Tsai WC, Wu HY, Peng YS, et al. - In this randomized, active-controlled trial with a crossover design, researchers determined how fibroblast growth factor 23 (FGF23) level in patients undergoing hemodialysis can be influenced in the short-term by the intake of low-phosphate diets. They also determined the optimal quantity of dietary phosphate restriction in these patients. Participants were recruited from the hemodialysis unit of tertiary teaching hospital in Taiwan and included 35 adults with ESKD undergoing thrice-weekly hemodialysis and having a serum phosphate level > 5.5 mg/dl or between 3.5 and 5.5 mg/dl with regular phosphate binder use. These patients were randomly 1:1 administered a very-low-phosphate diet, with a phosphate-to-protein ratio of 8 mg/g, or a low-phosphate diet, with a phosphate-to-protein ratio of 10 mg/g for 2 days, each with a 5-day washout during which patients were asked to adhere to their regular diet. They found that very-low-phosphate diet-induced reduction in FGF23 over the 2-day period was similar to that brought about by a low-phosphate diet during the same time span. An additional phosphate-lowering effect of the very-low-phosphate diet vs the low-phosphate diet was evident.