Dietary Interventions During Living Kidney Donations

Intermittent fasting with human fasting mimicking diet (Prolon®) will be performed for five days prior to living kidney donation in the donor. Prolon® a plant-based diet designed to attain fasting-like effects while provide providing both macro- and micronutrient. Each participant will obtain Prolon® diet during the first visit and the diet will stored at the participant's home at room temperature. Additionally, the participant will receive a food plan for the exact consumption of the diet. Regular phone with a predefined standardized questionnaire will be used to determine each participant's well-being, as well as his or her dietary adherence. Furthermore, the participants will be asked to write down each consumed food items they are consuming in diet-book, which is handed to them during the first visit. The participants are only allowed to consume water, coffee or tea without sugar simultaneously to the Prolon® diet.

Isocaloric, ketogenic diet will be performed for seven days prior to living kidney donation in the donor. The ketogenic diet is based on the KetoCal 4:1 formula diet (Nutricia Milupa GmbH, Erlangen, Germany). Main fat sources are plant oils including palm oil and sunflower oils. The formula diet is provided as a powder that has to be mixed with water before use. To avoid a shortage in protein uptake supplement formula diets K-AM and Fortimel® (both Nutricia Milupa GmbH, Erlangen, Germany) will be used additionally. Salt uptake will be standardized employing either broths or salt tablets to not interfere with the steady-state salt and water homeostasis. A salt ingestion of 5g/day, which is common for western diets, is aimed at. The participants will receive a daily food plan by the dietetics at the University Hospital of Cologne to ensure standardized food consumption

Isocaloric, dietary restriction of sulfur containing amino acids will be performed for seven days prior to living kidney donation in the donor. A dietary restriction of sulfur containing amino acids without restriction in protein uptake will be achieved by following the X Met X Cys Maxamaid formula diet (Nutricia Milupa GmbH, Erlangen, Germany). The formula diet is provided as a powder that has to be mixed with water before use. A minimum of methionine and cysteine uptake (10% of the common uptake per day) will be achieved by consuming individuial calculated amounts of the Fortimel® formula diet (Nutricia Milupa GmbH, Erlangen, Germany). To avoid a restriction in fat and energy uptake additionally the Calogen and Duocal formula diets (both Nutricia Milupa GmbH, Erlangen, Germany) will be used. A salt ingestion of 5g/day, which is common for western diets, is aimed at. The participants will receive a daily food plan to ensure standardized food consumption.

Participants in the control group will be instructed to adhere to a healthy, low-fat, moderate protein and high carbohydrate diet as described in current nutritional recommendations. The control diet will be based on the formula diet Fortimel® (Nutricia Milupa GmbH, Erlangen, Germany). Salt uptake will be standardized employing either broths or salt tablets to not interfere with the steady-state salt and water homeostasis. A salt ingestion of 5g/day, which is common for western diets, is aimed at.