Effect of Low Protein Diet on Bone Structure of Young Wistar Mice

<b>Background and Objective:</b> Malnutrition and stunting are major unresolved problems in Indonesia. Protein deficiency can cause stunted growth, as well as make physical and cognitive abilities cannot reach their maximum potential. During childhood the need for protein must be fulfilled so that the peak of bone formation during adolescence can be perfect. In malnourished children, a low protein diet will lead to thinning of the bone cortex. Due to the high rate of stunting and malnutrition in children due to protein deficiency, a study was conducted on the effects of feeding low protein diet on rat bones. <b>Materials and Methods:</b> Male Wistar rats (n = 10) at 6-8 weeks old (body weight around 250 g), control groups were fed a normal chow diet and low protein diet groups were given low protein chow diet (protein 5%) for 18 weeks, then the rats were sacrificed and the femoral bones were isolated. Body weight, femur weight, femur length were checked and bone density was examined using X-ray. <b>Results:</b> The body proportions of the low protein group rats were smaller and thinner than those of the control group. This difference is supported by the significant weight loss starting from the sixth week after low protein feeding. There are significant differences in body weight and femur weight between the control and low protein diet groups. Bone density decreases significantly in low protein diet group. Macroscopically, the femur length of the low protein group was shorter than the control group, however the femur length did not show significant differences statistically between the two groups. <b>Conclusion:</b> A low protein diet decreased the body weight of the rats, also causing impaired bone growth characterized by decreasing femur weight. The low protein diet also caused osteoporosis in the bones.

Growth performance and nitrogen excretion of broiler chickens fed low protein diets supplemented with crystalline amino acids

This study was conducted to determine the effects of amino acid (AA) supplementation in low-protein (LP) diets on growth performance and nitrogen (N) excretion. A total of 175 7-day-old Ross 308 male broilers, with a mean body weight (BW) of 165 g (standard deviation = 11.2 g), were grouped into five blocks by BW and allocated to seven treatments according to a randomized complete block design with five replicate cages at five birds per cage. Dietary treatments comprised a control diet containing 20.0% crude protein (CP) and six LP diets containing either 18.5% or 17.0% CP. These LP diets were supplemented with either no AA supplementation, indispensable AA, or both indispensable and dispensable AA (glutamic acid and glycine). Birds were fed experimental grower diets from day 7 to 21 and then commercial finisher diets until day 28. During the grower period (day 7 to 21), birds fed LP diets supplemented with indispensable AA exhibited greater (p < 0.05) BW, body weight gain (BWG), feed intake (FI), and gain-to-feed ratio (G:F) than birds fed LP diets without crystalline AA and were comparable to birds fed the control diet. During the finisher period (day 21 to 28), birds fed LP diets supplemented with indispensable AA showed greater (p < 0.05) BW than birds fed LP diets without crystalline AA, and their growth performance was comparable to birds fed the control diet. Throughout the overall period, supplementing indispensable AA in LP diets resulted in elevated (p < 0.05) BWG, FI, and G:F more than those of LP diets without crystalline AA and were comparable to those of the control diet. Supplementing indispensable AA in LP diets decreased amount and coefficient of N excretion as much as the control diet. Dispensable AA supplementation in LP diets did not influence growth performance and N excretion. In conclusion, supplementing indispensable AA in LP diets maintains growth performance and N excretion until the dietary CP lowers from 20.0% to 17.0% during the grower period. As long as dietary CP is above 17.0%, dispensable AA may not be deficient in LP diets during the grower period.

Association of a low protein diet with depressive symptoms and poor health-related quality of life in CKD

OBJECTIVES

A low protein diet (LPD) for chronic kidney disease (CKD) is a core dietary therapy to slow CKD progression. A study showed depressive symptoms are more common in populations with an LPD. In this cross-sectional study, we evaluated depressive symptoms and health-related quality of life (HRQOL) in patients with CKD.

METHODS

A total of 571 CKD patients were enrolled in this study. The LPD was defined with dietary protein intake ≤0.8 g/kg/day. We divided the CKD into mild CKD and advanced CKD according to severity, as well as diabetic kidney disease (DKD) and non-DKD according to DM. The logistic regression analysis was performed to evaluate the association between an LPD and depressive symptoms as well as HRQOL in CKD patients and each subgroup.

RESULTS

An LPD had significantly higher unadjusted Odds Ratio (OR) (1.81, [95% for Confidence Interval (CI), 1.18-2.76]) and multivariate-adjusted OR (1.80, [1.15-2.81]) for depressive symptoms. Moreover, an LPD showed significantly higher unadjusted OR (2.08, 1.44-3.01]) and multivariate OR (2.04, [1.38-3.02]) for poor HRQOL. In DKD subgroups, an LPD had a significant increase in unadjusted OR (2.00, [1.12-3.57]) and multivariate OR (1.99, [1.01-3.44]) for depressive symptoms. The advanced CKD group also showed that an LPD had significantly higher unadjusted OR (1.97, [1.13-3.42]) and multivariate OR (2.03, [1.12-3.73]) for depressive symptoms.

CONCLUSIONS

An LPD for CKD patients was significantly associated with depressive symptoms and poor HRQOL. Subgroup analysis indicated that DKD and advanced CKD are more predisposed to depressive symptoms and poor HRQOL.

Protein malnutrition in BALB/C mice: A model mimicking clinical scenario of marasmic-kwashiorkor malnutrition

Protein malnutrition continues to be a major global issue. A stable animal model to address protein malnutrition and its effect on various disease conditions is necessary. In the present study, we have formulated and standardized a low protein diet (LPD) to develop a protein malnutrition model using Balb/C mice. Healthy male Balb/C mice were weaned and exposed to LPD combinations while another group exposed to normal diet (18% protein). Animal survival, change in body weight, body mass index (BMI), biochemical parameters, antioxidant status, and liver histopathology were used to confirm the development of malnourished mice model (marasmic-kwashiorkor). Mice receiving 10% protein diet showed moderate weight gain, higher BMI, and no mortality compared to the 6% protein group. The former group showed remarkable differences in BMI, biochemical and antioxidant parameters. Further, histopathological changes against the normal group at weeks 20 and 30 confirmed the development of protein malnutrition in mice on 10% protein diet. The study confirms the development of a stable, economical, reproducible, and clinically relevant protein malnutrition model using the formulated 10% protein diet. Further, the model can be used for short and long-term studies to investigate the pathophysiology of malnutrition in any disease/condition.

Impact of low-protein diet on cardiovascular risk factors and kidney function in diabetic nephropathy: A systematic review and meta-analysis of randomized-controlled trials

AIM

To assess the efficacy of low-protein diets (LPD) on cardiovascular risk factors and kidney function in diabetic nephropathy (DN) based on randomized controlled trials (RCTs).

METHODS

A comprehensive systematic search was undertaken in PubMed/MEDLINE, Web of Science, SCOPUS and Embase databases from inception until January 2022 without using time or language restrictions. RCTs which reported the effects of LPD on cardiovascular risk factors and kidney function in DN were considered.

RESULTS

The results of the present study showed that a LPD significantly reduces urinary urea (WMD: -244.49 g/day, 95 % CI: -418.83, -70.16, P = 0.006) and HbA1c (WMD: -0.20, 95 % CI: -0.39, -0.01, P = 0.036) levels. However, the results did not show neither significant nor beneficial effect on other renal function and cardiovascular risk factors. Furthermore, the results of subgroup analysis showed LPD caused a further decrease in HbA1c during the follow-up period of ≤ 24 weeks, protein intake less than 0.8 g/kg/d and in individuals younger than 50 years. Albuminuria also showed a greater reduction in people under the age of 50 with type 1 diabetes (DMT1) following a LPD.

