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

20 Participants Needed

Trial Summary

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.

What data supports the effectiveness of the treatment for kidney stones?

Research suggests that a low-oxalate diet can help reduce the risk of kidney stones by decreasing the amount of oxalate in urine, which is a key factor in stone formation. Additionally, a high calcium diet may also help by reducing urinary oxalate levels, potentially lowering the risk of stones. ^{1 2 3 4 5}

Is a diet high or low in oxalates safe for humans?

Diets high in oxalates can increase the risk of kidney stones, especially if calcium intake is low, as oxalates bind calcium and other minerals. However, occasional consumption of high oxalate foods as part of a balanced diet is generally safe, and increasing calcium intake can help reduce oxalate absorption. ^{1 2 6 7 8}

How does the dietary oxalate treatment for kidney stones differ from other treatments?

This treatment focuses on adjusting dietary oxalate and calcium intake to manage kidney stones, which is unique because it uses food choices rather than medication to influence urinary oxalate levels. Increasing calcium intake can help reduce oxalate absorption, while limiting certain high-oxalate foods like spinach and nuts can decrease urinary oxalate, potentially lowering the risk of stone formation. ^{2 4 6 9 10}

What is the purpose of this trial?

This study will test whether oxalate stimulates urinary crystals and impacts the immune system in healthy subjects using two controlled diets (low and high oxalate).

Research Team

Tanecia Mitchell, PhD

Principal Investigator

University of Alabama at Birmingham

Eligibility Criteria

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

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

Treatment Details

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.

Participant Groups

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+

Findings from Research

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]

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 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]

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]

References

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

Effect of high and low calcium diets on stone forming risk during liberal oxalate intake. [2013]

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

A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones. [2022]

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

Dietary oxalate and calcium oxalate nephrolithiasis. [2013]

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

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

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

Urinary lithogenic risk profile in recurrent stone formers with hyperoxaluria: a randomized controlled trial comparing DASH (Dietary Approaches to Stop Hypertension)-style and low-oxalate diets. [2022]

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

Effect of dietary oxalate and calcium on urinary oxalate and risk of formation of calcium oxalate kidney stones. [2022]

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

Food oxalate: factors affecting measurement, biological variation, and bioavailability. [2022]

8. China pubmed.ncbi.nlm.nih.gov

Oxalate content of foods and its effect on humans. [2014]

9. England pubmed.ncbi.nlm.nih.gov

The influence of a high-oxalate/low-calcium diet on calcium oxalate renal stone risk factors in non-stone-forming black and white South African subjects. [2022]

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

Epidemiologic evidence for the role of oxalate in idiopathic nephrolithiasis. [2016]