A special, supplemented 'vegan' diet for nephrotic patients

Plant foods, healthy plant-based diets, and type 2 diabetes: a review of the evidence

Type 2 diabetes (T2D) is a metabolic chronic disease in which insulin resistance and insufficient insulin production lead to elevated blood glucose levels. The prevalence of T2D is growing worldwide, mainly due to obesity and the adoption of Western diets. Replacing animal foods with healthy plant foods is associated with a lower risk of T2D in prospective studies. In randomized controlled trials, the consumption of healthy plant foods in place of animal foods led to cardiometabolic improvements in patients with T2D or who were at high risk of the disease. Dietary patterns that limit or exclude animal foods and focus on healthy plant foods (eg, fruits, vegetables, whole grains, nuts, legumes), known as healthy, plant-based diets, are consistently associated with a lower risk of T2D in cohort studies. The aim of this review is to examine the differential effects of plant foods and animal foods on T2D risk and to describe the existing literature about the role of healthy, plant-based diets, particularly healthy vegan diets, in T2D prevention and management. The evidence from cohort studies and randomized controlled trials will be reported, in addition to the potential biological mechanisms that seem to be involved.

Personalized Low-Protein Diet Prescription in CKD Population: Merging Evidence From Randomized Trials With Observational Data

Nutritional therapy is a cornerstone of the clinical management of chronic kidney disease (CKD). Nevertheless, randomized controlled trials often have failed to show a relevant benefit of low-protein diets in nonselected CKD populations in terms of slowing the progression of kidney disease and need for dialysis. The more the target population is selected, the less the results can be generalizable to implement in clinical practice. On the contrary, observational studies, especially if performed with patient-centered, flexible approaches, point toward an extensive implementation of dietary protein restriction in different and unselected CKD populations. The observational evidence cannot be disregarded anymore. The most recent guidelines advise implementing low-protein diets or even very-low-protein diets in all CKD patients as early as stage 3. However, the lack of data from large randomized controlled trials on unselected CKD populations as well as on specific subpopulations, such as diabetic or obese patients, which nowadays comprise the majority of CKD subjects, reduces the generalizability of the recommendations. For some patient populations, such as those encompassing very old, nephrotic, or pregnant patients, the literature is even more limited because of the lower prevalence of these conditions and diffused prejudices against reducing protein intake. This pragmatic review discusses the need for integrating information derived from randomized trials with evidence derived from observational studies to guide feasible strategies for more successful implementation of low-protein diets in the treatment of all segments of the CKD population.

Medical Nutritional Therapy for Patients with Chronic Kidney Disease not on Dialysis: The Low Protein Diet as a Medication

The 2020 Kidney Disease Outcome Quality Initiative (KDOQI) Clinical Practice Guideline for Nutrition in chronic kidney disease (CKD) recommends protein restriction to patients affected by CKD in stages 3 to 5 (not on dialysis), provided that they are metabolically stable, with the goal to delay kidney failure (graded as evidence level 1A) and improve quality of life (graded as evidence level 2C). Despite these strong statements, low protein diets (LPDs) are not prescribed by many nephrologists worldwide. In this review, we challenge the view of protein restriction as an “option” in the management of patients with CKD, and defend it as a core element of care. We argue that LPDs need to be tailored and patient-centered to ensure adherence, efficacy, and safety. Nephrologists, aligned with renal dietitians, may approach the implementation of LPDs similarly to a drug prescription, considering its indications, contra-indications, mechanism of action, dosages, unwanted side effects, and special warnings. Following this framework, we discuss herein the benefits and potential harms of LPDs as a cornerstone in CKD management.

Comparison of vegetarian versus animal-based low protein diets on estimated glomerular filtration rates in chronic kidney disease patients: a systematic review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this review is to evaluate studies to determine the effect of a low-protein, vegetarian diet as compared to a low-protein, animal-based diet on estimated glomerular filtration rates (eGFR) in adults with chronic kidney disease (CKD).

