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.
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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
31
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.
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.
Prohealth Clinical Research Unit
Baltimore, Maryland, United States
24-hour Urine Albumin Excretion
Two 24-hour urine collections will be collected during the 3rd week of each period
Time frame: 3 weeks
Fibroblast Growth Factor-23 (FGF-23)
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
Time frame: 3 weeks
Systolic Blood Pressure
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.
Time frame: 2-3 weeks
Diastolic Blood Pressure
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.
Time frame: 2-3 weeks
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