Casein protein powder, traditionally known for muscle building, also has potential benefits for skin health. Its slow-digesting nature provides a sustained release of amino acids, which are crucial for skin repair and collagen production, making it potentially useful for overnight skin rejuvenation. While not a direct topical treatment, incorporating casein into your routine, especially before bed, may contribute to a smoother, firmer complexion and improved skin health, potentially reducing fine lines and wrinkles.