Nutrition Questionnaires and more

1. Dietary intake: Assessment of habitual dietary intake was done by means of an 180-item semi-quantitative FFQ and up to nine repeated 24-hour recalls. All measurements were repeated at one and two years of follow-up.
2. Eating behaviour was assessed by means of the Dutch Eating Behaviour Questionnaire (DEBQ). Additionally, eating behaviour was assessed by a questionnaire developed by research institute Wageningen Economic Research (WECR). The Food Choice Questionnaire (FCQ) was used to assess factors related to food choice. Food neophobia was scored using the Food Neophobia Scale. Eating Rate was assessed according to one of five rating categories. Determinants of intake of fruit vegetables and snacks was examined by means of a questionnaire as developed by Hooft van Huysduynen and colleagues (2014) based on determinants from the Theory of Planned Behaviour. All measurements were repeated at one and two years of follow-up.
3. Nutritional recovery biomarkers: Total 24-hour urinary nitrogen excretion was determined at the Division of Human Nutrition by the Kjeldahl technique 19 (Foss KjeltecTM 2300 analyzer). Urinary sodium and potassium concentrations were measured with an ion-selective electrode on a Roche 917 analyser (Indianapolis, USA). Urinary creatinine concentrations were measured at 520 nm on the Synchron LX20 by the modified Jaffé procedure using a commercial kit. Total 24-hour sodium and potassium excretion were calculated by multiplying total weight of collected urine by sodium or potassium concentration. Additionally, this was divided by 0.86 for sodium and by 0.81 for potassium, assuming that this percentage of intake is excreted in the urine. Urinary protein was calculated with the following formula: 6.25 * (urinary N / 0.81) accounting for faecal and skin losses (approximately 19%). All measurements were repeated at one and two years of follow-up
4. Anthropometrics: Height was measured with a stadiometer (SECA, Germany) to the nearest 0.1 cm. Weight was measured using a digital scale (SECA, Germany) to the nearest 0.1 kg. Waist and hip circumference was measured twice by a non-flexible measuring tape (SECA 201, Germany) to the nearest 0.5 cm; the average of the two measurements was included in the dataset. Prior to measurements, participants were asked to take off their shoes, sweaters and to empty their pockets. All measurements were repeated at one and two years of follow-up
5. Body composition: Body composition (i.e. total fat mass, lean body mass, body fat percentage) and bone mineral density were measured by a Dual-energy X-ray Absorptiometry (DXA) scan (Lunar prodigy, GE healthcare). If a participant did not fit the width outline of the scanner, only the right side of the body was scanned and results were mirrored. In a subsample (n=199), body composition (i.e. total fat, lean body mass, fat percentage) was measured using the Tanita body composition analyser (BC418MA, Tanita Corporation) instead of DXA. All measurements were repeated at one and two years of follow-up.
6. Vascular measurements: After 10 min of rest, blood pressure was measured on the left arm, six times with two minutes rest in between, while the participant was in supine position (IntelliSense HEM-907, Omron Health Care, USA). The second up to the sixth measurement were averaged; the first measurement was omitted to acclimatize the participant to the measurements. Dominant arm and room temperature were recorded. Advance Glycation Endproduct (AGE) accumulation was noninvasively measured in the human skin of the forearm, with an AGE-Reader (DiagnOptics B.V., Groningen, the Netherlands) on the inner side of the lower arm. Measurements were repeated three times and subsequently averaged. Arterial stiffness was assessed by pulse wave analysis of the radial artery by applanation tonometry (SphygmoCor® system, ATcor Medical, Sydney, Australia). A pressure-sensitive probe was placed on the radial artery to generate a pulse pressure wave. Subsequently, the corrected augmentation index (Aix) is estimated by combining the data of the brachial blood pressure measurements, central aortic pressure measurements, and heart rate measurements. All measurements were repeated at one and two years of follow-up.
7. Fasting blood biomarkers: Total cholesterol, HDL-cholesterol, triglycerides glucose, and creatinine were determined with enzymatic methods. LDL-cholesterol was calculated with the Friedewald equation. Catalytic activity concentration of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma glutamyltranspeptidase (γGT) levels were measured by international federation of clinical chemistry reference procedures at 37 °C degrees. For albumin determinations the bromocresol purple method was used. HbA1c was determined with HPLC measurement technology using an ADAMSTM A1c HA-8160 analyser (A. Menarini Diagnostics). Hb and Ht were assessed with colorimetric measurements using Advia 2120i Automatic analyser (Siemens, Erlangen, Germany) or using Sysmex XNseries (Sysmex inc., Lincolnshire, USA). Erythrocytes and leucocytes, including monocytes and lymphocytes, were determined with flow cytometry (Advia 2120i automatic analyser, Siemens, Germany or Sysmex XNseries, Sysmex inc., USA). An estimated Glomerular Filtration Rate (GFR) was calculated using the Modification of Diet in Renal Disease (MDRD) study equation as well as the new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. All measurements were repeated at one and two years of follow-up.

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