Vegetarian diet alternated with conventional low-protein diet for patients with chronic renal failure

Plant-based diets in patients with chronic kidney disease

Dietary protein restriction has been considered to be a nutritional-related strategy to reduce risk for end-stage kidney disease among patients with non-dialysis-dependent chronic kidney disease (CKD). However, there is insufficient evidence to recommend a particular type of protein to slow down the CKD progression. Recently, various plant-based diets could demonstrate some additional benefits such as a blood pressure-lowering effect, a reduction of metabolic acidosis as well as hyperphosphatemia, and gut-derived uremic toxins. Furthermore, the former concerns about the risk of undernutrition and hyperkalemia observed with plant-based diets may be inconsistent in real clinical practice. In this review, we summarize the current evidence of the proposed pleiotropic effects of plant-based diets and their associations with clinical outcomes among pre-dialysis CKD patients.

Mediterranean Dietary Pattern Adjusted for CKD Patients: The MedRen Diet

A number of studies in the general population showed that healthy dietary patterns, such as the Mediterranean Diet, can improve or prevent the development of several chronic diseases and are associated with a significant reduction in all-cause and cardiovascular mortality. The Mediterranean diet may also have favorable effects for the prevention of chronic kidney disease (CKD), but no evidence of renoprotection exists in CKD patients. The Mediterranean Renal (MedRen) diet is an adaptation of the Mediterranean diet recommendations comprising a quantitative reduction in the RDA values of protein, salt and phosphate intake for the general population. Hence, MedRen supplies 0.8 g/Kg of protein, 6 g of salt and less than 800 mg of phosphate daily. Obviously, there is a preference for products of plant origin, which contain more alkali, fibers, unsaturated fatty acids than animal-based food. The MedRen diet can be implemented easily in mild-to-moderate stages of CKD with good results, both in terms of adherence to prescriptions and metabolic compensation. In our opinion, it should be the first step of CKD stage 3 nutritional management. This paper describes the features and reports our experience in the implementation of the MedRen diet as an early nutritional approach to CKD.

Nutritional Adequacy of Essential Nutrients in Low Protein Animal-Based and Plant-Based Diets in the United States for Chronic Kidney Disease Patients

OBJECTIVES

The nutritional adequacy of both animal-based and plant-based low protein diets (LPDs) and moderate protein diets that are recommended for patients with chronic kidney disease have not been well examined. We therefore analyzed the nutrient content of three representative LPDs and moderate protein diets (lacto-ovo vegetarian, omnivorous, and vegan) containing foods that are likely to be prescribed for nondialyzed chronic kidney disease or chronic dialysis patients in the United States to determine the nutritional adequacy at different levels of protein intake.

METHODS

Theoretical 3-day menus were developed as per current renal dietary guidelines to model each diet at 7 different levels of protein intake (0.5-1.2 g/kilograms body weight/day [g/kg/d]). The diets were analyzed for their content of essential amino acids (EAAs) and other essential nutrients.

RESULTS

At an a priori recognized inadequate dietary protein level of 0.5 g/kg/d, all 3 diets failed to meet the Recommended Dietary Allowances (RDAs) for the following EAAs: histidine, leucine, lysine, and threonine. The omnivorous LPD met both the RDA and Estimated Average Requirement at levels of 0.6 g protein/kg/d or more. The lacto-ovo and vegan diets at 0.6 and 0.8 g protein/kg/d, respectively, were below the RDA for lysine. The amounts of several other vitamins and minerals were not uncommonly reduced below the RDA or Adequate Intake with all 3 LPDs.

CONCLUSION

In comparison to omnivorous LPDs, both vegan and lacto-ovo LPDs are more likely to be deficient in several EAAs and other essential nutrients. To provide sufficient amounts of all EAA, vegan and lacto-ovo LPDs must be carefully planned to include adequate amounts of appropriate dietary sources. Supplements of some other essential nutrients may be necessary with all three LPDs.

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.

