Kidney transplant recipients (KTR) have a considerably lower life expectancy as compared with the general population, primarily due to a high prevalence of cardiovascular diseases. KTR often develop an unfavourable cardio-metabolic risk profile characterized by weight gain, metabolic syndrome and post-transplantation diabetes mellitus (PTDM). In general, nutrition plays a key role in both the prevention and treatment of these cardio-metabolic derangements. However, in KTR most RCT's with a dietary intervention, failed to show significant improvement in cardio-metabolic health. This at least questions the efficacy of the diets of these intervention, which relied on general or diabetes guidelines, after kidney transplantation. KTR not only face a high cardio-metabolic risk, but also have a high risk for malnutrition and muscle mass depletion. More knowledge is required to determine the optimal diet and macronutrient composition for improvement of the cardio-metabolic risk factors in the context of the high malnutrition risk. In this regard, observational studies point towards the needs for a higher protein intake for better patient outcomes. Therefore, in this study, the investigators will examine if a high-protein, carbohydrate-reduced diet is more effective than a diet in line with the Dutch Dietary Guidelines for improvement of cardio-metabolic risk factors and for improvement of the body composition in KTR.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
30
the high-protein, carbohydrate-reduced diet will consist of 1.2-1.4 g/kg/d protein, 26-20en% carbohydrates and +/- 50en% fatty acids, with mainly unsaturated fatty acids. This diet consist of mainly unprocessed, fresh nutrient-dense food-products. Ultra-processed foods and alcoholic beverages will be totally avoided. Salt consumption will not exceed 5-6 g/d. The diet is ad libitum and caloric restriction will not be applied. The diet will be followed for 6 weeks.
the diet according to the Dutch Nutritional Guidelines will consist of a protein intake of 0.8-1.0 g/kg/d and 50-60en% carbohydrates, and +/-30en% fatty acids, with restriction of saturated fatty acids \<10en%. This diet consist of mainly unprocessed, fresh nutrient-dense food-products. Ultra-processed foods and alcoholic beverages will be totally avoided. Salt consumption will not exceed 5-6 g/d. The diet is ad libitum and caloric restriction will not be applied. The diet will be followed for 6 weeks.
Systolic blood pressure
Change in systolic blood pressure (in mmHg)
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Cardio-metabolic risk factors (lipids)
change in circulating triglyceride concentrations, low-density lipoprotein cholesterol (LDL-C) and HDL-C (in fasting serum levels) in mmol/L.
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Cardio-metabolic risk factors (diastolic blood pressure)
Change in diastolic blood pressure (in mmHg)
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Cardio-metabolic risk factors (waist circumference)
change in waist circumference (WC) in cm
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Cardio-metabolic risk factors (insulin resistance)
change in insulin resistance measuring by the homeostatic model assessment of insulin resistance (HOMA-IR index, fasting glucose, insulin)
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Body composition
change in fat and muscle mass measured by multi-frequency bio-electrical impedance analysis (BIA) BMI, weight
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Anthropometric measures
Change in weight in kilograms
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Anthropometric measures II
Change in Body Mass Index (BMI) in kilograms per square meter
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Body composition II
change in fat and muscle mass measured by multi-frequency bio-electrical impedance analysis (BIA)
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Quality of life (QoL)
change in QoL, 12-item short form health survey (SF-12)
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Fatigue
change in fatigue (measured by Dutch Checklist Individual Strength (CIS-20) questionnaire)
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Physical functioning
change in Hand Grip Strength (HSG)
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Physical functioning II
change in the five time sit to stand (FTSTS) test
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Nutritional intake
change in nutritional intake measured by a 3-day food diary
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
Nutritional intake II
change in nutritional intake measured by nutritional intake biomarkers from 24-hour urine measurements (sodium, potassium, and urea excretion for calculating the protein intake by use of the Maroni equation)
Time frame: before and after experimental diet (high-protein, carbohydrate-reduced diet - 6 weeks) / before and after active comparator (Dutch Nutritional Guidelines - 6 weeks) / wash-out period in between (6 weeks)
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