Human milk is composed of about 88% water, 7% lactose, 4% fat, 1% protein, various ions, vitamins and antibodies.
The ions are mainly sodium, potassium, chloride, calcium and phosphate. Antibodies are mostly of the IgA (secretory) type and, together with the antibodies the infant gains from its mother via the placenta, are responsible for the infant's passive immunity in its first few months of life.
The composition of colostrum is quite different, with a much lower caloric content and an ionic composition more like plasma. It is said to contain more antibodies.
Breastfeeding infants is recommended for all mothers for the first few months of a baby's life.
Lactation is good.