Inadequate energy and excess protein intakes may be associated with worsening renal function in chronic kidney disease

Biomedical Evaluation of Early Chronic Kidney Disease in the Air Force: Building a Predictive Model from the Taiwan Military Health Service

OBJECTIVE

Chronic kidney disease (CKD) is one of the most common diseases worldwide. The increasing prevalence and incidence of CKD have contributed to the critical problem of high medical costs. Due to stressful environments, aircrew members may have a high risk of renal dysfunction. A better strategy to prevent CKD progression in Air Force personnel would be to diagnosis CKD at an early stage. Since few studies have been conducted in Taiwan to examine the long-term trends in early CKD in Air Force aircrew members, this study is highly important. We investigated the prevalence of CKD and established a predictive model of disease variation among aircrew members.

MATERIALS AND METHODS

In this retrospective study, we included all subjects who had received physical examinations at a military hospital from 2004 to 2010 and who could be tracked for four years. The Abbreviated Modification of Diet in Renal Disease Formula (aMDRD) was used to estimate the glomerular filtration rate (GFR) and was combined with the National Kidney Foundation/ Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI) to identify CKD patients.

RESULTS

A total of 212 aircrew members were assessed. The results showed that the prevalence of CKD was 3.8%, 9.4%, 9.0%, and 9.4% in each of the four years. According to the logistic regression analysis, abnormal urobilinogen levels, ketones, and white blood cell (WBC) counts in urine and a positive urine occult blood test increased the risk of CKD. A positive urine occult blood test can be used to predict the future risk of CKD. Moreover, the generalized estimating equation (GEE) model showed that a greater risk of CKD with increased examination time, age and seniority had a negative effect. In conclusion, abnormal urobilinogen levels, ketones, and urine WBC counts in urine as well as a positive urine occult blood test might serve as independent predictors for CKD.

CONCLUSION

In the future, we can focus not only on annual physical examinations but also on simple and accurate examinations, such as urine occult blood testing, to determine the risk of CKD and prevent its progression in our aircrew members.

Association of carbohydrate intake from different sources with all-cause and cardiovascular mortality among chronic kidney disease populations: assessment of 1999-2018 National Health and Nutrition Examination Survey participation

This study analysed the data from the NHANES (1999-2018) to examine how different sources of carbohydrate intake affected the all-cause and cardiovascular mortality of 11,302 chronic kidney disease (CKD) patients. The data were adjusted for other factors using various methods. The results showed that CKD patients (stages 1-2 and 3-5) who consumed more carbohydrates from whole grains, fruits, vegetables and less carbohydrates from fruit juice or sauces had lower mortality rates. Replacing fat intake with carbohydrates from whole grains (HR = 0.86[0.78-0.95]), fruits (raw) (HR = 0.79[0.70-0.88]) and non-starchy vegetables (HR = 0.82[0.70-0.96]), but not protein intake, was linked to lower all-cause mortality. The fibre content in carbohydrates might partly account for the benefits of selected carbohydrate intake. This study provided practical recommendations for optimising the carbohydrate sources in CKD patients.

CNN-assisted SERS enables ultra-sensitive and simultaneous detection of Scr and BUN for rapid kidney function assessment

Kidney disease is highly prevalent and may result in severe clinical outcomes. Serum creatinine (Scr) and blood urea nitrogen (BUN) are the most widely used biomarkers for kidney function assessment, yet when measured alone, the result can be affected by a variety of parameters such as age, gender, protein consumption, etc. Measuring Scr and BUN simultaneously can eliminate most of the external influences and greatly improve the assessment of kidney function. In this study, a real-time kidney function assessment system based on dual biomarker detection was proposed. Scr and BUN were determined using surface-enhanced Raman scattering (SERS) within the concentration range of 10^-1 to 10^-6 M and 0.28 to 100 mg dl^-1, respectively. A one-dimensional convolutional neural network (1D-CNN) model was employed to quantitatively analyze the concentration of biomarkers from the SERS spectral measurements. Moreover, we simulated a variety of kidney health conditions with 16 groups of mixed Scr and BUN in serum. The proposed CNN-assisted SERS method was used to quantify both biomarkers and provide diagnostic results. The Au core-Ag shell nanoprobes provided ultra-sensitive SERS detection and the CNN model achieved excellent regression results with an R² of 0.9871 in the testing dataset. The system demonstrated a rapid and robust evaluation for the assessment of kidney function, providing a promising idea for medical diagnosis with the help of spectroscopy and deep learning methods.

Dietary Patterns and Perceptions in Older Adults With Chronic Kidney Disease in the Canadian Frailty Observation and Interventions Trial (CanFIT): A Mixed-Methods Study

Background:

People living with chronic kidney disease (CKD) have identified diet as an important aspect of their life and care. Understanding current consumption patterns in this population, and how they relate to patient perspectives of dietary recommendations, may help identify and design potential dietary intervention strategies in CKD.

Objective:

To investigate the dietary intake patterns of people with advanced-stage CKD, as well as subjective perspectives regarding dietary recommendations from participants and their caregivers.

Design:

Mixed-methods study with a sequential explanatory design.

Setting:

Manitoba, Canada.

Participants:

Individuals with late-stage CKD (CKD stages G4-G5, including dialysis) participating in the Canadian Frailty Observation and Interventions Trial (CanFIT).

Methods:

First, quantitative data were collected via a cross-sectional dietary assessment, using three 24-hour dietary recalls, a 36-question short diet questionnaire (SDQ), and a Nutrition Quality of Life (NQoL) tool (n = 59). Second, qualitative data were collected during 2 focus groups (n₁ = 12 and n₂ = 7) held with a subsample of individuals who had completed the dietary surveys, along with their caregivers. Focus groups explored topics related to diet and CKD; transcribed data were analyzed thematically. In the interpretation stage, the qualitative findings were combined with the quantitative results to help explain the latter and reach a deeper understanding of the subjective experiences of adults with CKD.

