Can I add casein to my blend? Matt Mazzino, RD, LD December 29, 2021 14:09 Updated Absolutely! If you'd like a blend that contains casein protein, send your registered dietitian a note at firstname.lastname@example.org. Related articles Can I get a different mix of protein sources? Do you offer a longer lasting form of protein? What should I mix my protein powder with? Are there amino acids in my protein powder? Is there egg protein in your protein powders? Comments 0 comments Please sign in to leave a comment.