Pregnancy, Proteinuria, Plant-Based Supplemented Diets and Focal Segmental Glomerulosclerosis: A Report on Three Cases and Critical Appraisal of the Literature

Chronic kidney disease (CKD) is increasingly recognized in pregnant patients. Three characteristics are associated with a risk of preterm delivery or small for gestational age babies; kidney function reduction, hypertension, and proteinuria. In pregnancy, the anti-proteinuric agents (ACE-angiotensin converting enzyme-inhibitors or ARBS -angiotensin receptor blockers) have to be discontinued for their potential teratogenicity, and there is no validated approach to control proteinuria. Furthermore, proteinuria usually increases as an effect of therapeutic changes and pregnancy-induced hyperfiltration. Based on a favourable effect of low-protein diets on proteinuria and advanced CKD, our group developed a moderately protein-restricted vegan-vegetarian diet tsupplemented with ketoacids and aminoacids for pregnant patients. This report describes the results obtained in three pregnant patients with normal renal function, nephrotic or sub-nephrotic proteinuria, and biopsy proven diagnosis of focal segmental glomerulosclerosis, a renal lesion in which hyperfiltration is considered of pivotal importance (case 1: GFR (glomerular filtration rate): 103 mL/min; proteinuria 2.1 g/day; albumin 3.2 g/dL; case 2: GFR 86 mL/min, proteinuria 3.03 g/day, albumin 3.4 g/dL; case 3: GFR 142 mL/min, proteinuria 6.3 g/day, albumin 3.23 g/dL). The moderately restricted diet allowed a stabilisation of proteinuria in two cases and a decrease in one. No significant changes in serum creatinine and serum albumin were observed. The three babies were born at term (38 weeks + 3 days, female, weight 3180 g-62th centile; 38 weeks + 2 days, female, weight 3300 g-75th centile; male, 38 weeks + 1 day; 2770 g-8th centile), thus reassuring us of the safety of the diet. In summary, based on these three cases studies and a review of the literature, we suggest that a moderately protein-restricted, supplemented, plant-based diet might contribute to controlling proteinuria in pregnant CKD women with focal segmental glomerulosclerosis. However further studies are warranted to confirm the potential value of such a treatment strategy.

Non-Traditional Aspects of Renal Diets: Focus on Fiber, Alkali and Vitamin K1 Intake

Renal diets for advanced chronic kidney disease (CKD) are structured to achieve a lower protein, phosphate and sodium intake, while supplying adequate energy. The aim of this nutritional intervention is to prevent or correct signs, symptoms and complications of renal insufficiency, delaying the start of dialysis and preserving nutritional status. This paper focuses on three additional aspects of renal diets that can play an important role in the management of CKD patients: the vitamin K1 and fiber content, and the alkalizing potential. We examined the energy and nutrients composition of four types of renal diets according to their protein content: normal diet (ND, 0.8 g protein/kg body weight (bw)), low protein diet (LPD, 0.6 g protein/kg bw), vegan diet (VD, 0.7 g protein/kg bw), very low protein diet (VLPD, 0.3 g protein/kg bw). Fiber content is much higher in the VD and in the VLPD than in the ND or LPD. Vitamin K1 content seems to follow the same trend, but vitamin K2 content, which could not be investigated, might have a different pattern. The net endogenous acid production (NEAP) value decreases from the ND and LPD to the vegetarian diets, namely VD and VLPD; the same finding occurred for the potential renal acid load (PRAL). In conclusion, renal diets may provide additional benefits, and this is the case of vegetarian diets. Namely, VD and VLPD also provide high amounts of fibers and Vitamin K1, with a very low acid load. These features may have favorable effects on Vitamin K1 status, intestinal microbiota and acid-base balance. Hence, we can speculate as to the potential beneficial effects on vascular calcification and bone disease, on protein metabolism, on colonic environment and circulating levels of microbial-derived uremic toxins. In the case of vegetarian diets, attention must be paid to serum potassium levels.