Results:

Quantitatively, nearly all (48/51; 94%) participants (mean age 70.8 ± 10.8 years) reported energy intakes below recommendations and most (86%) did not achieve recommended fiber intake. In addition, 15/21 (71%) of patients on dialysis had low protein intake. Qualitatively, 2 themes were identified: (1) Lacking/Needing dietary guidance—incomplete “information overload,” and (2) Experiencing difficulty in adapting to restrictions. Within the former theme, participants spoke of getting too much information at once, often at the wrong time. Within the latter theme, participants spoke of a loss of appetite, and cheating on their dietary recommendations.

Limitations:

Potential recall bias recalling dietary patterns, small sample size limiting generalizability, self-selection bias.

Conclusion:

Despite the reported lifestyle changes made by individuals with CKD, which negatively impacted their lives, many had suboptimal nutrition, especially in terms of energy and fiber. In addition, those on dialysis were not eating enough protein, which could be due to changing dietary recommendations as CKD progresses. Qualitative findings provided additional insight into how requisite CKD-dietary changes were perceived and how participants coped with these changes. The timing and delivery of the dietary education within CKD care in Manitoba may not be working for people with CKD as they progress through the disease.

Management of Acute Kidney Injury in Extremely Low Birth Weight Infants

Acute kidney injury (AKI) is a common problem in the neonatal intensive care unit (NICU). Neonates born at <1,000 g (extremely low birth weight, ELBW) are at an increased risk of secondary associated comorbidities such as intrauterine growth restriction, prematurity, volume restriction, ischaemic injury, among others. Studies estimate up to 50% ELBW infants experience at least one episode of AKI during their NICU stay. Although no curative treatment for AKI currently exists, recognition is vital to reduce potential ongoing injury and mitigate long-term consequences of AKI. However, the definition of AKI is imperfect in this population and presents clinical challenges to correct identification, thus contributing to under recognition and reporting. Additionally, the absence of guidelines for the management of AKI in ELBW infants has led to variations in practice. This review summarizes AKI in the ELBW infant and includes suggestions such as close observation of daily fluid balance, review of medications to reduce nephrotoxic exposure, management of electrolytes, maximizing nutrition, and the use of diuretics and/or dialysis when appropriate.

A Low-Protein Diet with a Renal-Specific Oral Nutrition Supplement Helps Maintain Nutritional Status in Patients with Advanced Chronic Kidney Disease

A low-protein diet (LPD) is recommended to patients with non-dialysis advanced chronic kidney disease (CKD) for delaying renal function decline. However, this approach potentially prevents an adequate calorie and micronutrient intake. We examined the influence of an LPD including a renal-specific oral nutrition supplement (RONS) on the nutrition status of patients with stage 3b–5 CKD. This multicenter, open-label study prospectively enrolled patients over 18 years of age, with an estimated glomerular filtration rate (eGFR) between 10 and 45 mL/min/1.73 m², serum albumin ≥3.0 g/dL, and body mass index ≤30 kg/m². All participants implemented the LPD with one serving of RONS daily for 6 months. Daily energy intake, nutrition status, renal function, and quality of life were assessed before and after the intervention. Of 53 enrolled patients, 35 (66.0%) completed the study. We found that RONS use increased patients’ energy intake and maintained their serum albumin, nutritional status, and quality of life. Body weight and handgrip strength increased significantly at 6 months after enrollment (p = 0.0357); eGFR slightly decreased at 3 and 6 months after enrollment, suggesting that patients’ residual renal function was preserved. Our findings support the conclusion that patients with non-dialysis advanced CKD may benefit from additional RONS besides their regular diet. Patients with advanced CKD receiving RONS might achieve better nutrition and delay renal function decline.

Skeletal myopathy in CKD: a comparison of adenine-induced nephropathy and 5/6 nephrectomy models in mice

Preclinical animal models of chronic kidney disease (CKD) are critical to investigate the underlying mechanisms of disease and to evaluate the efficacy of novel therapeutics aimed to treat CKD-associated pathologies. The objective of the present study was to compare the adenine diet and 5/6 nephrectomy (Nx) CKD models in mice. Male and female 10-wk-old C57BL/6J mice (n = 5-9 mice/sex/group) were randomly allocated to CKD groups (0.2-0.15% adenine-supplemented diet or 5/6 Nx surgery) or the corresponding control groups (casein diet or sham surgery). Following the induction of CKD, the glomerular filtration rate was reduced to a similar level in both adenine and 5/6 Nx mice (adenine diet-fed male mice: 81.1 ± 41.9 µL/min vs. 5/6 Nx male mice: 160 ± 80.9 µL/min, P = 0.5875; adenine diet-fed female mice: 112.9 ± 32.4 µL/min vs. 5/6 Nx female mice: 107.0 ± 45.7 µL/min, P = 0.9995). Serum metabolomics analysis indicated that established uremic toxins were robustly elevated in both CKD models, although some differences were observed between CKD models (i.e., p-cresol sulfate). Dysregulated phosphate homeostasis was observed in the adenine model only, whereas Ca2+ homeostasis was disturbed in male mice with both CKD models. Compared with control mice, muscle mass and myofiber cross-sectional areas of the extensor digitorum longus and soleus muscles were ∼18-24% smaller in male CKD mice regardless of the model but were not different in female CKD mice (P > 0.05). Skeletal muscle mitochondrial respiratory function was significantly decreased (19-24%) in CKD mice in both models and sexes. These findings demonstrate that adenine diet and 5/6 Nx models of CKD have similar levels of renal dysfunction and skeletal myopathy. However, the adenine diet model demonstrated superior performance with regard to mortality (∼20-50% mortality for 5/6 Nx vs. 0% mortality for the adenine diet, P < 0.05 for both sexes) compared with the 5/6 Nx surgical model.NEW & NOTEWORTHY Numerous preclinical models of chronic kidney disease have been used to evaluate skeletal muscle pathology; however, direct comparisons of popular models are not available. In this study, we compared adenine-induced nephropathy and 5/6 nephrectomy models. Both models produced equivalent levels of muscle atrophy and mitochondrial impairment, but the adenine model exhibited lower mortality rates, higher consistency in uremic toxin levels, and dysregulated phosphate homeostasis compared with the 5/6 nephrectomy model.

