Once ingested, casein coagulates (curdles) in the acidic environment of the stomach, which is why it is digested slowly. It moves into the intestine and is broken down into amino acids that can be used to initiate and maintain the process of muscle protein synthesis. This process takes several hours, with amino acid concentrations reaching their peak around 7 hours after ingestion.[1]
How does casein work?
Written by:
Fact-checked
by:
•Last Updated: May 16, 2025
Casein coagulates in the stomach's acidic environment, leading to slow digestion. It is then broken down into amino acids in the intestine, which peak in concentration approximately 7 hours after ingestion, thus supporting muscle protein synthesis.