CONCLUSION

The results of the present study showed that LPD significantly reduces urinary urea and HbA1c.

Assessment of limiting dietary amino acids in broiler chickens offered reduced crude protein diets

As lowering crude protein (CP) in poultry diets continues to minimize amino acid excess, it is important to understand the limiting order of amino acids and the impact of their deficiencies. Therefore, a pair of experiments were conducted to observe the effects of individual amino acid deletions on growth performance, carcass traits, and nutrient utilization. Both experiments involved 3 control diets based on wheat and soybean meal, including a 210.0 g/kg CP industry control (IC), 186.7 g/kg CP positive control (PC) supplemented with feed-grade amino acids to match the IC amino acid profile, 186.7 g/kg CP negative control (NC) with reducing N corrected apparent metabolizable energy (AME_N) by 0.5 MJ/kg and removing feed-grade amino acids beyond L-Lys-HCl, DL-Met, and L-Thr from PC. Ten deletion diets where the following supplemented amino acids were individually removed from the PC: Val, Ile, Leu, Trp, Arg, His, Phe + Tyr, glycine equivalence (Gly_equi), Pro, and Energy (0.5 MJ/kg reduction in AME_N of the PC). All diets were formulated to contain similar concentrations of digestible Lys, total sulfur amino acid (TSAA) and Thr. Experimental diets were offered to broiler chickens from 15 to 22 d post–hatch in a cage study (Exp. 1) to gain digestibility and nutrient utilization data; whereas they were offered from 15 to 35 d post–hatch in a floor-pen study (Exp. 2) to gain performance and carcass yield data. The removal of supplemented Val, Arg, and Ile resulted in reduction on broiler performance (P < 0.05), and the removal of Val, Arg, Ile, and Gly_equi negatively influenced carcass traits (P < 0.05). Results from both experiments indicate that Val and Arg are co-limiting in wheat-soybean meal diets, but that Ile and Gly_equi may potentially limit breast and thigh development.

The optimal dietary arginine level of laying hens fed with low-protein diets

Background

Arginine (Arg) is an essential amino acid (EAA) in poultry, an important substrate for protein synthesis and a precursor of several molecules. Supplementation of EAAs with low protein (LP) diet increases the utilization efficiency of dietary crude protein (CP). However, if the EAA requirement is changed in hens fed a LP diet remains to be elucidated. The aim of the present study was to evaluate the optimal level of dietary Arg in the LP diet of hens. A total of 1350 Hy-Line Brown laying hens were randomly allocated to six dietary treatments: a basal diet (16% CP, positive control), or an isoenergetic LP diet (14% CP, 0.80% Arg) supplemented 0, 0.05%, 0.10%, 0.15%, and 0.20% L-Arg, corresponding to 0.80%, 0.85%, 0.90%, 0.95% and 1.00% dietary Arg, respectively.

Results

The feed efficiency was decreased (P < 0.05) by 0.80% and 1.00% Arg-LP diets, compared to control. Within LP diets, dietary Arg level had significant quadratic effects (P < 0.05) on laying rate, egg mass, and feed efficiency. Compared to control, the plasma CAT activity or T-AOC content were decreased by 0.80% (P < 0.001). However, the hens offered 0.85% and 0.90% Arg-LP diets had higher CAT activity (P < 0.001) than 0.80% Arg-LP diet. In contrast, 1.00% Arg-LP group had the highest MDA and the lowest T-AOC content in plasma, liver, duodenal and jejunal mucosa (P < 0.05). Compared to control, the villus height was decreased by 0.80%, 0.95% and 1.00% Arg-LP diets, while the villus height to crypt depth (V/C) ratio was reduced by 0.95% and 1.00% Arg-LP diets in duodenum.

Conclusion

The result demonstrates that LP diet (14% CP) deficient in Arg (0.80% Arg) result in augmented oxidative damage and impaired development of intestinal mucosa. According to the quadratic broken-line regression model, the optimal dietary arginine levels for Hy-Line Brown laying hens fed with low protein diet (14% CP) aged 33 to 40 weeks are 0.85%, 0.86%, and 0.86% to obtained the maximum laying rate, egg mass, and feed efficiency, respectively.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00719-x.

Effect of nutritional status on acetaminophen pharmacokinetic profile

Short-term fasting increases acetaminophen exposure in healthy subjects, whereas no effect was observed after a high-fat diet. These findings suggest the necessity of considering nutritional status when assessing the risk of acetaminophen-induced toxicity. Further role of nutrition status on pharmacokinetic profile of acetaminophen (APAP) at toxic doses are not available. Our study aims to compare the effects of nutrition status on kinetic profile of APAP in 3 different dietary conditions like - Normal diet (ND), Low protein diet (LPD) and High fat diet (HFD) groups. To investigate the pharmacokinetic profile of APAP at toxic dose, 3 groups of animals were separated after weaning and for the next 15 weeks they were fed with their respective diets (ND, LPD and HFD). Animals were dosed with APAP (300 mg/kg p.o) and blood sampling was done at different time intervals. Plasma samples were analyzed using HPLC method. Data analysis was done by Non-compartment analysis using Phoenix WinNonlin 8.3 software. LPD group show higher values of C _max, T _max, T _1/2, and AUC _0-4, AUC _0-x values compared to ND and HFD groups. Our study compared APAP pharmacokinetic profile at toxic dose in three different diet regimes.

The association between low protein diet and body composition, muscle function, inflammation, and amino acid-based metabolic profile in chronic kidney disease stage 3-5 patients

BACKGROUND

Chronic kidney disease (CKD) is a global burden in the world. Low protein diet (LPD) recommendation is suggested in CKD patients to avoid or defer dialysis initiation and slow down CKD progression. However, nutritional imbalance and protein energy wasting represent key worries. The amino acid-based metabolic profile may provide a sensitive biomarker to evaluate CKD patients' nutrition status with LPD recommendations.

METHODS

We conducted a cross-sectional study in CKD stage 3-5 patients who had received LPD recommendation to evaluate the association between LPD and traditional markers (including plasma levels of albumin, pre-albumin, transferrin, total iron-binding capacity), inflammation markers (including peripheral leukocyte count and plasma levels of high-sensitivity C-reactive protein), body composition, muscle strength, and physical function, and novel nutrition markers (including amino acid-based metabolic profile) in CKD stage 3-5 patients.

RESULTS

In our study CKD stage 3-5 patients with the total number of 73, the mean age was around 71 ± 10 years old. The mean daily protein intake (DPI) was around 0.9 ± 0.3 g/kg/day and 25 (34%) patients met the recommended goal of DPI <0.8 g/kg/day. The mean daily calorie intake (DCI) was around 23 ± 6 kcal/kg/day, with only 11 (15%) patients met the recommend DCI with 30-35 kcal/kg/day. Compared to CKD patients with non-LPD, patients with LPD had significantly lower hemoglobin and albumin levels, shorter 6-min walking distance (6MWD), and lower leucine levels. Multivariable analysis found that lower hemoglobin and leucine levels, and shorter 6MWD were negatively and independently associated with LPD (all p < 0.05). Then ROC curve analysis found that the optimal cut-off value of leucine plasma levels was 95.5 μM with 60% sensitivity and 71% specificity to predict those CKD patients with LPD with the area under the curve of 0.646 (95% CI: 0.512-0.780).

CONCLUSION

LPD attainment was noted in 34% patients and most of CKD stage 3-5 patients (around 85%) had inadequate daily calorie intake although receiving standard dietary counseling routinely. A low protein diet and inadequate daily calorie intake in CKD patients were associated with shorter 6MWD, and lower hemoglobin and leucine levels. Plasma leucine levels lower than 95.5 μM may be a herald for muscle wasting and malnutrition in these CKD stage 3-5 patients with inadequate calorie intake.

