The effectiveness of daily protein supplementation with a plant protein blend vs milk protein to support integrated muscle protein synthesis rates with and without exercise in healthy older individuals.

Nutrition contains protein. The protein is made up of building blocks, called
amino acids. Following ingestion, these will be taken up by the gut and appear
in the blood. Blood transports the amino acids to the muscles and other organs.
Consumption of sufficient protein facilitates the availability of sufficient
amino acids for muscle protein accretion. Muscle protein accretion is required
to maintain and improve muscle health and enables us to walk, cycle, but also
exercise.
Nutrition guidelines prescribe a protein threshold of at least 0.8g protein/ kg
body mass/day, but is it suggested that older individuals should ingest more
protein. It is difficult to ingest sufficient protein through food products
only and thus ingestion of protein powders would be a strategy to improve
protein intake. Plant protein can be produced in a more sustainable way, but
the amino acid composition is suboptimal. Blending different plant proteins
would be a good way to improve the amino acid composition and thereby protein
quality similar to milk protein. This way both a plant protein mix and milk
protein could contribute to muscle accretion by increasing protein intake.

To assess the effectiveness of daily protein supplementation with either a
plant based protein blend or a milk protein on top of a standard diet to
stimulate integrated muscle protein synthesis rates in healthy older
individuals with and without exercise.

Randomized, parallel-group, double-blind intervention trial.

consumption of twice daily placebo (carbohydrates), plant blend (2x 20g protein
pea-corn-blend) or milk protein (2x 20g protein from milk protein concentrate)
while adhering to a diet containing 0.8g protein/kg body mass/d.

The burden and risks associated with participation in this study are moderate.
The participants will visit the university 4x after an overnight fast for
measurements (3 hours max). They will fill out a single medical questionnaire.
They will adhere to a prescribed nutrition pattern for 14 days. They will daily
ingest heavy water, sample saliva, and consume twice daily supplements. They
will also wear a step counter.
The venapunction can be unpleasant and result in a small hematoma. Biopsies
will be obtained by an experienced physician. participants can experience
stiffness in the thigh muscle for a few days after the biopsy and these days
there is a small risk for additional bleeding. Because of the 3 biopsies this
risk is present 3 times, but should not pose a big health concern. The
ingestion of heavy water has been applied in
numerous published studies and is entirely safe and non-toxic in the amounts
provided in the present study. Diets and supplements will be composed of
commercially available products.
The dexa scan provides insight in the body composition, but involves a small
dose of radiation, which is negligible and comparable to the yearly background
radiation dose.
There is no direct benefit for the participants when participating. They will
get insight into their body composition (DEXA) and receive 14 days worth of
food, which will decrease living expenses for that period.