxalate can lead to kidney stones or other kidney issues. Some evidence also links high oxalate levels to worsening kidney diseases.

Conversely, consuming foods low in oxalate has been shown to benefit individuals with kidney stones, potentially reducing the likelihood of recurrence. Some studies indicate that even a small increase in oxalate can significantly raise the risk of stones. Therefore, maintaining a low oxalate intake could be advantageous.

The current study tests both high and low oxalate diets to assess their effects. While a high oxalate diet may pose risks, a low oxalate diet appears to aid in managing kidney stone problems. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it explores how dietary choices can directly influence kidney stone formation, offering a potentially non-invasive way to manage or prevent this condition. Current treatments for kidney stones often involve medication or surgical procedures to remove or break down stones. However, this trial investigates dietary modifications — specifically, the effects of high and low oxalate diets — which could empower patients to manage their health through simple dietary changes. Understanding how these diets affect stone formation could lead to more personalized and proactive management strategies, reducing the need for more invasive treatments.

What evidence suggests that this trial's diets could be effective for kidney stones?

Research has shown that consuming foods high in oxalate can increase oxalate levels in urine, potentially leading to more kidney stones. One study found that increasing oxalate intake from 50 mg to 250 mg per day raised urinary oxalate by about 35%. This trial will assess the impact of a High Oxalate Diet followed by a Low Oxalate Diet, and vice versa, on kidney stone formation. Conversely, a diet low in oxalate may reduce the risk of kidney stones. Studies indicate that people on low oxalate diets often experience fewer kidney stones. In one case, even small increases in daily oxalate levels raised the risk of kidney stones by up to 60%. This suggests that managing oxalate intake could be important for controlling kidney stones. ^{2 5 6 7 8}

Who Is on the Research Team?

Tanecia Mitchell, PhD

Principal Investigator

University of Alabama at Birmingham

Are You a Good Fit for This Trial?

This trial is for healthy men and women aged 18-60, with a BMI of 20-30, who don't smoke or have kidney stones. Participants must not be pregnant, should avoid vigorous exercise and supplements during the study, and be willing to follow specific diets while collecting urine samples.

Inclusion Criteria

Your body mass index (BMI) is between 20 and 30.

Willing to abstain from vigorous exercise and vitamins/supplements during the study

Your comprehensive metabolic panel (CMP) results are within the normal range.

Exclusion Criteria

You use tobacco.

My doctor has advised against me joining this trial.

I have ongoing health issues.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Dietary Intervention

Participants consume a high or low oxalate diet for 4 days, followed by a washout period, then crossover to the opposite diet for another 4 days

14 days

Blood and 24-hour urine collections at baseline and post diet

Follow-up

Participants are monitored for changes in crystalluria, monocyte cellular energetics, mitochondrial function, transcriptomics, urinary oxalate, and monocyte subtypes

2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• High Oxalate Diet
• Low Oxalate Diet

Trial Overview The study investigates how different levels of dietary oxalate affect urinary crystals formation and immune response in healthy individuals. It involves adhering strictly to either a low or high oxalate diet provided by the researchers.

How Is the Trial Designed?

Group I: Low Oxalate Diet Followed by High Oxalate Diet Experimental Treatment 2 Interventions

Subjects will consume a low oxalate diet for four days, with blood and 24-hour urine collections occurring at baseline and post diet. A ten day wash out period will follow, during which the subject will consume a self-selected diet. Subjects will then consume the high oxalate diet for the final four days, with blood and 24-hour urine collections once again occurring at baseline and post diet.

Group II: High Oxalate Diet Followed by Low Oxalate Diet Experimental Treatment 2 Interventions

Subjects will consume a high oxalate diet for four days, with blood and 24-hour urine collections occurring at baseline and post diet. A ten day wash out period will follow, during which the subject will consume a self-selected diet. Subjects will then consume the low oxalate diet for the final four days, with blood and 24-hour urine collections once again occurring at baseline and post diet.

Who Is Running the Clinical Trial?

