Feeling gutted in chronic kidney disease (CKD): Gastrointestinal disorders and therapies to improve gastrointestinal health in individuals CKD, including those undergoing dialysis

Dieta de la Milpa: A Culturally-Concordant Plant-Based Dietary Pattern for Hispanic/Latine People with Chronic Kidney Disease

Chronic kidney disease (CKD) disproportionately affects minorities in the United States, including the Hispanic/Latine population, and is a public health concern in Latin American countries. An emphasis on healthy dietary patterns, including the Mediterranean and the Dietary Approaches to Stop Hypertension (DASH) diets, has been suggested as they are associated with a lower incidence of CKD, slower CKD progression, and lower mortality in kidney failure. However, their applicability may be limited in people from Latin America. The Dieta de la Milpa (Diet of the Cornfield) was recently described as the dietary pattern of choice for people from Mesoamerica (Central Mexico and Central America). This dietary pattern highlights the intake of four plant-based staple foods from this geographical region, corn/maize, common beans, pumpkins/squashes, and chilies, complemented with seasonal and local intake of plant-based foods and a lower intake of animal-based foods, collectively classified into ten food groups. Limited preclinical and clinical studies suggest several health benefits, including cardiometabolic health, but there is currently no data concerning CKD. In this narrative review, we describe and highlight the potential benefits of the Dieta de la Milpa in CKD, including acid-base balance, protein source, potassium and phosphorus management, impact on the gut microbiota, inflammation, and cultural appropriateness. Despite these potential benefits, this dietary pattern has not been tested in people with CKD. Therefore, we suggest key research questions targeting measurement of adherence, feasibility, and effectiveness of the Dieta de la Milpa in people with CKD.

Gut Microbiota and Uremic Retention Solutes in Adults With Moderate CKD: A 6-Day Controlled Feeding Study

OBJECTIVE

To determine serum and urine concentrations of the uremic retention solutes (URSs), indoxyl sulfate (IS), p-cresol sulfate (PCS), and trimethylamine N-oxide (TMAO), and gut microbiota composition in individuals with moderate chronic kidney disease (CKD) compared with matched adults without CKD in a 6-day controlled feeding study.

DESIGN AND METHODS

This study was a secondary analysis in which 8 adults with moderate CKD were matched for age, sex, and race with 8 adults without CKD in a parallel-arm, 6-day controlled feeding study. IS, PCS, and TMAO were quantified using liquid chromatography-mass spectrometry in fecal samples, fasting serum, and fasting spot urine samples collected at the end of the feeding period.

RESULTS

Fasting serum URS concentrations were 2.8 to 4.9x higher in CKD compared to controls (all P < .05). No differences were found in the composition of the gut microbiota between patients with and without CKD when analyzing samples for α-diversity, β-diversity, and only minor abundance differences across taxa were apparent. Estimated glomerular filtration rate (eGFR) was inversely related to each serum URS in the whole cohort (all P < .01). However, within groups the relationships between eGFR and serum URS remained strong for CKD patients for IS and TMAO (both P < .05) but weakened for PCS (P = .10). eGFR was only correlated with urine PCS in the whole cohort (P = .03); within groups, no correlation for eGFR with any urine URS was observed. Only urine TMAO was higher in CKD compared to controls (P < .05).

CONCLUSION

Serum URS concentrations are elevated in adults with CKD compared to matched non-CKD adults without differences in gut microbiota composition after consuming the same controlled study diet for 6 days. Future studies are needed to determine if specific dietary components may differentially alter the microbiota and URS.

Association between early postradical cystectomy kidney injury and perioperative outcome in enhanced recovery era

OBJECTIVE

To evaluate the incidence and predictors of early postoperative acute kidney injury (EP-AKI) during index hospitalization following radical cystectomy and its association with postoperative outcomes.

METHODS

All patients with bladder cancer who underwent radical cystectomy with intent-to-cure at our center between 2012 and 2020 were reviewed. EP-AKI during index hospitalization was evaluated using the Acute Kidney Injury Network criteria. The association between EP-AKI and demographics, clinicopathologic features, and perioperative outcomes, including length of hospital stay, complication rate, and readmission rate, were examined. A logistic regression analysis was performed to evaluate the predictors of EP-AKI.

RESULTS

Overall, 435 patients met eligibility, of whom 112 (26%) experienced EP-AKI during index hospitalization (90 [21%] stage 1, 17 [4%] stage 2, and 5 [1%] stage 3). EP-AKI was associated with a longer mean operative time (6.8 vs. 6.1 hours; P < 0.001), higher mean length of hospital stay (6.3 vs. 5.6; P = 0.02), 30-day complication rate (71% vs. 51%; P < 0.001), 90-day complication rate (81% vs. 69%; P = 0.01) and 90-day readmission rate (37% vs. 33%; P = 0.04). The rate of complications increased at higher stages of AKI. On multivariable analysis, perioperative blood transfusion (OR: 1.84, P = 0.02) and continent diversion (OR: 3.29, P < 0.001) were independent predictors of EP-AKI.