Nutritional Adequacy of Animal-Based and Plant-Based Asian Diets for Chronic Kidney Disease Patients: A Modeling Study

Plant-based low protein diets (LPDs) have gained popularity for managing chronic kidney disease (CKD) patients. The nutritional adequacy of these and other LPDs prescribed for CKD patients have not been carefully examined. This study assessed the nutrient composition of such LPDs and moderately high protein diets (MHPDs) that might be prescribed for patients in the Asia Pacific region with CKD who are not dialyzed or undergoing maintenance dialysis. Conventional diets containing at least 50% animal-based proteins and plant-based diets were also planned with protein prescriptions of 0.5 to 0.8 g/kg/day and MHPDs with protein prescriptions of 1.0 to 1.2 g/kg/day. Plant-based, lacto-, ovo-, and lacto-ovo-vegetarian and vegan LPDs and MHPDs were planned by replacing some or all of the animal proteins from the conventional diet. With 0.5 g protein/kg/day, all diets were below the Recommended Dietary Allowances (RDA) for at least one essential amino acid (EAA). At a protein prescription of 0.6 g/kg/day, only the conventional LPD met the RDA for all EAAs. This deficiency with the plant-based LPDs persisted even with several plant food substitutions. With a protein prescription ≥0.7 g/kg/day, all the plant-based and vegetarian LPDs provided the RDA for all EAA. The plant-based and vegetarian diets also contained relatively greater potassium, phosphorus, and calcium content but lower long-chain n-3 polyunsaturated fatty acids and vitamin B-12 than the conventional diet. Other essential micronutrients were commonly below the RDA even at higher protein intakes. The low contents of some essential micronutrients were found in both animal-based and plant-based diets. Prescription of all LPDs for CKD patients, especially plant-based and vegetarian LPDs, requires careful planning to ensure the adequacy of all nutrients, particularly essential amino acids. Consideration should be given to supplementing all animal-based and plant-based LPDs and MHPDs with multivitamins and certain trace elements.

Prevalence and correlates of hyperkalemia in a renal nutrition clinic

Hyperkalemia (HK) is a frequent complication of chronic kidney disease (CKD). Vegetable-based renal diets are considered at risk due to the high potassium (K) content. The aim of this study was to describe the prevalence and correlates of chronic hyperkalemia (HK) in CKD patients on nutritional care, and in particular, the risk of HK in patients on plant-based versus animal-based low-protein diets. We recruited adult patients affected by CKD not on dialysis, afferent to our renal nutrition clinic from November 2014 to May 2019. We evaluated a total of 870 accesses in 219 patients (172 m, 47 f, age 67 ± 13 years). HK was defined as mild when K serum level was 5.1-5.9 mEq/l, moderate when K serum level was 6.0-6.9 mEq/l, and severe HK when K serum level was ≥ 7 mEq/l. Biochemical, anthropometric data and medications were recorded. The prevalence of HK in all the renal nutrition visits was 26.1%; all but six cases were mild HK, whereas no severe HK was observed. The prevalence of HK was associated with decreased eGFR, up to 36.5% for eGFR < 20 ml/min. Medications were similar in hyperkalemic and normokalemic patients, RAASi being present in up to 85% of patients. In a follow-up of 40 ± 14 months, no association was found between HK and mortality, whereas HK, at the start of follow-up, showed a trend to increased ESRD risk. Serum potassium levels and prevalence of HK were not different between patients on animal-based low-protein diet and plant-based low-protein diet. In conclusion, chronic HK is quite prevalent in a renal nutrition clinic, especially when eGFR falls down below 60 ml/min, thereby reaching the highest prevalence in CKD stage 4. Hyperkalemia is mostly mild, being moderate to severe HK quite infrequent. Hyperkalemia was not associated with higher risk of mortality, whereas a trend, although not statistically significant, was observed for lower ESRD-free survival. Plant-based low-protein diet is not associated with significant higher prevalence of HK with respect to animal-based LPD at the same residual kidney function.

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.