Low-protein diets for chronic kidney disease patients: the Italian experience

BACKGROUND

Nutritional treatment has always represented a major feature of CKD management. Over the decades, the use of nutritional treatment in CKD patients has been marked by several goals. The first of these include the attainment of metabolic and fluid control together with the prevention and correction of signs, symptoms and complications of advanced CKD. The aim of this first stage is the prevention of malnutrition and a delay in the commencement of dialysis. Subsequently, nutritional manipulations have also been applied in association with other therapeutic interventions in an attempt to control several cardiovascular risk factors associated with CKD and to improve the patient's overall outcome. Over time and in reference to multiple aims, the modalities of nutritional treatment have been focused not only on protein intake but also on other nutrients.

DISCUSSION

This paper describes the pathophysiological basis and rationale of nutritional treatment in CKD and also provides a report on extensive experience in the field of renal diets in Italy, with special attention given to approaches in clinical practice and management. Italian nephrologists have a longstanding tradition in implementing low protein diets in the treatment of CKD patients, with the principle objective of alleviating uremic symptoms, improving nutritional status and also a possibility of slowing down the progression of CKD or delaying the start of dialysis. A renewed interest in this field is based on the aim of implementing a wider nutritional therapy other than only reducing the protein intake, paying careful attention to factors such as energy intake, the quality of proteins and phosphate and sodium intakes, making today's low-protein diet program much more ambitious than previous. The motivation was the reduction in progression of renal insufficiency through reduction of proteinuria, a better control of blood pressure values and also through correction of metabolic acidosis. One major goal of the flexible and innovative Italian approach to the low-protein diet in CKD patients is the improvement of patient adherence, a crucial factor in the successful implementation of a low-protein diet program.

The non-immunosuppressive management of childhood nephrotic syndrome

Idiopathic nephrotic syndrome (INS) is one of the most common renal diseases found in the paediatric population and is associated with significant complications, including infection and thrombosis. A high proportion of children enter sustained remission before adulthood, and therapy must therefore mitigate the childhood complications, while minimising the long-term risk to health. Here we address the main complications of INS and summarise the available evidence and guidance to aid the clinician in determining the appropriate treatment for children with INS under their care. Additionally, we highlight areas where no consensus regarding appropriate management has been reached. In this review, we detail the reasons why routine prophylactic antimicrobial and antithrombotic therapy are not warranted in INS and emphasise the conservative management of oedema. When pharmacological intervention is required for the treatment of oedema, we provide guidance to aid the clinician in determining the appropriate therapy. Additionally, we discuss obesity and growth, fracture risk, dyslipidaemia and thyroid dysfunction associated with INS. Where appropriate, we describe how recent developments in research have identified potential novel therapeutic targets.

The effects of soy protein on chronic kidney disease: a meta-analysis of randomized controlled trials

BACKGROUND/OBJECTIVES

There is a growing body of evidence to indicate that soy protein consumption may have a beneficial effect on kidney function. We performed a meta-analysis to evaluate the effects of soy protein consumption compared with animal protein consumption in patients with pre-dialysis chronic kidney disease (CKD).

SUBJECTS/METHODS

We conducted a structured electronic search of the databases PubMed, EMBASE, Cochrane Library and Chinese Biological Medicine for randomized controlled trials published up to March 2014. The outcome measures were serum creatinine (SCR), triglyceride (TG), total cholesterol (TC), calcium (Ca) and phosphorus concentrations. Weighted or standard mean differences were calculated for net changes using random-effects models.

RESULTS

The meta-analysis consisted of nine trials, comprising 197 subjects. Soy protein intake significantly reduced SCR and serum phosphorus concentrations. The mean difference was -6.231 μmol/l (95% confidence interval (CI): -11.109, -1.352 μmol/l) for SCR (P=0.012) and -0.804 (95% CI: -1.143, -0.464 μmol/l) for serum phosphorus (P=0.00). It also significantly reduced serum TG, with a pooled estimated change of -0.223 mmol/l (95% CI: -0.396, -0.051 mmol/l; P=0.011) after the exclusion of one trial indicated by sensitivity analyses. No statistically significant effects were observed for TC (-0.135 mmol/l (95% CI: -0.289, 0.019 mmol/l)) or Ca (0.023 mmol/l (95% CI: -0.016, 0.062 mmol/l)).

