Diet and Oxalate Absorption for Kidney Stones
Recruiting in Palo Alto (17 mi)
+1 other location
Age: 18+
Sex: Any
Travel: May Be Covered
Time Reimbursement: Varies
Trial Phase: Academic
Recruiting
Sponsor: University of Alabama at Birmingham
Must not be taking: Immunosuppressants, NSAIDs
Disqualifiers: Chronic kidney disease, Diabetes, others
No Placebo Group
Trial Summary
What is the purpose of this trial?The goal of this clinical trial study is to test if patients with idiopathic calcium oxalate kidney stones have an increased absorption of dietary oxalate, which would lead to increased urinary excretion of oxalate.
The study will recruit adult patients with a history of calcium oxalate kidney stones and healthy volunteers without kidney stones.
Participants will
* ingest fixed diets containing low and moderately high amounts of oxalate for 5 days at a time
* ingest a soluble form of oxalate and sugar preparations to test gut permeability
* collect urine, blood, stool and breath sample during the fixed diets and the soluble oxalate test
Will I have to stop taking my current medications?
The trial requires participants to stop taking supplements like vitamins, calcium, and herbal supplements for 2 weeks before and during the study. The protocol does not specify if you need to stop other medications, so it's best to discuss with the study team.
What data supports the effectiveness of the treatment for kidney stones?
Research shows that a high calcium diet can help protect against the formation of calcium oxalate stones, which are a common type of kidney stone. Additionally, studies indicate that a high-oxalate diet increases oxalate absorption in the gut, which can contribute to stone formation, suggesting that managing dietary oxalate intake is important for reducing kidney stone risk.
12345Is a high-oxalate diet safe for humans?
Research shows that a high-oxalate diet can increase oxalate absorption in the body, but it does not mention any specific safety concerns for healthy individuals. However, people with a high rate of oxalate absorption or certain intestinal conditions might experience increased urinary oxalate, which could be a risk factor for kidney stones.
12678How does the dietary oxalate treatment for kidney stones differ from other treatments?
This treatment focuses on adjusting dietary oxalate intake to manage kidney stones, which is unique because it targets the absorption of oxalate in the intestines rather than just reducing oxalate excretion. Unlike other treatments, it involves a dietary approach that can either increase or decrease oxalate intake to study its effects on stone formation.
128910Eligibility Criteria
This trial is for adults who've had calcium oxalate kidney stones and healthy volunteers without a history of these stones. Participants will follow specific diets and undergo tests to study how their bodies handle oxalate.Inclusion Criteria
Body Mass Index > 18.5 kg/m2
Normal fasting serum electrolytes on comprehensive metabolic profile
I am between 18 and 70 years old.
+3 more
Exclusion Criteria
My blood pressure or diabetes is not well-controlled.
My kidney function is severely reduced.
I have type 1 diabetes.
+7 more
Trial Timeline
Screening
Participants are screened for eligibility to participate in the trial
2-4 weeks
1 visit (in-person)
Low-oxalate diet and initial tests
Participants ingest a controlled low-oxalate diet for 5 days and collect urine samples for analysis
5 days
2 visits (in-person)
13C2-Oxalate gut absorption test
Participants undergo the 13C2-oxalate absorption test with hourly blood and urine collections
1 day
1 visit (in-person)
Wash-out period
Participants have a wash-out period where they eat freely before the next phase
1 week
High-oxalate diet
Participants consume a high-oxalate diet for 4 days and collect urine samples for analysis
4 days
1 visit (in-person)
Follow-up
Participants are monitored for safety and effectiveness after the dietary interventions
2 weeks
Participant Groups
The trial involves participants eating low and high-oxalate diets for five days each, taking an oxalate absorption test with sugar solutions, and providing urine, blood, stool, and breath samples to measure the effects.
