Breastmilk has many components. It is 87% water. It contains proteins, carbohydrates and fats. It has water soluble vitamins (such as B12, C, riboflavin, folate and others). It contains minerals and ions like calcium, chloride, magnesium, sodium and potassium among others. It has fat soluble vitamins like A, D, E and K. It has trace minerals such as iron, zinc, fluoride and more. It has amino acids which are the building blocks of proteins.
It also contains a large variety of living cells. Many of the living cells give babies immunities. Although there are a greater concentration of these cells in colostrum, mature milk also gives babies a great deal of living cells which protect against bacteria, viruses and molds.
Human milk is rich in fatty acids and especially long-chain poly-unsaturated fatty acids. These fatty acids are critical to helping babies develop retinal (eye) and neural (brain) tissues. (Marie Biancuzzo’s Breastfeeding the Newborn)
Mother’s milk changes during the day and the season, the same way your diet changes. It changes in fat content and flavor and gives the baby more types of tastes than formula does. Breastmilk gives your baby variety and formula always tastes the same.