Dietary Oxalate and Innate Immunity in Kidney Stone Disease

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).

Study Overview

• Status: Active, not recruiting
• Conditions: Kidney Stone
• Intervention / Treatment: Dietary supplement: Low Oxalate Diet; Dietary supplement: High Oxalate Diet

Detailed Description

Oxalate is a small molecule found in plants and plant-derived food. It has been shown that meals containing high amounts of oxalate can increase urinary oxalate excretion, which is a risk factor for calcium oxalate kidney stones (CaOx KS). Small increases in oxalate can stimulate urinary crystals to form which can elicit an immune response. This study consists of having healthy subjects consume both low and oxalate enriched diets to evaluate the effect of oxalate on urinary crystals and immune responses. Participants will receive a low or high oxalate diet for 4 days prior to having a wash out period for 6 days. Participants will then crossover to the opposite oxalate diet for four more days.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Alabama
    • Birmingham, Alabama, United States, 35233
      • University of Alabama at Birmingham

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 60 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Healthy subjects (men and women) between the ages of 18 and 60 years of age
• No calcium oxalate kidney stones or other medical conditions
• Normal comprehensive metabolic panel (CMP)
• Non tobacco users
• Not pregnant
• BMI between 20-30 kg/m2
• Willing to abstain from vigorous exercise and vitamins/supplements during the study
• Willing to consume only provided diets, accurately collect 24-hour urine samples, and have blood drawn

Exclusion Criteria:

• Inability to sign and read the informed consent
• Any medical, psychiatric, or social conditions that would prohibit participants from abiding by the study requirements
• Physician refusal
• Pregnant women
• Active medical problems
• History of kidney stones or any medical condition that could influence absorption or excretion of oxalate
• Tobacco users
• Taking medications or dietary supplements
• BMI >30 or <20

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Low Oxalate Diet Followed by High Oxalate Diet; 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.	Dietary supplement: Low Oxalate Diet; Participants will consume a diet that is controlled in its daily contents of oxalate and calcium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements, to exercise strenuously, or to consume food or drink that is not provided to them; Dietary supplement: High Oxalate Diet; Participants will consume a diet that is controlled in its daily contents of oxalate and calcium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements, to exercise strenuously, or to consume food or drink that is not provided to them.
Experimental: High Oxalate Diet Followed by Low Oxalate Diet; 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.	Dietary supplement: Low Oxalate Diet; Participants will consume a diet that is controlled in its daily contents of oxalate and calcium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements, to exercise strenuously, or to consume food or drink that is not provided to them; Dietary supplement: High Oxalate Diet; Participants will consume a diet that is controlled in its daily contents of oxalate and calcium, and in its content of carbohydrate, fat, and protein. Participants will be asked not to take any dietary supplements, to exercise strenuously, or to consume food or drink that is not provided to them.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Urinary Oxalate	Twenty-four hour urinary oxalate will be reported as mg/day.	Days 3-4 and 13-14
Change in Crystalluria	Crystalluria will be reported as particles/ml.	Days 3-4 and 13-14
Change in Monocyte Cellular Energetics and Mitochondrial Function	Cellular energetics and mitochondrial function will be reported as oxygen consumption rate (pmol/min/10,000 cells).	Days 1, 4, 11, and 14
Change in Monocyte Subtypes	Monocyte subtypes will be determined using flow cytometry (mean fluorescence intensity).	Days 1, 4, 11, and 14
Change in Monocyte Transcriptomics	Monocyte cellular transcriptomics will be determined using RNA sequencing (mRNA).	Days 1, 4, 11, and 14

Collaborators and Investigators

• Sponsor: University of Alabama at Birmingham
• Investigators: Principal Investigator: Tanecia Mitchell, PhD, University of Alabama at Birmingham

Study record dates

Study Major Dates

• Study Start (Actual): March 5, 2021
• Primary Completion (Estimated): May 1, 2026
• Study Completion (Estimated): May 1, 2026

Study Registration Dates

• First Submitted: August 1, 2019
• First Submitted That Met QC Criteria: August 7, 2019
• First Posted (Actual): August 9, 2019

Study Record Updates

• Last Update Posted (Actual): May 8, 2025
• Last Update Submitted That Met QC Criteria: May 5, 2025
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Keywords: diet therapy; dietary oxalate
• Additional Relevant MeSH Terms: Urogenital Diseases; Male Urogenital Diseases; Calculi; Pathological Conditions, Anatomical; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urolithiasis; Urinary Calculi; Kidney Calculi; Nephrolithiasis
• Other Study ID Numbers: IRB-300003865

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No