Low-salt low-protein diet and blood pressure control in patients with advanced diabetic kidney disease and heavy proteinuria

PURPOSE

To assess the associations between effects of low salt, low protein diet supplemented with keto-analogues (sLPD)-on salt intake, blood pressure (BP) and cardiovascular events (CVEs) in patients with advanced diabetic kidney disease (DKD) and heavy proteinuria.

METHODS

Prospective, single-center study (total duration of 15 months), enrolling 92 patients with advanced DKD (median eGFR 11.7 ml/min) and heavy proteinuria (median 4.8 g/g creatininuria). The intervention consisted in a low salt-low protein (0.6 g/kg-day) diet (sLPD) under intensive nutritional counselling, and adjustment of antihypertensive therapy. The endpoints of this sub-analysis were a salt intake ≤ 5 g/day, a mean blood pressure (MAP) ≤ 97 mmHg, corresponding to KDIGO target of 130/80 mmHg, and the rate of CVEs.

RESULTS

Salt intake decreased with 2.5 g/day and the proportion of patients reaching the salt intake endpoint increased with 58%. A salt intake ≤ 5 g/day was associated with a reduced MAP, BMI, proteinuria, fractional excretion of sodium, and eGFR, suggesting a salt-related volume contraction but was not related to protein intake. Mean arterial pressure decreased with 13 mmHg. MAP ≤ 97 mmHg was associated with lower proteinuria, salt, and protein intake, but the contribution of salt intake cannot be differentiated from that of protein intake. CVEs occurred in 20% of patients and were independently related to a lower age and MAP, and increased comorbidities. eGFR only minimally declined and no renal adverse events were noted. sLPD was nutritionally safe.

CONCLUSIONS

The multifactorial personalized intervention allowed a stable MAP reduction to KDIGO recommended levels (≤ 97 mmHg), related to the decrease in salt and protein intake. However, BP lower than 130/80 mmHg increased the cardiovascular but not the renal risk in heavy proteinuric patients with advanced DKD.

TRIAL REGISTRATION NUMBER

0341507433: NCT03415074. Registered 02/02/2015 in US National Library of Medicine, ClinicalTrials.gov (NCT).

Effects of Low Protein Diet on Modulating Gut Microbiota in Patients with Chronic Kidney Disease: A Systematic Review and Meta-analysis of International Studies

Background: Although associations between low protein diet (LPD) and changes of gut microbiota have been reported; however, systematic discernment of the effects of LPD on diet-microbiome-host interaction in patients with chronic kidney disease (CKD) is lacking. Methods: We searched PUBMED and EMBASE for articles published on changes of gut microbiota associated with implementation of LPD in CKD patients until July 2021. Independent researchers extracted data and assessed risks of bias. We conducted meta-analyses of combine p-value, mean differences and random effects for gut microbiota and related metabolites. Study heterogeneity was measured by Tau² and I² statistic. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Results: Five articles met inclusion criteria. The meta-analyses of gut microbiota exhibited enrichments of Lactobacillaceae (meta-p= 0.010), Bacteroidaceae (meta-p= 0.048) and Streptococcus anginosus (meta-p< 0.001), but revealed depletion of Bacteroides eggerthii (p=0.017) and Roseburia faecis (meta-p=0.019) in LPD patients compared to patients undergoing normal protein diet. The serum IS levels (mean difference: 0.68 ug/mL, 95% CI: -8.38-9.68, p= 0.89) and pCS levels (mean difference: -3.85 ug/mL, 95% CI: -15.49-7.78, p < 0.52) did not change between groups. We did not find significant differences on renal function associated with change of microbiota between groups (eGFR, mean difference: -7.21 mL/min/1.73 m², 95% CI: -33.2-18.79, p= 0.59; blood urea nitrogen, mean difference: -6.8 mg/dL, 95% CI: -46.42-32.82, p= 0.74). Other clinical (sodium, potassium, phosphate, albumin, fasting sugar, uric acid, total cholesterol, triglycerides, C-reactive protein and hemoglobin) and anthropometric estimates (body mass index, systolic blood pressure and diastolic blood pressure) did not differ between the two groups. Conclusions: This systematic review and meta-analysis suggested that the effects of LPD on the microbiota were observed predominantly at the families and species levels but minimal on microbial diversity or richness. In the absence of global compositional microbiota shifts, the species-level changes appear insufficient to alter metabolic or clinical outputs.

Effect of dietary near ideal amino acid profile on heat production of lactating sows exposed to thermal neutral and heat stress conditions

BACKGROUND

Reduced protein diet manifested potential to mitigate heat production based on the concept of ideal amino acid profile. The hypothesis of this study was that lactating sows fed a low crude protein (LCP) diet with supplemental amino acid produce less heat compared to those fed a high crude protein (HCP) diet under both thermal neutral (TN) and heat stress (HS) conditions.

METHODS

Thirty-two lactating sows were allotted to HCP (193 g CP/kg) and LCP (140 g CP/kg) diets under thermal neutral (TN, 21 ± 1.5 °C) or cycling heat stress (HS, 32 ± 1.5 °C daytime and 24 ± 1.5 °C nighttime) conditions. Diets contained 0.90% SID lysine and 10.8 MJ/kg net energy. Positive pressure indirect calorimeters were used to measure gas exchange in individual sows with litters, and individual piglets on days 4, 8, 14 and 18. Sow and litter weights were recorded on days 1, 10 and 21.

RESULTS

Sow total heat production (THP) was calculated by subtracting litter THP from sow + litter THP based on BW0.75. Sow BW and body protein (BP) loss was greater for LCP diet compared to HCP diet in peak lactation (P < 0.05 and P < 0.01, respectively) and throughout the entire lactation period (P < 0.05 and P = 0.056, respectively) under HS conditions. Heat-stressed sows fed HCP diet had higher (P < 0.05) rectal temperature at 13:00 (P < 0.05) and 19:00 (P < 0.01), and higher respiration rate at 07:00 (P <  0.05), 13:00 (P < 0.05) and 19:00 (P < 0.05) compared to TN sows fed HCP diet. In sows fed LCP diet, those under HS tended to have higher (P = 0.098) rectal temperature at 13:00 and had higher (P <  0.05) respiration rate at 07:00, 13:00 and 19:00 compared to TN sows. The relationship between daily THP and days in lactation of sows fed LCP diet was quadratic (P < 0.05), with an ascending trend until day 14 and a descending trend from days 14 to 18. Sows fed LCP diet had lower daily THP at day 18 (P < 0.001) compared to those fed the HCP diet under HS conditions.

CONCLUSION

Reduction in THP in sows fed LCP diet was largely associated with THP on day 18 of lactation under HS conditions. Feeding LCP diets alleviated the increased body temperature in sows under HS conditions throughout lactation, which was accompanied by a reduction in respiration rate. Total heat production is associated with days in lactation, in particular under HS conditions with THP appearing to peak between days 14 and 18.