CONCLUSION

A quarter of cystectomy patients experience acute kidney injury during index hospitalization, which is associated with higher length of stay, postoperative complication, and readmission rates. Perioperative blood transfusion and continent diversion are independent predictors of such injury.

The Dietary Fermentable Fiber Inulin Alters the Intestinal Microbiome and Improves Chronic Kidney Disease Mineral-Bone Disorder in a Rat Model of CKD

Background

Dietary fiber is important for a healthy diet, but intake is low in CKD patients and the impact this has on the manifestations of CKD-Mineral Bone Disorder (MBD) is unknown.

Methods

The Cy/+ rat with progressive CKD was fed a casein-based diet of 0.7% phosphate with 10% inulin (fermentable fiber) or cellulose (non-fermentable fiber) from 22 weeks to either 30 or 32 weeks of age (~30 and ~15 % of normal kidney function). We assessed CKD-MBD, cecal microbiota, and serum gut-derived uremic toxins. Two-way ANOVA was used to evaluate the effect of age and inulin diet, and their interaction.

Results

In CKD animals, dietary inulin led to changes in microbiota alpha and beta diversity at 30 and 32 weeks, with higher relative abundance of several taxa, including Bifidobacterium and Bacteroides , and lower Lactobacillus . Inulin reduced serum levels of gut-derived uremic toxins, phosphate, and parathyroid hormone, but not fibroblast growth factor-23. Dietary inulin decreased aorta and cardiac calcification and reduced left ventricular mass index and cardiac fibrosis. Bone turnover and cortical bone parameters were improved with inulin; however, bone mechanical properties were not altered.

Conclusions

The addition of the fermentable fiber inulin to the diet of CKD rats led to changes in the gut microbiota composition, lowered gut-derived uremic toxins, and improved most parameters of CKD-MBD. Future studies should assess this fiber as an additive therapy to other pharmacologic and diet interventions in CKD.

Significance Statement

Dietary fiber has well established beneficial health effects. However, the impact of fermentable dietary fiber on the intestinal microbiome and CKD-MBD is poorly understood. We used an animal model of progressive CKD and demonstrated that the addition of 10% of the fermentable fiber inulin to the diet altered the intestinal microbiota and lowered circulating gut-derived uremic toxins, phosphorus, and parathyroid hormone. These changes were associated with improved cortical bone parameters, lower vascular calcification, and reduced cardiac hypertrophy, fibrosis and calcification. Taken together, dietary fermentable fiber may be a novel additive intervention to traditional therapies of CKD-MBD.

Resistant Starch as a Dietary Intervention to Limit the Progression of Diabetic Kidney Disease

Diabetes is the leading cause of kidney disease, and as the number of individuals with diabetes increases there is a concomitant increase in the prevalence of diabetic kidney disease (DKD). Diabetes contributes to the development of DKD through a number of pathways, including inflammation, oxidative stress, and the gut-kidney axis, which may be amenable to dietary therapy. Resistant starch (RS) is a dietary fibre that alters the gut microbial consortium, leading to an increase in the microbial production of short chain fatty acids. Evidence from animal and human studies indicate that short chain fatty acids are able to attenuate inflammatory and oxidative stress pathways, which may mitigate the progression of DKD. In this review, we evaluate and summarise the evidence from both preclinical models of DKD and clinical trials that have utilised RS as a dietary therapy to limit the progression of DKD.

OUP accepted manuscript

Patients on chronic hemodialysis are counseled to reduce dietary sodium intake to limit their thirst and consequent interdialytic weight gain (IDWG), chronic volume overload and hypertension. Low-sodium dietary trials in hemodialysis are sparse and mostly indicate that dietary education and behavioral counseling are ineffective in reducing sodium intake and IDWG. Additional nutritional restrictions and numerous barriers further complicate dietary adherence. A low-sodium diet may also reduce tissue sodium, which is positively associated with hypertension and left ventricular hypertrophy. A potential alternative or complementary approach to dietary counseling is home delivery of low-sodium meals. Low-sodium meal delivery has demonstrated benefits in patients with hypertension and congestive heart failure but has not been explored or implemented in patients undergoing hemodialysis. The objective of this review is to summarize current strategies to improve volume overload and provide a rationale for low-sodium meal delivery as a novel method to reduce volume-dependent hypertension and tissue sodium accumulation while improving quality of life and other clinical outcomes in patients undergoing hemodialysis.