What's in Breast Milk That Makes It the Best Choice for Your Baby?

Learn About Its Content, Composition, and Makeup

For human babies, human breast milk is the ideal source of food and nutrition. Because of what's in breast milk, health organizations around the world recognize the importance of breast milk for young children and recommend exclusive breastfeeding for the first six months of life. After the first six months, breastfeeding is still recommended along with the addition of solid foods for a year, two years, or even longer. So, what's in breast milk that makes it the best choice?

Why Is Breast Milk the Best Source of Food for Your Child?

A mother makes breast milk specifically for her child. It contains everything that a human baby's body needs to grow, develop, mature, and survive. It's not only a complete source of nutrition, but it also helps to protect children from disease and illness as they grow.

The Difference Between Breast Milk and Infant Formula

As scientists study breast milk, they've discovered it contains over 200 different ingredients so far. We don't even know the full composition of breast milk or the importance and function of many of the contents yet. Without a complete analysis and a real understanding of what each element in breast milk does, it makes it very hard for the manufacturers of infant formula to try to copy its composition. So, even though infant formula is a safe, acceptable alternative to breast milk, it's not equal. It's just not possible to recreate the makeup and ever-changing status of breast milk.

The Composition of Breast Milk

As mentioned above, breast milk contains over 200 unique components that we currently know about. These different ingredients that make up your breast milk give your baby with the energy and nutrients he or she needs to grow and develop. Here are some of the major components that make up your breast milk.


Baby bottle with milk and pacifier
Breast milk is about 90% water. Vstock LLC / Getty Images

Breast milk is made up of about 90% water, and the rest of its contents can be found in that water. The human body needs water for almost everything it does. Among other things, it keeps your baby hydrated, helps to regulate body temperature, lubricates joints, and protects organs.  



Breast milk in bottle with baby
Which carbohydrates can be found in your breast milk?. dapan photography/Moment/Getty Images

Carbohydrates are the body's number one source of energy. The main carbohydrate in your breast milk is the milk sugar, lactose. Compared to cow's milk, there is much more lactose in human milk. Lactose not only provides your baby with a major source of energy for growth and development, but it's also linked to greater brain development.

Other carbohydrates found in breast milk such as oligosaccharides are needed to promote healthy bacteria in the intestines. These bacteria protect your baby's gut and help fight off infant diarrhea.



Mother breastfeeding baby in bed
What are the fats in breast milk and what do they do?. Kidstock/Blend Images/Getty Images

Lipids may only make up about 4% of breast milk, but they provide 50% of the calories that your baby gets from your milk. Lipids are a major source of energy, cholesterol, and essential fatty acids such as DHA. They are necessary for the development of your baby's brain, nervous system, and vision.

Lipids are also responsible for your baby's weight gain as he or she grows. Your breast milk should contain all the lipids that your little one needs. However, if you're on a vegetarian diet, you may need to to take a DHA supplement to be sure you're getting enough.



Breast milk in bottle
What are the proteins found in breast milk?. jyotirathod/DigitalVision Vectors/Getty Images

Proteins build, strengthen, and repair the body. They are also needed to make hormones, enzymes, and antibodies.

The protein in your breast milk is very easy for your baby to digest and your child needs protein to grow and develop. One very important protein in breast milk is lactoferrin. Lactoferrin moves iron through your baby's body, but it also helps to protect your newborn's intestines from infections.  



Baby drinking a bottle of breast milk
Which antibodies are in breast milk and what do they do?. Tom Merton/Caiaimage/Getty Images

Immunoglobulins are antibodies that fight off the germs that cause illness and disease. Your breast milk is like your baby's first vaccine. It contains antibodies that fight off bacteria, viruses, fungus, and parasites. The immune properties found in breast milk can also help protect your child from the common cold, ear infections, vomiting, diarrhea, and other dangerous infections that affect newborns and infants.

The main antibody in your breast milk is Secretory Immunoglobulin A (IgA). IgA coats your baby's lungs and intestines. It seals them to prevent germs from entering your baby's body and blood. The antibodies in your breast milk are even more important if you have a premature baby or a baby who will go to daycare.  



Baby bottle of milk on blue blanket
Which hormones are in breast milk?. MariaToutoudaki/Stockbyte/Getty Images

Hormones have many jobs in the human body. They control growth and development, metabolism, stress, pain, and blood pressure. The hormones in breast milk are prolactin, thyroid hormones, growth factors, relaxin, endorphins, erythropoietin, cortisol, leptin, estrogen, progesterone, and more. Scientists are still studying the hormones in breast milk trying to learn more about them and what they do for your baby.  



Woman with lab coat looking through microscope
Which enzymes have scientists identified in breast milk?. Caiaimage/Martin Barraud/OJO+/Getty Images

Scientists have found over 40 different enzymes in human breast milk. Some enzymes help with digestion by breaking down fats or proteins, and others protect your baby from germs and illness. Then, there are those enzymes that scientists aren't sure what they do. While we don't know all that the enzymes do, we do know that they play an important role in the health and development of your child.  



Vitamin Blocks
What are the vitamins in your breast milk?. Peter Dazeley/The Image Bank/Getty Images

Vitamins contribute to healthy bones, eyes, and skin. They also help to prevent diseases such as scurvy and rickets. Your breast milk contains the vitamins that are necessary for your baby's health as she grows.

However, the amount of Vitamin D, folate, or, depending on your diet, Vitamin B6 may be lower in certain women. Therefore, talk to your doctor and your baby's doctor about the recommended vitamin supplements that you may need to take while you're breastfeeding.



Atomic Mineral code dots
Which minerals are in breast milk?. Creative-idea / Getty Images

Breast milk is full of minerals. Some of the minerals in your breast milk are iron, zinc, calcium, sodium, chloride, magnesium, and selenium. Minerals, like vitamins, are needed for healthy growth and development. They help to build strong bones, make red blood cells to transport oxygen through the body, and keep muscles and nerves functioning properly.


American Academy of Pediatrics. New Mother’s Guide To Breastfeeding. Bantam Books. New York. 2011.

Ballard, O., & Morrow, A. L. Human Milk Composition: Nutrients and Bioactive Factors. Pediatric Clinics of North America. 2013; 60 (1): 49–74: http://doi.org/10.1016/j.pcl.2012.10.002

Lawrence, Ruth A., MD, Lawrence, Robert M., MD. Breastfeeding A Guide For The Medical Profession Eighth Edition. Elsevier Health Sciences. 2015.

Riordan, J., and Wambach, K. Breastfeeding and Human Lactation Fourth Edition. Jones and Bartlett Learning. 2014.