Altered molecular signatures during kidney development after intrauterine growth restriction of different origins

Abstract

This study was performed to identify transcriptional alterations in male intrauterine growth restricted (IUGR) rats during and at the end of nephrogenesis in order to generate hypotheses which molecular mechanisms contribute to adverse kidney programming. IUGR was induced by low protein (LP) diet throughout pregnancy, bilateral uterine vessel ligation (LIG), or intrauterine stress (IUS) by sham operation. Offspring of unimpaired dams served as controls. Significant acute kidney damage was ruled out by negative results for proteins indicative of ER-stress, autophagy, apoptosis, or infiltration with macrophages. Renal gene expression was examined by transcriptome microarrays, demonstrating 53 (LP, n = 12; LIG, n = 32; IUS, n = 9) and 134 (LP, n = 10; LIG, n = 41; IUS, n = 83) differentially expressed transcripts on postnatal days (PND) 1 and 7, respectively. Reduced Pilra (all IUGR groups, PND 7), Nupr1 (LP and LIG, PND 7), and Kap (LIG, PND 1) as well as increased Ccl20, S100a8/a9 (LIG, PND 1), Ifna4, and Ltb4r2 (IUS, PND 7) indicated that inflammation-related molecular dysregulation could be a “common” feature after IUGR of different origins. Network analyses of transcripts and predicted upstream regulators hinted at proinflammatory adaptions mainly in LIG (arachidonic acid-binding, neutrophil aggregation, toll-like-receptor, NF-kappa B, and TNF signaling) and dysregulation of AMPK and PPAR signaling in LP pups. The latter may increase susceptibility towards obesity-associated kidney damage. Western blots of the most prominent predicted upstream regulators confirmed significant dysregulation of RICTOR in LP (PND 7) and LIG pups (PND 1), suggesting that mTOR-related processes could further modulate kidney programming in these groups of IUGR pups.

Key messages

Inflammation-related transcripts are dysregulated in neonatal IUGR rat kidneys.

Upstream analyses indicate renal metabolic dysregulation after low protein diet.

RICTOR is dysregulated after low protein diet and uterine vessel ligation.

Electronic supplementary material

The online version of this article (10.1007/s00109-020-01875-1) contains supplementary material, which is available to authorized users.

Enzyme-treated soy protein supplementation in low protein diet improved flesh tenderness, juiciness, flavor, healthiness, and antioxidant capacity in on-growing grass carp (Ctenopharyngodon idella)

An 8-week feeding trial was conducted to investigate the effects of enzyme-treated soy protein (ETSP) supplementation in low protein diets on growth performance as well as flesh sensory quality and healthiness in on-growing grass carp. A total of 540 on-growing grass carp (initial average weight 325.72 ± 0.60 g) were fed six diets, which included a normal protein diet (28% crude protein) and five low protein diets (26% crude protein) supplemented with graded levels of ETSP (0.0, 0.8, 1.2, 1.6, and 2.0%). The results showed that reducing dietary protein by 2% decreased percentage weight gain, feed intake, and flesh flavor (aspartic acid, glutamic acid, histidine, and 5'-inosinic acid contents) and healthiness-related indices (linolenic acid (LA) and docosahexaenoic acid (DHA) contents and polyunsaturated fatty acids to saturated fatty acids ratio). Under the condition of reducing dietary protein by 2%, 0.8-1.2% ETSP supplementation restored above parameters to levels equal or superior to those in 28% crude protein diet group. Although reducing dietary protein by 2% did not deteriorate flesh tenderness and juiciness, 0.8-1.2% ETSP supplementation in low protein diets also improved the two indices compared with 28% crude protein diet. Moreover, ETSP-improved flesh quality was partly related to increased muscle antioxidant enzymes activities and their mRNA levels. In addition, ESTP-enhanced antioxidant enzyme mRNA levels were partly associated with the upregulation of NF-E2-related factor 2 (Nrf2) and target of rapamycin (TOR) signaling. Collectively, 0.8-1.2% ETSP supplementation in low protein diets improved growth performance as well as flesh sensory quality and healthiness in on-growing grass carp.

Effects of selenium deficiency and low protein intake on the apoptosis through a mitochondria-dependent pathway

OBJECTIVE

Selenium(Se)is an important trace element for human health. Studies have shown that selenium deficiency and low protein(Pr) intake are the primary risk factors for Keshan disease.The relationship between the cardiac malfunction induced by these two risk factors and the mitochondria-mediated apoptotic pathway is poorly understood.This study aimed to determine the effect of selenium deficiency and low protein intake on the mitochondria-mediated apoptotic pathway.

METHODS

In the present study, 120 weaning Wistar rats were randomly fed one of six different diets. The myocardial tissue sections were deparaffinized in water and subjected to hematoxylin-eosin staining. Mitochondrial changes in the myocardial tissue were observed and photographed using an H-7650 Hitachi transmission electron microscope. Levels of whole blood Se were measured using hydride generation atomic fluorescence spectrometry. Whole blood glutathione peroxidase (GSH-Px) activity was measured using a glutathione peroxidase cellular activity assay kit. Malondialdehyde (MDA), total-anti-oxidizing-capability(T-AOC)and reactive oxygen species(ROS)levels in serum and myocardial tissue were measured using MDA, T-AOC and ROS kits. Apoptosis was detected by immunohistochemistry.

RESULTS

Experimental results showed that the selenium-deficient diet decreased serum selenium levels and GSH-PX activity, which caused severe cardiac dysfunction. Importantly, the levels of MDA and ROS in serum and myocardial tissue defects were significantly increased, where as total-anti-oxidizing-capability(T-AOC) levels were dramatically decreased as a result of the combination of selenium deficiency and low protein intake (P<0.05).The levels of cleaved caspase-9 and cleaved caspase-3 were enhanced, but the expression of B-cell lymphoma-2 (Bcl-2) was reduced (P<0.05).

CONCLUSIONS

Our results suggest that selenium deficiency and low protein intake can cause oxidative stress in the myocardium and induce cell apoptosis via the mitochondria-mediated pathway.

Dietary restriction regimens for fighting kidney disease: Insights from rodent studies

This review critically discusses the research findings on the effects of various dietary restriction regimens in rodent models of kidney disease. Long-term caloric restriction executed at both early and progressive stages of kidney disease was found to exert beneficial effects in rodents. Moreover, some studies have also demonstrated the efficacy of short-term caloric restriction in treating the kidney disease of variable aetiologies possibly by improving mitochondrial dysfunction, autophagy process and suppression of inflammation. However, the mechanisms underlying these short-term caloric restriction mediated protective effects in rodent models of kidney disease are not completely understood. Importantly, few available evidences have also suggested that carbohydrate restriction can exert beneficial effects in aging and experimentally induced renal injury models, but the mechanisms are not explored yet. Interestingly, the benefits of low protein diet in kidney disease models are extensively reported in literature. However, in most of these studies implementation of the low protein dietary regimen was found to associated with increased high carbohydrate and caloric intake (non-isocaloric). Thus, testing the effects of low protein diet under isocaloric conditions might further help to particularly understand the role of dietary protein content in pathology of kidney disease. Moreover, the direct evidences comparing the efficacy of various dietary restriction regimens in rodent models of kidney diseases are also scarce at present.

[Dietary control of metabolic acidosis in chronic kidney disease]

Metabolic acidosis is a frequent complication of chronic kidney disease. Although it is known to appear at advanced stages, many studies suggest a state of "global protonic retention" starting at early stages of the disease, responsible of tissue damage, particularly musculoskeletal, alteration of protidic metabolism and endocrine disorders, promoting malnutrition and chronic inflammation, and finally increasing mortality. The majority of international recommandations suggest of supplementation by alkali, most of the time by sodium bicarbonate, to struggle against this complication. An interesting alternative to correct acidosis would consist on the modulation of the endogenous production of acid by playing with the alimentary incomes. In fact, it has been demonstrated that some different types of food produce or consume protons during their metabolism. Low protein diet and rich fresh fruits and vegetables diet would manage to correct at least as well as the supplementation by sodium bicarbonate the metabolic acidosis, and to struggle against its complications, noteworthy by slowing the decline of glomerular filtration rate by limiting the toxic adaptative fibrotic mechanisms, demonstrated by the decrease of urinary tubulo-interstitial suffering markers. Of the condition of being well led, those diets do not seem to expose patients to an over-risk of malnutrition or hyperkaliemia. They therefore appear to be an attractive alternative, efficiency and safe, to fight against chronic kidney disease metabolic acidosis and its complications.

