Casein compositions for increasing the rate of gastric emptying following ingestion of the composition, increasing the digestibility of a protein composition, or increasing the rate of delivery of amino acids to the blood, or for increasing the blood serum concentration of free leucine in a subject, preferably to substantially the same level as whey protein, the casein being about 10 to about 100% calcium depleted, having a degree of hydrolysis less than about 1% and having an unmodified phosphorylation pattern.