Effects of Intensive Individualized Nutrition Counseling on Nutritional Status and Kidney Function in Patients With Stage 3 and 4 Chronic Kidney Disease

OBJECTIVE

Although dietary modification is a critical component of chronic kidney disease (CKD) management, compliance with dietary recommendations is often suboptimal. This prospective intervention study was conducted to evaluate the effects and adherence of intensive, individualized nutrition counseling in CKD patients from a single nation Asian ethnic group.

METHODS

Patients with Stages 3 and 4 CKD were recruited from a tertiary hospital outpatient clinic in Korea. The intensive group received 3 monthly sessions of individualized intensive nutrition counseling. The control group received a one-time group program. The intensive group was compared with the control group at 3 months.

RESULTS

A total of 59 patients were enrolled, and 42 (71.2%) completed the study (23/32 of the intensive group; 19/27 of the control group). The mean age of the patients was 64.7 ± 12.5 years, and 81% were male. The most common nutritional diagnosis was an excessive intake of sodium (Na, 97.6%), followed by potassium (K, 78.6%), protein (52.4%), and phosphorus (P, 31.0%). After 3 months of nutrition counseling, K and P intakes decreased significantly in both the intensive group (K, 2,760.9 ± 677.4 vs. 1,500.7 ± 398.5 mg/d, P < .001; P, 1,010.5 ± 247.4 vs. 631.3 ± 178.1 mg/d, P < .001) and the control group (K, 2,090.8 ± 765.3 vs. 1,703.9 ± 490.0 mg/d, P = .036; P, 807.2 ± 163.8 vs. 679.1 ± 175.9 mg/d, P = .044). Meanwhile, protein (68.3 ± 21.8 vs. 45.4 ± 10.1 g/d, P = .001), Na (4,009.8 ± 1,418.2 vs. 2,224.6 ± 759.8 mg/d, P < .001), and energy intakes (1,857.1 ± 411.5 vs. 1,273.7 ± 231.5 kcal, P < .001) decreased in the intensive group, but were comparable in the control group. Notably, BMI decreased (BMI, 25.4 ± 2.5 vs. 24.9 ± 2.9 kg/m2, P = .014) while eGFR (43.1 ± 11.8 vs. 48.9 ± 13.7 mL/min/1.73m2, P = .002) improved significantly in the intensive group only.

CONCLUSION

Intensive individualized nutrition counseling results in better adherence to dietary recommendations and improvement in kidney function in CKD patients.

Long-Term Effects of Ketoanalogues on Mortality and Renal Outcomes in Advanced Chronic Kidney Disease Patients Receiving a Low-Protein Diet

The effects of ketoanalogues (KA) supplementation on mortality and progression to dialysis in patients with pre-dialysis stage 5 chronic kidney disease (CKD) receiving a low-protein diet (LPD) remain ambiguous. From Taiwan’s National Health Insurance Research Database during 1996–2011, 165 patients with pre-dialysis CKD on an LPD (0.6 g/kg/day) with KA supplementation were matched with 165 patients with pre-dialysis CKD on an LPD without KA supplementation. Of the 165 patients with advanced CKD receiving KA supplementation, 34 (20.6%) died, and 124 (75.2%) underwent long-term dialysis during the study period. There was no significant difference in mortality between the KA-user group and the KA-nonuser group (adjusted hazard ratio [HR], 1.41; 95% confidence interval [CI], 0.68–2.93; p = 0.355). KA supplementation significantly increased long-term dialysis risk (adjusted HR, 1.41; 95% CI, 1.04–1.90; p = 0.025) and combined outcome risk (defined as long-term dialysis and death; adjusted HR, 1.37; 95% CI, 1.02–1.83; p = 0.034). KA supplementation also increased long-term dialysis risk (adjusted HR, 1.49; 95% CI, 1.00–2.20; p = 0.048) in the subgroup of pre-dialysis patients with diabetes mellitus (DM), but not in those patients without DM. In conclusion, KA supplementation might increase long-term dialysis risk in patients with advanced CKD receiving an LPD, but it did not increase mortality.

The Effects of High-Protein Diets on Kidney Health and Longevity

Although high-protein diets continue to be popular for weight loss and type 2 diabetes, evidence suggests that worsening renal function may occur in individuals with-and perhaps without-impaired kidney function. High dietary protein intake can cause intraglomerular hypertension, which may result in kidney hyperfiltration, glomerular injury, and proteinuria. It is possible that long-term high protein intake may lead to de novo CKD. The quality of dietary protein may also play a role in kidney health. Compared with protein from plant sources, animal protein has been associated with an increased risk of ESKD in several observational studies, including the Singapore Chinese Health Study. Potential mediators of kidney damage from animal protein include dietary acid load, phosphate content, gut microbiome dysbiosis, and resultant inflammation. In light of such findings, adopting current dietary approaches that include a high proportion of protein for weight reduction or glycemic control should be considered with care in those at high risk for kidney disease. Given the possibility of residual confounding within some observational studies and the conflicting evidence from previous trials, long-term studies including those with large sample sizes are warranted to better ascertain the effects of high protein intake on kidney health.