Efficacy of low-protein diet in diabetic nephropathy: a meta-analysis of randomized controlled trials

Purpose

We aimed to systematically assess the efficacy of low-protein diet preventing progression of diabetic nephropathy based on randomized controlled trials (RCTs).

Methods

A systematic and electronic search was conducted. Initial searches of literature updated to September 2018 were made using the following databases including CNKI, VIP, Wanfang, Cochrane, PubMed, and Embase using the index words for qualified RCTs. Additional searches were performed to identify linked literature sources. Data of RCTs on low-protein diet versus control diet, efficacy analysis of kidney function, nutritional status or proteinuria were extracted. Random effects model and fixed effects model were applied to combine the data which were further analyzed by Chi-squared test and I²tests. The main outcomes were then analyzed through the use of relative risks (RR), mean difference (MD) and its 95% confidence interval (95% CI).

Results

Twenty articles were included in the present meta-analysis with a total of 690 patients in the low-protein diet group (LPD) and a total of 682 patients in the control group. Moderate to strong evidence indicated that LPD was significantly effective for decreasing the urinary albumin excretion rate (SMD:0.62, 95%CI:0.06–1.19) and proteinuria (SMD:0.69, 95%CI:0.22–1.16) versus the control group. No statistical difference, however, was found in glycosylated hemoglobin (SMD:0.17, 95%CI:-0.18–0.51), serum creatinine (SMD:0.20, 95%CI:-0.26–0.66), as well as glomerular filtration rate (SMD:0.21, 95%CI:-0.29–0.71) between the two groups.

Conclusion

The current meta-analysis reveals an effective role of low-protein diet in improving diabetic nephropathy. However, the small number of involved patients may limit the accuracy of results. High-quality RCTs with a larger sample size in the future are required to confirm the current findings.

[Low protein diet supplemented with ketoanalogues of amino acids in patients with chronic renal insufficiency]

Restricted protein diets in patients with chronic kidney disease have been debated for several decades. In chronic kidney disease as in other chronic diseases, the modulation of the nutritional intake is the object of a certain renewal. It is supported by recent studies that highlight the importance of modulating nutrient intake by diets that are healthier, less rich in animal proteins and richer in plants. The recent reintroduction in France of amino acid supplements and ketoanalogs of amino acids allows the prescription of a very restricted diet. Historical studies have only focused on the relationship between protein intake and renal function degradation. Recent studies on acid loading, bone metabolism or potassium intake allow revisiting the interest of restricted diets. As with any change in eating habits, the selection of patients, information, education and monitoring during the diet are very important and help prevent undernutrition: this is the purpose of this short review.

A pilot study

INTRODUCTION

The effectiveness of a low protein diet (LPD) to delay the progression of chronic kidney disease (CKD) remains controversial. The questions persist regarding which LPD for which CKD patients? Our study aimed to investigate the role of LPD in selected patients with CKD stage G3a.

METHODS

Forty-seven selected patients (23 men, mean age 55 ± 12), in stage G3a of CKD (eGFR: 45-59 ml/min) were included in this prospective 12 months study with a recommended dietary protein intake (DPI) of 0.8 g/kg/day. The DPI was estimated from 24 h urinary urea nitrogen excretion (Maroni formula).  All patients were trained by dietitian-nutritionist and had one baseline control and three visits. The clinical data, blood pressure, diet-adherence, eGFR, albumin, cholesterol, hemoglobin, proteinuria, and BMI were analyzed.

RESULTS

According to the adherence to LPD, the patients were divided into Adherent group (AG, n =24, 51 %) with DPI of 0.75 ± 0.25 g/kg/day and non-Adherent group (NAG, n =23, 49 %) with DPI of 1.3 ± 0.31 g/kg/day. During the follow up the eGFR decreased from 57.68 ± 4.0 to 56.11 ± 4.8, and from 55.45 ± 7.0 to 52.46 ± 7.2 for AG and NAG, respectively. The real drop of eGFR after 12 months was 1.57 for AG and 2.99 ml/min for NAG. The difference was statistically significant (p <0.01).

CONCLUSION

Despite the significant percentage of non-adherent patients, our pilot study confirms the beneficial effect of LPD on CKD progression. Adherent patients in G3a stage protect more successfully their GFR compared with non-adherent patients after 12 months. CKD stages with mild reduction of GFR are more challenging for further clinical studies. HIPPOKRATIA 2018, 22(4): 178-182.

The Role for Protein Restriction in Addition to Renin-Angiotensin-Aldosterone System Inhibitors in the Management of CKD

In experimental studies a low-protein diet (LPD) and renin-angiotensin-aldosterone system (RAAS) inhibitors are both reported to slow the progression of chronic kidney disease (CKD) and reduce proteinuria. RAAS activity contributes to increased blood pressure, fluid retention, and positive sodium balance, but also to kidney damage by enhancing glomerular capillary filtration pressure and synthesis of profibrotic molecules such as transforming growth factor β. It has been well established that an LPD decreases glomerular hyperfiltration and the generation of uremic toxins, as well as the burden of acid load, phosphorus, and sodium. In different animal CKD models, a significant reduction in proteinuria and glomerulosclerosis has been achieved when an RAAS inhibitor and LPD were combined. To date, high-quality intervention trials investigating this combined strategy are lacking. We summarize the experimental and clinical studies that have examined a potential additive action of these therapies on CKD progression. We outline potential mechanisms of action and additive efficacy of an LPD and RAAS inhibitors in CKD, with a particular emphasis on phosphate levels, uremic toxin production, acid load, and salt intake. Finally, although the evidence is inadequate to recommend combining RAAS inhibitors and an LPD to slow the progression of CKD, we provide a perspective to support a large-scale randomized clinical trial to study this combination.

Once-weekly hemodialysis combined with low-protein and low-salt dietary treatment as a favorable therapeutic modality for selected patients with end-stage renal failure: a prospective observational study in Japanese patients

Background

For patients with end-stage renal failure (ESFR), thrice-weekly hemodialysis is a standard care. Once-weekly hemodialysis combined with low-protein and low-salt dietary treatment (OWHD-DT) have been rarely studied. Therefore, here, we describe our experience on OWHD-DT, and assess its long-term effectiveness.

Methods

We instituted OWHD-DT therapy in 112 highly motivated patients with creatinine clearance below 5.0 mL/min. They received once-weekly hemodialysis on a diet of 0.6 g/kg/day of protein adjusted for sufficient energy intake, and less than 6 g/day of salt intake. Serial changes in their clinical, biochemical and nutritional parameters were prospectively observed, and the weekly time spent for hospital visits as well as their monthly medical expenses were compared with 30 age, sex- and disease-matched thrice-weekly hemodialysis patients.

Results

The duration of successfully continued OWHD-DT therapy was more than 4 years in 11.6% of patients, 3 years in 16.1%, 2 years in 24.1% and 1 year in 51.8%. Time required per week for hospital attendance was 66.7% shorter and monthly medical expenses were 50.5% lower in the OWHD-DT group than in the thrice-weekly hemodialysis group (both p < 0.001). Patient survival rates in the OWHD-DT group were better than those in the Japan Registry (p < 0.001). Serum urea nitrogen significantly decreased; hemoglobin significantly increased; and albumin and body mass index were not significantly different from baseline values. In the OWHD-DT patients, serum albumin at 1 and 2 years after initiation of therapy was significantly higher compared with prevalent thrice-weekly hemodialysis patients. Furthermore, residual urine output was significantly higher in the OWHD-DT patients than in those receiving thrice-weekly hemodialysis (p < 0.05). Interdialytic weight gain over the course of the entire week between treatments in patients on OWHD-DT were 0.9 ± 1.0, 2.0 ± 1.3, 1.9 ± 1.2, 1.9 ± 1.5 and 1.8 ± 1.0 kg at 1, 6, 12, 18 and 24 months, respectively, though the weekly weight gain for thrice-weekly hemodialysis group (summed over all 3 treatments) was 8.6 ± 0.63 kg, p < 0.001.

