Phosphate Binders and Nonphosphate Effects in the Gastrointestinal Tract

Phosphate binders are commonly prescribed in patients with end-stage kidney disease to prevent and treat hyperphosphatemia. These binders are usually associated with gastrointestinal distress, may bind molecules other than phosphate, and may alter the gut microbiota, altogether having systemic effects unrelated to phosphate control. Sevelamer is the most studied of the available binders for nonphosphate-related effects including binding to bile acids, endotoxins, gut microbiota-derived metabolites, and advanced glycation end products. Other binders (calcium- and noncalcium-based binders) may bind vitamins, such as vitamin K and folic acid. Moreover, the relatively new iron-based phosphate binders may alter the gut microbiota, as some of the iron or organic ligands may be used by the gastrointestinal bacteria. The objective of this narrative review is to provide the current evidence for the nonphosphate effects of phosphate binders on gastrointestinal function, nutrient and molecule binding, and the gut microbiome.