Dietary Assessment of Korean Non-dialysis Chronic Kidney Disease Patients with or without Diabetes

BACKGROUND

Dietary intervention at the early stage of chronic kidney disease (CKD) is important for preventing progression to the end-stage renal disease (ESRD). However, few studies have investigated dietary intake of CKD patients in non-dialysis stage. Therefore, we investigated the dietary intake of Korean non-dialysis CKD patients and aimed to establish baseline data for the development of dietary education and intervention strategies for CKD patients.

METHODS

Three hundred fifty CKD patients who visited Seoul National University Hospital outpatient clinic from February 2016 to January 2017 were recruited for this cross-sectional study. Subjects on dialysis and those who had undergone kidney transplantation were excluded. Dietary intake, demographic information, and biochemical characteristics of 256 subjects who completed three-day dietary records were analyzed. Subjects were divided into four groups based on diabetes mellitus (DM) (DM-CKD and Non-DM-CKD groups) and kidney function (Early-CKD and Late-CKD groups).

RESULTS

Total energy intake was lower in the Late-CKD group compared with the Early-CKD group. In men, carbohydrate intake was higher and protein and fat intakes tended to be lower in the Late-CKD group compared with the Early-CKD group. In women, carbohydrate intake tended to be lower in the DM-CKD group than the Non-DM-CKD group. Protein intake tended to be higher in the DM-CKD groups. Phosphorus and sodium intakes were higher in the DM-CKD groups compared with the Non-DM-CKD groups in women, and tended to be higher in the DM-CKD groups in men.

CONCLUSION

DM and kidney function affected energy and nutrient intakes. Subjects in the Late-CKD group consumed less energy than those in the Early-CKD group. Non-DM subjects seemed to restrict protein intake starting from the Early-CKD stage than subjects with DM. Subjects in this study had low energy and high sodium intakes compared with recommended levels. Protein intake was lower in advanced CKD patients, but their intake level was still higher than the recommendation. Dietary intervention strategies for non-dialysis CKD patients need to be customized depending on the presence of DM and kidney function.

Patients with chronic kidney disease are not well adhered to dietary recommendations: a cross-sectional study

Background

Nutrition and dietary patterns are modifiable factors that can be utilized to prevent or slow the progression of Chronic kidney disease (CKD). Adherence to current dietary recommendations can reduce the incidence, or slow the progression of CKD and reduce mortality. The objectives of this study was to compare the dietary nutrient intake of CKD patients (CKD above stage 3 including hemodialysis) to dietary recommendations and to assess the correlations of those dietary nutrient intakes with each other and with chosen laboratory measurements.

Methods

A hospital-based cross-sectional study was conducted among 100 patients with CKD. A consecutive 7 days dietary record supplemented with interviews for data completion was used to assess dietary intake. Recent clinical laboratory measurements were obtained from patients’ medical records. The obtained dietary data were analyzed by the Ethiopian food composition database and the nutrisurvey software. Dietary energy and nutrients intake were compared with recommendations for CKD patients.

Results

The dietary energy intake (DEI) of almost all patients was below recommended levels. The average Dietary protein intake (DPI) was above the recommended levels (0.95 ± 0.27 g/kg/day) for about 60% of the respondents. Besides, 38% and only two of the respondents had their dietary phosphorus and potassium intakes above recommended levels, respectively. Estimated Glomerular filtration rate (eGFR) was positively correlated with both total and animal protein intakes while blood levels of creatinine and urea were negatively correlated with animal protein intake.

Conclusion

Patients with CKD are not well adhered to dietary recommendations and some nutrients showed correlation with chosen clinical laboratory measurements. Besides, DEI and DPI were below and above recommended levels, respectively, for most patients. Besides, more than one-third of the participants had phosphorus intakes above recommendation. These non-optimal dietary nutrient intakes may contribute to fast clinical deterioration and mortality.

Effects of dietary intake and nutritional status on cerebral oxygenation in patients with chronic kidney disease not undergoing dialysis: A cross-sectional study

BACKGROUND

Dietary management is highly important for the maintenance of renal function in patients with chronic kidney disease (CKD). Cerebral oxygen saturation (rSO2) was reportedly associated with the estimated glomerular filtration rate (eGFR) and cognitive function. However, data concerning the association between cerebral rSO2 and dietary intake of CKD patients is limited.

METHODS

This was a single-center observational study. We recruited 67 CKD patients not undergoing dialysis. Cerebral rSO2 was monitored using the INVOS 5100c oxygen saturation monitor. Energy intake was evaluated by dietitians based on 3-day meal records. Daily protein and salt intakes were calculated from 24-h urine collection.

RESULTS

Multivariable regression analysis showed that cerebral rSO2 was independently associated with energy intake (standardized coefficient: 0.370) and serum albumin concentration (standardized coefficient: 0.236) in Model 1 using parameters with p < 0.10 in simple linear regression analysis (body mass index, Hb level, serum albumin concentration, salt and energy intake) and confounding factors (eGFR, serum sodium concentration, protein intake), and the energy/salt index (standardized coefficient: 0.343) and Hb level (standardized coefficient: 0.284) in Model 2 using energy/protein index as indicated by energy intake/protein intake and energy/salt index by energy intake/salt intake in place of salt, protein and energy intake.

CONCLUSIONS

Cerebral rSO2 is affected by energy intake, energy/salt index, serum albumin concentration and Hb level. Sufficient energy intake and adequate salt restriction is important to prevent deterioration of cerebral oxygenation, which might contribute to the maintenance of cognitive function in addition to the prevention of renal dysfunction in CKD patients.