CONCLUSIONS

The meta-analysis suggested a protective effect of soy protein consumption on SCR and serum phosphorus concentrations in pre-dialysis CKD patients. It may also have a significant effect on lowering serum TG concentrations. However, nonsignificant effects on TC and Ca were observed. Evidence was limited because of the relatively small number of available trials and subjects.

Which low-protein diet for which CKD patient? An observational, personalized approach

OBJECTIVES

Low protein diets (LPDs) are milestones in chronic kidney disease (CKD). Concerns over compliance and safety limit their use. The aim of this study was to test the feasibility and main results of a multiple-choice approach to LPDs, adapted to patient preferences.

METHODS

From December 2007 to January 2013, all CKD patients (stages 4/5; progressive stage 3) without contraindications (malnutrition, short life expectancy), were offered two main LPDs (proteins 0.6 g/kg daily): Vegan supplemented (LPD-KA) or with "aproteic" commercial food (LPD-ACF). LPDs followed a qualitative approach based on forbidden and allowed food; one to three free meals per week, and flexible control policy (1-3 mo). Start of dialysis, death, and combined outcome (death-dialysis) were analyzed by Kaplan-Meier curves and Cox model. Comparison with dialysis in patients with glomerular filtration rate (GRF) <15 mL/min, (corresponding to "early" dialysis start) employed standardized mortality rates, with respect to the Italian and the United States Dialysis Registry.

RESULTS

One hundred eighty-five patients (222 patient-years) started at least a trial of LPD-KA, 122 (177 patients-years) LPD-ACF; only 3 patients with GFR <30 mL/min denied an LPD trial. Patients who chose LPD-KA were younger than those on LPD-ACF (63 versus 74 y), had less comorbidity (82% versus 93%), higher proteinuria (1.4 versus 0.7 g/d) and lower GFR (17 versus 23 mL/min) (P < 0.001). Median daily protein intake was 0.7 g/kg on both diets (Maroni-Mitch formula). The combined outcome (death or dialysis) was not influenced by the diet chosen (Cox analysis). Relative risk for death on the diet (patients with GFR <15 mL/min) was 0.5 with respect to the Italian Registry and 0.3 to the United States Dialysis Registry. The diets had comparable costs (1 y on dialysis: 50 patient-years on LPD).

CONCLUSIONS

The choice of diet is strictly linked to patient characteristics, thus supporting a multiple-choice offer. Once corrected for baseline data, both LPDs led to similar results, suggesting at least survival equivalence with dialysis, at lesser cost.

Vegetarian low-protein diets supplemented with keto analogues: a niche for the few or an option for many?

BACKGROUND

Low-protein diets are often mentioned but seldom used to slow chronic kidney disease (CKD) progression. The aim of the study was to investigate the potential for implementation of a simplified low-protein diet supplemented with alpha-keto analogues (LPD-KA) as part of the routine work-up in CKD patients.

METHODS

In an implementation study (December 2007-November 2011), all patients with CKD Stages IV-V not on dialysis, rapidly progressive Stage III and/or refractory proteinuria, were offered either a simplified LPD-KA, or commercially available low-protein food. LPD-KA consisted of proteins 0.6 g/kg/day, supplementation with Ketosteril 1 pill/10 Kg, 1-3 free-choice meals/week and a simplified schema based on 'allowed' and 'forbidden' foods. 'Success' was defined as at least 6 months on LPD-KA. Progression was defined as reduction in glomerular filtration rate (GFR)[(Chronic Kidney Disease Epidemiology Collaboration) formula CKD-EPI] in patients with at least 6 months of follow-up.

RESULTS

Of about 2500 patients referred (8% CKD Stages IV-V), 139 started LPD-KA; median age (70 years) and prevalence of comorbidity (79%) were in line with the dialysis population. Start of dialysis was the main reason for discontinuation (40 cases, unplanned in 7); clinical reasons were recorded in 7, personal preference in 14 and improvement and death in 8 each. The low gross mortality (4% per year) and the progression rate (from -8 to 0 mL/min/year at 6 months) are reassuring concerning safety. None of the baseline conditions, including age, educational level, comorbidity or kidney function, discriminated the patients who followed the diet for at least 6 months.

