Human Breast Milk Composition

Nutrition for Infants

• Breast milk is the primary source of nutrition for infants up to the age of 6 months.

Lactogenesis

• The phase of lactogenesis between mid-pregnancy and two days postpartum is called Stage I or Secretory Differentiation.
• Stage II of lactogenesis, also known as Secretory Activation, involves the increased production of lactose, glucose, and milk lipids.

Human Milk Components

• The major components of human milk are carbohydrates, proteins, lipids, and other nutrients.
• Human milk contains over 200 separate chemical compounds.

Immunologic Functions of Human Milk

• T-lymphocytes, B-lymphocytes, neutrophils, macrophages, and epithelial cells in human milk provide immunological protection to the infant.

Milk Production and Maintenance

• The production and maintenance of mature milk from day 9 postpartum until weaning is referred to as Stage III of lactogenesis or Galactopoiesis.
• High levels of prolactin and progesterone maintain milk production during this stage.

Regulation of Milk Production

• The presence of milk in the alveoli inhibits the production of milk, a process called autocrine control.
• The hormone prolactin allows the synthesis of breast milk components by stimulating lactocytes.
• Insulin and cortisol are also involved in the regulation of milk production.

Colostrum and Transitional Breast Milk

• The primary function of colostrum, also known as 'the first milk', is to provide immunological protection to the infant.
• The transition from colostrum to mature milk occurs around 7-10 days postpartum.
• Transitional breast milk is characterized by a higher concentration of immunoglobulins and lower levels of lactose and lipids compared to mature milk.

Hormonal Regulation

• Progesterone is responsible for changes in the breasts during pregnancy to enable the production of milk.
• The primary role of Adrenocorticotropic hormone (ACTH) in breast milk production is to stimulate the release of cortisol, which helps regulate milk production.
• When the alveolus is full of milk, prolactin receptors are downregulated, reducing the production of milk.