Effect of Unripe Banana Flour on Gut-Derived Uremic Toxins in Individuals Undergoing Peritoneal Dialysis: A Randomized, Double-Blind, Placebo-Controlled, Crossover Trial

Exploring the gut microbiome: probiotics, prebiotics, synbiotics, and postbiotics as key players in human health and disease improvement

The human gut microbiome accompanies us from birth, and it is developed and matured by diet, lifestyle, and environmental factors. During aging, the bacterial composition evolves in reciprocal communication with the host's physiological properties. Many diseases are closely related to the gut microbiome, which means the modulation of the gut microbiome can promote the disease targeting remote organs. This review explores the intricate interaction between the gut microbiome and other organs, and their improvement from disease by prebiotics, probiotics, synbiotics, and postbiotics. Each section of the review is supported by clinical trials that substantiate the benefits of modulation the gut microbiome through dietary intervention for improving primary health outcomes across various axes with the gut. In conclusion, the review underscores the significant potential of targeting the gut microbiome for therapeutic and preventative interventions in a wide range of diseases, calling for further research to fully unlock the microbiome's capabilities in enhancing human health.

Green banana resistant starch: A promising potential as functional ingredient against certain maladies

This review covers the significance of green banana resistant starch (RS), a substantial polysaccharide. The food industry has taken an interest in green banana flour due to its 30% availability of resistant starch and its approximately 70% starch content on a dry basis, making its use suitable for food formulations where starch serves as the base. A variety of processing techniques, such as heat-moisture, autoclaving, microwaving, high hydrostatic pressure, extrusion, ultrasound, acid hydrolysis, and enzymatic debranching treatments, have made significant advancements in the preparation of resistant starch. These advancements aim to change the structure, techno-functionality, and subsequently the physiological functions of the resistant starch. Green bananas make up the highest RS as compared to other foods and cereals. Many food processing industries and cuisines now have a positive awareness due to the functional characteristics of green bananas, such as their pasting, thermal, gelatinization, foaming, and textural characteristics. It is also found useful for controlling the rates of cancer, obesity, and diabetic disorders. Moreover, the use of GBRS as prebiotics and probiotics might be significantly proved good for gut health. This study aimed at the awareness of the composition, extraction and application of the green banana resistant starch in the future food products.

Using the concept of food as medicine to mitigate inflammation in patients undergoing peritoneal dialysis

The most common kidney replacement therapy (KRT) worldwide is hemodialysis (HD), and only 5%-10% of patients are prescribed peritoneal dialysis (PD) as KRT. Despite PD being a different method, these patients also present particular complications, such as oxidative stress, gut dysbiosis, premature aging, and mitochondrial dysfunction, leading to an inflammation process and high cardiovascular mortality risk. Although recent studies have reported nutritional strategies in patients undergoing HD with attempts to mitigate these complications, more information must be needed for PD patients. Therefore, this review provides a comprehensive analysis of recent studies of nutritional intervention to mitigate inflammation in PD patients.

A Historical Perspective on Uremia and Uremic Toxins

Uremia, also known as uremic syndrome, refers to the clinical symptoms in the final stage of renal failure. The definition of the term has changed over time due to an improved comprehension of the kidney's function and the advancement of dialysis technology. Here, we aim to present an overview of the various concepts that have developed regarding uremia throughout the years. We provide a comprehensive review of the historical progression starting from the early days of Kolff and his predecessors, continuing with the initial research conducted by Niwa et al., and culminating in the remote sensing hypothesis of Nigam. Additionally, we explore the subsequent investigation into the function of these toxins as signaling molecules in various somatic cells.

