Human breast milk is known to provide the most complete nutrition to growing infants. There may be more gained from breastfeeding than simply nutritional fulfillment-recent research has uncovered benefits related to the development and health of infants. Breastfeeding has been shown to stimulate immune system development by exposing the infant to bacteria and antibodies from the mother. Breastfeeding may also benefit nursing mothers by improving insulin sensitivity and glucose tolerance as well as decreasing postpartum weight gain. In place of breastfeeding, formulas are able to provide an infant with necessary nutrition. Many infant formulas have been enriched with probiotics and prebiotics to provide formula-fed infants with similar immune system benefits. Research on these formulas is inconclusive at this time, though hydrolyzed formulas have the potential to prevent autoimmune diseases and food allergies. Research has found many differences between breastfed and formula-fed infants. For instance, children who had been exclusively breastfed for more than three months showed significantly higher cardiovascular fitness levels than those who were formula-fed. Additionally, at 6 months of age, breastfed infants were found to have a lower protein intake and leaner body mass compared to formula-fed infants. The microbiome of breastfed infants also differs from formula-fed infants, with breastfed infants having higher concentrations of beneficial Bifidobacterium species (spp.) and formula-fed infants hosting a wide range of potentially pathogenic bacteria including Clostridium spp., Streptococcus spp., Staphylococcus spp. and Enterobacteriaceae family. Pharmacists can play a vital role by providing breastfeeding-related services to patients including education, breast pump or infant formula selection, and counseling regarding medication use during lactation.