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Study of Dietary Additive Phosphorus on Proteinuria and Fibroblast Growth Factor-23 (SODA-POP)

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ClinicalTrials.gov Identifier: NCT02020785
Recruitment Status : Completed
First Posted : December 25, 2013
Results First Posted : June 5, 2019
Last Update Posted : June 5, 2019
Sponsor:
Collaborator:
Johns Hopkins University
Information provided by (Responsible Party):
Alexander Chang, Geisinger Clinic

Brief Summary:

Phosphorus-based food additives are commonly used by food manufacturers for many applications, such as enhancing flavor, in ready-to-eat foods and beverages. While these additives can significantly increase an individual's daily phosphorus intake, little is known about the effect of dietary phosphorus on kidney health. In this study, the investigators will first lower baseline phosphorus intake to about 1000mg/d by educating participants to avoid foods with phosphorus additives. Then, participants will be randomized to a higher phosphorus period (~2gm/d) and a lower phosphorus period (~1gm/d) by providing unaltered, commercially-available food/beverage products with and without phosphorus additives.

The investigators hypothesize that participants will have higher urine albumin excretion and fibroblast growth factor-23 (FGF-23) during the higher phosphorus period compared to the lower phosphorus period.


Condition or disease Intervention/treatment Phase
Albuminuria Other: Higher phosphorus period Other: Lower phosphorus period Not Applicable

Detailed Description:
The Study of Dietary Additive Phosphorus on Proteinuria and FGF-23 (SODA-POP) was a single-center, randomized, double-blind, two-period cross-over study that examined the effect of higher vs. lower phosphorus intake for 3 week periods, achieved by addition of commercially available diet beverages and breakfast bars to diet on albuminuria and fibroblast growth factor 23, in adults with presumed early chronic kidney disease (estimated glomerular filtration rate >= 45 ml/min/1.73m2; and urine albumin/creatinine ratio >=17 mg/g for men or >=25 mg/g for women).

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 31 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Randomized Cross-over Study Examining the Effects of Phosphorus Additives on Urinary Albumin Excretion and Fibroblast Growth Factor-23
Study Start Date : January 2014
Actual Primary Completion Date : September 2015
Actual Study Completion Date : September 2015


Arm Intervention/treatment
Active Comparator: Higher phosphorus period
Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks
Other: Higher phosphorus period

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks.

All participants at the beginning of the study will receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.


Placebo Comparator: Lower phosphorus period
Commercially-available unaltered food/beverage products without phosphorus additives (<10mg/d of phosphorus) will be given for 3 weeks
Other: Lower phosphorus period

Commercially-available unaltered food/beverage products without phosphorus additives (<10mg/d of phosphorus) will be given for 3 weeks.

All participants at the beginning of the study will receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.





Primary Outcome Measures :
  1. 24-hour Urine Albumin Excretion [ Time Frame: 3 weeks ]
    Two 24-hour urine collections will be collected during the 3rd week of each period

  2. Fibroblast Growth Factor-23 (FGF-23) [ Time Frame: 3 weeks ]

    Plasma FGF-23 will be measured at the end of each 3 week period in the morning after an overnight fast.

    As this is a small pilot study, we will not adjust for multiple comparisons. A p value<0.05 will be considered statistically significant for both outcomes



Secondary Outcome Measures :
  1. Systolic Blood Pressure [ Time Frame: 2-3 weeks ]
    Blood pressure was measured at the end of weeks 1, 2, and 3. At each visit, 3 readings were obtained in the seated position by trained and certified observers after 5 minutes of rest with an Omron HEM-907 device (Omron Healthcare Inc, Bannockburn, Ill) using a standardized protocol. We used the average of all blood pressure measurements at the end of weeks 1, 2, and 3 for each period.

  2. Diastolic Blood Pressure [ Time Frame: 2-3 weeks ]
    Blood pressure measured at the end of weeks 1, 2, and 3. At each visit, 3 readings were obtained in the seated position by trained and certified observers after 5 minutes of rest with an Omron HEM-907 device (Omron Healthcare Inc, Bannockburn, Ill) using a standardized protocol. We used the average of all these readings taken during end of weeks 1, 2, and 3 for each period.



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Ages Eligible for Study:   21 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

Adults at least 21 years of age with at least microalbuminuria

Exclusion Criteria:

Estimated glomerular filtration rate <45ml/min/1.73m2, poorly controlled diabetes or hypertension, nephrotic syndrome, hyperparathyroidism, Paget's Disease, multiple myeloma, uncontrolled thyroid disease, chronic antacid use, use of phosphorus binders, phosphorus supplements, or high-dose vitamin D, inability to complete feeding study, investigator discretion


Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02020785


Locations
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United States, Maryland
Prohealth Clinical Research Unit
Baltimore, Maryland, United States, 21207
Sponsors and Collaborators
Geisinger Clinic
Johns Hopkins University
Investigators
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Principal Investigator: Alex R Chang, MD, MS Geisinger Clinic
Study Director: Lawrence J Appel, MD, MPH Johns Hopkins University
Publications:
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Responsible Party: Alexander Chang, Clinical Investigator, Geisinger Clinic
ClinicalTrials.gov Identifier: NCT02020785    
Other Study ID Numbers: NA_00082089
13CRP16970085 ( Other Grant/Funding Number: American Heart Association )
Satellite Dialysis ( Other Grant/Funding Number: National Kidney Foundation )
First Posted: December 25, 2013    Key Record Dates
Results First Posted: June 5, 2019
Last Update Posted: June 5, 2019
Last Verified: February 2019
Keywords provided by Alexander Chang, Geisinger Clinic:
proteinuria
Additional relevant MeSH terms:
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Proteinuria
Albuminuria
Urination Disorders
Urologic Diseases
Urological Manifestations