Synbiotics, prebiotics and probiotics for people with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a major public health problem affecting 13% of the global population. Prior research has indicated that CKD is associated with gut dysbiosis. Gut dysbiosis may lead to the development and/or progression of CKD, which in turn may in turn lead to gut dysbiosis as a result of uraemic toxins, intestinal wall oedema, metabolic acidosis, prolonged intestinal transit times, polypharmacy (frequent antibiotic exposures) and dietary restrictions used to treat CKD. Interventions such as synbiotics, prebiotics, and probiotics may improve the balance of the gut flora by altering intestinal pH, improving gut microbiota balance and enhancing gut barrier function (i.e. reducing gut permeability).

OBJECTIVES

This review aimed to evaluate the benefits and harms of synbiotics, prebiotics, and probiotics for people with CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 9 October 2023 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) measuring and reporting the effects of synbiotics, prebiotics, or probiotics in any combination and any formulation given to people with CKD (CKD stages 1 to 5, including dialysis and kidney transplant). Two authors independently assessed the retrieved titles and abstracts and, where necessary, the full text to determine which satisfied the inclusion criteria.

DATA COLLECTION AND ANALYSIS

Data extraction was independently carried out by two authors using a standard data extraction form. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. The methodological quality of the included studies was assessed using the Cochrane risk of bias tool. Data entry was carried out by one author and cross-checked by another. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Forty-five studies (2266 randomised participants) were included in this review. Study participants were adults (two studies in children) with CKD ranging from stages 1 to 5, with patients receiving and not receiving dialysis, of whom half also had diabetes and hypertension. No studies investigated the same synbiotic, prebiotic or probiotic of similar strains, doses, or frequencies. Most studies were judged to be low risk for selection bias, performance bias and reporting bias, unclear risk for detection bias and for control of confounding factors, and high risk for attrition and other biases. Compared to prebiotics, it is uncertain whether synbiotics improve estimated glomerular filtration rate (eGFR) at four weeks (1 study, 34 participants: MD -3.80 mL/min/1.73 m², 95% CI -17.98 to 10.38), indoxyl sulfate at four weeks (1 study, 42 participants: MD 128.30 ng/mL, 95% CI -242.77 to 499.37), change in gastrointestinal (GI) upset (borborymgi) at four weeks (1 study, 34 participants: RR 15.26, 95% CI 0.99 to 236.23), or change in GI upset (Gastrointestinal Symptom Rating Scale) at 12 months (1 study, 56 participants: MD 0.00, 95% CI -0.27 to 0.27), because the certainty of the evidence was very low. Compared to certain strains of prebiotics, it is uncertain whether a different strain of prebiotics improves eGFR at 12 weeks (1 study, 50 participants: MD 0.00 mL/min, 95% CI -1.73 to 1.73), indoxyl sulfate at six weeks (2 studies, 64 participants: MD -0.20 μg/mL, 95% CI -1.01 to 0.61; I² = 0%) or change in any GI upset, intolerance or microbiota composition, because the certainty of the evidence was very low. Compared to certain strains of probiotics, it is uncertain whether a different strain of probiotic improves eGFR at eight weeks (1 study, 30 participants: MD -0.64 mL/min, 95% CI -9.51 to 8.23; very low certainty evidence). Compared to placebo or no treatment, it is uncertain whether synbiotics improve eGFR at six or 12 weeks (2 studies, 98 participants: MD 1.42 mL/min, 95% CI 0.65 to 2.2) or change in any GI upset or intolerance at 12 weeks because the certainty of the evidence was very low. Compared to placebo or no treatment, it is uncertain whether prebiotics improves indoxyl sulfate at eight weeks (2 studies, 75 participants: SMD -0.14 mg/L, 95% CI -0.60 to 0.31; very low certainty evidence) or microbiota composition because the certainty of the evidence is very low. Compared to placebo or no treatment, it is uncertain whether probiotics improve eGFR at eight, 12 or 15 weeks (3 studies, 128 participants: MD 2.73 mL/min, 95% CI -2.28 to 7.75; I² = 78%), proteinuria at 12 or 24 weeks (1 study, 60 participants: MD -15.60 mg/dL, 95% CI -34.30 to 3.10), indoxyl sulfate at 12 or 24 weeks (2 studies, 83 participants: MD -4.42 mg/dL, 95% CI -9.83 to 1.35; I² = 0%), or any change in GI upset or intolerance because the certainty of the evidence was very low. Probiotics may have little or no effect on albuminuria at 12 or 24 weeks compared to placebo or no treatment (4 studies, 193 participants: MD 0.02 g/dL, 95% CI -0.08 to 0.13; I² = 0%; low certainty evidence). For all comparisons, adverse events were poorly reported and were minimal (flatulence, nausea, diarrhoea, abdominal pain) and non-serious, and withdrawals were not related to the study treatment.

