The impact of ingesting a whole-food animal-based versus plant-based protein rich meal on the muscle protein synthetic response in healthy older men and women

Food intake stimulates muscle protein synthesis rates. The magnitude of the
anabolic response to feeding forms a key factor in regulating muscle mass
maintenance. Ingestion of animal-derived proteins generally leads to a greater
stimulation of muscle protein synthesis when compared to the ingestion of
plant-derived proteins. What is often neglected is that the anabolic properties
of protein isolates do not necessarily reflect the anabolic response to the
ingestion of the whole-foods from which they are derived. This discrepancy is
due to the presence or absence of other components normally found within
whole-food matrices, which influence protein digestion and amino acid
absorption from animal based and plant based protein sources. A rapid and
robust post-prandial release of food-derived amino acids is of particular
relevance for older individuals, who typically show a blunted muscle protein
synthetic response to feeding

To compare the post-prandial muscle protein synthetic response following
ingestion of a whole-food meal containing meat versus the ingestion of a meal
containing only plant-based protein sources in vivo in healthy, older men and
women.

randomized, counter-balanced, cross-over design, researchers and participants
are not blinded, analysts are blinded.

Participants will undergo 2 test days. On one test day participants will
consume a meal containing meat, the other day participants will consume a meal
without meat.

The burden and risks involved in participating in this experiment are small.
Participants will visit the University on three occasions (screening + 2 test
days). The first visit will involve a screening visit (~2 h), during which the
eligibility of the participant will be assessed. During the screening visit, a
medical questionnaire is filled out, and a DEXA scan will be performed to
assess body composition, where the level of radiation is very low compared to
the background radiation level in the Netherlands.
The participants will participate in 2 test days of ~12h. Insertion of the
catheters during the test days is comparable to a normal blood draw and the
only risk is a small local hematoma. During each of the 2 experimental test
days 16 blood samples (170mL/day) will be obtained. The total amount of blood
collected during this study is less than the amount of a blood donation and
will be completely restored in approximately 1 month. The stable isotope amino
acids tracers that will be infused intravenously during the experimental trial
are produced according to GMP standards and are safe for human use. Throughout
each test day, muscle biopsies will be obtained under local anaesthesia by an
experienced physician, but may cause some minor discomfort. The discomfort is
comparable to muscle soreness or the pain one has after bumping into the corner
of a table. Additional expired breath samples will be collected and analysed
for 13C/12C ratio, this procedure is comparable to gently exhaling in a balloon
and does not involve any risks.
For each visit participants are required to come to the university in a fasted
state, not having consumed any food or beverages (except for water) as from
22:00 the evening before. Also, 2 days prior to the experimental test days
participants need to record their food intake and activities performed. During
these 2 days participants are not allowed to perform heavy physical exercise or
drink alcohol. There is no direct benefit for the participants, except from
their contribution to scientific knowledge on the impact of whole food protein
ingestion on stimulation of muscle protein synthesis.