Manufacturers make sodium caseinate by treating milk casein with sodium hydroxide. The result is a powder that disperses quickly in liquids, unlike micellar casein, so it appears in many protein shakes, meal replacements, and processed foods. Despite the easy mixing, the protein still clots into a gel inside the stomach, which slows digestion and delivers amino acids over a longer period.
Athletes and others use it as a general protein supplement, especially for a slow supply of amino acids between meals or before bed. Some people prefer it over micellar casein because it blends more smoothly, but that is only a convenience factor. The digestion speed and tolerance remain the same.