GNC Pro Performance 100% Casein Protein - Chocolate Supreme Maintaining adequate protein levels throughout the day can be a challenge. Casein is a slow-release protein naturally rich in glutamine and branched chain amino acids (BCAA). 100% Casein contains 25 grams of protein providing slow and steady amino acids for muscle growth and maintenance over several hours. A perfect choice for overnight and long-period lean muscle recovery. 100% Casein supports your wellness and performance goals. High-Quality Gluten Free Protein Supports Muscle Recovery with Slow-Digesting Protein Tested and certified Banned Substance Free