Franny Jongbloed

185 7 FEASIBILITY AND SAFETY OF A PREOPERATIVE DIET daily nutritional intake values. Experienced dieticians analyzed the diaries and calculated the DER, the average kilocalorie intake, and the average protein, fat and carbohydrate intake. Outcome parameters Subjective measurements To analyze subjective health outcomes, all patients were asked to fill in a standardized questionnaire, the Visual Analogue Score (VAS), for evaluation of nausea, pain and general wellbeing 30 . The VAS questionnaire uses a scale ranging from zero to 10, with zero representing no pain, nausea or decrease in wellbeing and 10 corresponding to the worst pain, nausea or decrease in wellbeing. The questionnaires were completed at three different time points: one day prior to starting the dietary intervention, on day three of the intervention and one day after completion of the 5-day intervention period when normal food intake was resumed. Side effects and discomfort were defined as any secondary effect related to the intervention. A distinction was made between major side effects and minor discomfort. Major side effects were defined as symptoms related to the intervention that remained days or weeks after the intervention or that required hospitalization. Minor discomfort included symptoms that caused discomfort during the intervention, but immediately disappeared after the dietary intervention. Objective measurements Before and after the dietary intervention, the following data were obtained from all patients: body weight, age, gender, length, and estimated physical activity level and duration. During the outpatient clinic visit and one day after the dietary intervention, two tubes of blood were collected: a 5.0 mL BD Vacutainer CPT tube (Franklin Lakes, NJ, USA) and a 5.0 mL BD Vacutainer® SST™ II Advance serum tube. After centrifuging for 20 min at 1500× g or for 10 min at 2300× g, respectively, both the plasma and serumwere collected and stored at −80 °C until further analysis. Only blood samples from patients that had fasted overnight were used for the analysis. “Fasted” was defined as no food intake overnight, i.e. for at least eight hours prior to blood withdrawal. In serum samples the metabolic parameters albumin, urea, creatinine, glucose, ferritin, cholesterol, free fatty acids, triglycerides and high-density lipoprotein (HDL), and in plasma samples parameters prealbumin (PAB) and retinol binding protein (RBP) were measured and processed on the UniCel D×C 800 Synchron (R) Chemistry System (Beckman, Poway, CA, USA). Insulin was analyzed using the Access 2 ImmunoAssay System (Beckman) (Table S2). In addition, 143 metabolic markers were measured in serum samples by Brainshake (Brainshake Ltd., Helsinki, Finland), as summed