Effect of Over-the-counter Dietary Supplements on Kidney Stone Risk

Not Applicable

Completed

• Conditions: Hyperoxaluria
• Interventions: Dietary Supplement: Bilberry; Dietary Supplement: Cranberry; Dietary Supplement: Aloe vera with cactus; Dietary Supplement: Cinnamon; Dietary Supplement: Green tea extract; Dietary Supplement: Milk thistle; Dietary Supplement: Turmeric; Dietary Supplement: Aloe vera

• Registration Number: NCT02404701
• Lead Sponsor: University of Wisconsin, Madison

Brief Summary

The purpose of this study is to ascertain whether certain supplements promote excessive urinary oxalate excretion and increase the risk for calcium oxalate kidney stones. Supplements that enhance urinary oxalate excretion, as a result of their oxalate concentration or from some other mechanism (e.g., providing substrate for oxalate biosynthesis) will be identified by the investigators.

Detailed Description

The investigators hypothesize that certain over-the-counter dietary supplements will increase urinary excretion of oxalate as measured in 24-h urine collections. The investigators further hypothesize that the concentration of oxalate in dietary supplements may not be associated with urinary oxalate excretion, suggesting that other nutritional components of the supplements may be exerting an influence over oxalate biosynthesis, oxalate absorption in the gastrointestinal tract, and/or renal oxalate handling. These other factors include the form of oxalate in the supplement (water- vs. non water-soluble) and the supplement's concentration of ascorbic acid.

Study Timeline

• Study Start: 2015-02
• Study First Submitted: 2015-03-26
• Study First Submitted QC: 2015-03-26
• Study First Posted: 2015-03-31
• Status Verified: 2016-10
• Primary Completion: 2016-10
• Study Completion: 2016-10
• Last Update Submitted: 2016-10-26
• Last Update Posted: 2016-10-27

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 45

Inclusion Criteria

• At least 18 years of age, no prior personal history of kidney stones

Exclusion Criteria

• Personal history of kidney stones (by subjects' report); known allergy to any of the dietary supplements to be used in the study (by subjects' report); short bowel; active ulcerative colitis or irritable bowel disease; Crohns or Celiac disease; renal tubular acidosis; current use of topiramate or other carbonic anhydrase inhibitor, steroids, allopurinol, thiazide diuretics, or supplemental ascorbic acid >250 mg/day.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Bilberry	Bilberry	1 softgel (1000 mg), 2 times/day
Cranberry	Cranberry	3 capsules (810 mg), 2 times/day
Aloe vera with cactus	Aloe vera with cactus	1 capsule (500 mg), 2 times/day
Cinnamon	Cinnamon	1 capsule (500 mg), 2 times/day
Green tea extract	Green tea extract	2 capsules (630 mg), 2 times/day
Milk thistle	Milk thistle	1 capsule (250 mg), 3 times/day
Turmeric	Turmeric	1 capsule (450 mg turmeric + 50 mg turmeric extract), 1 time/day
Aloe vera	Aloe vera	1 capsule (470 mg), 2 times/day

Primary Outcome Measures

Name	Time	Method
Within-subject change in 24-hour urinary oxalate excretion from before and after supplementation	7 days	24-hour urine samples will be analyzed for oxalate by ion chromatography. The difference in oxalate between the baseline (non-supplement) and supplement phase will be assessed.

Trial Locations

Locations (1)

Department of Urology, School of Medicine & Public Health, University of Wisconsin; 🇺🇸 Madison, Wisconsin, United States