Low-Oxalate Diet for Kidney Stones
Recruiting in Palo Alto (17 mi)
Age: 18+
Sex: Any
Travel: May Be Covered
Time Reimbursement: Varies
Trial Phase: Academic
Recruiting
Sponsor: University of Chicago
Disqualifiers: Bowel surgery, Inflammatory bowel disease, others
No Placebo Group
Approved in 1 Jurisdiction
Trial Summary
What is the purpose of this trial?
This study aims to learn more about how oxalate, a compound found in many foods, may affect a person's chances of forming kidney stones. Active participation in this study will last for around one week. For the first two days, subjects will be asked to eat a special diet at home. From Days 3-5, they will eat special meals delivered to their home from a research clinic at the University of Chicago. They will also collect 24-hour urine samples at home on Days 4 and 5. On Day 6, they will come in to the research clinic at the University of Chicago in Hyde Park, where they will spend most of the day. They will receive a special liquid that contains oxalate, and we will have them eat a specially prepared breakfast that is low in oxalate and citrate.
Will I have to stop taking my current medications?
The trial information does not specify whether you need to stop taking your current medications. It's best to discuss this with the study coordinators or your doctor.
What data supports the effectiveness of the low-oxalate diet treatment for kidney stones?
Is a low-oxalate diet safe for humans?
How does the low-oxalate diet treatment for kidney stones differ from other treatments?
The low-oxalate diet treatment for kidney stones is unique because it focuses on reducing oxalate intake, which can help lower urinary oxalate levels and potentially prevent stone formation. Unlike other treatments that may involve medication or surgery, this approach is dietary and requires careful management of food choices, often with guidance from a dietitian.1291011
Eligibility Criteria
This trial is for adults aged 18-70 who have had bariatric surgery or are obese, with a history of calcium-based kidney stones and high urine oxalate levels. It's not for those with certain bowel surgeries, inflammatory bowel disease, or non-calcium based kidney stones.Inclusion Criteria
I am 18-70, had Roux-en-Y surgery, and developed calcium kidney stones with high urine oxalate levels after.
I am 18-70 years old, not obese, and have had at least one calcium kidney stone.
I am aged 18-70, have a BMI of 30 or more, have had at least one calcium-based kidney stone, and my urine oxalate level is high.
Exclusion Criteria
I have had bowel surgery or have a history of specific types of kidney stones or inflammatory bowel disease.
I have had gastric bypass and specific types of bowel surgery or stones.
Trial Timeline
Screening
Participants are screened for eligibility to participate in the trial
2-4 weeks
Diet Preparation
Participants follow a special low-oxalate diet at home for the first two days
2 days
No visits
Controlled Diet and Sample Collection
Participants receive special meals from the research clinic and collect 24-hour urine samples at home
3 days
No visits
Clinic Visit and Testing
Participants visit the research clinic for administration of a special liquid containing oxalate and a low-oxalate breakfast
1 day
1 visit (in-person)
Follow-up
Participants are monitored for changes in urine oxalate and sucralose levels after the intervention
1 week
Treatment Details
Interventions
- Special low-oxalate diet followed by all-day visit to University of Chicago research clinic (Behavioural Intervention)
Trial OverviewParticipants will follow a special low-oxalate diet at home and then eat meals provided by the University of Chicago research clinic. They'll also provide urine samples and consume a liquid containing oxalate during an all-day clinic visit to study its effects on kidney stone formation.
Participant Groups
1Treatment groups
Experimental Treatment
Group I: Subjects who will follow low-oxalate diet followed by visit to research clinicExperimental Treatment1 Intervention
30 stone-forming participants will be recruited to this study.
Special low-oxalate diet followed by all-day visit to University of Chicago research clinic is already approved in United States for the following indications:
🇺🇸 Approved in United States as Low-Oxalate Diet for:
- Prevention of Kidney Stones
- Management of Hyperoxaluria
Find a Clinic Near You
Research Locations NearbySelect from list below to view details:
University of Chicago Medical CenterChicago, IL
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Who Is Running the Clinical Trial?
University of ChicagoLead Sponsor
University of Alabama at BirminghamCollaborator
References
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
Low-oxalate, low-fat dietary regimen in hyperoxaluria following jejunoileal bypass. [2013]Previous studies have shown that the severity of enteric hyperoxaluria can be reduced in hospitalized patients who receive a diet low in oxalate and fat. Little is known of the value of such a diet in the patients' home conditions. Ten patients with hyperoxaluria (greater than 0.45 mmol/24 h) following jejuno-ileal bypass were therefore studied while on their ordinary diet and also on a diet with low-oxalate, low-fat content. The mean urinary excretion of oxalate decreased during the dietary treatment from 1.1 to 0.7 mmol/24 h. The diet was demanding, though not unfeasible for the patients. Careful and regular dietary information, preferably by a dietitian, is recommended in such cases.
