RecruitingNAINTERVENTIONAL

VITAL: Vaccination, Immunity, Time-restricted Eating, Aging and Lifestyle

The VITAL study is exploring if a specific eating pattern, known as time-restricted eating (TRE), can boost the immune system in older adults. For four weeks, some participants will eat all their meals within an 8-hour window each day, while others will continue their usual eating habits. After this, everyone will receive standard seasonal flu and COVID-19 vaccines. Researchers will then check blood samples to see if the TRE group shows a stronger response to the vaccines, indicating a better working immune system. The goal is to find a simple, low-cost way to help older people better protect themselves against infections.

At a glance

Status

Recruiting

Phase

Sponsor

Charite University, Berlin, Germany

Enrolment target

Start

10 Sep 2025

Estimated completion

01 Jan 2027

Vaccination Immunosenescence Metabolism

What is this study about?

As we get older, our immune systems can become a bit slower and less effective, a natural process known as 'immunosenescence'. This means older adults might not respond as strongly to vaccines like those for flu and COVID-19, making them more vulnerable to these illnesses.

This study is investigating a particular eating pattern called Time-Restricted Eating (TRE). This simply means eating all your meals within a set window each day – for this study, it's an 8-hour window, with the remaining 16 hours being a fasting period where you don't eat any food. The idea is that this type of eating might help to 'rejuvenate' or improve how our cells clean themselves and how our immune system works, without needing to count calories.

We're hoping that if older adults follow this TRE pattern for four weeks, their bodies will respond better to the flu and COVID-19 vaccines they receive afterwards. If successful, this could offer a straightforward and inexpensive way for older people to boost their immunity and get better protection from common infections.

Key takeaways

This study explores if eating within an 8-hour window can boost immunity in older adults.
It aims to see if this improves protection from seasonal flu and COVID-19 vaccines.
Participation involves following a specific eating pattern or usual habits for four weeks.
Blood tests will check immune responses before and after vaccination.
The goal is a simple, cost-effective way to improve health for older people.
You'll get your standard vaccines from your GP during the study.

Who may be eligible?

This study is looking for healthy men and women between the ages of 60 and 85. Your weight should be within a healthy or moderately overweight range (BMI between 20 and 35). You should also typically eat over a longer period than 11 hours daily, usually starting your first meal before 10 AM.

To join, you must be willing to receive your seasonal flu and COVID-19 vaccinations shortly after the study's eating phase, and you'll need to arrange these appointments with your GP. You also need to be able to stick to the eating plan, which means eating all your food within an 8-hour window each day, with no snacks or drinks containing calories during the other 16 hours.

You cannot join if you've had certain vaccinations or a flu infection recently, have severe reactions to vaccines, or are currently using certain weight-loss medications. People with specific health conditions like diabetes treated with medication, severe high blood pressure, or diseases affecting the immune system are also not able to participate. Also excluded are those who have recently used other fasting diets or have jobs affecting regular eating patterns. The study doctor will make the final decision on whether it's safe for you to take part.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you between 60 and 85 years old?
Do you currently eat over a period longer than 11 hours most days?
Are you willing and able to only eat during an 8-hour window for four weeks?
Are you planning to get your seasonal flu and COVID-19 vaccines during the study period?
Do you NOT have conditions like treated diabetes, severe high blood pressure, or a compromised immune system?
Have you NOT used other fasting diets within the last six months?

Answer every question to see your result.

What does participation involve?

If you join the study, you'll be randomly assigned to one of two groups: either you'll follow the time-restricted eating plan for four weeks, eating your meals within an 8-hour window daily, or you'll continue with your usual eating habits. Importantly, you won't be told to change what you eat, just when you eat it. After these four weeks, everyone will receive their seasonal flu and COVID-19 vaccines from their GP, as normal.

You'll have several visits for blood tests and other measurements – at the start, at the end of the four-week eating period, and then two more times after your vaccinations (about 2 weeks and then 12-14 weeks later) to check your immune response. These tests will help us understand how your body's cells are working and how well you've responded to the vaccines. The total duration of your participation, including follow-up after vaccination, will be around 16-18 weeks.

Potential risks and benefits

Taking part in this study could potentially offer benefits by helping us understand how a simple eating pattern might boost your immune system and make vaccines more effective. This knowledge could lead to new ways to improve health for older adults. You might also find personal benefits from trying time-restricted eating, such as improved energy levels, although this is not guaranteed. However, there are potential risks, such as feeling hungry or experiencing changes in energy levels, especially during the fasting periods. There are no changes to your current medications related to the study. You have the right to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (1)

Clinical Research Unit, Experimental & Clinical Research Center, Campus Buch, Charité
Verified postcode
Berlin, Germany· Recruiting

Common questions

What exactly is 'time-restricted eating'?

It means you eat all your meals and snacks within a set short window each day, and then fast for the rest of the time. For this study, it's an 8-hour eating window and a 16-hour fasting period.

Do I have to change what I eat, or just when?

The study focuses on *when* you eat, not *what* you eat. You'll continue to eat your usual foods, just within the specified time window.

Will I still get my usual flu and COVID-19 vaccines?

Yes, you will receive your standard seasonal flu and COVID-19 vaccines from your GP shortly after the four-week eating phase of the study ends.

What happens during the study visits?

You'll have a few visits where we'll take blood samples and perform other measurements to check your body's response, especially to the vaccines. These are standard checks, not special treatments.

Can I leave the study if I change my mind?

Absolutely. Your participation is voluntary, and you can withdraw from the study at any point without it affecting your medical care.

How to find out more

Sebastian Hofer, Dr. rer. nat.

sebastian.hofer@charite.de +493094062372 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.