Similac is the first and only baby formula with 2'-FL Human Milk Oligosaccharides (HMOs), a unique immune nourishing prebiotic previously only found in breast milk.
2'-FL is backed by more than 15 years of extensive research and Similac Pro-Advance with 2'-FL helps strengthen baby's immune system to be more like a breastfed infant than ever before. Most prebiotics are known to support gut health (that's where 70% of the immune system exists). Similac with 2'-FL not only supports gut health, but also circulates in the bloodstream to support your baby's immune system throughout the body.