The Content and Composition of Breast Milk

Stages of Breast Milk Production:

Colostrum, Transitional milk, and Mature milk.

Difference Between Breast Milk And Other Body Fluids:

The most amazing aspect of breast milk is that it is actually live. It's not a consistent body fluid such as blood -- it's a secretion of the mammary gland -- and it is constantly changing its composition, dependent, of course, on the interaction with the baby.

The Composition Of Breast Milk:

Breast milk, which is 90% water, consists of: nutrient proteins, non-protein nitrogen compounds, lipids, oligosaccharides, vitamins, minerals, hormones, enzymes, growth factors and protective agents.

It has 10% solids for energy and growth.

Typical Milk Volume:

  • From birth to 24 hours, colostrum averages about 37 ml
  • From 24 to 96 hours, there is a slow rise in volume
  • Day 5: approximately 500 ml/day
  • 3 to 5 months: 750 ml/day
  • 6 months: 800 ml/day

Milk Content Is Changed By:

  • Stage of lactation
  • Baby's gestation period
  • Mother's age
  • Time of feeding
  • Baby's feeding patterns

Immunoprotective Elements Of Breast Milk:

The Objective Conclusion:

With all of the amazing facts and figures about the composition of breast milk, what can we conclude? The distinction between breast milk and formula is powerful and should be carefully considered when deciding how to feed your baby. Feeding decisions are very personal, but being armed with knowledge about your choices can influence the growth and development of your baby.

We must ensure that breastfed babies are not being underfed since it is impossible to measure how much milk is in the breast (and it is equally as important that formula-fed babies are not being overfed.) Research has shown that as a result of the amazing content of breast milk breastfed babies have better gastric motility, mucosal mass, intestinal host defenses, brain and retinal growth.

During the first six months of life, breast milk is the optimal source of nutrition for babies. It is comprised of nutrients, enzymes, hormones, growth factors, host defense agents, vitamins A, C, B complex, binding proteins, lysozyme and antibodies, in addition to many other factors that build a strong, healthy human being.


Daly SEJ and Hartmann PE. Infant Demand and Milk Supply. Part I: Infant Demand and Milk Production in Lactating Women and Part 2: The Short-Term Control of Milk Synthesis in Lactating Women.Journal of Human Lactation 11(1), 21-37. 1995.

Lawrence RA. "Breastfeeding: A Guide For the Medical Professional". St. Louis, MO: Mosby. 1999.

Riordan J and Auerbach KG. "Breastfeeding and Human Lactation". Boston: Jones and Bartlett. 1998.

Wagner CL, Anderson DM, and Pittard WB. "Special Properties of Human Milk." Clinical Pediatrics. 6(35) 283-293. 1996.

Continue Reading