Overview
The aim of this study is to investigate the effects of a four-week time-restricted eating (TRE) intervention on autophagy, immune function, and vaccine response to a seasonal influenza and COVID-19 vaccines in older healthy subjects.
Description
Aging impairs immune cell autophagy and reduces vaccine efficacy, leaving older adults highly vulnerable to influenza and other infectious diseases. Time-Restricted Eating (TRE), by limiting daily food intake to an 8-hour window without detailed calorie counting, modulates nutrient-sensing pathways (e.g., mTOR inhibition, AMPK activation) and boosts autophagic flux in preclinical models. In a randomized, controlled trial, healthy volunteers aged 60-85 will follow either four weeks of TRE or their usual eating pattern. After that, all will receive a standard seasonal vaccines against influenza and COVID-19 outside of the trial at their general practitioner (min. 2 days and max. 14 days after the stop of intervention). Blood and physiologic measurements at baseline, after four weeks of study intervention will quantify autophagy in immune cells, metabolome/proteome shifts, body composition, blood pressure, and arterial stiffness, among others. At two additional visits after the vaccination (2 weeks and 12-14 weeks after the vaccination), immune responses to the vaccination will be monitored in the blood. The investigators hypothesize that TRE-induced restoration of autophagy and amelioration of immunosenescence will correlate with stronger vaccine responses, offering a simple, low-cost strategy to rejuvenate immunity and improve preventive care in the elderly.
Eligibility
Inclusion Criteria:
- Male and female participants, enrolled in a 1:1 ratio
- Age 60-85 years
- Body mass index (BMI) 20-35 kg/m²
- Capacity to give informed consent
- Existing health insurance to allow evaluation and treatment of any incidental findings
- Usual daily eating window > 11 hours
- First meal of the day before 10:00 AM
- Willingness to receive seasonal influenza and COVID-19 vaccination and proof of scheduled appointment
- Willingness and ability to follow a prescribed TRE dietary regimen (8-hour daily eating window; 16-hour fast without any caloric intake)
- Appointment for simultaneous influenza and COVID-19 vaccination pre-arranged with primary care physician and coordinated with study team to align with TRE intervention
Exclusion Criteria:
- Any vaccination (especially influenza and/or COVID-19) within 6 months before the intervention start
- Vaccinations not related to the study, administered during the study period from V0 to V4
- History of influenza infection within 6 months prior to initiation of the study intervention
- History of severe adverse reactions to prior vaccinations
- Use of pharmacological weight-loss agents (e.g., semaglutide)
- Diabetes mellitus under ongoing pharmacological treatment
- Symptoms of systemic inflammatory or autoimmune disease
- Immunosuppression (including use of immunosuppressive drugs)
- Severe hypertension (systolic > 180 mmHg or diastolic > 110 mmHg)
- Diseases or functional disorders which, in the opinion of the study physician, preclude participation in the study
- Participation in any fasting intervention (e.g., TRE, alternate-day fasting, 5:2, 18:6) within 6 months before enrollment
- Participation in another diet or weight-loss program (e.g., intensive athletic training)
- Night-shift or rotating-shift work
- Severe, active, or unstable medical conditions requiring treatment
- Postoperative recovery phase
- Antibiotic therapy within 3 months before enrollment
- Acute or chronic infections
- Therapeutic or medically prescribed special diets
- Vegan diet
- Current smoker
- Weight change > 2 kg in the month before enrollment
- Known substance, drug, or alcohol abuse
- Anemia
- Claustrophobia
- Legal incapacity or any other circumstance that prevents full understanding of the nature, importance, and implications of the study