What Are the Hormones in Breast Milk?

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These are always present in breast milk and many of them retain normal activity when taken in, but hormone levels do shift over time.

Here are the primary hormones:

  • Thyroid Stimulating Hormone: Protects babies who have deficient activity of the thyroid gland
  • Prostaglandins: Play a part in the movement of food through the digestive tract, aid in peristalsis, and guard the protective lining of the stomach against inflammation and the death of important tissue
  • Cortisol: Aids in pancreatic growth of the infant and controls the transport of fluids and salt to the infant's gastrointestinal tract
  • Epidermal Growth Factor: A major growth-promoting agent in breastmilk

The Epidermal Growth Factor (EGF) is significant as it builds up certain types of tissues and strengthens the formation of DNA in the digestive tract. Research has also shown that it helps speed up the healing of injuries of the tissue covering the cornea. Other important results of EGF are that it helps the cells lining the small intestine mature and there is increased lactase (an enzyme in digestive juices that speeds up the breakdown of lactose, the major carbohydrate in milk, into glucose (a sugar essential for energy production) and galactose, which is a simple sugar) activity, and net calcium transport.


McCleary MJ. "Epidermal Growth Factor: An Important Constituent of Human Milk." Journal of Human Lactation, 7(3) 123-128.


Lawrence RA. Breastfeeding: A Guide for the Medical Profession. Mosby 1999.

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