What does breast milk contain?

Protein, fat, carbs. The aap recommends exclusive breastfeeding for the first 6 months for a good reason. The proteins in breastmilk are easily digested and immunoglobulins protect your baby from bacteria and viruses. The fat help with brain and eye development. Breastmilk also contains vitamins and carbohydrates (mainly lactose) in the perfect combinations for your baby's health.
Great stuff! Breast milk is the perfect food for babies: it has the right balance of fat, sugar, and protein, and it contains other nutrients like iron in small but very digestible amounts. The most unique and irreplaceable part of breast milk is immunity. Milk has antibodies, the tiny immune shields that protect against infections, and that vaccines will promote later in infancy and life.