AUTHORS' CONCLUSIONS

We found very few studies that adequately test biotic supplementation as alternative treatments for improving kidney function, GI symptoms, dialysis outcomes, allograft function, patient-reported outcomes, CVD, cancer, reducing uraemic toxins, and adverse effects. We are not certain whether synbiotics, prebiotics, or probiotics are more or less effective compared to one another, antibiotics, or standard care for improving patient outcomes in people with CKD. Adverse events were uncommon and mild.

The role of residual renal function on potassium intake and excretion in patients on peritoneal dialysis

BACKGROUND

Patients on chronic dialysis are at increased risk of developing disorders in potassium balance. The preservation of residual renal function (RRF), frequently observed in patients on peritoneal dialysis (PD), may contribute to better control of serum potassium. This study aimed to investigate the role residual renal function on potassium intake and excretion in PD patients.

METHODS

In this cross-sectional study, dietary potassium was evaluated by the 3-day food record. Potassium concentration was determined in serum, 24 h dialysate, stool ample, and 24 h urine of patients with diuresis > 200 mL/day, who were considered non-anuric.

RESULTS

Fifty-two patients, 50% men, 52.6 ± 14.0 years, and PD vintage 19.5 [7.0-44.2] months, were enrolled. Compared to the anuric group (n = 17, 33%), the non-anuric group (n = 35, 67%) had lower dialysate potassium excretion (24.8 ± 5.3 vs 30.9 ± 5.9 mEq/d; p = 0.001), higher total potassium intake (44.5 ± 16.7 vs 35.1 ± 8.1 mEq/d; p = 0.009) and potassium intake from fruit (6.2 [2.4-14.7] vs 2.9 [0.0-6.0]mEq/d; p = 0.018), and no difference in serum potassium (4.8 ± 0.6 vs 4.8 ± 0.9 mEq/L; p = 0.799) and fecal potassium (2.2 ± 0.5 vs 2.1 ± 0.7 mEq/L; p = 0.712). In non-anuric patients, potassium intake correlated directly with urinary potassium (r = 0.40; p = 0.017), but not with serum, dialysate, or fecal potassium. In the anuric group, potassium intake tended to correlate positively with serum potassium (r = 0.48; p = 0.051) and there was no correlation with dialysate or fecal potassium.

CONCLUSION

The presence of residual renal function constitutes an important factor in the excretion of potassium, which may allow the adoption of a less-restrictive diet.

Natural products from plants and microorganisms: Novel therapeutics for chronic kidney disease via gut microbiota regulation

