Reflex Nutrition Micellar Casein Is a slow release protein source. Reflex Nutrition was one of the first companies in the world to introduce Micellar Casein as a pure unadulterated protein supplement to the market back in the 90s. During the time since the quality of the product has improved along with the flavour and mix-ability, today it is one of the Go To time release protein powders. This product does not contain any other types of added protein, especially soy, added glycine or anything that would water the product down. As a result it delivers more protein per 100 grams than nearly any other time release protein on the market today.