RecruitingNAINTERVENTIONAL

Effect of Vegetarien Diet on Protein Digestibility in Young and Elderly Volunteers

This study is investigating how our bodies process protein from plants, specifically peas. It's comparing two groups: younger adults (18-23 years old) and older adults (65-75 years old). Within these age groups, the researchers are looking at both vegetarians and people who eat meat (omnivores). The main goal is to understand if age or diet makes a difference in how well we digest and use plant-based proteins. This is really important because more people are choosing plant-based diets, and older adults, in particular, need enough protein to stay healthy. The findings could help guide better eating advice for different age groups and diets.

At a glance

Status

Recruiting

Phase

Sponsor

Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement

Enrolment target

Start

22 Oct 2025

Estimated completion

31 Dec 2026

Vegetarian Diet Elderly Young Healthy Adults

What is this study about?

You know how some people are choosing to eat more plant-based foods, like vegetables, beans, and lentils? And how older people often need more protein to keep their muscles strong? This study is trying to understand something really important about this: how well our bodies actually use the protein from plants.

Proteins are the building blocks of our body, and usually, protein from animals (like meat or dairy) is thought to be easier to digest than protein from plants. But plant-based diets can also be very good for your gut health. So, this study wants to see what really happens when people eat plant protein, specifically from peas. They are looking at younger adults and older adults, and comparing those who eat a vegetarian diet with those who also eat meat. This helps us see if age or your usual diet changes how your body uses plant protein.

The findings from this research will be very helpful. They'll tell us if older adults, who need more protein, can properly get it from plant-based foods. This knowledge can then be used to give better advice to people about what to eat to stay healthy, especially as we get older or choose to eat more plant-based meals.

Key takeaways

This study explores how our bodies digest protein from peas.
It compares younger and older adults, and vegetarians and meat-eaters.
Participation involves two clinic visits, eating a pea meal, and giving blood and urine samples.
The study helps understand if age or diet changes how we use plant protein.
Findings could help give better dietary advice for different groups, especially older adults.
Your contribution is valuable for scientific knowledge, with no guaranteed direct personal benefit.

Who may be eligible?

You might be able to join this study if you are a healthy adult, either between 18 and 23 years old, or between 65 and 75 years old. You should have a normal weight or be slightly overweight (your BMI should be between 18 and 30). You can be either male or female.

When it comes to your diet, you should either be an omnivore (meaning you regularly eat meat, more than 3 times a week, and most of your protein comes from animal sources) or a vegetarian (meaning you don't eat meat or fish, and most of your protein comes from plants). You must also be in good general health, without certain long-term health conditions like diabetes, severe blood pressure issues, or serious stomach, liver, or kidney problems. You cannot be pregnant or consume a lot of alcohol.

There are also some things that would mean you couldn't take part. For example, if you have any known food allergies, certain infections like HIV or hepatitis, or if you have anaemia (low iron in your blood). You also can't be taking part if you're under legal protection or can't give your clear consent to join the study.

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 18-23 or 65-75 years old?
Do you have a healthy weight (BMI 18-30)?
Are you generally in good health, without serious ongoing conditions like diabetes or severe blood pressure?
Do you either regularly eat meat OR follow a vegetarian diet (no meat/fish)?
Are you not pregnant and do not have any known food allergies?
Do you consume alcohol responsibly (not more than 2 drinks per day)?

Answer every question to see your result.

What does participation involve?

If you decide to take part, you'll visit the clinic on two separate days. These visits will be about 4 weeks to 2 months apart.

On each visit day, you'll be given a meal made from peas. This meal will have special labels (harmless, safe 'tracers') added to the protein, so the researchers can track how your body uses it. On the first visit day, after eating the pea meal, nurses will take blood samples regularly over 8 hours (about 156ml of blood in total, which is roughly a small mugful). You'll also collect all your urine every 2 hours.

On the second visit day, you'll also eat a pea-based meal, and the researchers will again look at how your body handles the protein. The total time you'll be involved in the study is the duration between your two clinic visits, likely between 4 weeks and 2 months.

Potential risks and benefits

Any research study has potential benefits and risks. The main benefit of taking part is contributing to important scientific knowledge about diet and health, which could help many people in the future, especially older adults and those eating plant-based diets. There are no direct personal benefits guaranteed. Possible risks include discomfort from blood draws (like bruising or slight pain) and the time commitment for the clinic visits. We want to reassure you that the special labels used in the pea meal are completely safe. You are free to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (1)

Centre de Recherche sur Volontaire, Hopital Avicenne (AP-HP)
Verified postcode
Bobigny, France· Recruiting

Common questions

What kind of pea meal will I eat?

You'll eat a pea-based meal (around 100g dry weight) that has special, harmless 'tracers' added to the protein so researchers can track it.

Why are there different age groups in the study?

The study wants to see if your age affects how well your body digests and uses protein from plants. Older adults often have different protein needs.

How much blood will be taken?

During one of the study days, about 156ml of blood will be taken over 8 hours. This is roughly the amount in a small mug.

Do I need to be a strict vegetarian to join?

No, the study includes both people who eat meat regularly (omnivores) and vegetarians, so you could fit into either group.

Can I leave the study at any time?

Yes, you have the right to withdraw from the study at any point, and you don't need to give a reason.

How to find out more

Juliane Calvez, PhD

juliane.calvez@agroparistech.fr +33189100875 Official trial record

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