Dysbiosis of gut microbiota plays a fundamental role in the pathogenesis and development of chronic kidney disease (CKD) and its complications. Natural products from plants and microorganisms can achieve recognizable improvement in renal function and serve as an alternative treatment for chronic kidney disease patients with a long history, yet less is known on its beneficial effects on kidney injury by targeting the intestinal microbiota. In this review, we summarize studies on the effects of natural products from plants and microorganisms, including herbal medicines and their bioactive extracts, polysaccharides from plants and microorganisms, and phytochemicals, on the prevention and treatment of chronic kidney disease through targeting gut microflora. We describe the strategies of these anti-CKD effects in animal experiments including remodulation of gut microbiota structure, reduction of uremic toxins, enhancement of short-chain fatty acid (SCFA) production, regulation of intestinal inflammatory signaling, and improvement in intestinal integrity. Meanwhile, the clinical trials of different natural products in chronic kidney disease clinical practice were also analyzed and discussed. These provide information to enable a better understanding of the renoprotective effects of these effective natural products from plants and microorganisms in the treatment of chronic kidney disease. Finally, we propose the steps to prove the causal role of the intestinal microflora in the treatment of chronic kidney disease by natural products from plants and microorganisms. We also assess the future perspective that natural active products from plants and microorganisms can beneficially delay the onset and progression of kidney disease by targeting the gut flora and highlight the remaining challenges in this area. With the continuous deepening of studies in recent years, it has been proved that gut microbiota is a potential target of natural active products derived from plants and microorganisms for chronic kidney disease treatment. Fully understanding the functions and mechanisms of gut microbiota in these natural active products from plants and microorganisms is conducive to their application as an alternative therapeutic in the treatment of chronic kidney disease.

Probiotics, Prebiotics, and Synbiotics for Patients on Dialysis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The current systematic review and meta-analysis investigated the effects of probiotic, prebiotic, and synbiotic administration on inflammation, metabolic parameters, nutritional status, and uremic toxin in dialysis patients.

METHODS

Up to June 2021, publications were searched in Cochrane Library, PubMed, EMBASE, and Web of Science databases. The protocol was submitted to the International Prospective Register of Systematic Reviews and was approved.

RESULTS

This meta-analysis included 18 randomized controlled trials which were eligible. This meta-analysis discovered that probiotic, prebiotic, and synbiotic supplements could reduce C-reactive protein (standardized mean difference (SMD), -0.38; 95% confidence interval (CI), -0.68 to -0.08; P = .01), interleukin 6 (SMD, -0.48; 95% CI, -0.76 to -0.20; P = .00), and indoxyl sulfate (SMD, -0.24; 95% CI, -0.48 to -0.01; P = .045) and increase high-density lipoprotein cholesterol (SMD, 0.25; 95% CI, 0.03 to 0.46; P = .025) compared with the control group but had no significant influence on tumor necrosis factor α, albumin, hemoglobin, triglyceride, total cholesterol, low-density lipoprotein cholesterol, calcium, phosphorus, uric acid, or p-cresyl sulfate in dialysis patients.

CONCLUSIONS

Probiotic, prebiotic, and synbiotic administration could reduce C-reactive protein, interleukin 6, and indoxyl sulfate and increase high-density lipoprotein cholesterol in dialysis patients. To better examine the impact, large-scale, long-term, controlled diets and well-designed randomized controlled trials are needed.

Effectiveness of Microecological Preparations for Improving Renal Function and Metabolic Profiles in Patients With Chronic Kidney Disease

Background

Determining whether microecological preparations, including probiotics, prebiotics, and synbiotics, are beneficial for patients with chronic kidney disease (CKD) has been debated. Moreover, determining which preparation has the best effect remains unclear. In this study, we performed a network meta-analysis of randomized clinical trials (RCTs) to address these questions.

Methods

MEDLINE, EMBASE, PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials were searched. Eligible RCTs with patients with CKD who received intervention measures involving probiotics, prebiotics, and/or synbiotics were included. The outcome indicators included changes in renal function, lipid profiles, inflammatory factors, and oxidative stress factors.

