Effect of Dietary Phosphorous Restriction on Fibroblast Growth 2 Factor-23 and sKlotho Levels in Patients with Stages 1-2 Chronic Kidney Disease

Hyperphosphatemia has emerged as an independent risk factor for cardiovascular disease (CVD) and excess mortality in chronic kidney disease (CKD). The study evaluates the effect of dietary phosphorus (Ph) restriction (DPhR) at an early stage as a therapeutic strategy for delaying CKD progression and preventing CVD. Methods: This was a one-year interventional study conducted on 79 stage 1 and 2 CKD patients. The dietary phosphorus intake (DPhI), fibroblast growth factor-23 (FGF-23), sKlotho and serum phosphorous (SP) levels were analyzed. Patients were categorized into two groups based on their DPhI, recommended DPhI (RPhI) with <1000 mg/day of dietary phosphorous (dietary counselling) and high DPhI (HPhI) with >1000 mg/day (dietary intervention). For comparisons of differences between the two groups, independent t-test; for correlation analysis, Pearson correlation; for identifying the significant associated risk factors for CKD, binary logistic regression analysis and for comparing the means across the three visits, repeated measures ANOVA were used for statistical analysis. Results: The mean age and glomerular filtration rate (GFR) of CKD patients were 38 ± 12 years and 82.95 ± 16.93 mL/min/1.73 m2. FGF-23, SP, dietary protein and DPhI were significantly higher and sKlotho was significantly lower in HPhI group than RPhI group. In HPhI group; GFR, sKlotho, SP and FGF-23 correlated significantly with DPhI. Risk factors with a statistical bearing on the progression of CKD were animal-based diet, family history of CKD and hypertension. In HPhI group; GFR, DPhI, SP and FGF-23 levels significantly improved within the intervention period whereas a significant increase in sKlotho levels was observed in both the groups. Conclusion: Restricting DPhI emerged as a favorable therapeutic strategy for CKD patients for improving renal function and controlling hyperphosphatemia. The results of the present study may serve as the basis for future interventional studies with dietary phosphate restriction in the initial stages of CKD that would preserve renal function. Highlights: Early restriction of dietary phosphorus prevents decline in eGFR, elevation in FGF23 and increases Klotho levels.