Diet Impact on Kidney Stones in Obese Individuals

Not currently recruiting at 1 trial location

Overseen By Naim Maalouf, MD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of Alabama at Birmingham

Must not be taking: Immunosuppressants, Antibiotics

Disqualifiers: Diabetes, Gout, Liver disease, others

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

Compensation: Varies

Number of Visits: Unknown

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial examines how diet affects kidney stones in individuals who are obese and form calcium oxalate stones. Researchers aim to understand how the body processes oxalate, a compound in many foods, and its role in kidney stone formation. Participants will follow a specific controlled diet, also known as a dietary intervention or nutritional therapy, for a few days while researchers monitor their urine and blood. Suitable candidates have experienced calcium oxalate kidney stones (comprising more than 50% of the stone) and are willing to adhere to a set diet and pause certain supplements and medications. As an unphased trial, this study provides a unique opportunity to advance scientific understanding of diet's impact on kidney stones.

Will I have to stop taking my current medications?

Yes, you will need to stop taking medications for kidney stone prevention, like thiazides, allopurinol, febuxostat, and citrate preparations, for 14 days before the study starts and during the study. You can restart these medications after the study ends.

What prior data suggests that this dietary intervention is safe?

Research shows that changing one's diet can safely help manage kidney stones. Studies have found that adjusting eating habits can reduce the risk of developing new stones, especially the common type made of calcium oxalate. A diet with normal amounts of calcium, less salt, and less meat proves more effective at preventing stones than merely reducing calcium intake.

Importantly, following a diet to prevent kidney stones has not raised any serious safety concerns. Most individuals can adhere to these diets without major issues, making dietary changes a safe option for managing or preventing kidney stones. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it explores the impact of a controlled diet on kidney stones in obese individuals, a group that often struggles with this painful condition. Unlike traditional treatments that might focus on medications or surgery to manage kidney stones, this approach uses a tailored diet to potentially reduce stone formation naturally. By monitoring how diet changes affect urine composition and absorption of certain substances, researchers aim to uncover new dietary strategies that might prevent kidney stones more effectively, offering a non-invasive and lifestyle-centered option.

What evidence suggests that this controlled diet is effective for kidney stones?

Research has shown that dietary changes can significantly reduce the risk of kidney stones. This trial will assess the effects of a controlled diet on kidney stone formation in obese individuals. One study found that a diet with normal calcium levels and reduced animal protein lowered the recurrence of stones by 51%. Other studies have discovered that low-fat or low-calorie diets aid in weight loss and might also decrease the risk of stone formation. Improved diet quality is associated with a reduced likelihood of developing kidney stones. These findings suggest that dietary changes could effectively manage and prevent kidney stones, particularly for overweight individuals. ^{6 7 8 9 10}

Who Is on the Research Team?

Dean G Assimos, MD

Principal Investigator

University of Alabama at Birmingham

Are You a Good Fit for This Trial?

This trial is for adults with normal (BMI ≥ 18.5 to < 25) or obese (BMI ≥ 30 to ≤ 45) who form calcium oxalate kidney stones, can consent, and follow a controlled diet without vigorous exercise. Excluded are those with diabetes, abnormal blood tests, certain kidney diseases, gastrointestinal disorders affecting oxalate transport, recent cancer treatment, pregnancy or breastfeeding women not using birth control.

Inclusion Criteria

No food allergies or intolerance to any of the food in study menus

Willingness to not undertake vigorous exercise during the controlled dietary study

I am willing to stop my kidney stone prevention meds for the study duration.

Exclusion Criteria

I have been diagnosed with primary hyperparathyroidism.

I have high oxalate levels in my urine due to intestinal issues.

Your fasting blood test shows abnormal results for your body's chemical levels.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Controlled Dietary Study

Participants consume a controlled diet for five days, provide urine collections, and undergo blood sampling after ingesting carbon-13 oxalate and sucralose

5 days

Daily visits for urine collection and blood sampling

Follow-up

Participants are monitored for safety and effectiveness after the controlled dietary study

2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Controlled Diet

Trial Overview The study investigates how obesity affects the body's processing of oxalate in people prone to calcium oxalate kidney stones. Participants will follow a controlled diet and ingest Carbon-13 Oxalate and Sucralose to track their metabolism and urinary excretion patterns.

How Is the Trial Designed?

