title: Dietary interventions for mineral and bone disorder in people with chronic kidney disease.
abstract: BACKGROUND
  Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a systemic dysfunction of mineral and bone metabolism in people with CKD. Recent research shows that phosphate retention plays a significant role in the development of CKD-MBD. Compared with drug therapies, dietary interventions may be simple, inexpensive and feasible for phosphate retention. However, there is little evidence to support these interventions.
  
  
  OBJECTIVE
  Our objective was to assess the benefits and harms of any dietary intervention for preventing and treating CKD-MBD.
  
  
  METHODS
  We searched Cochrane Kidney and Transplant's Specialised Register to 27 August 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review. We also searched the Chinese Biomedicine Database (CBM) (1976 to August 2015), China Knowledge Resource Integrated Database (CNKI) (1979 to August 2015), and VIP (1989 to August 2015).
  
  
  METHODS
  Randomised controlled trials (RCTs) and quasi-RCTs looking at dietary interventions for prevention or treatment of CKD-MBD were eligible for inclusion.
  
  
  METHODS
  Two authors independently assessed the eligibility, methodological quality, and extracted data. Continuous outcomes (serum calcium level, serum phosphorus level, calcium × phosphate product, parathyroid hormone (PTH), fibroblast growth factor 23 (FGF-23) and alkaline phosphatase) were expressed as mean difference (MD) with 95% confidence interval (CI). Dichotomous outcomes (mortality) were expressed as risk ratio (RR) with 95% CI. We used a random-effects model to meta-analyse studies.
  
  
  RESULTS
  Nine studies were included in this review which analysed 634 participants. Study duration ranged from 4 to 24 weeks. The interventions included calcium-enriched bread, low phosphorus intake, low protein intake, very low protein intake, post haemodialysis supplements and hypolipaemic diet. Only one study reported death; none of the included studies reported cardiovascular events or fractures. There was insufficient reporting of design and methodological aspects among the included studies to enable robust assessment of risk of bias.There was limited and low-quality evidence to indicate that calcium-enriched bread increased serum calcium (1 study, 53 participants: MD -0.16 mmol/L, 95% CI -0.51 to -0.31), decreased serum phosphorus (53 participants: MD -0.41 mmol/L, 95% CI -0.51 to -0.31) and decreased the calcium × phosphate product (53 participants: MD -0.62 mmol²/L², 95% CI -0.77 to -0.47).Very low protein intake was not superior to conventional low protein intake in terms of effect on serum phosphorus (2 studies, 41 participants: MD -0.12 mmol/L, 95% CI -0.50 to 0.25), serum calcium (MD 0.00 mmol/L, 95% CI -0.17 to 0.17), or alkaline phosphatase (MD -22.00 U/L, 95% CI -78.25 to 34.25). PTH was significantly lower in the very low protein intake group (2 studies, 41 participants: MD -69.64 pmol/L, 95% CI -139.83 to 0.54).One study reported no significant difference in the number of deaths between low phosphorus intake and normal diet (279 participants: RR 0.18, 95% CI 0.01 to 3.82). Low phosphorus intake decreased serum phosphorus (2 studies, 359 participants: MD -0.18 mmol/L, 95% CI -0.29 to -0.07; I(2) = 0%).One study reported post-haemodialysis supplements did not increase serum phosphorus compared to normal diet (40 participants: MD 0.12 mmol/L, 95% CI -0.24 to 0.49).One study reported low phosphorus intake plus lanthanum carbonate significantly decreased FGF-23 (19 participants: MD -333.80 RU/mL, 95% CI -526.60 to -141.00), but did not decrease serum phosphorus (19 participants: MD -0.10 mg/dL, 95% CI -0.38 to 0.58) or PTH (19 participants: MD 31.60 pg/mL, 95% CI -29.82 to 93.02).
  
  
  CONCLUSIONS
  There was limited low quality evidence to indicate that dietary interventions (calcium-enriched bread or low phosphorus/protein intake) may positively affect CKD-MBD by increasing serum calcium, decreasing serum phosphorus, the calcium × phosphate product and FGF-23. Large and well-designed RCTs are needed to evaluate the effects of various interventions for people with CKD-MBD.
authors.affiliation: Department of Nephrology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.
authors.forename: Zhuangzhu
authors.initials: Z
authors.lastname: Liu
authors.forename: Guobin
authors.initials: G
authors.lastname: Su
authors.forename: Xinfeng
authors.initials: X
authors.lastname: Guo
authors.forename: Yifan
authors.initials: Y
authors.lastname: Wu
authors.forename: Xusheng
authors.initials: X
authors.lastname: Liu
authors.forename: Chuan
authors.initials: C
authors.lastname: Zou
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Qianchun
authors.initials: Q
authors.lastname: Yang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xu
authors.forename: Weizhong
authors.initials: W
authors.lastname: Ma
mesh_terms: D000085:Acetates / Q000008:administration & dosage; D000469:Alkaline Phosphatase / Q000097:blood; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000097:blood / Q000209:etiology / Q000628:therapy*; D001939:Bread; D002118:Calcium / Q000097:blood; D017610:Calcium Compounds / Q000008:administration & dosage; D002130:Calcium Phosphates / Q000097:blood; D002136:Calcium, Dietary / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage; D000089703:Fibroblast Growth Factor-23; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000008:administration & dosage; D010758:Phosphorus / Q000008:administration & dosage / Q000097:blood*; D016032:Randomized Controlled Trials as Topic; D051436:Renal Insufficiency, Chronic / Q000150:complications*
chemical_list: D000085:Acetates; D017610:Calcium Compounds; D002130:Calcium Phosphates; D002136:Calcium, Dietary; D004044:Dietary Proteins; C000717427:FGF23 protein, human; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D010758:Phosphorus; D000089703:Fibroblast Growth Factor-23; C020243:calcium phosphate; D000469:Alkaline Phosphatase; D002118:Calcium; C120662:calcium acetate