Casein protein is a dairy protein that people supplement. It is a slow-digesting source of protein which slowly release amino acids into your system. This is why people often supplement it before they go to bed as it helps with the recovery of their muscles whilst they are sleeping. Studies have also shown that casein protein also boosts muscle growth with several other benefits.
Casein proteins are pH sensitive and gel in the acidic environment of the stomach. As a result, it can take more than twice as long for caseins to be broken down into their amino acid subcomponents than whey and other proteins. Because of their unique time-released qualities, caseins are aptly described as anti-catabolic or muscle-protecting proteins.