Clinical Trial: Study of Dietary Additive Phosphorus on Proteinuria and Fibroblast Growth Factor-23

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Randomized Cross-over Study Examining the Effects of Phosphorus Additives on Urinary Albumin Excretion and Fibroblast Growth Factor-23

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 during the higher phosphorus period compared to the lower phosphorus period.


Detailed Summary:
Sponsor: Geisinger Clinic

Current Primary Outcome:

  • 24-hour urine albumin excretion [ Time Frame: 3 weeks ]
    Two 24-hour urine collections will be collected during the 3rd week of each period
  • 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



Original Primary Outcome:

  • 24-hour urine albumin excretion [ Time Frame: 3 weeks ]
    Two 24-hour urine collections will be collected during the 3rd week of each period
  • Fibroblast growth factor-23 (FGF-23) [ Time Frame: 3 weeks ]
    Intact FGF-23 will be collected at the end of each 3 week periods in the morning after an overnight fast


Current Secondary Outcome: Mean Systolic and Diastolic Blood Pressure [ Time Frame: 2-3 weeks ]

Measured 3 times during each period (beginning of weeks 2 and 3, and end of week 3)


Original Secondary Outcome:

Information By: Geisinger Clinic

Dates:
Date Received: December 19, 2013
Date Started: January 2014
Date Completion:
Last Updated: October 8, 2015
Last Verified: October 2015