Adherence to the restricted protein diet advised to nondialyzed chronic kidney disease patients.

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Docenten och dietisten Carla Avesani arbetar som njurdietist och bedriver forskning vid Rio de Janeiro State University i Brasilien inom området nutrition vid njursvikt. Hon har fått mycket uppmärksamhet för sina studier om bland annat kroppssammansättning, energiförbrukning samt kostintag och följsamhet till kostbehandling vid njursvikt.

Förutom en diger publiceringslista sitter hon även i det redaktionella rådet för tidskriften Journal of renal nutrition. Tack vare hennes postdoktorsanställning på Karolinska institutet har hon knutit många kontakter med svenska forskare inom njurmedicin och därmed blev det möjligt för henne att föreläsa på Nordisk Njurmedicinsk Vårkonferens i april 2017.

Ett referat från hennes föreläsningar publicerades i Dialäsen nummer 4, men vi har också fått möjlighet att publicera en av hennes artiklar skriven för International Society of Renal Nutrition and Metabolism och som handlar om fördelar, farhågor och följsamhet till behanding med proteinreducerad kost vid njursvikt utan dialys.

SINTRA EYRE, leg dietist

The restricted protein diet is commonly advised to nondialyzed chronic kidney disease (CKD) patients under conservative treatment. According to the National Kidney Foundation (K/DOQI), the amount of protein prescribed varies from 0.6 to 0.8 g/kg of desirable body weight (DBW)/day [1]. For patients with lower renal function (glomerular filtration rate (GFR) < 30 ml/min/1.73 m2), a very restricted protein diet with 0.3 g/kg/day supplemented with a mixture a ketoacids of aminoacids also stands as an alternative regimen[2]. One important highlight when advising restriction of protein intake is a close monitoring of the energy intake to ensure maintenance of adequate nutrition status [1]. The recommended energy intake to achieve neutral nitrogen balance and to avoid loss of body weight varies from 25 to 35 kcal/kg DBW/day, depending on the patient´s nutritional status, age and physical activity level [1].

The main strengths of lowering the protein intake are well discussed on a review by Fouque & Aparicio [2] and are described on Box 1. Of them, the capacity to provide better control serum bicarbonate, phosphorus, urea nitrogen and cholesterol, as well as to improve the insulin sensitivity and to diminish proteinuria stands out due its benefits for the overall control of the metabolic disturbances commonly observed in CKD patients.

Box 1. Reasons for controlling the dietary protein intake in nondialyzed chronic kidney disease patients [2]
Adequate adaptation to a reduction of protein intake

Decrease load on remaining nephrons

Improve insulin resistance

Reduce oxidative stress

Ameliorate proteinura

Reduce serum parathyroid hormone levels

Improve lipid profile

Additive effect on angioetensin-converting-enzyme inhibitors

Decrease likelihood of patient death or delay initiation of dialysis


However, some health care practitioners are still concerned about the risk of deterioration of the nutrition status when prescribing the restricted protein diet, as previous demonstrated [3]. However, when the prescription of low protein diet is coupled with close monitoring of the energy intake, the nutritional status is well preserved [4-6].

Another important issue when prescribing a restricted protein diet is the low adherence to such regimen. Some studies have shown that adherence to the low protein diet (0.6 to 0.8 g/kg/day) is low and varies between 20 to 46% [7, 8]. Improving these low rates are of importance, mainly if we consider  that low adherence to long-term therapies (such as following a diet and changing food habits), may lead to worse outcome and increased costs to public health. Other relevant reasons for improving the adherence to long term therapies were proposed by the document from the World Health Organization [9] and are described in Box 2.

Box 2. Main reasons for improving the adherence to long term therapies, as proposed by the document from the World Health Organization [9]
Poor adherence to long-term therapies lead to poor health outcomes and increased health care costs

Improving adherence enhances patients’ safety

Adherence is an important modifier of health system effectiveness

Increasing the effectiveness of adherence interventions may have a far greater impact on the health of the population than any improvement in specific medical treatments


The causes beyond the low rate of adherence to the restricted protein diet is diverse and include social and economic factors (i.e. poverty, low educational level), treatment-related factors (i.e. lack of a renal dietitian in the personnel and short consultations without follow up at pre-dialysis care), condition related factors (education on proper use of medication) and patient-related factors (i.e. limited knowledge of the reasons behind this dietary approach and of the food sources rich in protein; dietary dissatisfaction and lack of self-perception of success) [10]. In order to overcome these conditions and improve the adherence to the restricted protein diet, one should identify the reasons impairing the adherence to the treatment and preferably work according to the steps to achieve effectiveness of medical nutritional therapy [11]. First, it is necessary to work on screening methods to assess which kind of nutrition intervention the patient needs. Second, it should be invested on the quality of the nutrition care and intervention provided, which should be adequate to the patients’s environment (cognitive capacity, social and economic condition, logistic and etc). Third, tools to assess the intermediate outcomes, such as improve in the nutritional intake and amelioration of biochemical and physiological indicators, should be established. Fourth, clinical outcomes (improvement or stabilization of the disease), cost outcomes (intensity of care and hospitalization) and patient outcome (improve in quality of life and minimization of death, disease disability, discomfort, dissatisfaction) should be constantly assessed to measure the effectiveness of the medical nutritional therapy. This model can be applied to CKD patients, as proposed by the guidelines from the American Dietetic Association, aiming to assist to dietitians to provide optimal and consistent care to renal patients [11].

