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

• 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: Geisinger Clinic
• Collaborator: Johns Hopkins University
• Information provided by (Responsible Party): Alexander Chang, Geisinger Clinic

Study Description

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).

Study Design

• 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

Arms and Interventions

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.

Outcome Measures

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.

Eligibility Criteria

• 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

Contacts and Locations

Locations

United States, Maryland

Prohealth Clinical Research Unit

Baltimore, Maryland, United States, 21207

Sponsors and Collaborators

Geisinger Clinic

Johns Hopkins University

Investigators

• Principal Investigator: Alex R Chang, MD, MS; Geisinger Clinic
• Study Director: Lawrence J Appel, MD, MPH; Johns Hopkins University

More Information

Publications:

Chang A, Batch BC, McGuire HL, Vollmer WM, Svetkey LP, Tyson CC, Sanguankeo A, Anderson C, Houston J, Appel LJ. Association of a reduction in central obesity and phosphorus intake with changes in urinary albumin excretion: the PREMIER study. Am J Kidney Dis. 2013 Nov;62(5):900-7. doi: 10.1053/j.ajkd.2013.04.022. Epub 2013 Jun 28.

• 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
• 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:

Proteinuria; Albuminuria; Urination Disorders; Urologic Diseases; Urological Manifestations