Group I: Controlled Dietary Study Experimental Treatment 2 Interventions

Participants will consume the controlled diet for five days. After one day on the diet, subjects will provide three 24-hour urine collections. On the last dayof the diet, subjects will come in a fasted state to ingest a small amount of carbon-13 oxalate and sucralose, with hourly urine collections and blood samples being taken before and after the ingestion.

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

In a study involving 192,126 participants over 3,259,313 person-years, five modifiable risk factors (body mass index, fluid intake, DASH diet, dietary calcium intake, and sugar-sweetened beverage intake) were found to account for over 50% of kidney stone incidents, highlighting their significant role in prevention.

The most impactful risk factor was lower fluid intake, which had a population attributable fraction of 26.0%, suggesting that increasing fluid consumption could substantially reduce the occurrence of kidney stones in the general population.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Dietary and Lifestyle Risk Factors Associated with Incident Kidney Stones in Men and Women. Ferraro, PM., Taylor, EN., Gambaro, G., et al.[2019]

A 12-week low-calorie diet for obese adults with idiopathic calcium oxalate kidney stones did not lead to a decrease in 24-hour urinary lithogenic parameters, indicating that weight loss alone may not reduce stone risk.

Despite some participants achieving a BMI below 30 kg/m², the study suggests that calcium oxalate stone formation is likely influenced by factors beyond just body weight, highlighting the complexity of this condition.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effect of a low-calorie diet on 24-hour urinary parameters of obese adults with idiopathic calcium oxalate kidney stones. Danilovic, A., Marchini, GS., Pucci, ND., et al.[2022]

In a study of 112 patients who received dietary recommendations to prevent kidney stones, patients recalled about 67% of the advice given, with better recall for key recommendations like increasing fluid intake and reducing meat consumption.

Patients who received fewer than four dietary recommendations had a higher recall rate (47% recalled all recommendations) compared to those given more than three, suggesting that simplifying dietary advice may improve patient adherence and understanding.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Factors associated with patient recall of individualized dietary recommendations for kidney stone prevention. Penniston, KL., Wertheim, ML., Nakada, SY., et al.[2018]

Citations

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

Nutritional Management of Kidney Stones (Nephrolithiasis) Patients who consumed a diet with a normal calcium intake (i.e., 1,200 mg/d) plus a low animal protein intake had a 51% lower incidence of recurrent stones than ...

2. sciencedirect.com sciencedirect.com/science/article/abs/pii/S1548559508001742

Prospects for Dietary Therapy of Recurrent Nephrolithiasis Randomized trials show that diets consisting of low-fat content or low-caloric content cause modest weight loss and might be effective in reducing stone ...

3. link.springer.com link.springer.com/article/10.1007/s00345-022-04268-w

Dietary weight loss strategies for kidney stone patients An energy-restricted diet with or without meal replacement could be a promising weight loss strategy for overweight kidney stone patients.

4. frontiersin.org frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1538289/full

Healthy dietary patterns, biological aging, and kidney stones Conclusion: These findings provide valuable insights into the complex interplay between dietary patterns, biological aging, and the risk of kidney stone.

5. cariguidelines.org cariguidelines.org/nutrition-therapy-for-the-prevention-of-kidney-stones/

Nutrition therapy for the prevention of kidney stones Improved diet quality has been associated with a lower risk of kidney stones (12). The cross-sectional National Health and Nutrition Examination Surveys have ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC7353736/

Dietary and lifestyle factors for primary prevention of ... Another RCT showed that a DASH-style diet nonsignificantly decreased urine calcium oxalate supersaturation among stone formers with ...

7. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC8229448/

Nutrition and Kidney Stone Disease - PMC Diet modification is an effective method to correct urinary risk factors for kidney stone formation, particularly of the most common stone type calcium oxalate.

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

Kidney Stone Diet Plan and Prevention Learn about managing kidney stones with a specialized diet. Discover the role of hydration, types of kidney stones, and dietary tips for prevention.

9. sciencedirect.com sciencedirect.com/science/article/abs/pii/S030228380900267X

Diet, Fluid, or Supplements for Secondary Prevention of ... High fluid intake decreased risk of recurrent nephrolithiasis. Reduced soft drink intake lowered risk in patients with high baseline soft drink consumption.

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

Kidney Stones: Medical Mangement Guideline A multicomponent diet consisting of normal calcium, low sodium, low animal protein intake was shown to be superior to a low calcium diet in preventing stone ...