2Treatment groups
Experimental Treatment
Active Control
Group I: Idiopathic Calcium Oxalate Kidney Stone PatientsExperimental Treatment3 Interventions
Low and High oxalate fixed diets. Soluble oxalate absorption test.
Group II: Healthy non-kidney stone forming individualsActive Control3 Interventions
Low and High oxalate fixed diets. Soluble oxalate absorption test.
Find a Clinic Near You
Research Locations NearbySelect from list below to view details:
University of Alabama at BirminghamBirmingham, AL
UTSWDallas, TX
Loading ...
Who Is Running the Clinical Trial?
University of Alabama at BirminghamLead Sponsor
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)Collaborator
University of Texas Southwestern Medical CenterCollaborator
References
Effect of high and low calcium diets on stone forming risk during liberal oxalate intake. [2013]Recent studies suggest that a high calcium diet protects against calcium oxalate stone formation. We compared the effect of high and low calcium diets on urinary saturation of calcium oxalate during liberal oxalate intake.
Influence of a high-oxalate diet on intestinal oxalate absorption. [2018]Hyperoxaluria is a major risk factor for renal stones. In most cases, it is sustained by increased dietary loads. In healthy individuals with a normal Western diet, the majority of urinary oxalate is usually derived from endogenous metabolism. However, up to 50% may be derived from the diet. We were interested in the effect of a high-oxalate diet on oxalate absorption, not merely on the frequently studied increased oxalate excretion. In study I, 25 healthy volunteers were tested with the [13C2]oxalate absorption test once while following a low-oxalate (63 mg) and once while following a high-oxalate (600 mg) diet for 2 days each. In study II, four volunteers repeated study I, and afterwards continued with a high-oxalate diet (600 mg oxalate/day) for 6 weeks. In the last week, the [13C2]oxalate absorption test was repeated. After 4 weeks of individual normal diet, the oxalate absorption test with a high-oxalate diet was performed again. The results of study I show that the mean [13C2]oxalate absorption under low-oxalate diet was 7.9 +/- 4.0%. In the presence of oxalate-rich food, the percent absorption for the soluble labelled oxalate almost doubled (13.7 +/- 6.3%). The results of study II show that the mean [13C2]oxalate absorption of the four volunteers under low-oxalate diet was 7.3 +/- 1.4%. The absorption increased to 14.7+/-5.2% under 600 mg oxalate. After 6 weeks under a high-oxalate diet, the [13C2]oxalate absorption was significantly decreased (8.2 +/- 1.7%). After the wash-out phase, the absorption was again high (14.1 +/- 2.2%) under the 600 mg oxalate challenge.
Effect of dietary changes on urinary oxalate excretion and calcium oxalate supersaturation in patients with hyperoxaluric stone formation. [2022]To test the hypothesis that patients with hyperoxaluria, who modified their dietary calcium intake, would reduce their urinary oxalate excretion without raising their urinary calcium excretion. Diet is a major factor in idiopathic calcium oxalate urolithiasis, yet controversy exists regarding the ideal clinical recommendations. Approximately 20% of patients with calcium oxalate stone formation have hyperoxaluria (> or = 45 mg oxalate/d). Calcium supplements to bind dietary oxalate have been suggested, but clinical evidence of this therapy is lacking.
Intestinal oxalate absorption is higher in idiopathic calcium oxalate stone formers than in healthy controls: measurements with the [(13)C2]oxalate absorption test. [2022]We assessed the importance of oxalate hyperabsorption for idiopathic calcium oxalate urolithiasis, oxalate absorption in healthy volunteers and recurrent calcium oxalate stone formers was compared.
Effect of dietary intake on urinary oxalate excretion in calcium renal stone formers. [2019]To investigate the influence of dietary intake on urinary oxalate excretion in calcium renal-stone formers.