Results

Twenty-eight RCTs with 1,373 patients were ultimately included. Probiotics showed greater effect in lowering serum creatinine [mean difference (MD) −0.21, 95% confidence interval (CI) −0.34, −0.09] and triglycerides (MD −9.98, 95% CI −19.47, −0.49) than the placebo, with the largest surface area under the cumulative ranking curve, while prebiotics and synbiotics showed no advantages. Probiotics were also able to reduce malondialdehyde (MDA) (MD −0.54, 95% CI −0.96, −0.13) and increase glutathione (MD 72.86, 95% CI 25.44, 120.29). Prebiotics showed greater efficacy in decreasing high-sensitivity C-reactive protein (MD −2.06, 95% CI −3.79, −0.32) and tumor necrosis factor-α (MD −2.65, 95% CI −3.91, −1.39). Synbiotics showed a partially synergistic function in reducing MDA (MD −0.66, 95% CI −1.23, −0.09) and high-sensitivity C-reactive protein (MD −2.01, 95% CI −3.87, −0.16) and increasing total antioxidant capacity (MD 145.20, 95% CI 9.32, 281.08).

Conclusion

The results indicated that microbial supplements improved renal function and lipid profiles and favorably affected measures of oxidative stress and inflammation in patients with CKD. After thorough consideration, probiotics provide the most comprehensive and beneficial effects for patients with CKD and might be used as the best choice for microecological preparations.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022295497, PROSPERO 2022, identifier: CRD42022295497.

Effects of Microbiota-Driven Therapy on Circulating Indoxyl Sulfate and P-Cresyl Sulfate in Patients with Chronic Kidney Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Indoxyl sulfate (IS) and p-cresyl sulfate (PCS), protein-bound uremic toxins, exacerbate the deterioration of renal function and increase the risk of cardiovascular events in chronic kidney disease (CKD) patients. The effects of microbiota-driven therapy (probiotics, prebiotics, or synbiotics) on decreasing circulating IS and PCS concentrations are controversial; thus, we performed the present systematic review and meta-analysis to assess the effects of microbiota-driven therapy on circulating IS and PCS concentrations in CKD patients. PubMed, EMBASE, and Cochrane Library databases were systematically searched from inception to 22 July, 2021, and randomized controlled trials (RCTs) investigating the effects of microbiota-driven therapy on circulating IS and PCS concentrations in CKD patients were included. In all, 14 RCTs with 513 participants were eligible for the meta-analysis. The effects of microbiota-driven therapy on the circulating IS and PCS concentrations were evaluated with weighted mean differences (WMDs) measured by a fixed-effects model or a random-effects model. Compared with placebo, microbiota-driven therapy had no statistically significant effect on the circulating IS concentration (WMD: -1.64 mg/L; 95% CI: -3.46, 0.18 mg/L; P = 0.077) but it decreased the circulating PCS concentration (WMD: -2.42 mg/L; 95% CI: -3.81, -1.04 mg/L; P = 0.001). In the subgroup analyses, prebiotic (n = 6) and synbiotic (n = 3) supplementation significantly decreased the circulating PCS concentration, whereas probiotic (n = 3) supplementation did not. Meta-regression showed that the effects of microbiota-driven therapy were not associated with the supplementation time or the year of publication. Moreover, there was no significant evidence of publication bias. This review found that microbiota-driven therapy decreased the circulating PCS concentration in CKD patients. Additional large, well-designed RCTs with improved methodology and reporting are necessary to assess the effects of microbiota-driven therapy on circulating IS and PCS concentrations in the long term. This systematic review was registered at www.crd.york.ac.uk/prospero/ as CRD42021269146.

Probiotics, Prebiotics, and Synbiotics Improve Uremic, Inflammatory, and Gastrointestinal Symptoms in End-Stage Renal Disease With Dialysis: A Network Meta-Analysis of Randomized Controlled Trials

Background

Probiotics, prebiotics, and synbiotics are three different supplements to treat end stage renal disease (ESRD) patients by targeting gut bacteria. The comprehensive comparison of the effectiveness of different supplements are lacking.

Objectives

The purpose of this network meta-analysis (NMA) is to assess and rank the efficacy of probiotics, prebiotics, and synbiotics on inflammatory factors, uremic toxins, and gastrointestinal symptoms (GI symptoms) in ESRD patients undergoing dialysis.