CONCLUSIONS

Our data suggest a wider offer of LPD-KA to patients with severe and progressive CKD. The promising results in terms of mortality and progression need confirmation with different study designs.

Potential Benefits of Renal Diets on Cardiovascular Risk Factors in Chronic Kidney Disease Patients

Dietary manipulation, including protein, phosphorus, and sodium restriction, when coupled with the vegetarian nature of the renal diet and ketoacid supplementation can potentially exert a cardiovascular protective effect in chronic renal failure patients by acting on both traditional and nontraditional cardiovascular risk factors. Blood pressure control may be favored by the reduction of sodium intake and by the vegetarian nature of the diet, which is very important also for lowering serum cholesterol and improving plasma lipid profile. The low protein and phosphorus intake has a crucial role for reducing proteinuria and preventing and reversing hyperphosphatemia and secondary hyperparathyroidism, which are major causes of the vascular calcifications, cardiac damage, and mortality risk of uremic patients. The reduction of nitrogenous waste products and lowering of serum PTH levels may also help ameliorate insulin sensitivity and metabolic control in diabetic patients, as well as increase the responsiveness to erythropoietin therapy, thus allowing greater control of anemia. Protein-restricted diets may have also anti-inflammatory and anti-oxidant properties. Thus, putting aside the still debatable effects on the progression of renal disease and the more admitted effects on uremic signs and symptoms, it is possible that a proper nutritional treatment early in the course of renal disease may be useful also to reduce the cardiovascular risk in the renal patient. However, conclusive data cannot yet be drawn because quality studies are lacking in this field; future studies should be planned to assess the effect of renal diets on hard outcomes, as cardiovascular events or mortality.

Renal function parameters of Thai vegans compared with non-vegans

In Asia, vegetarianism is a well-established eating behavior. It appears that the adoption of a vegan diet leads to a lessening of several health risk factors. Although vegetarianism has some notable effects on the hematological system, the effect on the nephrological system has not been well clarified. The pattern of renal function parameters was studied in 25 Thai vegans compared with 25 non-vegetarians. Of the studied parameters, it was found that urine protein was significantly different (p < 0.05) in vegans and controls. Vegans had significantly lower urine protein level.

Are High-Protein, Vegetable-Based Diets Safe for Kidney Function? A Review of the Literature

In individuals with chronic kidney disease, high-protein diets have been shown to accelerate renal deterioration, whereas low-protein diets increase the risk of protein malnutrition. Vegetarian diets have been promoted as a way to halt progression of kidney disease while maintaining adequate nutrition. We review the literature to date comparing the effects of animal and vegetable protein on kidney function in health and disease. Diets with conventional amounts of protein, as well as high-protein diets, are reviewed. The literature shows that in short-term clinical trials, animal protein causes dynamic effects on renal function, whereas egg white, dairy, and soy do not. These differences are seen both in diets with conventional amounts of protein and those with high amounts of protein. The long-term effects of animal protein on normal kidney function are not known. Although data on persons with chronic kidney disease are limited, it appears that high intake of animal and vegetable proteins accelerates the underlying disease process not only in physiologic studies but also in short-term interventional trials. The long-term effects of high protein intake on chronic kidney disease are still poorly understood. Several mechanisms have been suggested to explain the different effects of animal and vegetable proteins on normal kidney function, including differences in postprandial circulating hormones, sites of protein metabolism, and interaction with accompanying micronutrients.

