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A practical approach of salt and protein restriction for CKD patients in Japan

BMC NephrologyBMC series – open, inclusive and trusted201617:87

https://doi.org/10.1186/s12882-016-0298-3

Received: 14 February 2016

Accepted: 14 June 2016

Published: 19 July 2016

Abstract

Dietary management, in particular salt and protein restriction is fundamental for the proper care of CKD patients. Therefore, a practical guide to the dietary treatment may be helpful among progressive CKD patients. In Japan, two academic societies such as Japanese Society of Nephrology and Japanese Society for Dialysis Therapy have recently published Guidelines for Dietary Management for non-dialysis dependent CKD and dialysis-dependent CKD, respectively.

In this manuscript, we summarized the practical guide for salt and protein restriction from the Japanese Society of Nephrology to retard the progression of CKD to endstage renal disease. This guide will promote further the collaboration of Nephrologists and Dietitians.

Background

CKD is common and the number of patients on renal replacement therapy (RRT) is estimated more than 330,000 in Japan [1]. It is becoming a social and economic burden. More than half of incident dialysis patients are CKD associated with diabetes mellitus (DM) and hypertension. Early detection and treatment would be necessary to retard the progression of CKD. Therefore, life-style modification including dietary management is important in patients with DM, hypertension, dyslipidemia, obesity, metabolic syndrome, and hyperuricemia. Among the dietary management, salt and protein restriction are critical for CKD patients, however it is influenced by differences in ethnic, regional, and cultural factors. We recently summarized a manual for dietician and other medical staff concerning life-style and dietary management in CKD patients (written in Japanese) [2, 3].

Discussion

Manual for dietary management

Table 1 summarized the guidance for lifestyle and dietary modification in CKD patients. Firstly, it is important diagnose the current stage of CKD (eGFR and proteinuria), cause of CKD, and also it is helpful to obtain the recent trend in CKD progression, pattern and slope of eGFR decline. Check the current medication and adherence to the drug therapy. Cessation of smoking and weight control should be accompanied with salt restriction and protein restriction. Until favorable results obtained, several rounds will be needed (Table 2).
Table 1

Guidance for Lifestyle and dietary modification in CKD patients (Cited with permission from the Japanese Society of Nephrology)

1. Lifestyle and Dietary Modification

2. Weight control: BMI < 25.0 kg/m2

3. Salt restriction: NaCl 3 to 6 g/day (if hypertensive)

Target blood pressure: <130/80 mmHg

4. Protein restriction (Body weight as body mass index 22.0 kg/m2)

Stage 3a: 0.8 to 1.0 g/kg/day

Stage 3b: 0.6 to 0.8 g/kg/day

Stage 4/5: 0.6 to 0.8 g/kg/day

Stage 5D: HD patient 0.9 to 1.2 g/kg/day

PD patient 0.9 to 1.2 g/kg/day

5. Potassium restriction (if hyperkalemia)

Stage 3b: ≤2000 mg/day

Stage 4/5: ≤1500 mg/day

6. Glucose (if DM present): HbA1c < 7.0 %

7. Lipids (if dyslipidemia): LDL-C < 120 mg/dL

Table 2

Flow chart for Lifestyle and dietary modification (Cited with permission from the Japanese Society of Nephrology)

1st Round

1) Obtain good rapport with patient

2) Make a checklist for individual patient

3) Clear the priority (What is the category in the checklist?)

For: Protein restriction, Salt restriction

Use the manual of Guidance (30 min in each guidance)

For: Weight control, Hypertension, Hyperglycemia

Hyperkalemia, Smoking cessation, Hyperlipidemia, Hyperuricemia, Use algorithm (30 min in each guidance)

2nd Round: If not satisfactory, repeat the guidance again

If the first priority was successful, then try second

3rd Round: If not satisfactory, repeat the guidance again (Continue counselling)

If the second priority was not-successful, then repeat the guidance again

Steps for salt and protein restriction

  1. 1.

    Use the checklist

    Obtain clinical and laboratory information of the patient.

     
  2. 2.

    Check the current problem

    Adherence to drug therapy should be checked. Important categories are body mass index (BMI), blood pressure, fasting blood glucose, LDL-cholesterol.