Nutrients, Nutraceuticals, and Xenobiotics Affecting Renal Health

Chronic kidney disease (CKD) affects 8–16% of the population worldwide. In developed countries, the most important risk factors for CKD are diabetes, hypertension, and obesity, calling into question the importance of educating and acting on lifestyles and nutrition. A balanced diet and supplementation can indeed support the maintenance of a general health status, including preservation of renal function, and can help to manage and curb the main risk factors for renal damage. While the concept of protein and salt restriction in nephrology is historically acknowledged, the role of some nutrients in renal health and the importance of nutrition as a preventative measure for renal care are less known. In this narrative review, we provide an overview of the demonstrated and potential actions of some selected nutrients, nutraceuticals, and xenobiotics on renal health and function. The direct and indirect effects of fiber, protein, fatty acids, curcumin, steviol glycosides, green tea, coffee, nitrates, nitrites, and alcohol on kidney health are reviewed here. In view of functional and personalized nutrition, understanding the renal and systemic effects of dietary components is essential since many chronic conditions, including CKD, are related to systemic dysfunctions such as chronic low-grade inflammation.

Dietary intake of non-dialysis chronic kidney disease patients: the PROGREDIR study. A cross-sectional study

BACKGROUND

Despite evidence that diet is very important in relation to chronic kidney disease (CKD) progression, studies in this field are scarce and have focused only on some specific nutrients. We evaluated the energy, macronutrient and micronutrient intakes and dietary patterns of non-dialysis CKD participants in the PROGREDIR study.

DESIGN AND SETTING

Cross-sectional study; CKD cohort, São Paulo, Brazil.

METHODS

Baseline data on 454 participants in the PROGREDIR study were analyzed. Dietary intake was evaluated through a food frequency questionnaire. Dietary patterns were derived through principal component analysis. Energy and protein intakes were compared with National Kidney Foundation recommendations. Linear regression analysis was performed between energy and nutrient intakes and estimated glomerular filtration rate (eGFR), and between sociodemographic and clinical variables and dietary patterns.

RESULTS

Median energy and protein intakes were 25.0 kcal/kg and 1.1 g/kg, respectively. In linear regression, protein intake (β = -3.67; P = 0.07) was related to eGFR. Three dietary patterns (snack, mixed and traditional) were retained. The snack pattern was directly associated with male gender (β = 0.27; P = 0.006) and inversely with diabetes (β = -0.23; P = 0.02). The traditional pattern was directly associated with male gender (β = 0.27; P = 0.007) and schooling (β = 0.40; P < 0.001) and inversely with age (β = -0.01; P = 0.001) and hypertension (β = -0.34; P = 0.05).

CONCLUSIONS

We identified low energy and high protein intake in this population. Protein intake was inversely related to eGFR. Dietary patterns were associated with age, gender, schooling level, hypertension and diabetes.

Diet and enteral nutrition in patients with chronic kidney disease not on dialysis: a review focusing on fat, fiber and protein intake

The clinical data available on dietary requirements of patients with chronic kidney disease (CKD) not on dialysis are limited and largely inconclusive in terms of the renal, cardiovascular and nutritional outcomes achievable through dietary modifications. Restriction of protein intake during the early stages of CKD may in fact slow its progression, but at the same time this approach may also lead to protein-energy wasting, if energy intake is not adequate and properly monitored. Unfortunately, compliance to dietary recommendations is traditionally low in this patient population. A switch from saturated to mono- and polyunsaturated fats is generally recognized as advantageous for cardiac health; however, the benefits in term of renal function are largely unknown. Similarly, the association between dietary fiber intake and kidney disease is largely unknown. In fact, while there is evidence on the positive health effects of dietary fibers in the general population, nutritional guidelines for CKD lack formal recommendations concerning fiber intake. This paper reviews data and evidence from clinical trials and meta-analyses on renal and cardiovascular outcomes related to modifications in protein, fat and fiber intake. Suggestions for maintaining nutritional status through patient-oriented dietary patterns and enteral supplementation in CKD patients on conservative therapy are also presented.

Long-Term Effects of High-Protein Diets on Renal Function

Chronic kidney disease (CKD) has a prevalence of approximately 13% and is most frequently caused by diabetes and hypertension. In population studies, CKD etiology is often uncertain. Some experimental and observational human studies have suggested that high-protein intake may increase CKD progression and even cause CKD in healthy people. The protein source may be important. Daily red meat consumption over years may increase CKD risk, whereas white meat and dairy proteins appear to have no such effect, and fruit and vegetable proteins may be renal protective. Few randomized trials exist with an observation time greater than 6 months, and most of these were conducted in patients with preexisting diseases that dispose to CKD. Results conflict and do not allow any conclusion about kidney-damaging effects of long-term, high-protein intake. Until additional data become available, present knowledge seems to substantiate a concern. Screening for CKD should be considered before and during long-term, high-protein intake.

Correlations of dietary energy and protein intakes with renal function impairment in chronic kidney disease patients with or without diabetes

Dietary energy and protein intake can affect progression of chronic kidney disease (CKD). CKD complicated with diabetes is often associated with a decline in renal function. We investigated the relative importance of dietary energy intake (DEI) and dietary protein intake (DPI) to renal function indicators in nondiabetic and diabetic CKD patients. A total of 539 Stage 3-5 CKD patients [estimated glomerular filtration rate (eGFR)<60 mL/min/1.73 m² using the Modification of Diet in Renal Disease equation] with or without diabetes were recruited from outpatient clinics of Nephrology and Nutrition in a medical center in Taiwan. Appropriateness of DEI and DPI was used to subcategorize CKD patients into four groups:(1) kidney diet (KD) A (KD-A), the most appropriate diet, was characterized by low DPI and adequate DEI; (2) KD-B, low DPI and inadequate DEI; (3) KD-C, excess DPI and adequate DEI; and (4) KD-D, the least appropriate diet, excess DPI and inadequate DEI. Inadequate DEI was defined as a ratio of actual intake/recommended intake less than 90% and adequate DEI as over 90%. Low DPI was defined as less than 110% of recommended intake and excessive when over 110%. Outcome measured was eGFR. In both groups of CKD patients, DEI was significantly lower (p<0.001) and DPI higher (p=0.002) than recommended levels. However, only in the nondiabetic CKD patients were KD-C and KD-D significantly correlated with reduced eGFR compared with KD-A at increments of -5.63 mL/min/1.73 m² (p = 0.029) and -7.72 mL/min/1.73 m² (p=0.015). In conclusion, inadequate energy and excessive protein intakes appear to correlate with poorer renal function in nondiabetic CKD patients. Patients with advanced CKD are in need of counseling by dietitians to improve adherence to diets.

