Discover our closest formula to breast milk: Similac Pro-Advance Step 2. Breast milk inspires all our research and innovation when it comes to infant formula. Our non-GMO formula also contains an exclusive blend of 2’-FL, DHA, lutein and vitamin E, making it our most advanced and closest formula to breast milk. 2’-FL is a unique component of breast milk that helps build baby’s immune system. Parents who fed their babies Similac with 2’-FL reported 3 TIMES FEWER respiratory infections. With Similac Pro-Advance, you can trust that you are giving your baby the nutrients they need to grow.