The Science Behind What Breast Milk is Made Of

Pregnancy is an exciting, beautiful and deeply personal time, during which your body will naturally start to accommodate your growing baby while producing and responding to new hormones. It's also a time when your body will prepare to make breast milk, a vital source of nutrition and wellness for your little one.

The Science of Breast Milk Composition

You may already know that your breasts will make milk on an “on-demand” basis when you begin breastfeeding. This means that how often and how much milk is removed from the breasts are primary factors that determine continued production of breast milk. In short, more milk will be produced if your breasts are emptied more frequently through nursing or pumping.

In fact, research shows that nearly every mother’s milk supply follows a relatively predictable journey through a few distinct lactation phases. However, you may be wondering about the science of breast milk composition itself; specifically, what makes it the ideal nutrition for your little one? How do your milk’s diverse components work together to protect your baby? How does your breast milk differ from formula? You've got questions, and we've got answers!

What is Breast Milk Made of?

It’s important to remember that breast milk is a living fluid that changes throughout your breastfeeding journey to meet the evolving needs and overall development of your baby. Colostrum (or “first milk”) is different from mature milk that's produced later as your baby grows. In fact, colostrum contains about double the amount of protein of later milk. It is jam-packed with vital components to address the unique health needs of your baby while promoting overall well-being, particularly in the areas of intestinal development and infection risk reduction.

Breast milk itself contains millions of live cells per millimeter. These include leukocytes to protect your little one from infection and stem cells that can then transform into other cell types like fat, bone, liver, and brain cells. In fact, the stem cells that your newborn receives from your breast milk may even act as the foundation for their own internal building and repair system.

Many healthy fats, such as omega-3 fatty acids, are also prevalent in breast milk and optimize crucial brain growth and development, especially in preterm babies who may have missed specific markers from the final trimester of pregnancy.

As vital as healthy fats, stem cells, and leukocytes are, they are only a tiny fraction of what breast milk is made of. In actuality, there are thousands of important ingredients in your breast milk. To find out what they are and how they benefit your growing baby, take a look at this detailed breakdown.

What Makes Breast Milk Different from Formula?

The overwhelming majority of breast milk’s components cannot be replicated artificially. In most cases, formula contains only water, fat, protein, DHA/ARA, carbohydrates, vitamins, and minerals. While the science of breast milk composition continues to evolve, breastfeeding is still considered the gold standard for your baby’s nutritional, developmental, and wellness needs.