Yes you can take protein, I recommend Gold Standard Whey Protein, GNC has it, but I buy mine from Vitamin Discount Center, check out some of your local stores to see if they carry the product, most of the time it will be way cheaper than GNC! (I pay $39.99 for mine, and it last nearly 2 months with daily use!)
http://www.gnc.com/product/index.jsp?productId=3267237&cp=3593187.2108294