Constipation in CKD

Constipation is one of the most common gastrointestinal disorders among patients with chronic kidney disease (CKD) partly because of their sedentary lifestyle, low fiber and fluid intake, concomitant medications (e.g., phosphate binders), and multiple comorbidities (e.g., diabetes). Although constipation is usually perceived as a benign, often self-limited condition, recent evidence has challenged this most common perception of constipation. The chronic symptoms of constipation negatively affect patients' quality of life and impose a considerable social and economic burden. Furthermore, recent epidemiological studies have revealed that constipation is independently associated with adverse clinical outcomes, such as end-stage renal disease (ESRD), cardiovascular (CV) disease, and mortality, potentially mediated by the alteration of gut microbiota and the increased production of fecal metabolites. Given the importance of the gut in the disposal of uremic toxins and in acid-base and mineral homeostasis with declining kidney function, the presence of constipation in CKD may limit or even preclude these ancillary gastrointestinal roles, potentially contributing to excess morbidity and mortality. With the advent of new drug classes for constipation, some of which showing unique renoprotective properties, the adequate management of constipation in CKD may provide additional therapeutic benefits beyond its conventional defecation control. Nevertheless, the problem of constipation in CKD has long been underrecognized and its management strategies have scarcely been documented. This review outlines the current understanding of the diagnosis, prevalence, etiology, outcome, and treatment of constipation in CKD, and aims to discuss its novel clinical and therapeutic implications.

Chronic hyperkalemia in non-dialysis CKD: controversial issues in nephrology practice

Chronic hyperkalemia is a major complication of chronic kidney disease (CKD) that occurs frequently, heralds poor prognosis, and necessitates careful management by the nephrologist. Current strategies aimed at prevention and treatment of hyperkalemia are still suboptimal, as evidenced by the relatively high prevalence of hyperkalemia in patients under stable nephrology care, and even in the ideal setting of randomized trials where best treatment and monitoring are mandatory. The aim of this review was to identify and discuss a range of unresolved issues related to the management of chronic hyperkalemia in non-dialysis CKD. The following topics of clinical interest were addressed: diagnosis, relationship with main comorbidities of CKD, therapy with inhibitors of the renin-angiotensin-aldosterone system, efficacy of current dietary and pharmacological treatment, and the potential role of the new generation of potassium binders. Opinion-based answers are provided for each of these controversial issues.

Self-management interventions for adults with chronic kidney disease: a scoping review

OBJECTIVE

To systematically identify and describe self-management interventions for adult patients with chronic kidney disease (CKD).

SETTING

Community-based.

PARTICIPANTS

Adults with CKD stages 1-5 (not requiring kidney replacement therapy).

INTERVENTIONS

Self-management strategies for adults with CKD.

PRIMARY AND SECONDARY OUTCOME MEASURES

Using a scoping review, electronic databases and grey literature were searched in October 2016 to identify self-management interventions for adults with CKD stages 1-5 (not requiring kidney replacement therapy). Randomised controlled trials (RCTs), non-RCTs, qualitative and mixed method studies were included and study selection and data extraction were independently performed by two reviewers. Outcomes included behaviours, cognitions, physiological measures, symptoms, health status and healthcare.

RESULTS

Fifty studies (19 RCTs, 7 quasi-experimental, 5 observational, 13 pre-post intervention, 1 mixed method and 5 qualitative) reporting 45 interventions were included. The most common intervention topic was diet/nutrition and interventions were regularly delivered face to face. Interventions were administered by a variety of providers, with nursing professionals the most common health professional group. Cognitions (ie, changes in general CKD knowledge, perceived self-management and motivation) were the most frequently reported outcome domain that showed improvement. Less than 1% of the interventions were co-developed with patients and 20% were based on a theory or framework.

CONCLUSIONS

There was a wide range of self-management interventions with considerable variability in outcomes for adults with CKD. Major gaps in the literature include lack of patient engagement in the design of the interventions, with the majority of interventions not applying a behavioural change theory to inform their development. This work highlights the need to involve patients to co-developed and evaluate a self-management intervention based on sound theories and clinical evidence.