Randomized controlled trial of a low animal protein, high fiber diet in the prevention of recurrent calcium oxalate kidney stones. [2019]Low protein diets are commonly prescribed for patients with idiopathic calcium nephrolithiasis, who account for > 80% of new diagnoses of kidney stones. This dietary advice is supported by metabolic studies and epidemiologic observational studies but has not been evaluated in a controlled trial. Using 1983-1985 data from three Northern California Kaiser Permanente Medical Centers, the authors randomly assigned 99 persons who had calcium oxalate stones for the first time to a low animal protein, high fiber diet that contained approximately 56-64 g daily of protein, 75 mg daily of purine (primarily from animal protein and legumes), one-fourth cup of wheat bran supplement, and fruits and vegetables. Intervention subjects were also instructed to drink six to eight glasses of liquid daily and to maintain adequate calcium intake from dairy products or calcium supplements. Control subjects were instructed only on fluid intake and adequate calcium intake. Both groups were followed regularly for up to 4.5 years with food frequency questionnaires, serum and urine chemistry analysis, and abdominal radiography; and they were urged to comply with dietary instructions. In the intervention group of 50 subjects, stones recurred in 12 (7.1 per 100 person-years) compared with two (1.2 per 100 person-years) in the control group; both groups received a mean of 3.4 person-years of follow-up (p = 0.006). After adjustment for possible confounding effects of age, sex, education, and baseline protein and fluid intake, the relative risk of a recurrent stone in the intervention group was 5.6 (95% confidence interval 1.2-26.1) compared with the control group. The authors conclude that advice to follow a low animal protein, high fiber, high fluid diet has no advantage over advice to increase fluid intake alone.
The role of diet in the pathogenesis and therapy of nephrolithiasis. [2013]The epidemic of nephrolithiasis in the developed world in the twentieth century is in part the result of the diet consumed in these affluent nations. High protein intake is probably the most important factor. The patients who develop nephrolithiasis may have an increased calciuric response to diet protein and perhaps to diet sodium. The benefits of dietary modification include not only a tendency to reduce urinary calcium excretion but also increased urinary citrate and reduced urinary oxalate excretion. High fluid intake is also an important component of the therapeutic armamentarium of the physician treating patients with recurrent stone formation. The benefit of dietary therapy in patients with recurrent stone formation has not as yet been rigorously tested in controlled studies. Furthermore, there are few valid clinical studies of various pharmacologic agents such as thiazides, phosphates, allopurinol, and citrate. In the absence of clear-cut advantage of any specific pharmacologic agent, it appears that many patients may benefit from dietary modification rather than embarking on a life-long use of medications to prevent stone recurrences.
Oral calcium supplement decreases urinary oxalate excretion in patients with enteric hyperoxaluria. [2017]We studied the effect of oral calcium supplementation in patients with enteric hyperoxaluria. Three patients with renal stone events following ileal resection were given oral calcium supplement. One of the three patients was put on a low-fat diet. The treatment reduced urinary oxalate excretion to the normal range. Subsequently, 2 patients reduced the dose of calcium supplementation at their own discretion and consequently developed renal stones again together with hyperoxaluria. Based on these observations, we believe that an adequate dose of calcium can normalize urinary oxalate excretion.
Empiric use of potassium citrate reduces kidney-stone incidence with the ketogenic diet. [2021]Kidney stones are an adverse event with the ketogenic diet (KD), occurring in approximately 6% of children who are started on this therapy for intractable epilepsy. Potassium citrate (Polycitra K) is a daily oral supplement that alkalinizes the urine and solubilizes urine calcium, theoretically reducing the risk for kidney stones.
Calcium oxalate kidney stones: another reason to encourage moderate calcium intakes and other dietary changes. [2013]Conventional medical thought several decades ago was to restrict the amount of calcium intake in individuals with a history of calcium oxalate stones. In the past decade, several studies have suggested that increasing the intake of calcium may actually reduce the risk of calcium oxalate stone formation. The largest randomized trial of diet and stone recurrence was recently completed. Interestingly, individuals that had normal calcium intakes and lower intakes of protein and salt had a significantly reduced rate of calcium oxalate stone recurrence. This recent trial along with several past epidemiologic studies should be discussed with patients at high risk of stone recurrence. Currently, health professionals have a wealth of information that can be distributed to individuals at high risk of nephrolithiasis, and simple dietary recommendations may be one of the best ways to reduce the risk of calcium oxalate stones.
Prospects for dietary therapy of recurrent nephrolithiasis. [2014]The goal of this article is to propose a randomized controlled trial (RCT) that tests a hypothesis that dietary manipulation prevents recurrent kidney stones. Dietary interventions based on epidemiologic and pathophysiologic data are reviewed. The only diet trial successful in preventing stones showed that calcium intake of 1,200 mg/d, accompanied by restriction of animal protein, salt, and oxalate ingestion, was superior to 400 mg of calcium and restricted oxalate intake. This study may be worth repeating in women and in a society in which salt restriction might be less effective (eg, United States). The net result of diet trials establishes significant positive effects on urine chemistries, but these have not yet shown efficacy with regard to stone recurrence. Oxalate restriction alone could be effective, but many questions regarding which populations to study are not defined, and dietary oxalate's contribution to stone formation is disputed. Would such a study be limited to patients identified as having high dietary oxalate intake or high intestinal oxalate absorption? Would colonization with Oxalobacter formigenes influence the result? The increased prevalence of stones is linked to weight gain and obesity, making weight loss a possible therapy to prevent stones. 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 formation. Because the efficacy of thiazides in the prevention of stones in patients with hypercalciuria is clear, I propose dietary comparison of higher calcium intake to thiazides for the prevention of calcium-based kidney stones.