Assessment of dietary intake of children with chronic kidney disease

OBJECTIVE

Our aim was to characterize the nutrient intake of children with chronic kidney disease (CKD) relative to recommended intake levels.

METHODS

We conducted a cross-sectional study of dietary intake assessed by Food Frequency Questionnaire (FFQ) in The North American Chronic Kidney Disease in Children (CKiD) prospective cohort study. Nutrient intake was analyzed to estimate the daily consumption levels of various nutrients and compared with national guidelines for intake.

RESULTS

There were 658 FFQs available for analysis; 69.9 % of respondents were boys, with a median age [Interquartile range (IQR)] of 11 years (8-15). Median daily sodium, potassium, and phosphorus intake was 3089 mg (2294-4243), 2384 mg (1804-3076), and 1206 mg (894-1612) respectively. Sodium and phosphorus consumptions were higher than recommended in all age groups. Caloric intake decreased with dropping glomerular filtration rate (GFR) (p = 0.003). The median daily caloric intakes were 1307 kcal in male children 2-3 years old, 1875 kcal in children 4-8 years old, 1923 kcal in those 9-13 years old, and 2427 kcal in those 14-18 years old. Respective levels for girls were 1467 kcal, 1736 kcal, 1803 kcal, and 2281 kcal. Median protein intake exceeded recommended levels in all age groups, particularly among younger participants. Younger children were more likely than older children to exceed the recommended intakes for phosphorus (p < 0.001) and the age-specific recommended caloric intake (p < 0.001). Macronutrient distribution (carbohydrate:fat:protein) was consistent with recommendation.

CONCLUSIONS

Children in the CKiD cohort consumed more sodium, phosphorus, protein, and calories than recommended. The gap between actual consumption and recommendations indicates a need for improved nutritional counseling and monitoring.

Effects of dietary soy protein on skeletal muscle volume and strength in humans with various physical activities

BACKGROUND

In recent years, the number of bedridden people is rapidly increasing due to aging or lack of exercise in Japan. This problem is becoming more serious, since there is no countermeasure against it. In the present study, we designed to investigate whether dietary proteins, especially soy, had beneficial effects on skeletal muscle in 59 volunteers with various physical activities.

METHODS

We subjected 59 volunteers with various physical activities to meal intervention examination. Persons with low and high physical activities were divided into two dietary groups, the casein diet group and the soy diet group. They ate daily meals supplemented with 7.8 g of powdered casein or soy protein isolate every day for 30 days. Bedridden patients in hospitals were further divided into three dietary groups: the no supplementation diet group, the casein diet group and the soy diet group. They were also subjected to a blood test, a urinalysis, magnetic resonance imaging analysis and muscle strength test of the knee before and after the meal intervention study.

RESULTS

Thirty-day soy protein supplementation significantly increased skeletal muscle volume in participants with low physical activity, compared with 30-day casein protein supplementation. Both casein and soy protein supplementation increased the volume of quadriceps femoris muscle in bedridden patients. Consistently, soy protein significantly increased their extension power of the knee, compared with casein protein. Although casein protein increased skeletal muscle volume more than soy protein in bedridden patients, their muscle strength changes by soy protein supplementation were bigger than those by casein protein supplementation.

CONCLUSIONS

The supplementation of soy protein would be one of the effective foods which prevent the skeletal muscle atrophy caused by immobilization or unloading.

High Serum Adiponectin Level Is a Risk Factor for Anemia in Japanese Men: A Prospective Observational Study of 1,029 Japanese Subjects

Erythroid abnormalities including anemia and polycythemia are often observed in the general clinical setting. Because recent studies reported that adiponectin negatively affects hematopoiesis, we performed a prospective observational study to assess the relationship between anemia and adiponectin, as well as other parameters, in 1029 Japanese subjects (477 men and 552 women) 40 years of age and older. Body measurements, blood tests, and nutrition intake studies were performed at baseline, and 5 to 7 years later (follow-up). Hemoglobin (Hb) and hematocrit (Hct) levels in men with high serum adiponectin levels were lower at follow-up than at baseline. Multiple regression analysis showed that age, body mass index, adiponectin, and glutamic-pyruvic transaminase were significantly associated with erythroid-related variables (red blood cells, Hb, and Hct) in both men and women (P <0.05). In a logistic regression analysis, adiponectin, fasting blood glucose, and β-natriuretic peptide were significant risk factors for anemia in men, and blood urea nitrogen and amylase were significant risk factors in women. Physical features and nutrient intake were not risk factors for anemia. Our study demonstrates, both clinically and epidemiologically, that a high serum adiponectin level decreases the amounts of erythroid-related variables and is a risk factor for anemia in Japanese men.