Dietary Approach to Recurrent or Chronic Hyperkalaemia in Patients with Decreased Kidney Function

Whereas the adequate intake of potassium is relatively high in healthy adults, i.e., 4.7 g per day, a dietary potassium restriction of usually less than 3 g per day is recommended in the management of patients with reduced kidney function, especially those who tend to develop hyperkalaemia including patients who are treated with angiotensin pathway modulators. Most potassium-rich foods are considered heart-healthy nutrients with high fibre, high anti-oxidant vitamins and high alkali content such as fresh fruits and vegetables; hence, the main challenge of dietary potassium management is to maintain high fibre intake and a low net fixed-acid load, because constipation and metabolic acidosis are per se major risk factors for hyperkalaemia. To achieve a careful reduction of dietary potassium load without a decrease in alkali or fibre intake, we recommend the implementation of certain pragmatic dietary interventions as follows: Improving knowledge and education about the type of foods with excess potassium (per serving or per unit of weight); identifying foods that are needed for healthy nutrition in renal patients; classification of foods based on their potassium content normalized per unit of dietary fibre; education about the use of cooking procedures (such as boiling) in order to achieve effective potassium reduction before eating; and attention to hidden sources of potassium, in particular additives in preserved foods and low-sodium salt substitutes. The present paper aims to review dietary potassium handling and gives information about practical approaches to limit potassium load in chronic kidney disease patients at risk of hyperkalaemia.

Nutritional support in the tertiary care of patients affected by chronic renal insufficiency: report of a step-wise, personalized, pragmatic approach

Background

Dietary treatment is helpful in CKD patients, but nutritional interventions are scarcely implemented. The main concern of the renal diets is its feasibility with regards to daily clinical practice especially in the elderly and co-morbid patients. This study aimed to evaluate the effects of a pragmatic, step-wise, personalized nutritional support in the management of CKD patients on tertiary care.

Methods

This is a case-control study. It included 823 prevalent out-patients affected by CKD stage 3b to 5 not-in-dialysis, followed by tertiary care in nephrology clinics; 305 patients (190 males, aged 70 ± 12 years) received nutritional support (nutritional treatment Group, NTG); 518 patients (281 males, aged 73 ± 13 years) who did not receive any dietary therapy, formed the control group (CG). In the NTG patients the dietary interventions were assigned in order to prevent or correct abnormalities and to maintain a good nutritional status. They included manipulation of sodium, phosphate, energy and protein dietary intakes while paying special attention to each patient’s dietary habits.

Results

Phosphate and BUN levels were lower in the NTG than in the CG, especially in stage 4 and 5. The prevalence of hyperphosphatemia was lower in the NTG than in CG in stage 5 (13.3 % vs 53.3 %, p < 001, respectively), in stage 4 (4.1 % vs 18.3 % vs, p < 0.001) and stage 3b (2.8 % vs 9.5 % p < 0.05). Serum albumin was higher in NTG than in CG especially in stage 5 . The use of calcium-free intestinal phosphate binders was significantly lower in NTG than in CG (11 % vs 19 % p < 0.01), as well as that of Erythropoiesis stimulating agents (11 % vs 19 %, p < 0.01), and active Vitamin D preparations (13 % vs 21 %, p < 0.01).

Conclusions

This case-control study shows the usefulness of a nutritional support in addition to the pharmacological good practice in CKD patients on tertiary care. Lower phosphate and BUN levels are obtained together with maintenance of serum albumin levels. In addition, a lower need of erythropoiesis stimulating agents, phosphate binders and active Vitamin D preparations was detected in NTG. This study suggests that a nutritional support may be useful in the management of the world-wide growing CKD burden.

"Dietaly": practical issues for the nutritional management of CKD patients in Italy

Evidence exists that nutritional therapy induces favorable metabolic changes, prevents signs and symptoms of renal insufficiency, and is able to delay the need of dialysis. Currently, the main concern of the renal diets has turned from the efficacy to the feasibility in the daily clinical practice.Herewith we describe some different dietary approaches, developed in Italy in the last decades and applied in the actual clinical practice for the nutritional management of CKD patients.A step-wise approach or simplified dietary regimens are usually prescribed while taking into account not only the residual renal function and progression rate but also socio-economic, psychological and functional aspects.The application of the principles of the Mediterranean diet that covers the recommended daily allowances for nutrients and protein (0.8 g/Kg/day) exert a favorable effect at least in the early stages of CKD. Low protein (0.6 g/kg/day) regimens that include vegan diet and very low-protein (0.3-0.4 g/Kg/day) diet supplemented with essential amino acids and ketoacids, represent more opportunities that should be tailored on the single patient's needs.Rather than a structured dietary plan, a list of basic recommendations to improve compliance with a low-sodium diet in CKD may allow patients to reach the desired salt target in the daily eating.Another approach consists of low protein diets as part of an integrated menu, in which patients can choose the "diet" that best suits their preferences and clinical needs.Lastly, in order to allow efficacy and safety, the importance of monitoring and follow up of a proper nutritional treatment in CKD patients is emphasized.

