True about breast feeding –
Breast milk is beneficial for both preterm and term infants because the composition of breast milk varies according to the needs and age of the infants. For example, preterm milk contains more protein `S', sodium, iron, immunoglobulins and calories as they are needed by the preterm baby.
Breast milk and energy by different constituents

Carbohydrate                                      30-40%
Protein                                                  7-10%
Fat                                                          45-60%

Breast milk contains N-acetyl-D glucose and lactose which promotes lactobacillus. On the other hand, high content of glucose and casein in formula feeds inhibits the growth of lactobacillus.
Breast milk appears to be protective for necrotizing enterocolitis. Almost all patients of neonatal necrotizing enterocolitis are artificially fed.
Low protein contents of breast milk along with a higher concentration of secretory IgA decreases the absorption of protein macromolecules ---> Less chances of allergy and asthma
Best for both preterm & term
Promote lactobacillus growth in bowel
Decrease allergic disorder
All of these