Restricting Dietary Protein and Phosphorus May Improve CKD-MBD
Very low protein intake was not superior to traditional low protein diets, however.
Limited scientific evidence suggests that dietary interventions such as calcium-enriched bread and low phosphorus/protein consumption can provide some benefit for patients with chronic kidney disease-mineral and bone disorders (CKD-MBD), a new review finds.
Zhuangzhu Liu, MD, of Guangdong Provincial Hospital in Guangzhou, China, and colleagues examined 9 randomized trials of dietary interventions for CKD-MBD. The interventions included calcium-enriched bread, a low phosphorus diet, a low protein diet, a very low protein diet, post-hemodialysis supplements, and a low lipid diet. CKD stage varied among the 634 participants. None of the studies examined cardiovascular events or fractures.
Calcium-enriched bread (vs. calcium acetate) increased serum calcium (mean difference 0.16 mmol/L), decreased serum phosphorus (-0.41 mmol/L), and decreased the calcium-phosphate product (-0.62 mmol2/L2), according to results published in the Cochrane Database of Systematic Reviews.
Low phosphorus diets decreased serum phosphorus in 2 of 3 studies. The other showed a low phosphorus diet plus lanthanum carbonate decreased fibroblast growth factor 23 (FGF-23) only. One study also looked at mortality and reported no differences.
Very low protein intake (0.3–0.4 g protein/kg/day) was not better than a low protein diet (0.8-0.6 g protein/kg/day) at lowering phosphorus, increasing calcium, and decreasing alkaline phosphatase. Parathyroid hormone levels were significantly lower with a very low protein diet, however.
Compared with a normal diet, post-hemodialysis supplements did not increase serum phosphorus. A low lipid diet also provided no meaningful benefit over statin therapy.
The studies were low quality and “suboptimal,” the investigators acknowledged. They encouraged large, well-designed randomized controlled trials of dietary interventions (including combination approaches) for patients with CKD-MBD that examine crucial end points such as cardiovascular events, fractures, and mortality. Future studies should also report adverse events such as protein-energy malnutrition, hypophosphatemia, and hyper- and hypocalcemia.