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.

Low protein diets in patients with chronic kidney disease: a bridge between mainstream and complementary-alternative medicines?

Dietary therapy represents an important tool in the management of chronic kidney disease (CKD), mainly through a balanced reduction of protein intake aimed at giving the remnant nephrons in damaged kidneys a "functional rest". While dialysis, transplantation, and pharmacological therapies are usually seen as "high tech" medicine, non pharmacological interventions, including diets, are frequently considered lifestyle-complementary treatments. Diet is one of the oldest CKD treatments, and it is usually considered a part of "mainstream" management. In this narrative review we discuss how the lessons of complementary alternative medicines (CAMs) can be useful for the implementation and study of low-protein diets in CKD. While high tech medicine is mainly prescriptive, prescribing a "good" life-style change is usually not enough and comprehensive counselling is required; the empathic educational approach, on which CAMs are mainly, though not exclusively based, may support a successful personalized nutritional intervention.There is no gold-standard, low-protein diet for all CKD patients: from among a relatively vast choice, the best compliance is probably obtained by personalization. This approach interferes with the traditional RCT-based analyses which are grounded upon an assumption of equal preference of treatments (ideally blinded). Whole system approaches and narrative medicine, that are widely used in the study of CAMs, may offer ways to integrate EBM and personalised medicine in the search for innovative solutions respecting individualization, but gaining sound data, such as with partially-randomised patient preference trials.

Low-protein diets in CKD: how can we achieve them? A narrative, pragmatic review

Low-protein diets (LPDs) have encountered various fortunes, and several questions remain open. No single study, including the famous Modification of Diet in Renal Disease, was conclusive and even if systematic reviews are in favour of protein restriction, at least in non-diabetic adults, implementation is lagging. LPDs are considered difficult, malnutrition is a threat and compliance is poor. LPDs have been reappraised in this era of reconsideration of dialysis indications and timing. The definition of a normal-adequate protein diet has shifted in the overall population from 1 to 1.2 to 0.8 g/kg/day. Vegan-vegetarian diets are increasingly widespread, thus setting the groundwork for easier integration of moderate protein restriction in Chronic Kidney Disease. There are four main moderately restricted LPDs (0.6 g/kg/day). Two of them require careful planning of quantity and quality of food: a 'traditional' one, with mixed proteins that works on the quantity and quality of food and a vegan one, which integrates grains and legumes. Two further options may be seen as a way to simplify LPDs while being on the safe side for malnutrition: adding supplements of essential amino and keto acids (various doses) allows an easier shift from omnivorous to vegan diets, while protein-free food intake allows for an increase in calories. Very-low-protein diets (vLPDs: 0.3 g/kg/day) combine both approaches and usually require higher doses of supplements. Moderately restricted LPDs may be adapted to virtually any cuisine and should be tailored to the patients' preferences, while vLPDs usually require trained, compliant patients; a broader offer of diet options may lead to more widespread use of LPDs, without competition among the various schemas.

Adaptive changes of pancreatic protease secretion to a short-term vegan diet: influence of reduced intake and modification of protein

In our previous study, we demonstrated that abstaining from meat, for 1 month, by healthy omnivores (lacto-ovovegetarian model) resulted in a statistical decrease in pancreatic secretion as measured by faecal elastase-1 output. However, no correlation between relative and non-relative changes of energy and nutrient consumption and pancreatic secretion was documented. Therefore, in the present study, we aimed to assess the changes of exocrine pancreatic secretion with a more restrictive dietetic modification, by applying a vegan diet. A total of twenty-one healthy omnivores (sixteen females and five males) participated in the prospective study lasting for 6 weeks. The nutrient intake and faecal output of pancreatic enzymes (elastase-1, chymotrypsin and lipase) were assessed twice during the study. Each assessment period lasted for 7 d: the first before the transition to the vegan diet (omnivore diet) and the second during the last week of the study (vegan diet). The dietary modification resulted in a significant decrease in faecal elastase-1 (P < 0·05) and chymotrypsin output (P < 0·04). The lipase excretion remained unchanged. The decrease in proteolytic enzymes was documented to be positively correlated with a decreased protein intake (P < 0·05). In addition, elastase-1 and chymotrypsin outputs were also related to the changes of protein type, plantv.animal (P < 0·04 andP < 0·03, respectively). It was concluded that significant reduction and modification of protein intake due to a short-term vegan diet resulted in an adaptation of pancreatic protease secretion in healthy volunteers.