University of Alabama at Birmingham

Lead Sponsor

Trials

1,677

Recruited

2,458,000+

Published Research Related to This Trial

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 an animal study with male Sprague-Dawley rats, a diet high in hydroxy-L-proline, a precursor of oxalate, led to increased urinary oxalate levels and the formation of calcium oxalate crystals in the kidneys, indicating a direct link between dietary oxalate and kidney stone formation.

When the dietary oxalate was reduced, there was a significant decrease in urinary oxalate and associated kidney crystal deposits, suggesting that cutting back on oxalate can improve kidney function and reduce the risk of stone recurrence.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Dietary oxalate and calcium oxalate nephrolithiasis. Khan, SR., Glenton, PA., Byer, KJ.[2013]

A study involving 10 healthy participants found that a high calcium diet (1,000 mg daily) led to higher urinary calcium levels and lower urinary oxalate levels compared to a low calcium diet (400 mg daily) while consuming a liberal oxalate diet.

Despite lower oxalate levels, the overall urinary saturation of calcium oxalate was significantly higher on the high calcium diet, suggesting that such a diet may increase the risk of calcium oxalate stone formation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effect of high and low calcium diets on stone forming risk during liberal oxalate intake. Matsumoto, ED., Heller, HJ., Adams-Huet, B., et al.[2013]

Restricting dietary oxalate intake can help reduce the risk of calcium oxalate kidney stones, especially in individuals who absorb oxalate at high rates; only a few specific foods like spinach and chocolate significantly increase urinary oxalate excretion.

Increasing calcium intake may help lower urinary oxalate levels by binding oxalate in the gut, suggesting that a balanced approach to calcium and oxalate consumption is important for effective dietary management of kidney stone risk.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effect of dietary oxalate and calcium on urinary oxalate and risk of formation of calcium oxalate kidney stones. Massey, LK., Roman-Smith, H., Sutton, RA.[2022]

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC4525130/

Nutritional Management of Kidney Stones (Nephrolithiasis) A low oxalate diet is recommended for the prevention of CaOx stones; however, a recent study showed that dietary oxalate had little effect on urinary oxalate ...

2. sciencedirect.com sciencedirect.com/science/article/pii/S0085253815474629

Contribution of dietary oxalate to urinary oxalate excretion When the calcium content of a diet containing 250 mg of oxalate was reduced from 1002 mg to 391 mg, urinary oxalate excretion increased by a mean of 28.2 ± 4.8% ...

3. urotoday.com urotoday.com/conference-highlights/wcet-2024/154190-wcet-2024-dietary-management-in-urolithiasis-patients-myths-truths.html

Dietary Management in Urolithiasis Patients: Myths & Truths He also highlighted data from studies showing that a low-oxalate diet can reduce kidney stone recurrence, though the efficacy depends on the ...

4. auanet.org auanet.org/guidelines-and-quality/guidelines/kidney-stones-medical-mangement-guideline

Kidney Stones: Medical Mangement Guideline The beneficial effect of dietary moderation in reducing the risk of recurrent stones was demonstrated by Hoskings and co-workers, who found a reduction in stone ...

5. mayoclinicproceedings.org mayoclinicproceedings.org/article/S0025-6196(24)00090-9/fulltext

Oxalate Metabolism: From Kidney Stones to ... There is emerging evidence that increased concentrations of oxalate could be a driver of chronic kidney disease progression. Furthermore, ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC7551439/

Dietary Oxalate Intake and Kidney Outcomes - PMC The increased load of dietary oxalate presented to the kidneys has been linked to different kidney-related conditions and injuries.

7. kidney.org kidney.org/kidney-topics/kidney-stone-diet-plan-and-prevention

Kidney Stone Diet Plan and Prevention A diet low in calcium actually increases your chances of developing kidney stones. Don't reduce the calcium in your diet. Work to cut back on the sodium in your ...

8. sciencedirect.com sciencedirect.com/science/article/pii/S1001929423000433

Associations of Oxalate Consumption and Some Individual ... In this review, the associations of the risk of kidney stones with oxalate consumption and some individual habits, such as smoking, alcohol drinking, and opium ...