Short-Term Effects of Very-Low-Phosphate and Low-Phosphate Diets on Fibroblast Growth Factor 23 in Hemodialysis Patients

Abstract

Background and objectivesThe short-term effects of low-phosphate diets on fibroblast growth factor 23 (FGF23) level and the optimal amount of dietary phosphate restriction in patients undergoing hemodialysis remain unknown.Design setting, participants, & measurementsThis was a randomized, active-controlled trial with a crossover design that included 35 adults with ESKD undergoing thrice-weekly hemodialysis and with a serum phosphate level >5.5 mg/dl or between 3.5 and 5.5 mg/dl with regular phosphate binder use at a hemodialysis unit of tertiary teaching hospital in Taiwan. Subjects were randomized 1:1 to receive 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 subjects adhered to their usual diet. The primary outcome measure was mean difference in change-from-baseline intact FGF23 level between intervention groups. Secondary outcomes included difference in change-from-baseline serum phosphate, intact parathyroid hormone (PTH), and C-terminal FGF23 level between intervention groups.ResultsThere was no significant difference in the mean change-from-baseline in intact FGF23 levels between the two study diets. The very-low-phosphate diet significantly lowered serum phosphate (mean difference, 0.6 mg/dl; 95% confidence interval [95% CI], 0.2 to 1.0; P=0.002). There were no significant differences in change-from-baseline intact PTH and C-terminal FGF23 levels between the two study diets.ConclusionsOver the 2-day period, the FGF23-lowering effect of the very-low-phosphate diet is similar to that of the low-phosphate diet. The very-low-phosphate diet has an additional phosphate-lowering effect compared with the low-phosphate diet.

Inflammation and Premature Ageing in Chronic Kidney Disease

“…However, there is a lack of studies linking diets that lower P i levels to a beneficial clinical outcome [86,87]. Furthermore, whereas low-P i diets can reduce FGF-23 levels in CKD [88], there was no dose-dependent effect of P i lowering on FGF-23 reduction when low-and very low phosphate diets were compared in a recent short-term, randomized, crossover trial in 35 ESKD patients [89]. Therefore, non-pharmacological lifestyle-changing prevention strategies might provide a benefit on components of the ageing process, but randomized controlled trials are needed to prove these associations.…”

FGF23 and Phosphate–Cardiovascular Toxins in CKD

“…Tsai et al compared the effects of a very-low phosphate diet (phosphate-to-protein ratio of 8 mg/g) and low phosphate (phosphate-to-protein ratio of 10 mg/g) diet in hemodialysis patients. Both diets similarly reduced intact FGF23 levels, whereas phosphate levels were only lowered by the very low phosphate diet [141].…”

Acute effects of dietary phosphorus intake on markers of mineral metabolism in hemodialysis patients: post hoc analysis of a randomized crossover trial

“…Figure 1 shows the study design and outcome assessments. We performed a post hoc analysis of a randomized active-controlled crossover single-center clinical trial in which we randomly assigned participants (at an allocation ratio of 1:1) to receive a very-low-phosphorus diet with a PPR of 8 mg/g or a low-phosphorus diet with a PPR of 10 mg/g [ 18 ]. Within each 9-day period, each patient consumed each study diet regimen for 2 days; the order of the diets was random, and the two diets were separated by a 5-day washout period.…”

“…Within each 9-day period, each patient consumed each study diet regimen for 2 days; the order of the diets was random, and the two diets were separated by a 5-day washout period. The study protocol, sample size calculation method, and primary outcomes have previously been published in detail [ 18 ]. The original study was approved by the institutional review board at Far Eastern Memorial Hospital (FEMH-106108-F) and was registered online before study initiation (ClinicalTrials.gov ID = NCT03367338).…”

“…In a previous randomized active-controlled crossover trial conducted on ESKD patients receiving hemodialysis, we found no benefit of a 2-day dietary intervention with a very-low-phosphorus diet (8 mg/g phosphorus-to-protein ratio, PPR) compared with a low-phosphorus diet (10 mg/g PPR) on the outcome of an FGF23 change from baseline [ 18 , 19 ]. However, serum intact FGF23 levels were lower than the baseline in both diet groups.…”