Dietary soya protein during pregnancy and lactation in rats with hereditary kidney disease attenuates disease progression in offspring

Dietary soya protein substitution for casein initiated at weaning slows disease progression in animal models of chronic renal disease. As there is increasing evidence that fetal programming can have a significant impact on kidney physiology and function in offspring, the objective of the current study was to determine whether exposure to soya protein in the diet earlier than weaning would have further benefits. Han:SPRD-cy (cy/+) breeder rats were fed a casein-based or soya protein-based diet 2 weeks prior to mating, throughout pregnancy and during lactation. Following this maternal period, 3-week-old pups were given either the same or the alternate diet for a 7-week weaning period. Dietary soya protein compared with casein in the maternal or weaning period both independently resulted in less renal inflammation (macrophage infiltration lower by 24% (P=0.0003) and 32% (P<0.001), respectively). When soya protein was given in both feeding periods, the effect was additive. Soya protein substitution for casein resulted in less oxidative damages as indicated by 28% lower oxidized-LDL staining (P=0.013) when present in the maternal period, or in the weaning period (by 56%, P<0.0001). Renal cell proliferation was reduced by 29-33% (P<0.05) in rats given soya protein whether the exposure was during the maternal or weaning period. Soya protein compared with casein in the maternal period also resulted in 33% (P=0.0013) less proteinuria, indicating superior renal function. Dietary soya protein during pregnancy and lactation represents a potential preventative approach in treating for those with congenital kidney diseases.

Therapeutic approach to FSGS in children

Therapy of primary focal segmental glomerulosclerosis (FSGS) in children incorporates conservative management and immunosuppression regimens to control proteinuria and preserve kidney function. In long-term cohort studies in adults and children with primary FSGS, renal survival has been directly associated with degree of proteinuria control. This educational article reviews the current therapeutic approach toward children with primary FSGS.

Continuum of therapy in progressive renal diseases (from predialysis to transplantation): analysis of a new organizational model

In the aging of Western populations, decreased mortality is counterbalanced by an increase in morbidity, particularly involving chronic diseases such as most renal diseases. The price of the successful care of chronic conditions, such as cardiovascular diseases or diabetes, is a continuous increase in new dialysis patients. However, the increased survival of patients on chronic renal replacement therapies poses new challenges to nephrologists and calls for new models of care. Since its split from internal medicine, nephrology has seen a progressive trend toward super specialization and the differentiation into at least 3 major branches (nephrology, dialysis, and transplantation), following a path common to several other fields of internal medicine. The success in the care of chronic patients is owed not only to a careful technical prescription, but also to the ability to teach self-care and attain compliance; this requires good medical practice and a sound patient-physician relationship. In this context, the usual models of care may fail to provide adequate coordination and, despite valuable single elements, could end up as an orchestra without a conductor. We propose an integrated model of care oriented to the type of patient (tested in our area especially for diabetic patients): the patient is followed-up by the same team from the first signs of renal disease to eventual dialysis or transplantation. This model offers an interesting alternative both for patients, who usually seek continuity of care, and for nephrologists who prefer a holistic and integrated patient-physician approach.

The low-AGE content of low-fat vegan diets could benefit diabetics - though concurrent taurine supplementation may be needed to minimize endogenous AGE production

Increased endogenous generation of advanced glycation endproducts (AGEs) contributes importantly to the vascular complications of diabetes, in part owing to activation of the pro-inflammatory RAGE receptor. However, AGE-altered oligopeptides with RAGE-activating potential can also be absorbed from the diet, and indeed make a significant contribution to the plasma and tissue pool of AGEs; this contribution is especially prominent when compromised renal function impairs renal clearance of AGEs. Perhaps surprisingly, foods rich in both protein and fat, and cooked at high heat, tend to be the richest dietary sources of AGEs, whereas low-fat carbohydrate-rich foods tend to be relatively low in AGEs. Conceivably, this reflects the fact that the so-called "AGEs" in the diet are generated primarily, not by glycation reactions, but by interactions between oxidized lipids and protein; such reactions are known to give rise to certain prominent AGEs, such as epsilonN-carboxymethyl-lysine and methylglyoxal. Although roasted nuts and fried or broiled tofu are relatively high in AGEs, low-fat plant-derived foods, including boiled or baked beans, typically are low in AGEs. Thus, a low-AGE content may contribute to the many benefits conferred to diabetics by a genuinely low-fat vegan diet. Nonetheless, the plasma AGE content of healthy vegetarians has been reported to be higher than that of omnivores - suggesting that something about vegetarian diets may promote endogenous AGE production. Some researchers have proposed that the relatively high-fructose content of vegetarian diets may explain this phenomenon, but there so far is no clinical evidence that normal intakes of fructose have an important impact on AGE production. An alternative or additional possibility is that the relatively poor taurine status of vegetarians up-regulates the physiological role of myeloperoxidase-derived oxidants in the generation of AGEs - in which case, taurine supplementation might be expected to suppress elevated AGE production in vegetarians. Thus, a taurine supplemented low-fat vegan diet may be recommended as a strategy for minimizing AGE-mediated complications in diabetics and in patients with renal failure.

