Dietary fiber effects in chronic kidney disease: a systematic review and meta-analysis of controlled feeding trials.
OBJECTIVE
Chronic kidney disease (CKD) is a major health concern associated with increased risk of cardiovascular disease, morbidity and mortality. Current CKD practice guidelines overlook dietary fiber, which is chronically low in the renal diet. However, increasing dietary fiber has been proposed to ameliorate the progress of CKD. We therefore conducted a systematic review and meta-analysis on the effect of dietary fiber intake on serum urea and creatinine as classical markers of renal health in individuals with CKD.


METHODS
We searched MEDLINE, EMBASE, CINHAL and the Cochrane Library for relevant clinical trials with a follow-up ⩾7 days. Data were pooled by the generic inverse variance method using random-effects models and expressed as mean difference (MD) with 95% confidence intervals (95% CIs). Heterogeneity was assessed by the Cochran Q statistic and quantified by I(2).


RESULTS
A total of 14 trials involving 143 participants met the eligibility criteria. Dietary fiber supplementation significantly reduced serum urea and creatinine levels in the primary pooled analyses (MD, -1.76 mmol/l (95% CI, -3.00, -0.51), P<0.01 and MD, -22.83 mmol/l (95% CI, -42.63, -3.02), P=0.02, respectively) with significant evidence of interstudy heterogeneity only in the analysis of serum urea.


CONCLUSIONS
This is the first study to summarize the potential beneficial effects of dietary fiber in the CKD population demonstrating a reduction in serum urea and creatinine, as well as highlighting the lack of clinical trials on harder end points. Larger, longer, higher-quality clinical trials measuring a greater variety of uremic toxins in CKD are required (NCT01844882).
1] Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada [2] Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada.
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Chiavaroli
1] Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada [2] School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, Ontario, Canada.
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Mirrahimi
1] Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada [2] Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada [3] Department of Pathology and Molecular Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada [4] Division of Endocrinology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada.
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Sievenpiper
1] Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada [2] Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada [3] Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada [4] Division of Endocrinology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada.
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Jenkins
1] Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada [2] Clinical Nutrition and Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Ontario, Canada [3] Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada.
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Darling
D015415:Biomarkers / Q000097:blood; D003131:Combined Modality Therapy; D018849:Controlled Clinical Trials as Topic; D003404:Creatinine / Q000097:blood; D018592:Cross-Over Studies; D004043:Dietary Fiber / Q000378:metabolism / Q000627:therapeutic use*; D019587:Dietary Supplements; D018450:Disease Progression; D005285:Fermentation; D000069196:Gastrointestinal Microbiome; D006801:Humans; D017410:Practice Guidelines as Topic; D006435:Renal Dialysis; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000178:diet therapy* / Q000503:physiopathology / Q000628:therapy; D014508:Urea / Q000097:blood
D015415:Biomarkers; D004043:Dietary Fiber; D014508:Urea; D003404:Creatinine