[Incidence of hyperoxaluria in idiopathic calcium nephrolithiasis]. [2013]Urinary excretion rate of oxalate was measured in 79 patients with idiopathic calcium (Ca) nephrolithiasis and the results were compared with those obtained in 28 healthy volunteers. The group of stone formers consisted of 20 patients with idiopathic hypercalciuria (IHC) of the absorptive type, 23 patients with IHC of the renal type, 11 patients with hypercalciuria secondary to dietary factors, 1 patient with hyperuricosuria (as an isolated finding) and 24 patients without hypercalciuria nor hyperuricosuria. Classification was based upon the urinary excretion rate of uric acid, as well as that of calcium measured under 3 different dietary conditions (i.e. free diet, free diet supplemented with 3 g Ca/day for 3 days, and diet free of dairy products for 5 days). On a free diet, normal values of oxaluria ranged from 125 to 435 mumol/24 h; an elevated value was observed in 11 (14%) patients, 5 of whom belonged to the subgroup without hypercalciuria nor hyperuricosuria. On a low Ca diet, mild hyperoxaluria occurred in 3 controls and in 19 patients, the tendency to develop hyperoxaluria being particularly marked in the subgroup with absorptive-IHC. Moreover, there was a positive correlation between oxaluria on a low Ca diet and the estimated degree of intestinal absorption of Ca. This study confirms the finding that on a free diet, the incidence of mild hyperoxaluria amongst idiopathic stone formers is rather low. It shows, however, that a significant percentage of patients classically referred to as "without metabolic disorder" have in fact slight hyperoxaluria, an observation with a potential therapeutic impact. Finally, it shows that on a low Ca diet, patients with absorptive-IHC are particularly prone to develop hyperoxaluria: the latter observation renders questionable the relevance of a low Ca diet for patients with absorptive IHC, unless their intake of oxalate is simultaneously reduced.
Hyperoxaluria in patients with recurrent calcium oxalate calculi: dietary and other risk factors. [2022]The presence of mild hyperoxaluria in recurrent calcium oxalate stone formers is controversial. The aim of this study was to identify recurrent stone formers with mild hyperoxaluria and to classify them further by assessing their response to a low oxalate diet. In addition, the prevalence of other risk factors for stone formation in this group of patients was investigated. A total of 207 consecutive patients with recurrent renal calculi were screened and 40 (19%) were found to have mild hyperoxaluria. Of these, 18 (45%) responded to dietary oxalate restriction by normalising their urinary oxalate. The remaining 22 patients were classified as having idiopathic hyperoxaluria and were subdivided into those in whom urinary oxalate excretion was consistently elevated in all specimens measured and those in whom the elevation was intermittent in nature. Dietary oxalate restriction had a partially beneficial effect in lowering oxalate excretion in the patients with persistent hyperoxaluria. No difference in urinary oxalate excretion was found after dietary restriction in the patients with intermittent hyperoxaluria. Other risk factors, including dietary, absorptive and renal hypercalciuria and hypocitraturia, were documented, the prevalence of which (65%) was not significantly different from that (62.5%) found in 40 age- and sex-matched calcium stone formers without hyperoxaluria. The prevalence of hyperuricosuria was significantly greater in patients with hyperoxaluria when compared with stone controls. Further studies are required to elucidate the underlying mechanisms of hyperoxaluria in recurrent stone formers.
Influence of the calcium content of the diet on the incidence of mild hyperoxaluria in idiopathic renal stone formers. [2018]Urinary oxalate excretion was measured in 101 male idiopathic calcium (Ca) stone formers studied on 3 dietary conditions (free-choice, Ca-enriched, and low-Ca diet). The population consisted of 38 normocalciuric and 63 hypercalciuric patients. Mean oxalate excretion was similar in normocalciuric and in hypercalciuric patients, on free-choice as well as on Ca-enriched diet. In both conditions the incidence of hyperoxaluria (greater than or equal to 435 mumol/24 h) within each group of stone formers was also similar, ranging from 11 to 22%. On low-Ca diet, however, mean oxalate excretion increased significantly (p less than 0.01) in hypercalciurics but not in normocalciurics; on this diet, the incidence of hyperoxaluria was particularly high in the hypercalciurics (33%), compared with the normocalciurics (13%). On low-Ca diet, oxalate excretion was positively correlated with the estimated degree of intestinal absorption of calcium (p = 0.01). These results show that among idiopathic stone formers, mild hyperoxaluria is not a rare finding and that this disorder can be encountered in each group of patients; its incidence, however, is influenced by the calcium content of the diet. On a low-Ca diet, patients with intestinal Ca hyperabsorption are particularly prone to develop hyperoxaluria, an observation which leads to question the relevance of such a dietary advice unless oxalate intake is simultaneously reduced.