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.
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
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
45
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.
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.
Department of Urology, School of Medicine & Public Health, University of Wisconsin
Madison, Wisconsin, United States
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.
Time frame: 7 days
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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.
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.
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.
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.
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.
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.