Methods

Randomized clinical trials were searched from the PubMed, Embase, and Cochrane Register of Controlled Trials databases, from their inception until 4 September 2021. Random-effect model were used to obtain all estimated outcomes in network meta-analysis (NMA). Effect estimates were presented as mean differences (Mean ± SD) with 95% confidence interval (CI). The comprehensive effects of all treatments were ranked by the surface under the cumulative ranking (SUCRA) probabilities.

Results

Twenty-five studies involved 1,106 participants were included. Prebiotics were superior in decreasing Interleukin-6 (IL-6; SMD –0.74, 95% CI [–1.32, –0.16]) and tumor-necrosis factor-α (TNF-α; SMD –0.59, 95% CI [–1.09, –0.08]), synbiotics were more effective in declining C-reactive protein (CRP; SMD –0.69, 95% CI [–1.14, –0.24]) and endotoxin (SMD –0.83, 95% CI [–1.38, –0.27]). Regarding uremic toxins, prebiotics ranked highest in reducing indoxyl sulfate (IS; SMD –0.43, 95% CI [–0.81, –0.05]), blood urea nitrogen (BUN; SMD –0.42, 95% CI [–0.78, –0.06]), and malondialdehyde (MDA; SMD –1.88, 95% CI [–3.02, –0.75]). Probiotics were rated as best in alleviating GI symptoms (SMD: –0.52, 95% CI [–0.93, –0.1]).

Conclusion

Our research indicated prebiotics were more effective in declining IL-6, TNF-α, IS, MDA, and BUN, synbiotics lowering CRP and endotoxin significantly, and probiotics were beneficial for alleviating GI symptoms, which may contribute to better clinical decisions. This study was registered in PROSPERO (Number: CRD42021277056).

Systematic Review Registration

[http://www.crd.york.ac.uk/PROSPERO], identifier [CRD42021277056].

The Microbiome and Uremic Solutes

Uremic retention solutes, especially the protein-bound compounds, are toxic metabolites, difficult to eliminate with progressive renal functional decline. They are of particular interest because these uremic solutes are responsible for the pathogenesis of cardiovascular and chronic kidney diseases. Evidence suggests that the relation between uremic toxins, the microbiome, and its host is altered in patients with chronic kidney disease, with the colon’s motility, epithelial integrity, and absorptive properties also playing an important role. Studies found an alteration of the microbiota composition with differences in species proportion, diversity, and function. Since uremic toxins precursors are generated by the microbiota, multiple therapeutic options are currently being explored to address dysbiosis. While an oral adsorbent can decrease the transport of bacterial metabolites from the intestinal lumen to the blood, dietary measures, supplements (prebiotics, probiotics, and synbiotics), and antibiotics aim to target directly the gut microbiota composition. Innovative approaches, such as the modulation of bacterial enzymes, open new perspectives to decrease the plasma level of uremic toxins.

Nutrition, Immunology, and Kidney: Looking Beyond the Horizons

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is epidemic throughout the word. Despite various novel therapeutic opportunities, CKD is still associated with high morbidity and mortality. In CKD, patient's chronic inflammation is frequent and related with adverse outcomes. Both innate and adaptive immunity are dysfunctional in CKD. Therefore, it is plausible to interfere with dysfunctional immunity in these patients. In the current review, we present the updated experimental and clinical data summarizing the effects of nutritional interventions including natural products and dietary supplements on immune dysfunction in the context of CKD.

RECENT FINDINGS

Nutritional interventions including natural products and dietary supplements (e.g., curcumin, sulforaphane, resistant starch, anthocyanin, chrysin, short chain fatty acids, fish oil resistant starch) slow down the inflammation by at least 6 mechanisms: (i) decrease nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB); (ii) decrease NLR family pyrin domain containing 3 (NLRP3); (iii) decrease interleukin-1 (IL-1), decrease interleukin-6 (IL-6) secretion; (iv) decrease polymorphonuclear priming); (v) promote anti-inflammatory pathways (nuclear factor-erythroid factor 2-related factor 2 (NFR2); (vi) increase T regulatory (Tregs) cells). Natural products and dietary supplements may provide benefit in terms of kidney health. By modulation of nutritional intake, progression of CKD may be delayed.