Non-dialytic management of acute kidney injury in newborns

Treating acute kidney injury (AKI) in newborns is often challenging due to the functional immaturity of the neonatal kidney. Because of this physiological limitation, renal replacement therapy (RRT) in this particular patient population is difficult to execute and may lead to unwanted complications. Although fluid overload and electrolyte abnormalities, as seen in neonatal AKI, are indications for RRT initiation, there is limited evidence that RRT initiated in the first year of life improves long-term outcome. The underlying cause of AKI in a newborn patient should determine the treatment strategies to restore appropriate renal function. However, our understanding of this common clinical condition remains limited, as no standardized, evidence-based definition of neonatal AKI currently exists. Non-dialytic management of AKI in these patients may restore appropriate renal function to these patients without exposure to complications often encountered with RRT.

Controversies surrounding high-protein diet intake: satiating effect and kidney and bone health

Long-term consumption of a high-protein diet could be linked with metabolic and clinical problems, such as loss of bone mass and renal dysfunction. However, although it is well accepted that a high-protein diet may be detrimental to individuals with existing kidney dysfunction, there is little evidence that high protein intake is dangerous for healthy individuals. High-protein meals and foods are thought to have a greater satiating effect than high-carbohydrate or high-fat meals. The effect of high-protein diets on the modulation of satiety involves multiple metabolic pathways. Protein intake induces complex signals, with peptide hormones being released from the gastrointestinal tract and blood amino acids and derived metabolites being released in the blood. Protein intake also stimulates metabolic hormones that communicate information about energy status to the brain. Long-term ingestion of high amounts of protein seems to decrease food intake, body weight, and body adiposity in many well-documented studies. The aim of this article is to provide an extensive overview of the efficacy of high protein consumption in weight loss and maintenance, as well as the potential consequences in human health of long-term intake.

Major depressive disorder in hemodialysis patients in China

INTRODUCTION

Major depressive disorder (MDD) has been regarded as the most common psychiatric disorder among hemodialysis (HD) patients. However, few studies have investigated MDD in HD patients in Mainland China. This study sought to investigate the prevalence and treatment of MDD, as well as the sociodemographic and clinical characteristics in this population.

METHODS

Two hundred sixty HD patients were screened with the nine-item Patient Health Questionnaire, and the formal diagnosis of MDD was further assessed using the Diagnostic and Statistical Manual of Mental Disorders, 4th edition. Severity of depressive symptoms was assessed with Hamilton Rating Scale for Depression. Finally, patients meeting diagnostic criteria were compared with those who did not on demographic and clinical characteristics.

RESULTS

Among the 260 subjects, 26.2% screened positively and 10% were confirmed to have a diagnosis of MDD. Among HD patients with MDD, 69.2% had severe or very severe depressive symptoms. There was no evidence of a clinical diagnosis or of treatment for MDD in any of the patients' medical records. Those with shorter duration of HD, lower monthly income, and lower levels of blood urea nitrogen were significantly more likely to have a diagnosis of MDD.

DISCUSSION

MDD is frequent in HD patients. Regular screening and professional diagnosis should be undertaken to increase the detection and treatment of MDD in HD patients. The effectiveness of interventions for MDD in HD patients deserves further research.

Weight-loss diets in people with type 2 diabetes and renal disease: a randomized controlled trial of the effect of different dietary protein amounts

BACKGROUND

Higher-protein weight-loss diets (defined as >25% of energy as protein) are not recommended for individuals with type 2 diabetes because of their potential adverse effect on renal function.

OBJECTIVE

We aimed to examine the effect of such diets on renal function over 12 mo in people with type 2 diabetes and early renal disease.

DESIGN

Overweight and obese people with type 2 diabetes were screened to identify those with an albumin:creatinine ratio from 3 to 30 mg/mmol. Seventy-six subjects were randomly assigned to either a moderate-protein weight-loss diet or a standard-protein weight-loss diet for 12 mo. The primary endpoint was the change in renal function as assessed by the isotope glomerular filtration rate (GFR), estimated GFR, and cystatin C. Forty-five subjects (moderate protein: n = 21; standard protein: n = 24) completed the study.

RESULTS

The mean (±SE) weight loss was not different between diets at 9.7 ± 13.4 kg for the moderate-protein diet and 6.6 ± 7.1 kg for the standard-protein diet. There were no changes in renal function or albuminuria or blood pressure, although glycated hemoglobin was lowered with both diets. Changes in renal function were related to the baseline estimated GFR. Patients with stage 1-3 renal disease (<120 mL · min(-1) · 1.73 m(-2); n = 33) had an improvement in renal function, whereas patients with hyperfiltration (>120 mL · min(-1) · 1.73 m(-2); n = 12) had a decrease in the GFR. After adjustment for weight loss, the baseline GFR remained a significant predictor of outcomes with no effect of dietary treatment. An average difference in protein intake between diets of 19 ± 6 g/d was achieved.

CONCLUSION

Weight loss improved renal function, but differences in dietary protein had no effect. This trial was registered at the Australian and New Zealand Clinical Trial Register as ACTRN12608000045314.

Nonprotein calorie supplement improves adherence to low-protein diet and exerts beneficial responses on renal function in chronic kidney disease

OBJECTIVE

Malnutrition is common in patients with chronic kidney disease (CKD) who are on low-protein diets and is a powerful predictor of morbidity and mortality in CKD. Studies have shown that patients on low-protein diets often have difficulty meeting nutritional energy requirements. Our study evaluated the effects of a nonprotein calorie (NPC) supplement on renal function and nutritional status in patients on a low-protein diet.

DESIGN

This was a prospective, randomized, open-label, controlled clinical trial.

SUBJECTS

A total of 109 patients with CKD (men, 67%; mean age, 54.5 ± 13 years) with stage 3 to 4 disease were randomly assigned to the intervention group (n = 55) or the control group (n = 54).