Isolated soy protein consumption reduces urinary albumin excretion and improves the serum lipid profile in men with type 2 diabetes mellitus and nephropathy

Soy protein was shown to exhibit several beneficial effects on renal function in nondiabetic patients with nephropathy, and to improve serum lipids. This study examined the effects of isolated soy protein consumption on urinary albumin excretion, serum lipids, plasma amino acids, and isoflavones in diabetic patients with nephropathy. Male patients (n = 14) with type 2 diabetes and nephropathy were followed in a crossover design for 7 mo. The study comprised two 8-wk intervention periods, placed between a 4-wk lead-in and two 4-wk washout periods. In the 2 intervention periods, 0.5 g/(kg. d) of the dietary protein was provided as either isolated soy protein (ISP) or casein, in random order. Blood and urine samples were collected at the beginning and end of each period. Data were analyzed by multiple linear regression for a repeated-measure design. ISP consumption led to changes of -9.5% in urinary albumin excretion (P < 0.0001), -0.45 in the total-to-HDL-cholesterol ratio (P < 0.05), -0.20 in the LDL-to-HDL cholesterol ratio (P < 0.05), and +4.3% in HDL cholesterol (P = 0.0040). Plasma arginine concentrations, the arginine-to-lysine ratio, and plasma isoflavone concentrations were higher after ISP consumption (P < 0.05). Urinary albumin excretion was negatively correlated with plasma total isoflavones (rho = -0.441), daidzein (rho = -0.326), and O-desmethylangolesin (rho = -0.389) (P < 0.05). The findings indicate that isolated soy protein consumption improves several markers that may be beneficial for type 2 diabetic patients with nephropathy.

Type 2 diabetes and the vegetarian diet

Based on what is known of the components of plant-based diets and their effects from cohort studies, there is reason to believe that vegetarian diets would have advantages in the treatment of type 2 diabetes. At present there are few data on vegetarian diets in diabetes that do not in addition have weight loss or exercise components. Nevertheless, the use of whole-grain or traditionally processed cereals and legumes has been associated with improved glycemic control in both diabetic and insulin-resistant individuals. Long-term cohort studies have indicated that whole-grain consumption reduces the risk of both type 2 diabetes and cardiovascular disease. In addition, nuts (eg, almonds), viscous fibers (eg, fibers from oats and barley), soy proteins, and plant sterols, which may be part of the vegetarian diet, reduce serum lipids. In combination, these plant food components may have a very significant impact on cardiovascular disease, one of the major complications of diabetes. Furthermore, substituting soy or other vegetable proteins for animal protein may also decrease renal hyperfiltration, proteinuria, and renal acid load and in the long term reduce the risk of developing renal disease in type 2 diabetes. The vegetarian diet, therefore, contains a portfolio of natural products and food forms of benefit for both the carbohydrate and lipid abnormalities in diabetes. It is anticipated that their combined use in vegetarian diets will produce very significant metabolic advantages for the prevention and treatment of diabetes and its complications.