The Human Microbiome in Chronic Kidney Disease: A Double-Edged Sword

Chronic kidney disease (CKD) is an increasing global health burden. Current treatments for CKD include therapeutics to target factors that contribute to CKD progression, including renin–angiotensin–aldosterone system inhibitors, and drugs to control blood pressure and proteinuria control. Recently, associations between chronic disease processes and the human microbiota and its metabolites have been demonstrated. Dysbiosis—a change in the microbial diversity—has been observed in patients with CKD. The relationship between CKD and dysbiosis is bidirectional; gut-derived metabolites and toxins affect the progression of CKD, and the uremic milieu affects the microbiota. The accumulation of microbial metabolites and toxins is linked to the loss of kidney functions and increased mortality risk, yet renoprotective metabolites such as short-chain fatty acids and bile acids help restore kidney functions and increase the survival rate in CKD patients. Specific dietary interventions to alter the gut microbiome could improve clinical outcomes in patients with CKD. Low-protein and high-fiber diets increase the abundance of bacteria that produce short-chain fatty acids and anti-inflammatory bacteria. Fluctuations in the urinary microbiome are linked to increased susceptibility to infection and antibiotic resistance. In this review, we describe the potential role of the gut, urinary and blood microbiome in CKD pathophysiology and assess the feasibility of modulating the gut microbiota as a therapeutic tool for treating CKD.

Effects of Resistant Starch on Patients with Chronic Kidney Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Chronic kidney disease (CKD) is a main health problem associated with increased risk of cardiovascular disease, morbidity, and mortality. Recent studies shown that the progression of CKD may be related to the change of intestinal flora. Resistant starch (RS) is a type of dietary fiber that can act as a substrate for microbial fermentation. Some studies have found that the supplementation of RS can improve the intestinal flora disorder in CKD patients. However, the specific effect of RS on CKD patients remains controversial.

OBJECTIVE

We designed this meta-analysis to identify and assess the effects of RS on patients with CKD.

METHODS

A comprehensive search of MEDLINE, Embase, Web of Science, and Cochrane systematic review databases was conducted in January 2020, and all new trials were updated in August 2021. Randomized trials were collected to assess the effects of RS on patients with CKD. The weighted average effect size of the net change was calculated by using the random-effects model.

RESULTS

The meta-analysis included 8 studies involving 301 participants. RS intake significantly reduced serum indolephenol sulfate (IS), blood phosphorus, IL-6, and uric acid levels in dialysis patients. The mean difference (MD) of serum IS (P = 0.0002) in the dialysis subgroup was -12.57 μmol/L (95% CI: -19.28, -5.86 μmol/L). The MD of blood phosphorus (P = 0.03) was -0.39 mg/dl (95% CI: -0.78, -0.01 mg/dl). The MD of serum uric acid (P = 0.004) between the dialysis subgroup and the nondialysis subgroup was -31.58 mmol/L (95% CI: -52.99, -10.17 mmol/L). The mean difference (MD) of IL-6 (P = 0.02) in the dialysis subgroup was -1.16 μmol/L (95% CI: -2.16, -0.16 μmol/L). However, there was no significant change of RS on hs-CRP, serum creatinine, blood urea nitrogen (BUN), blood paracresol sulfate, and blood lipid.

CONCLUSIONS

The intake of RS reduced the serum IS, serum phosphorus, IL-6, and uric acid levels significantly in dialysis patients, while hs-CRP, serum creatinine, BUN, serum paracresol sulfate, and blood lipid showed no significant changes.