Out of the cascade of events proposed to improve the effectiveness of medical nutrition therapy, the quality of the intervention and nutrition care provided is of particular interest, since it will comprise the development of comprehensive nutrition program to improve adherence. These strategies should be acceptable for the patient and capable of yielding the benefits of lowering the protein intake, even if not to the desired level initially planned. Three categories of strategies that complete one the other can be drawn: educational, behavioral and organizational [10]. Educational interventions rely on the transmission and dissemination of information and instruction with or without motivational appeal, with the intermediate aim of affecting patient´s knowledge and attitudes. This strategy however is not enough to solely achieve better adherence and behavioral strategies should also be implemented. They should aim to influence specific non-adherent behaviors directly, but they fail to achieve and maintain long term changes. Lastly, organizational strategies focusing primarily on clinic and regimen convenience and on the personnel for fostering dietary adherence should be developed. Table 1 describes some examples of strategies according to three categories described.


Table 1: Strategies to improve adherence to restricted protein diet according to educational, behavioral and organizational categories [10]

Categories Strategies
Educational Material such as mini-classes (10 to 15 min), games (puzzles, crossword), folders and interactive media.
Behavioral Self monitoring of food intake (food diaries), family involvement in the treatment to increase support, guided groups investigating the main obstacles to perceive the regimen and how to overcome them.
Organizational Recipes, food models, household utensils, cooking workshops, constant follow-up.


However, interventional studies aiming to assess the role of these strategies in increasing the adherence to the restricted protein are scarce. To the best of our knowledge, there are only 3 studies that were controlled, randomized and longitudinal that investigated the role of education program on predialyzsis CKD patients [12-14]. Of them, 2 studies did not have adherence as primary outcome [12, 13]. In a study aiming to assess the impact of a nutritional counseling program on the nutritional status of patients on CKD stages 3 and 4 following a restricted protein diet (0.8 g/kg DBI/day), it was shown that after a follow up of 12 weeks, an improvement in subjective global assessment scores and in energy intake was observed in patients randomly assigned to the nutritional counseling group, but not in the patients on the control group [12]. In other study, Flescher et al [13] investigated whether a comprehensive 12 week nutritional program comprised by individual counseling, group cooking classes and an exercise program, would reduce cardiovascular risk factors and to slow the progression of CKD parameters. The authors found that the group randomly assigned to the nutrition program improved more parameters related to cardiovascular risk factors and progression of CKD than the patients not on the education group. The only study evaluating the role of educational program on improving the adherence to the low protein diet during a follow up of 16 weeks showed positive results, in which the group randomized to the education program + individual counseling got closer to the targeted protein prescription than did the control group, that received the individual counseling alone. Of notice, nutritional status was preserved throughout the studied period [14]. All together, these studies show the potential benefit of education program to the overall clinical and nutritional status of nondialyzed CKD patients. However, assessment on the impact of these education programs on long term adherence is still lacking.

Yet, studies investigating methods that can be applied to assess adherence needs to be performed. Up to now, the Nutrition NKF K/DOQI recommends the use of the protein equivalent of nitrogen appearance (PNA, also referred as protein catabolic rate – PCR) to monitor the protein intake [1]. However, this method requires the collection of 24 hour urine, which is cumbersome and requires the patient´s collaboration. In addition, the estimation of protein intake will be valid only when neutral nitrogen balance is maintained, a condition not always present in CKD patients. Lastly, a single PNA measurement may not be representative of the usual protein intake and more than one assessment is necessary. Overall, PNA is a method of choice, but one should not rely only in this tool to monitor the protein intake. Food records or 24 hour food recall can be used to examine food habits, sources of consumed protein, adequacy of the ratio high to low biological value protein and even, the total protein intake. Moreover, they allow the assessment of energy intake, which is also important to be monitored. Therefore, PNA together with a dietary assessment method can be used to better estimate and monitor the protein intake.



The adherence to restricted protein diet is low and needs to be improved. There are few studies devoting attention to the role of nutrition education programs in CKD patients. These studies showed positive results, with improvement in the nutritional status, lower progression of CKD parameters and better adherence to the low protein diet. Therefore, nutrition education program specific tailored to CKD patients and that respect the cultural and social environment of the targeted population needs to be developed. The long term efficacy of these programs needs to be investigated.




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Carla Maria Avesani. Adjunct Professor. Department of Applied Nutrition, Nutrition Institute, Rio de Janeiro State University. Email:

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