     
  3. 3.

    Guidance by category

    Salt (NaCl) Restriction, Protein Restriction

     
  4. 4.

    Guidance by algorithm

    BMI, Blood Pressure, Blood Glucose, Lipid, Smoking Cessation, Potassium, Uric Acid

     
  5. 5.

    Useful materials

    Salt content in food staff

     

Salt restriction

  1. 1)

    Rationale

    Salt restriction is essential for CKD patients. If not adequately controlled, salt retention may cause edema, heart failure and hypertension. Daily intake from foods and additives should be estimated carefully. In particular, salt intake may vary with cooking process.

     
  2. 2)

    Practical Guide

    We summarized several tools to help adhering to salt restriction.

     
  1. a)
    Salt content in seasoning (Fig. 1)
    Fig. 1

    Estimating of salt content in the seasoning material

    Use spoon to estimate the amount of added seasoning, in particular when uses common seasoning materials such as table salt, source, and Miso.

    Estimate roughly as salt (gram) per one small spoon.

    Select low salt seasoning and law salt food staffs (Avoid too much).

    Check the salt ingredient in each food staff.

     
  2. b)
    Salt content in processed food (Fig. 2)
    Fig. 2

    Rough estimate of salt content in the processed foods

    Processed foods are difficult to check. When expressed as salt content as “mg”, salt content should be calculated as: Na (mg) X 2.54/1000 = Salt (g)

     
  3. c)
    Tips for cooking (Fig. 3)
    Fig. 3

    Tips for salt restriction Use other than soy-source

    Salt restricted food is often regarded as “non-palatable”. Adherence to salt restriction could be improved by using other seasoning materials without salt. It may take time to adjust salt restriction.

     
  4. d)
    Restaurant (Fig. 4)
    Fig. 4

    Examples of salty foods at restaurants. (All figures are cited from “Manual for CKD life and dietary guidance manual for physicians and co-medical staffs; edited by the Japanese Society of Nephrology”. Sample Legends: Sample 1. A sample of breakfast. Sample 2. A sample of lunch. Sample 3. A sample of dinner. Sample 4. A sample of balanced diet. (All cited from “Manual for CKD life and dietary guidance manual for physicians and co-medical staffs; edited by the Japanese Society of Nephrology”)

    Generally, cooked-food and diet outside home are salt-rich, although it may differ by restaurant or region. It may be helpful to “recall what and how much have eaten, etc.” Advice to check the nutrient content when buy the cooked foods.

     
Some tips;
  • /Ask low salt cooking at restaurant/Do not drink soup when ordering/

  • /Use separate dish for dressing or mayonnaise/Select food easy to estimate salt intake/When eat-out, restrict salt more than usual at home

  1. e)

    Avoid too much salt restriction

    Too much, less than 3 g/day, salt restriction is dangerous if adequate food intake has not accompanied.

     

Protein restriction

  1. 1.

    Rationale

    Ingested protein is finally metabolized to water, carbon dioxide, and other compounds, mainly containing nitrogen. Protein (amino acids) is used to construct body protein and also used for energy production. Water and nitrogen compounds are excreted from kidney. Nitrogenous compounds will retain in the blood as kidney function deteriorates resulting uremic symptoms such as nausea, vomiting, anorexia, and anemia. Electrolyte-imbalance such as hyperkalemia, hyperphosphatemia, and metabolic acidosis may appear in CKD stage 3 patients. To prevent such symptoms, protein restriction is indicated timely in accordance with remaining kidney function to prevent complications and also retard the progression of CKD.

     
  2. 2.

    Quality of protein

    Human body is constructed by protein such as elastin, collagen, hemoglobin, enzymes, and hormones. Essential amino acid such as leucine, isoleucine, valine, lysine, tryptophan, phenylalanine, threonine, methionine, histidine should be supplied as human cannot synthesize them. Foods with high content of essential amino acid expressed as high amino acid score is regarded as good quality protein food staff. Generally, animal meats are high amino acid score, but not so high in vegetables including soybean products (Table 3).
    Table 3

    Amino-acid score in common food in Japan(1973 FAO/WHO) (Cited with permission from the Japanese Society of Nephrology)

