The impact of milk protein glycation on protein digestion and absorption in healthy young men

Protein intake is an essential stimulus for muscle protein anabolism. The
muscle protein synthetic response to protein ingestion is mainly determined by
the post-prandial plasma amino acid response. Milk protein often undergoes
glycation during commonly applied milk processing procedures (Maillard
reaction). We have previously shown that glycated protein results in lower
postprandial amino acid levels. The level of protein glycation in processed
dairy products might therefore be an important modulator of the overall protein
quality of a product, and its ability to stimulate protein metabolism. However,
it has not yet been investigated if the glycation level of dietary protein
modulates its appearance in plasma as amino acids.

To compare the appearance of dietary protein-derived amino acids in plasma
after ingestion of a milk protein powder with different levels of protein
glycation in healthy young men.

Double blinded, randomized cross-over study.

All subjects will perform two experiments in a double-blinded, randomized
order: ingest 40 g of milk protein with 5% glycation level in 600 mL water, or
40 g of milk protein with 50% glycation level in 600 mL water. After ingestion,
blood samples will be taken at regular intervals during a 6 hour period.

The burden and risks with participation are small. A DEXA scan will be done to
assess body composition, where the level of radiation is very low compared to
the background radiation level in the Netherlands. Furthermore, we will ask the
participants to fill out a medical questionnaire. Insertion of the catheters
during the test day is comparable to a blood draw and could result in a small
hematoma. We will take 15 blood samples during the experimental period. The
total amount of blood we draw (150 mL each test day) is much less than the
amount of a blood donation (500 mL) and will be completely restored in
approximately 1 month. Participants will come to the university three times: 1
screening (~1h) and 2 experimental days (~8.5h each). On the experimental test
days, the subjects will be asked to remain fasted (with the exception of the
experimental drinks). In addition, subjects will be asked in the two days prior
to the test days not to perform any type of intense physical activity and to
avoid consuming caffeine and alcohol in the 12h and 24h prior to the test days,
respectively. Participants will be asked to record their nutritional intake and
daily activities in the two days prior to the experimental test days. There is
no direct benefit to the participant, only their contribution to the scientific
knowledge on the impact of protein glycation on protein digestion and
absorption. The milk protein supplements are produced according to food safety
standards and are safe for human use.