Conclusions

OWHD-DT may be a favorable therapeutic modality for selected highly motivated patients with ESRF. However, this treatment cannot be seen as a general maintenance strategy.

Trial registration

UMIN000027555, May 30, 2017 (retrospectively registered).

Long-term effects of early antibiotic intervention on blood parameters, apparent nutrient digestibility, and fecal microbial fermentation profile in pigs with different dietary protein levels

Backgroud

This study aimed to determine the effects of early antibiotic intervention (EAI) on subsequent blood parameters, apparent nutrient digestibility, and fecal fermentation profile in pigs with different dietary crude protein (CP) levels. Eighteen litters of piglets (total 212) were randomly allocated to 2 groups and were fed a creep feed diet with or without in-feed antibiotics (olaquindox, oxytetracycline calcium and kitasamycin) from postnatal d 7 to d 42. On d 42, the piglets within the control or antibiotic group were mixed, respectively, and then further randomly assigned to a normal- (20%, 18%, and 14% CP from d 42 to d 77, d 77 to d 120, and d 120 to d 185, respectively) or a low-CP diet (16%, 14%, and 10% CP from d 42 to d 77, d 77 to d 120, and d 120 to d 185, respectively), generating 4 groups. On d 77 (short-term) and d 185 (long-term), serum and fecal samples were obtained for blood parameters, microbial composition and microbial metabolism analysis.

Results

EAI increased (P < 0.05) albumin and glucose concentrations in low-CP diet on d 77, and increased (P < 0.05) urea concentration in normal-CP diet. On d 185, EAI increased (P < 0.05) globulin concentration in normal-CP diets, but decreased glucose concentration. For nutrient digestibility, EAI increased (P < 0.05) digestibility of CP on d 77. For fecal microbiota, the EAI as well as low-CP diet decreased (P < 0.05) E. coli count on d 77. For fecal metabolites, on d 77, EAI decreased (P < 0.05) total amines concentration but increased skatole concentration in low-CP diet. On d 185, the EAI increased (P < 0.05) putrescine and total amines concentrations in low-CP diets but reduced (P < 0.05) in the normal-CP diets. The low-CP diet decreased the concentrations of these compounds.

Conclusions

Collectively, these results indicate that EAI has short-term effects on the blood parameters and fecal microbial fermentation profile. The effects of EAI varied between CP levels, which was characterized by the significant alteration of glucose and putrescine concentration.

Electronic supplementary material

The online version of this article (doi:10.1186/s40104-017-0192-2) contains supplementary material, which is available to authorized users.

Protein malnutrition during fetal programming induces fatty liver in adult male offspring rats

We evaluated the effects of protein malnutrition on liver morphology and physiology in rats subjected to different malnutrition schemes. Pregnant rats were fed with a control diet or a low protein diet (LPD). Male offspring rats received a LPD during gestation, lactation, and until they were 60 days old (MM group), a late LPD that began after weaning (CM), or a LPD administrated only during the gestation-lactation period followed by a control diet (MC). On day 60, blood was collected and the liver was dissected out. We found a decrease in MM rats' total body (p < 0.001) and liver (p < 0.05) weight. These and CM rats showed obvious liver dysfunction reflected by the increase in serum glutamic pyruvic transaminase (SGOT) (MM p < 0.001) and serum glutamic pyruvic transaminase (SGPT) (MM and CM p < 0.001) enzymes, and liver content of cholesterol (MM and CM p < 0.001) and triglycerides (MM p < 0.01; CM p < 0.001), in addition to what we saw by histology. Liver dysfunction was also shown by the increase in gamma glutamyl transferase (GGT) (MM, MC, and CM p < 0.001) and GST-pi1 (MM and CM p < 0.001, MC p < 0.05) expression levels. MC rats showed the lowest increment in GST-pi1 expression (MC vs. MM; p < 0.001, MC vs. CM; p < 0.01). ROS production (MM, CM, and MC: p < 0.001), lipid peroxidation (MM, CM, and MC p < 0.001), content of carbonyl groups in liver proteins (MM and CM p < 0.001, MC p < 0.01), and total antioxidant capacity (MM, CM, and MC p < 0.001) were increased in the liver of all groups of malnourished animals. However, MM rats showed the highest increment. We found higher TNF-α (MM and CM p < 0.001), and IL-6 (MM and CM p < 0.001) serum levels and TGF-β liver content (MM p < 0.01; CM p < 0.05), in MM and CM groups, while MC rats reverted the values to normal levels. Pro-survival signaling pathways mediated by tyrosine or serine/threonine kinases (pAKT) (MM and CM p < 0.001; MC p < 0.01) and extrasellular signal-regulated kinase (pERKs) (MM p < 0.01; CM p < 0.05) appeared to be activated in the liver of all groups of malnourished rats, suggesting the presence of cells resistant to apoptosis which would become cancerous. In conclusion, a LPD induced liver damage whose magnitude was related to the developmental stage at which malnutrition occurs and to its length.

Diet in chronic kidney disease in a Mediterranean African country

BACKGROUND

Mediterranean diet is characterized by low to moderate consumption of animal protein and high consumption of fruits, vegetables, bread, beans, nuts, seeds and other cereals. It has been associated with reduced risk of cardiovascular disease. However, it is not suitable for chronic kidney disease because of high potassium intake.

DISCUSSION

Tunisia is an emerging Mediterranean country with limited resources, a high prevalence of chronic hemodialysis treatment and high dialysis expenditures. In order to limit dialysis cost, primary and secondary prevention of chronic renal disease are of paramount importance. In addition to drugs, secondary prevention includes diet measures (e.g. salt diet, protein diet). The aims of diet practice in chronic kidney disease are to slow chronic renal failure progression and to prevent its complications like hyperphosphatemia and hyperkaliemiae. A few decades ago, a Tunisian diet was exclusively Mediterranean, and protein consumption was not excessive. However, today, protein consumption is more comparable to western countries. Salt consumption is also excessive. Some Tunisian diets still include food with high potassium intake, which are not suitable for patients with chronic kidney disease. Therefore, the role of the dietician is extremely important to help calculate and create a dietary regimen tailored to each of our patients. Advice about diets should be adapted to both the patient and population habits to improve adherence rate. As such, the purpose of this article is to provide our own experience regarding medical nutrition therapy in patients with chronic kidney disease in Tunisia, with some changes in food habits. Prevention is far better than treatment. In this perspective, dietary measures must be at the core of our intervention.

Role of low protein diet in management of different stages of chronic kidney disease - practical aspects

BACKGROUND

Chronic kidney disease (CKD) is a worldwide public health problem and more so in India. With limited availability and high cost of therapy, barely 10 % of patients with incident end stage renal disease (ESRD) cases get treatment in India. Therefore, all possible efforts should be made to retard progression of CKD. This article reviews the role of low protein diet (LPD) in management of CKD subjects and suggests how to apply it in clinical practice.

