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

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.

Study Overview

• Status: Completed
• Conditions: Hyperoxaluria
• Intervention / Treatment: Dietary supplement: Aloe vera with cactus; Dietary supplement: Cranberry; Dietary supplement: Green tea extract; Dietary supplement: Bilberry; Dietary supplement: Cinnamon; Dietary supplement: Milk thistle; Dietary supplement: Turmeric; Dietary supplement: Aloe vera

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 Type: Interventional
• Enrollment (Actual): 45
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Wisconsin
    • Madison, Wisconsin, United States, 53705-2281
      • Department of Urology, School of Medicine & Public Health, University of Wisconsin

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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 Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

8

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Aloe vera with cactus; 1 capsule (500 mg), 2 times/day	Dietary supplement: Aloe vera with cactus; Eligible participants who provide consent/authorization will report for an orientation visit (1 of 3 visits), during which participants will: provide a medical history and a 24-hour diet recall, have height and weight measured, learn how to collect 24-hour urine, receive instructions on following a standardized diet for 7 days, learn to use a food scale and provide diet records, and receive a 4-day supply of the supplement they were allocated to take along with instructions. After 3 days on the diet (no supplement), participants will return their first (of 2) diet record and 24-hour urine collection. After 4 days on the diet while taking the supplement, participants will return their second (and final) completed diet record and their second (and final) 24-hour urine collection.; Other Names: Walgreens
Experimental: Cranberry; 3 capsules (810 mg), 2 times/day	Dietary supplement: Cranberry; Eligible participants who provide consent/authorization will report for an orientation visit (1 of 3 visits), during which participants will: provide a medical history and a 24-hour diet recall, have height and weight measured, learn how to collect 24-hour urine, receive instructions on following a standardized diet for 7 days, learn to use a food scale and provide diet records, and receive a 4-day supply of the supplement they were allocated to take along with instructions. After 3 days on the diet (no supplement), participants will return their first (of 2) diet record and 24-hour urine collection. After 4 days on the diet while taking the supplement, participants will return their second (and final) completed diet record and their second (and final) 24-hour urine collection.; Other Names: Puritan's Pride
Experimental: Green tea extract; 2 capsules (630 mg), 2 times/day	Dietary supplement: Green tea extract; Eligible participants who provide consent/authorization will report for an orientation visit (1 of 3 visits), during which participants will: provide a medical history and a 24-hour diet recall, have height and weight measured, learn how to collect 24-hour urine, receive instructions on following a standardized diet for 7 days, learn to use a food scale and provide diet records, and receive a 4-day supply of the supplement they were allocated to take along with instructions. After 3 days on the diet (no supplement), participants will return their first (of 2) diet record and 24-hour urine collection. After 4 days on the diet while taking the supplement, participants will return their second (and final) completed diet record and their second (and final) 24-hour urine collection.; Other Names: Puritan's Pride
Experimental: Bilberry; 1 softgel (1000 mg), 2 times/day	Dietary supplement: Bilberry; Eligible participants who provide consent/authorization will report for an orientation visit (1 of 3 visits), during which participants will: provide a medical history and a 24-hour diet recall, have height and weight measured, learn how to collect 24-hour urine, receive instructions on following a standardized diet for 7 days, learn to use a food scale and provide diet records, and receive a 4-day supply of the supplement they were allocated to take along with instructions. After 3 days on the diet (no supplement), participants will return their first (of 2) diet record and 24-hour urine collection. After 4 days on the diet while taking the supplement, participants will return their second (and final) completed diet record and their second (and final) 24-hour urine collection.; Other Names: Puritan's Pride
Experimental: Cinnamon; 1 capsule (500 mg), 2 times/day	Dietary supplement: Cinnamon; Eligible participants who provide consent/authorization will report for an orientation visit (1 of 3 visits), during which participants will: provide a medical history and a 24-hour diet recall, have height and weight measured, learn how to collect 24-hour urine, receive instructions on following a standardized diet for 7 days, learn to use a food scale and provide diet records, and receive a 4-day supply of the supplement they were allocated to take along with instructions. After 3 days on the diet (no supplement), participants will return their first (of 2) diet record and 24-hour urine collection. After 4 days on the diet while taking the supplement, participants will return their second (and final) completed diet record and their second (and final) 24-hour urine collection.; Other Names: Puritan's Pride
Experimental: Milk thistle; 1 capsule (250 mg), 3 times/day	Dietary supplement: Milk thistle; Eligible participants who provide consent/authorization will report for an orientation visit (1 of 3 visits), during which participants will: provide a medical history and a 24-hour diet recall, have height and weight measured, learn how to collect 24-hour urine, receive instructions on following a standardized diet for 7 days, learn to use a food scale and provide diet records, and receive a 4-day supply of the supplement they were allocated to take along with instructions. After 3 days on the diet (no supplement), participants will return their first (of 2) diet record and 24-hour urine collection. After 4 days on the diet while taking the supplement, participants will return their second (and final) completed diet record and their second (and final) 24-hour urine collection.; Other Names: Puritan's Pride
Experimental: Turmeric; 1 capsule (450 mg turmeric + 50 mg turmeric extract), 1 time/day	Dietary supplement: Turmeric; Eligible participants who provide consent/authorization will report for an orientation visit (1 of 3 visits), during which participants will: provide a medical history and a 24-hour diet recall, have height and weight measured, learn how to collect 24-hour urine, receive instructions on following a standardized diet for 7 days, learn to use a food scale and provide diet records, and receive a 4-day supply of the supplement they were allocated to take along with instructions. After 3 days on the diet (no supplement), participants will return their first (of 2) diet record and 24-hour urine collection. After 4 days on the diet while taking the supplement, participants will return their second (and final) completed diet record and their second (and final) 24-hour urine collection.; Other Names: Puritan's Pride
Experimental: Aloe vera; 1 capsule (470 mg), 2 times/day	Dietary supplement: Aloe vera; Eligible participants who provide consent/authorization will report for an orientation visit (1 of 3 visits), during which participants will: provide a medical history and a 24-hour diet recall, have height and weight measured, learn how to collect 24-hour urine, receive instructions on following a standardized diet for 7 days, learn to use a food scale and provide diet records, and receive a 4-day supply of the supplement they were allocated to take along with instructions. After 3 days on the diet (no supplement), participants will return their first (of 2) diet record and 24-hour urine collection. After 4 days on the diet while taking the supplement, participants will return their second (and final) completed diet record and their second (and final) 24-hour urine collection.; Other Names: Puritan's Pride

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Within-subject change in 24-hour urinary oxalate excretion from before and after supplementation	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.	7 days

Collaborators and Investigators

• Sponsor: University of Wisconsin, Madison
• Investigators: Principal Investigator: Kristina L Penniston, PhD, RD, Department of Urology, University of Wisconsin School of Medicine and Public Health

Study record dates

Study Major Dates

• Study Start: February 1, 2015
• Primary Completion (Actual): October 1, 2016
• Study Completion (Actual): October 1, 2016

Study Registration Dates

• First Submitted: March 26, 2015
• First Submitted That Met QC Criteria: March 26, 2015
• First Posted (Estimate): March 31, 2015

Study Record Updates

• Last Update Posted (Estimate): October 27, 2016
• Last Update Submitted That Met QC Criteria: October 26, 2016
• Last Verified: October 1, 2016

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Kidney Diseases; Urologic Diseases; Pathological Conditions, Anatomical; Urolithiasis; Urinary Calculi; Calculi; Nephrolithiasis; Kidney Calculi
• Other Study ID Numbers: 2015-0076