What Exactly Is in My Breastmilk?

What Exactly Is in My Breastmilk?

What is in breastmilk?

You have probably heard that breastmilk supplies all the nutrients your infants needs. But have you ever wondered exactly what is in your milk? While we know the components or “ingredients” in breastmilk, the composition will be different for each mom.

Breast milk is a living substance that is ever-changing to meet the needs of your growing child. And your milk is tailor-made specifically for YOUR baby - day by day, month by month, and feeding by feeding. Your body changes the composition of milk to meet your little one’s specific needs. No two breastmilk samples are exactly alike.  

Breastmilk components:


Breastmilk contains many fats which help your baby's body and brain grow. It is rich in Omega 3 fatty acids like DHA. The level of these fats is automatically adjusted to your infant's specific needs.   

“Fat is the most important nutrient in breastmilk; the absence of cholesterol and DHA, vital nutrients for growing brains and bodies, may predispose a child to adult heart and central nervous system diseases.” - Dr. Sears (https://www.askdrsears.com/topics/feeding-eating/breastfeeding/why-breast-is-best/comparison-human-milk-and-formula)  


Breastmilk is rich in many proteins, including cholesterol and DHA, intestinal and digestive help (lactoferrin), antimicrobials, brain-building blocks, and sleep-inducing proteins. It is very rare for an infant to be allergic or sensitive to human milk proteins.  


Breastmilk contains lactose (milk sugar) and oligosaccharides, which help with digestion and intestinal health.  Lactose is important for brain health and growth. Human milk has higher lactose volumes than other milk from mammals.  

Immune boosters

Breastmilk is full of living white blood cells that boost your baby's immune system. Just one teaspoon of breastmilk contains approximately three million germ-killing cells.   As you are exposed to germs and as you interact with, feed, and kiss your baby, your body is able to take “messages” back that translate to specific antibodies in your milk, which then provide protection for your baby. This is why you do not have to stop breastfeeding when you are sick - your milk is actually protecting your baby!     

Vitamins and minerals

Readily-absorbed vitamins and minerals are found in breastmilk. Zinc, iron, and calcium are the highest absorbed.

Enzymes and hormones

Thyroid enzymes, prolactin (the hormone that tells you to make milk), oxytocin, and many more are found in breastmilk. The hormones and enzymes found in breastmilk will highly vary from mother to mother, depending on the age of the baby, the mother's diet, and many other factors. Studies show that when a breastfeeding mother eats a variety of foods, her baby may be more willing to try more foods when the time comes to introduce solids, due to the various flavor changes in breastmilk.  


Commonly referred to as a “liquid gold,” this is the first milk you make for your baby. It is higher in proteins and immune factors than mature milk, which gives it that gold, yellow, or orange hue. This milk is very rich, and your baby will remove small amounts frequently in the first few days of life.  


What is in colostrum?

Colostrum is the first milk that your newborn will receive. During the second trimester of pregnancy (about 14-16 weeks) your body begins to produce colostrum. This milk is very thick, sticky, and has a smell that is similar to amniotic fluid, which your baby practices swallowing in the womb. The similarities between colostrum and amniotic fluid are intentional by nature – this smell will help your baby find the breast after birth, and the consistency is familiar.  

Packed with antibodies, this thick and sticky milk coats the newborn stomach and prepares the digestive system for mature milk and even solid foods as they grow. With a high white blood cell count, colostrum also protects your little one from any infections as they adjust to the world outside the womb.  

Colostrum is breastmilk, and the only difference in colostrum and mature milk is the composition – it is tailor-made for your newborn in the first few days following birth. Often called “liquid gold” because of its golden color, colostrum is produced in small amounts, as newborns have small tummies and need small but frequent feedings.

What comes next? - Transitional Milk

Around 3-5 days postpartum, you should start to feel a fullness in the breast, which is often referred to as your breastmilk “coming in.” The colostrum has been there all along, but this process is a response to your baby beginning to remove more milk with each feeding.  

Days 5-14 postpartum, breastmilk is referred to as “transitional milk”. As your breastmilk starts to shift from colostrum to more mature milk, you may notice it becomes more creamy, white, or even bluish in color. It is produced in larger amounts and it continues to change to meet your new baby's needs.  

During this time, responsive breastfeeding, also known as feeding on demand, is especially important for establishing your milk supply. Your baby may want to cluster feed or feed frequently, and that is perfectly normal and helpful in the process of breastfeeding.  

Breastmilk is tailored to your baby's needs

About two weeks or 15 days postpartum, breastmilk has transitioned to “mature milk.” Like all other phases, this milk has all the nutrients your baby needs – composed specifically for your little one. While the nutritional content of breastmilk stays largely the same, it continues to be customized to your little one.   When you bring your baby to the breast, your body responds to the saliva exchange and customizes the composition of your milk.

No two breastmilk feedings are exactly alike and as your baby continues to grow, this process ensures that your milk continues to meet their needs. For example, if you are sick or have been exposed to an illness, your body will begin to produce additional antibodies in your milk to protect your baby. The fat and water content may also vary from feeding to feeding, depending on your little one's needs. This customization applies to pumped breastmilk as well.

Even if you are exclusively pumping, your milk is still tailored to your baby's needs because of your close interactions with your baby, including kissing, snuggling and skin-to-skin .  

Is some breastmilk better than none?

Absolutely! Every single drop of breastmilk that you can offer your baby counts. Recent studies have shown that a daily intake of even 50 ml of breastmilk (maybe even less, the research is still limited) provides significant benefits. Breastfeeding does not have to be “all or nothing,” and we recognize there are many reasons supplementation with pumped milk or infant formula may be necessary.

As your baby reaches six months and begins complimentary solids, breastmilk continues to be the main source of nutrition until 12 months. Even into the toddler years, breastmilk can provide custom nutritional benefits.  

Although we know much about the composition of breastmilk, we are still learning about it every single day. Many of the components of breastmilk are still considered “undiscovered,” and additional research continues to be done to find out more. The benefits of breastfeeding, for both mom and baby, are truly ongoing and far reaching. If you are concerned that you are not able to produce the breastmilk that your baby needs, talk with your lactation professional and/or pediatrician for help in making an empowered decision that best fits your feeding goals.

References: https://www.askdrsears.com/topics/feeding-eating/breastfeeding/why-breast-is-best/comparison-human-milk-and-formula



Back to blog