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

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.