DISCUSSION

The role of LPD in retarding progression of CKD is well established in animal experimental studies. However, its role in human subjects with CKD is perceived to be controversial based on the modification of diet in renal disease (MDRD) study. We believe that beneficial effect of LPD could not be appreciated due to shorter duration of follow-up in the MDRD study. Had the study been continued longer, it may have been possible to appreciate beneficial effect of LPD. It is our contention that in all cases of CKD that are slowly progressive, LPD can significantly retard progression of CKD and delay the need for renal replacement therapy (RRT). To be able to apply LPD for a long period, it is important to prescribe LPD at earlier stages (1,2,3) of CKD and not at late stage as recommended by KDIGO guidelines. Many clinicians are concerned about worsening nutritional status and hence reluctant to prescribe LPD. This actually is true for patients with advanced CKD in whom there is spontaneous decrease in calorie and protein intake. In our experience, nutritional status of patients in early stages (1,2,3) of CKD is as good as that of healthy subjects. Prescribing LPD at an early stage is unlikely to worsen status. The role of LPD in retarding progression of CKD is well established in animal experimental studies. Even in human subjects, there is enough evidence to suggest that LPD retards progression of CKD in carefully selected subjects. It should be prescribed to those with good appetite, good nutritional status and a slowly progressive CKD at an early stage (stage 1,2,3). It may also be prescribed at stage 4 & 5 of CKD if the appetite and nutritional status are good.

Compliance, illiteracy and low-protein diet: multiple challenges in CKD and a case of self-empowerment

BACKGROUND

Low-protein diets (LPD) are an important means of delaying the need for dialysis and attaining a stable metabolic balance in chronic kidney disease (CKD). Many authors consider a low educational level and illiteracy to be adverse features for a good dietary compliance.

CASE PRESENTATION

We report the case of a 77-year old woman, illiterate, affected by advanced CKD (stage 4 according to KDIGO guidelines). She was initially ashamed of her problem and did not declare it, leading to an overzealous reduction in protein intake. However, with her daughter's help, who translated the dietary prescription into images, she overcame the barrier represented by illiteracy and was able to correctly follow the prescriptions, attaining good kidney function stability and preserving an adequate nutritional status.

CONCLUSIONS

The case underlines the importance of a personalized approach to dietary prescriptions and suggests that it is possible to achieve a good compliance to the dietary treatment of CKD also in patients with relevant cultural barriers.

Controversial issues in CKD clinical practice: position statement of the CKD-treatment working group of the Italian Society of Nephrology

This position paper of the study group "Conservative treatment of Chronic Kidney Disease-CKD" of the Italian Society of Nephrology addresses major practical, unresolved, issues related to the conservative treatment of chronic renal disease. Specifically, controversial topics from everyday clinical nephrology practice which cannot find a clear, definitive answer in the current literature or in nephrology guidelines are discussed. The paper reports the point of view of the study group. Concise and practical advice is given on several common issues: renal biopsy in diabetes; dual blockade of the renin-angiotensin-aldosterone system (RAAS); management of iron deficiency; low protein diet; dietary salt intake; bicarbonate supplementation; treatment of obesity; the choice of conservative therapy vs. dialysis. For each topic synthetic statements, guideline-style, are reported.

A practical approach to a low protein diet in Brazil

BACKGROUND

Chronic kidney disease (CKD) is an emerging health public problem in Brazil. Nutritional counseling with focus on protein restriction is a promising strategy to treatment of nondialysis CKD patients due its effects on slowing renal loss. However, Brazilian people have high protein intake, which is a challenge when low protein diet (LPD) should be prescribed. This review describes a practical approach to the dietetic management of nondialysis CKD patients in Brazil.

DISCUSSION

Although Brazilian cuisine varies greatly by region, Brazil has current trends of incorporating Western dietary habits, including high intake of red meat. Traditional plant-based foods, such as rice and beans, are also important contributors to the high protein content to the Brazilian diet. Thus, a successful implementation of LPD requires adaptation of these dietary habits, with reduction of portion sizes and adequate food substitution options. Intensive nutritional counseling with specialized renal dietitians is also important to improve compliance to the LPD. Moreover, the precarious health system organization and economic problems are barriers to nutritional care, which could be solved with intensive and specialized perspectives of treatment. The adherence to protein restriction is important for better metabolic and clinical control of nondialysis CKD patients. Early dietetic attention, nutrition education strategies and intensive specialized nutritional counseling are essential to achieve diet habits that promote adherence to the LPD without excluding cultural characteristics of the Brazilian diet.

North American experience with Low protein diet for Non-dialysis-dependent chronic kidney disease

Whereas in many parts of the world a low protein diet (LPD, 0.6-0.8 g/kg/day) is routinely prescribed for the management of patients with non-dialysis-dependent chronic kidney disease (CKD), this practice is infrequent in North America. The historical underpinnings related to LPD in the USA including the non-conclusive results of the Modification of Diet in Renal Disease Study may have played a role. Overall trends to initiate dialysis earlier in the course of CKD in the US allowed less time for LPD prescription. The usual dietary intake in the US includes high dietary protein content, which is in sharp contradistinction to that of a LPD. The fear of engendering or worsening protein-energy wasting may be an important handicap as suggested by a pilot survey of US nephrologists; nevertheless, there is also potential interest and enthusiasm in gaining further insight regarding LPD’s utility in both research and in practice. Racial/ethnic disparities in the US and patients’ adherence are additional challenges. Adherence should be monitored by well-trained dietitians by means of both dietary assessment techniques and 24-h urine collections to estimate dietary protein intake using urinary urea nitrogen (UUN). While keto-analogues are not currently available in the USA, there are other oral nutritional supplements for the provision of high-biologic-value proteins along with dietary energy intake of 30–35 Cal/kg/day available. Different treatment strategies related to dietary intake may help circumvent the protein- energy wasting apprehension and offer novel conservative approaches for CKD management in North America.

Efficacy of the Essential Amino Acids and Keto-Analogues on the CKD progression rate in real practice in Russia - city nephrology registry data for outpatient clinic

Background

Renal replacement therapy (RRT) is growing by 10 % per year in Russia, but pre-dialysis care which can retard CKD progression and delay the start of RRT remains limited. We evaluate the effect of Essential Amino Acids and Keto-analogues (EAA/KA) on CKD progression.

Methods

The effect of low protein diet (LPD), supplemented by EAA/KA, on GFR slope changes between first and second treatment period (five sequential visits per period) in 96 patients withs CKD Stage 3B-5 was compared to GFR slope changes in the control group of 96 patients, randomly selected from matched (by gender, age, diagnosis and CKD Stage) cohort of 320 patients from the city Registry. The mean baseline eGFR was 23 ± 9 ml/min/1.73 m2; 29 % had CKD3B, 45 % - CKD4, 26 % - CKD5.

Results

The rate of eGFR decline changed from −2.71 ± 2.38 to −2.01 ± 2.26 ml/min/1.73 m2 per year in the treatment group and from −2.18 ± 2.01 to −2.04 ± 2.18 ml/min/1.73 m2 per year in the control group. Only in the treatment group the difference was significant (p = 0.04 and p = 0.6). Standardized effect size for intervention was significant in treatment group: −0.3 (of pooled SD), 95 % CI −0.58 ÷  −0.02 and non-significant in control group: −0.07 (−0.35 ÷ +0.22). The univariate and multivariate analysis of EAA/KA therapy effect demonstrated that it was probably more effective in patients of older age, with higher time-averaged proteinuria (PU), lower phosphate level, in patients with glomerular v. interstitial diseases, and in females. Only the latter factor was significant at pre-specified level (<0.05).

Conclusions

LPD combined with EAA/KA supplementation lead to the decrease of the CKD progression both in well-designed clinical study and in real nephrology practice in wide variety diseases and settings. Registry data can be helpful to reveal patients with optimal chances for beneficial effect of LPD supplemented by EAA/KA.

Trial registration

ISRCTN28190556 06/05/2016.

