The Effect of a 2-week Preoperative Vegan Diet Versus Omnivorous Diet on the Protein Turnover in the Osteoarthritic Knee

Inclusion criteria

• Written informed consent;
• Patients scheduled for total knee arthroplasty;
• BMI between 20-32 kg/m2;
• Aged 60 - 80 years;
• Mentally competent, as judged by the treating physician;

Exclusion criteria

• Following a vegetarian or vegan diet or a diet that affects protein intake during the six months prior to the study;
• Participating in a structured progressive exercise training program in the past three months;
• Lost more than 4 kg body weight during three months prior to the study;
• Chronic use of medications that affect protein metabolism (i.e. systemic corticosteroids, or prescription strength acne medications);
• Being diagnosed with one of the following: diabetes mellitus, rheumatoid arthritis, peripheral artery disease Fontaine III or IV, COPD GOLD III or IV, neoadjuvant chemotherapy or radiotherapy, phenylketonuria, collagen disorders (e.g. Marfan and Ehler-Danlos);
• Alcohol abuse;
• Surgical intervention to the knee in the past four weeks;
• Total parenteral nutrition at day of surgery;
• Glomerular filtration rate (GFR) <20 mL/min/1.73 m2;
• Allergic or intolerant to any product included in the diets;
• Osteoarthritis of the knee secondary to septic arthritis, osteonecrosis, fracture, osteochondritis dissecans, or malignant processes;
• Any other medical condition that may interfere with the safety of the participants or the outcome parameters, in the investigators judgement;
• Not willing to stop nutritional supplements, with the exception of vitamin D and supplements on medical advice.
• Investigator's uncertainty about the willingness or ability of the participant to comply with the protocol instructions;
• Participation in other studies that may have an impact on the outcomes during the three months before the start of the current study.