Adherence to the Mediterranean diet is associated with renal function among healthy adults: the ATTICA study

BACKGROUND

No data exist regarding the effect of the Mediterranean diet on renal function. We studied the association between adherence to the Mediterranean diet and markers of renal function among 3042 people without any evidence of chronic disease.

METHODS

During 2001 and 2002, a random sample was selected of 1514 men and 1528 women (aged 18 to 89 years) from Greece. Urea and creatinine were measured, and the creatinine-clearance (CCr) rate was estimated according to the formula of Cockcroft and Gault. Adherence to the Mediterranean diet was assessed using a validated diet score (MedDietScore) that incorporated the inherent characteristics of this diet.

RESULTS

The CCr rate was positively associated with MedDietScore (b+/-SE, 0.24+/-0.09, P=.007). Moreover, urea and creatinine levels were inversely associated with MedDietScore (b+/-SE, -0.05+/-0.02, P=.01, and -0.004+/-0.001, P < .001, respectively). Multiple linear regression analysis revealed that for each 10/55 additional points in diet score, a 3.7-unit increase in CCr rate in women (P < .001) and a 10.1-unit increase in CCr rate in men were evident (P < .001). Further analysis revealed that the CCr rate was positively correlated with the consumption of fruits (rho =0.08, P=.009) and moderate alcohol consumption, and inversely correlated with the consumption of potatoes (rho=-0.11, P < .001), red meat (rho=-0.12, P=.001), and poultry (rho=-0.07, P=.02).

CONCLUSIONS

Greater adherence to the Mediterranean diet was independently associated with reduced urea and creatinine and increased CCr rates among healthy men and women. This finding adds to the knowledge regarding the benefits of a traditional Mediterranean diet in human health.

Effect of a soy protein diet on serum lipids of renal transplant patients

OBJECTIVE

The aim of the present study was to evaluate the effect of a soy-protein diet on plasma lipid levels of renal transplant recipients with moderate hypercholesterolemia.

DESIGN

Dietary intervention case-control observational study.

SETTING

Renal transplantation outpatient clinic.

PATIENTS

Fifteen stable patients who had renal transplantation (serum creatinine < 2 mg/dL) with moderate hypercholesterolemia (low-density lipoprotein [LDL] cholesterol > 140 mg/dL).

INTERVENTION

After a baseline dietary interview, dietary counseling was given individually with the goal of substituting 25 g of animal protein with 25 g of soy protein for a 5-week period, using commercially available soy foods, according to each patient's own preference. Main outcome measures Before and after the soy-diet period, plasma lipid profiles including total, LDL, and high-density lipoprotein (HDL) cholesterol, triglycerides, apolipoprotein A1 and B were determined. Protein catabolic rate was assumed as a measure of dietary protein intake.

RESULTS

Two patients dropped out. After the soy diet, total cholesterol (254 +/- 22 to 231 +/- 31 mg/dL, P <.05) and LDL cholesterol (165 +/- 20 versus 143 +/- 20 mg/dL, P <.01) decreased significantly. No significant changes were observed regarding HDL cholesterol and triglycerides. Dietary protein intake did not differ at baseline (73.2 +/- 22.9 g/day) and during the soy diet (72.6 +/- 15.6 g/day), when the reported actual soy protein intake resulted 26 +/- 8 g/day.

CONCLUSIONS

This study shows that soy proteins given as part of the daily protein intake have beneficial effects on serum LDL cholesterol levels of renal transplant recipients with moderate hypercholesterolemia. Soy proteins could be of use in the nutritional management of renal transplant recipients.