Adherence to ketoacids/essential amino acids-supplemented low protein diets and new indications for patients with chronic kidney disease

BACKGROUND

Low protein diets (LPD) have long been prescribed to chronic kidney disease patients with the goals of improving metabolic abnormalities and postpone the start of maintenance dialysis.

METHODS

We reviewed the recent literature addressing low protein diets supplemented with ketoacids/essential aminoacids prescribed during chronic kidney disease and their effects on metabolic, nutritional and renal parameters since 2013.

RESULTS

We show new information on how to improve adherence to these diets, on metabolic improvement and delay of the dialysis needs, and preliminary data in chronic kidney disease associated pregnancy. In addition, data on incremental dialysis have been reviewed, as well as potential strategies to reverse protein energy wasting in patients undergoing maintenance dialysis.

CONCLUSION

These recent data help to better identify the use of low protein diets supplemented with ketoacids/essential aminoacids during chronic kidney disease.

Low protein diet during gestation and lactation increases food reward seeking but does not modify sucrose taste reactivity in adult female rats

INTRODUCTION

Nutritional deficiencies during neural development may lead to irreversible changes, even after nutritional rehabilitation, promoting morphological and functional adaptations of structures involved with various behaviours including feeding behaviour. However, the ability of the exposure low protein diet during gestation and lactation to affect the hedonic component of food intake is still poorly understood, especially in females.

METHODS

Wistar rats were divided into two groups according to the diet offered to the dams during pregnancy and lactation: control female (CF; diet with 17% protein, n=7) and low protein female (LPF; diet with 8% protein, n=7). The following parameters were evaluated: (a) body weight during weaning, 30, 45, 60, 75, 90 days of life; (b) standard diet intake from 110 to 132 days of life; (c) fat diet and consumption of simple carbohydrates (HFHS) for 1h at 145 days of life; (d) incentive runway task 60 days after 82 days of life; (e) taste reactivity at 90 days of life; and (f) neuronal activation in the caudate putamen, amygdala, paraventricular nucleus of the hypothalamus under stimulus HFHS at 145 days of life.

RESULTS

The exposure, a low protein diet during gestation and lactation, decreased the body weight throughout the study period from weaning to 90 days of life. However, there was no significant change in the body weight of low protein females from 110 to 132 days of life compared with the control females. There was an increase in the rate of the search for reward and reduced the latency of the perception of bitter taste. The exposure, a low protein diet during gestation and lactation, also promoted hypophagy in adult females compared with control animals. The low protein female had increased HFHS diet consumption compared with the control. Undernutrition increased neuronal activation in response to HFHS diet consumption compared with female controls in the amygdala and in the caudate putamen.

CONCLUSION

Females subjected to the exposure, a low protein diet during gestation and lactation, exhibit hypophagy on a standard diet but a higher consumption of a diet rich in lipids and simple carbohydrates. And also were more motivated by the pursuit of reward and reduced latency of the bitter taste reactivity, and increased the number of immunoreactive cells c-fos protein activated in the caudate putamen, amygdala and paraventricular nucleus.

Effects of aging and maternal protein restriction on the muscle fibers morphology and neuromuscular junctions of rats after nutritional recovery

Changes in the nutritional status of mothers may predispose their offspring to neuromuscular disorders in the long term. This study evaluated the effects of maternal protein restriction during pregnancy and lactation on the muscle fibers and neuromuscular junctions (NMJs) of the soleus muscle in the offspring of rats at 365 days of age that had undergone nutritional recovery. Wistar rats were divided into two groups: control (CG)--the offspring of mothers fed a normal protein diet (17%) and restricted (RG)--offspring of mothers fed a low protein diet (6%). After lactation, the male pups received standard chow ad libitum. At 365 days, samples of soleus muscle were collected for muscle fiber analysis (HE staining, NADH-TR reaction and ultrastructure), intramuscular collagen quantification (picrosirius red staining) and NMJs analysis (non-specific esterase technique). The cross-sectional area of type I fibers was reduced by 20% and type IIa fibers by 5% while type IIb fibers increased by 5% in the RG compared to the CG. The percentage of intramuscular collagen was 19% lower in the RG. Disorganization of the myofibrils and Z line was observed, with the presence of clusters of mitochondria in both groups. Regarding the NMJs, in the RG there was a reduction of 10% in the area and 17% in the small diameter and an increase of 7% in the large diameter. The results indicate that the effects of maternal protein restriction on muscle fibers and NMJs seem to be long-lasting and irreversible.

Dietary protein in urea cycle defects: How much? Which? How?

Dietary recommendations for patients with urea cycle disorders (UCDs) are designed to prevent metabolic decompensation (primarily hyperammonaemia), and to enable normal growth. They are based on the 'recommended daily intake' guidelines, on theoretical considerations and on local experience. A retrospective dietary review of 28 patients with UCDs in good metabolic control, at different ages, indicates that most patients can tolerate a natural protein intake that is compatible with metabolic stability and good growth. However, protein aversion presents a problem in many patients, leading to poor compliance with the prescribed daily protein intake. These patients are at risk of chronic protein deficiency. Failing to recognise this risk, and further restricting protein intake because of persistent hyperammonaemia may aggravate the deficiency and potentially lead to episodes of metabolic decompensation for which no clear cause is found. These patients may need on-going supplementation with essential amino acids (EAA) to prevent protein malnutrition. Current recommendations for the management of acute metabolic decompensation include cessation of protein intake whilst increasing energy (calorie) intake in the first 24h. We have found that plasma concentrations of all EAA are low at the time of admission to hospital for metabolic decompensation, with correlation between low EAA concentrations, particularly branched-chain amino acids, and hyperammonaemia. Thus, supplementation with EAA should be considered at times of metabolic decompensation. Finally, it would be advantageous to treat patients in metabolic decompensation through enteral supplementation, whenever possible, because of the contribution of the splanchnic (portal-drained viscera) system to protein retention and metabolism.

Nutritional mismatch in postnatal life of low birth weight rat offspring leads to increased phosphorylation of hepatic eukaryotic initiation factor 2 α in adulthood

OBJECTIVE

Epidemiological studies have established that low birth weight offspring, when faced with a nutritional mismatch in postnatal life, have an increased risk of developing the metabolic syndrome. Our laboratory and others have demonstrated that maternal protein restriction (MPR) leads to high cholesterol and insulin resistance in the offspring due to impaired liver function, though the underlying molecular mechanisms remain elusive. Recent in vitro studies have associated decreased phosphorylation of Akt1 (Serine 473), a marker of insulin sensitivity, with increased phosphorylation of eukaryotic initiation factor (eIF)-2α (Serine 51), a key regulator of protein translation attenuation. The main aim of the study was to determine whether nutritional mismatch in MPR offspring leads to elevated phospho-eIF2α (Ser51) levels in the liver.

MATERIALS/METHODS

To investigate if this occurs long-term in MPR offspring, pregnant Wistar rats were fed a control (20%) protein diet (control) or a low (8%) protein diet during pregnancy and postnatal life (LP1), or during pregnancy and lactation (LP2).

RESULTS

At postnatal day 130, LP2 offspring exhibited increases in hepatic phosphorylation of eIF2α (Ser51) concomitant with decreases in the phosphorylation of Akt1 (Ser473), while LP1 offspring exhibited the converse relationship. Interestingly, in embryonic day 19 livers derived from control or MPR pregnancy, no changes in eIF2α (Ser51) or Ak1 (Ser473) phosphorylation were observed.

CONCLUSION

Collectively, our data provide robust evidence that phosphorylation of eIF2α (Ser51) is inversely correlated with phosphorylated Akt1 (Ser473) in vivo. Moreover, this study demonstrates that this inverse relationship is adversely influenced in these MPR offspring by a mismatch in the postnatal nutritional environment.