Kidney Transplant; Complications
Conditions
Keywords
kidney transplantation, metabolic syndrome, high-protein diet, dietary intervention
Brief summary
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.
Interventions
OTHERhigh-protein, carbohydrate-reduced diet
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.
OTHERDutch Nutritional Guidelines
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.
Sponsors
University Medical Center Groningen
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Age 18 years or older. * Given informed consent. * At least 6 months after kidney transplantation. * Stable renal function with an estimated glomerular filtration rate (eGFR) \> 30 mL/min. * Raised systolic blood pressure (≥130 mmHg) and at least two more features of metabolic syndrome: central obesity (waist circumference ≥102 for men and ≥88cm for women), elevated triglycerides (≥ 1.7 mmol/L), reduced HDL-C (\< 1.0 mmol/L for men and \< 1.3 mmol/L for women) or on drug treatment for reduced HDL, elevated plasma glucose (≥ 5.6 mmol/L) or on drug treatment for elevated glucose9. * Approval by nephrologist for participation in the study.
Exclusion criteria
* Active medical illness, including rejection of the graft. * Psychopathology or serious cognitive impairment. * Necessity to follow specific dietary measures for health purposes that conflict with the study diets. * Use of insulin or sulfonylurea (SU)-derivates. * Language barrier. * Pregnancy or lactating. * Serum potassium \> 5.0 mmol/L that requires dietary measures. * Moderate or severe malnutrition (Patient-Generated Subjective Global Assessment (PG-SGA) stage B or C). In this case, patient will be referred to a renal dietician. * Participation in other intervention trials.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Systolic blood pressure | 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) | Change in systolic blood pressure (in mmHg) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Cardio-metabolic risk factors (diastolic blood pressure) | 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) | Change in diastolic blood pressure (in mmHg) |
| Cardio-metabolic risk factors (waist circumference) | 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) | change in waist circumference (WC) in cm |
| Cardio-metabolic risk factors (insulin resistance) | 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) | change in insulin resistance measuring by the homeostatic model assessment of insulin resistance (HOMA-IR index, fasting glucose, insulin) |
| Body composition | 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) | change in fat and muscle mass measured by multi-frequency bio-electrical impedance analysis (BIA) BMI, weight |
| Anthropometric measures | 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) | Change in weight in kilograms |
| Anthropometric measures II | 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) | Change in Body Mass Index (BMI) in kilograms per square meter |
| Cardio-metabolic risk factors (lipids) | 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) | change in circulating triglyceride concentrations, low-density lipoprotein cholesterol (LDL-C) and HDL-C (in fasting serum levels) in mmol/L. |
| Quality of life (QoL) | 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) | change in QoL, 12-item short form health survey (SF-12) |
| Fatigue | 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) | change in fatigue (measured by Dutch Checklist Individual Strength (CIS-20) questionnaire) |
| Physical functioning | 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) | change in Hand Grip Strength (HSG) |
| Physical functioning II | 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) | change in the five time sit to stand (FTSTS) test |
| Nutritional intake | 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) | change in nutritional intake measured by a 3-day food diary |
| Nutritional intake II | 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) | 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) |
| Body composition II | 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) | change in fat and muscle mass measured by multi-frequency bio-electrical impedance analysis (BIA) |
Outcome results
None listed