    Food

    Amino-acid score

    Salmon

    100

    Saury

    100

    Mackerel

    100

    Pork, Sirloin

    100

    Beef

    100

    Chicken, Round

    100

    Milk

    100

    Chicken Egg

    100

    Polished Rice

    65

    Soba

    65

    Sweet Potato

    88

    Potato

    68

    Soybean

    86

    Fermented Soybean (Natto)

    84

    Okura

    57

    Green Beans

    68

    Turnip

    45

    Asparagus

    68

    If protein intake is over 60 g/day, deficiency of essential amino acid is rarely occur. However, in case of protein restriction, insufficient intake of essential amino acid and energy may occur, therefore careful monitoring is recommended to prevent protein-energy wasting (PEW). CKD patients with stage 3b to 5 should be managed with trained dietician and nephrologist.

     
  3. 3.

    Lipid intake

    Lipid intake should be 20 to 25 % of the total energy intake. N-3 poly-unsaturated fatty acid is recommended for preventing atherosclerosis.

     
  4. 4.

    Energy intake

    While practicing protein restriction, adequate energy intake should be maintained. Too strict protein restriction may result energy intake deficiency. In particular patients with CKD stage 4 to 5. When energy intake is not sufficient, ingested protein is used for energy, but not for protein construction, resulting muscle and/or wasting. In patients with CKD stage 3b to 5, protein restriction of less than 0.8 g/kg/day should be performed with guidance of special medical team.

     
  5. 5.
    Practical Guide (Table 4)
    Table 4

    Nutrient content in food common in Japan, expressed grams of food): Food Samples for protein restriction, adjusted to body size (Cited with permission from the Japanese Society of Nephrology)

    Height, cm

    174

    157

    152

    148

    Energy, kcal/day

    2000

    1800

    1600

    1400

    Protein, g/day

    55

    45

    40

    35

    Rice,

    540

    480

    390

    330

    Egg

    50

    25

    25

    25

    Meat

    60

    60

    50

    45

    Fish

    60

    60

    50

    45

    Soybeans

    20

    20

    20

    0

    Milk Products

    120

    90

    90

    90

    Vegetables

    300

    300

    300

    300

    Potato

    100

    100

    100

    100

    Fruits

    120

    120

    120

    120

    Sugar/sweets

    20

    20

    20

    20

    Harusame (Gelatin Noodles)

    25

    25

    25

    25

    Oils

    25

    25

    25

    25

    Energy Additive, kcal

    100

    100

    100

    100

    Three meals a day. Energy Additive; ex) soft-drinks containing carbohydrate 250 ml100 kcal

    Patients are instructed to adhere protein restriction by using learning tools to estimate amount of protein, amino acid score, and salt. (Sample 1, 2, 3 and 4)
    Sample 1

    A sample of breakfast

    Sample 2

    A sample of lunch

    Sample 3

    A sample of dinner

    Sample 4

    A sample of balanced diet (All cited from “Manual for CKD life and dietary guidance manual for physicians and co-medical staffs; edited by the Japanese Society of Nephrology”)

    .
     

Summary

We have done a strategic outcome study for chronic kidney disease: Frontier of Renal Outcome Modifications in Japan (FROM-J study) [4]. Management of CKD requires multi-disciplinary involvement. In this study, we prospectively observed the effects of intervention from dietitians and supportive care in CKD patients in addition to usual care recommended by Japanese Society of Nephrology [5]. Through this study, we published practical guidebook with full involvement from dietitian’s society [2, 3].

Declarations

Acknowledgements

Not applicable.

Funding

This study was supported in part by a Grant-in-Aid for Research on Advanced Chronic Kidney Disease (REACH-J). Practical Research Project for Renal Diseases from Japan Agency for Medical Research and development, AMED.

Availability of data and materials

Not applicable.

Authors’ contributions

Both authors contributed equally to the manuscript.

Competing interests

The authors declare that they have no competing interests.

Consent for publication

Not applicable.

Ethics approval and consent to participate

Not applicable.

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Authors’ Affiliations

(1)
Clinical Research Support Center, Tomishiro Central Hospital
(2)
Department of Nephrology, Faculty of Medicine, University of Tsukuba
(3)
Division of Nephrology

References

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Copyright

© The Author(s). 2016