Dietary oxalate and calcium oxalate nephrolithiasis. [2013]Patients with calcium oxalate kidney stones are advised to decrease the consumption of foods that contain oxalate. We hypothesized that a cutback in dietary oxalate would lead to a decrease in the urinary excretion of oxalate and decreased stone recurrence. We tested the hypothesis in an animal model of calcium oxalate nephrolithiasis.
Diet to reduce mild hyperoxaluria in patients with idiopathic calcium oxalate stone formation: a pilot study. [2022]To assess whether a normal-calcium, low-animal protein, low-salt diet is effective in reducing hyperoxaluria in idiopathic calcium oxalate nephrolithiasis compared with a traditional low-oxalate diet, routinely recommended by clinicians
Effect of dietary oxalate and calcium on urinary oxalate and risk of formation of calcium oxalate kidney stones. [2022]Dietary restriction of oxalate intake has been used as therapy to reduce the risk of recurrence of calcium oxalate kidney stones. Although urinary oxalate is derived predominantly from endogenous synthesis, it may also be affected by dietary intake of oxalate and calcium. The risk of increasing urinary oxalate excretion by excessive consumption of dietary oxalate is greatest in individuals with a high rate of oxalate absorption, both with and without overt intestinal disease. Although oxalate-rich foods enhanced excretion of urinary oxalate in normal volunteers, the increase was not proportional to the oxalate content of the food. Only eight foods--spinach, rhubarb, beets, nuts, chocolate, tea, wheat bran, and strawberries--caused a significant increase in urinary oxalate excretion. Restriction of dietary calcium enhances oxalate absorption and excretion, whereas an increase in calcium intake may reduce urinary oxalate excretion by binding more oxalate in the gut. This review of the literature indicates that initial dietary therapy for stone-forming individuals can be limited to the restriction of foods definitely shown to increase urinary oxalate. The effects of oxalate-restricted diets on urinary oxalate should be evaluated by means of laboratory analyses of urine composition. Subsequent long-term therapy can be recommended if beneficial results are obtained from oxalate restriction at an appropriate calcium intake.
[13C2]oxalate absorption in children with idiopathic calcium oxalate urolithiasis or primary hyperoxaluria. [2013]Intestinal oxalate absorption is an important part of oxalate metabolism influencing its urinary excretion and its measurement can be a valuable diagnostic tool in hyperoxaluric disorders. In this study, we use [(13)C(2)]oxalate absorption under standardized dietary conditions to assess intestinal oxalate absorption and its impact on urinary oxalate excretion. Tests were conducted in age-matched pediatric patients that included 60 with idiopathic calcium oxalate urolithiasis, 13 with primary hyperoxaluria, and 35 healthy children. In the idiopathic stone formers, median oxalate absorption was significantly higher than that in the controls or in patients with primary disease. From standardized values obtained in control patients, oxalate hyperabsorption was detected in 23 patients with idiopathic disease but not in any patients with primary hyperoxaluria; therefore, a significant correlation between intestinal absorption and urinary excretion was found only in those with the idiopathic disease. We have shown that increased intestinal oxalate absorption is an important risk factor of idiopathic calcium oxalate urolithiasis. In contrast, low intestinal oxalate absorption in patients with primary hyperoxaluria indicates that only foods with excessive oxalate content be restricted from their diet.
The impact of dietary oxalate on kidney stone formation. [2018]The role of dietary oxalate in calcium oxalate kidney stone formation remains unclear. However, due to the risk for stone disease that is associated with a low calcium intake, dietary oxalate is believed to be an important contributing factor. In this review, we have examined the available evidence related to the ingestion of dietary oxalate, its intestinal absorption, and its handling by the kidney. The only difference identified to date between normal individuals and those who form stones is in the intestinal absorption of oxalate. Differences in dietary oxalate intake and in renal oxalate excretion are two other parameters that are likely to receive close scrutiny in the near future, because the research tools required for these investigations are now available. Such research, together with more extensive examinations of intestinal oxalate absorption, should help clarify the role of dietary oxalate in stone formation.