INTERVENTION

All participants received individualized dietary counseling aimed at achieving a daily protein intake of 0.6 to 0.8 g and a daily energy intake of 30 to 35 kcal/kg. The intervention group consumed a 200-kcal NPC supplement daily. The control group received dietary counseling only.

MAIN OUTCOME MEASURE

The estimated glomerular filtration rate (eGFR) was calculated using the 4-variable Modification of Diet in Renal Disease (MDRD) Study equation. Urine protein excretion, dietary protein and energy intake, and serum levels of creatinine, urea nitrogen, cholesterol, triglycerides, and albumin were assessed at baseline, at 12 weeks, and at 24 weeks.

RESULTS

Dietary protein intake and urine protein excretion levels decreased significantly in the intervention group and were significantly lower than those of the control group. In addition, serum levels of creatinine and urea nitrogen decreased significantly, and eGFR increased significantly in the intervention group compared with baseline assessments. No significant differences were observed in the control group.

CONCLUSIONS

The NPC supplement improved patient adherence to the low-protein diet and reduced urine protein excretion in patients with CKD.

Optimizing bone health in older adults: the importance of dietary protein

Age-related bone loss is progressive and can lead to osteoporosis. While it is accepted that both dietary calcium and vitamin D are important and beneficial for skeletal health, the impact of dietary protein on calcium metabolism and bone balance remains controversial. Contrary to the hypothesis that increasing dietary protein contributes to bone loss, research supports the notion that protein may play a pivotal role in maintenance of bone health by several mechanisms; for example, increasing dietary protein increases IGF-1, calcium absorption, muscle strength and mass, all of which could potentially benefit the skeleton. A moderate increase in dietary protein recommendations for the aging population (above the recommended dietary allowance of 0.8 g/kg) may be beneficial to bone health, while still falling within the safe and acceptable range for protein intake (as defined by the dietary reference intakes).

High-calorie diet partially ameliorates dysregulation of intrarenal lipid metabolism in remnant kidney

Chronic renal failure (CRF) is associated with malnutrition and renal tissue accumulation of lipids, which can contribute to progression of renal disease. This study was designed to explore the effect of a high-calorie diet on pathways involved in lipid metabolism in the remnant kidney of rats with CRF. 5/6 nephrectomized rats were randomized to receive a regular diet (3.0 kcal/g) or a high-calorie diet (4.5 kcal/g) for 12 weeks. Renal lipid contents and abundance of molecules involved in cholesterol and fatty acid metabolism were studied. The CRF group consuming a regular diet exhibited growth retardation; azotemia; proteinuria; glomerulosclerosis; tubulointerstitial injury; heavy lipid accumulation in the remnant kidney; up-regulation of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), ATP-binding cassette transporter-1 (ABCA1), liver X receptor (LXR) α/β, carbohydrate-responsive element binding protein (ChREBP) and acyl-CoA carboxylase (ACC); and down-regulation of peroxisome proliferator-activated receptor-α (PPAR-α), carnitine palmitoyltransferase-1 (CPT1) and liver-type fatty acid binding protein (L-FABP). The high-calorie diet restored growth; reduced the severity of tubulointerstitial injury, proteinuria and azotemia; partially lowered renal tissue lipid contents; attenuated the up-regulation of mediators of lipid influx (LOX-1), lipid efflux (LXR-α/β and ABCA1) and fatty acid biosynthesis (ChREBP and ACC); and reversed the down-regulation of factors involved in fatty acid oxidation (PPAR-α, CPT1 and L-FABP). In conclusion, a high-calorie diet restores growth, improves renal function and structure, and lowers lipid burden in the remnant kidney. The latter is associated with and most likely due to reduction in lipid influx and enhancement of fatty acid oxidation.

Serum bicarbonate levels and the progression of kidney disease: a cohort study

BACKGROUND

Animal models of kidney disease have linked metabolic acidosis with renal damage. The role of low serum bicarbonate levels in kidney disease progression in humans has not been studied.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Adults visiting a medical clinic in the Bronx, NY, from January 1, 2001, to December 31, 2003, were included in the study (n = 5,422) and followed up until June 30, 2007.

PREDICTOR

Serum bicarbonate level.

OUTCOMES

Kidney disease progression was defined as either a decrease in estimated glomerular filtration rate (eGFR) by 50% or reaching an eGFR less than 15 mL/min/1.73 m(2) (n = 337).

MEASUREMENTS

Patients' baseline demographics, comorbid conditions, laboratory data, and socioeconomic status were recorded. Serial outpatient serum creatinine levels were collected (median, 5 measurements/person).

RESULTS

Mean age was 52 years, 69% were women, 45% were African American, 31% were Hispanic, 21% had diabetes mellitus, 41% had hypertension, and 9% had a baseline eGFR less than 60 mL/min/1.73 m(2). Kidney disease progressed as defined in 337 patients (6.2%). Compared with the reference group (bicarbonate level, 25 to 26 mEq/L), hazard ratios for progression after adjustment for potential confounders were 1.54 (95% confidence interval [CI], 1.13 to 2.09) for bicarbonate levels of 22 mEq/L or less, 0.97 (95% CI, 0.70 to 1.35) for 23 to 24 mEq/L, and 1.14 (95% CI, 0.84 to 1.55) for 27 mEq/L or greater (global P for inclusion of serum bicarbonate level in the model = 0.01). These results were similar using different definitions of the outcome (eGFR decrease of 30%, 1,288 outcomes [24%]; or doubling of serum creatinine level, 268 outcomes [4.9%]).

LIMITATIONS

Data used in the study were collected for clinical, not research, purposes.

CONCLUSIONS

Low serum bicarbonate level is associated with progression of kidney disease independent of baseline eGFR and other clinical, demographic, and socioeconomic factors. Prospective studies are needed to confirm this relationship and evaluate the efficacy of alkali supplements for slowing progression.