Treatment of nephrotic adults with a supplemented, very low-protein diet

Optimal dietary protein intake for adults with the nephrotic syndrome has not been established; very low-protein diets are believed to be contraindicated. Sixteen patients with the nephrotic syndrome were nevertheless prescribed a very low protein diet (0.3 g/kg) supplemented by 10 to 20 g/d essential amino acids (or, in a few cases, ketoacids) for an average of 10 months (range, 1 to 36 months). In 11 patients with initial glomerular filtration rates (GFRs) < or = 30 mL/min/3 m2 of height (ht)2, significant but modest improvement was seen (on the average) in proteinuria, serum albumin, and serum cholesterol; all 11 eventually went on to dialysis. The other five patients, with initial GFRs of 32 to 69 ml/min/3 m2 of ht2, had either focal segmental glomerulosclerosis, diabetic nephropathy, or, in one patient, both. The nephrotic syndrome associated with these disorders rarely remits spontaneously. However, during the following 3 to 15 months mean proteinuria decreased from 9.3 to 1.9 g/d, mean serum albumin increased from 2.5 g/dL to 3.8 g/dL, and mean serum cholesterol decreased from 415 mg/dL to 255 mg/dL (all P < 0.001). The GFR either remained constant or increased. Four of these five patients have resumed normal or nearly normal diets and remain in remission or near-remission for 6 to 24 months. We conclude that severe protein restriction plus an essential amino acid supplement may induce prolonged remission in adults with the nephrotic syndrome provided that GFR is not severely reduced. The mechanism of this paradoxical response to protein restriction remains to be determined.

Lipid-lowering therapy in patients with renal disease

A growing number of clinical trials have examined the effects of different lipid lowering strategies in patients with renal disease. We carried out a meta-analysis to compare and contrast the relative efficacy of various antilipemic therapies in different renal disease settings. Studies that investigated one or more therapies designed to lower serum lipids were combined using weighted multiple linear regression. The analysis adjusted treatment effects for differences in baseline lipid levels and possible placebo effects. The results showed that antilipemic therapies generally had similar effects on lipids in different renal disease settings. In nephrotic syndrome the greatest and most consistent reductions in low density lipoprotein cholesterol (LDL) were seen with 3-hydroxy-3-methylglutaryl co-enzyme A (HMG-CoA) reductase inhibitors (regression coefficient with 95% confidence interval in mg/dl = -63, -79 to -46). Similar results were seen for LDL in renal transplant (-51, -57 to -45), renal insufficiency (-62, -82 to -42), hemodialysis (-65, -80 to -50) and continuous ambulatory peritoneal dialysis (CAPD) patients (-84, -104 to -64). Fibric acid analogues had less effect on LDL, but caused greater reductions in triglycerides: -132, -178 to -87, in nephrotic syndrome; -69, -93 to -45 in transplant: -107, -169 to -45 in renal insufficiency; -72, -120 to -24 in hemodialysis; and -96, -162 to -30 in CAPD. In general, the effects of diet and other therapies were less consistent. Despite possible limitations of this meta-analysis, the results provide a useful framework for choosing antilipemic therapy, and point to areas for future long-term studies examining the safety and efficacy of lipid lowering strategies in patients with renal disease.

Does prolonged protein restriction preceding dialysis lead to protein malnutrition at the onset of dialysis?

It has recently been suggested that prolonged protein restriction preceding dialysis may induce protein malnutrition and thus confer a poor prognosis during dialysis. We examined the records of all patients who were prescribed a very low protein diet (0.3 g/kg ideal body weight) plus supplemental essential amino acids and/or ketoacids for 6 to 72 months (median 26 months) preceding renal replacement, numbering 43. Hypoalbuminemia immediately preceding dialysis was present in only two patients. Final serum albumin averaged 4.1 +/- 0.4 (SD) g/dl. Final transferrin was subnormal in eight patients, but had been subnormal in six of these, without attendant hypoalbuminemia, for one to four years. Mean final transferrin was 241 +/- 56 mg/dl. Final serum cholesterol was below 150 mg/dl in six subjects, all of whom had normal levels of albumin (mean 4.0 +/- 0.2 g/dl) and a normal mean value for transferrin (211 +/- 22 mg/dl). In five patients who exhibited subnormal albumin and transferrin and high cholesterol concentrations at the beginning of dietary therapy, albumin and transferrin levels rose to normal or nearly normal, and hypercholesterolemia receded during the ensuing four months. Thus this predialysis dietary regimen, rather than causing protein malnutrition, prevents it; when protein malnutrition is present, this regimen corrects it.