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  • Post last modified:September 6, 2020

components of breast milk

We have all heard how great breast milk is for our babies. Breastfeeding has been proven to give the baby a whole slew of benefits.

So what are the components of breast milk that make this magic liquid work so well?

Actually, the content of human milk is not completely known. (Hello, is this the 21st century??)

Well, human milk is a complex substance and it changes over time.

breastmilk foremilk hindmilkThe milk in the picture is regular “mature” breast milk, which is a yellow-white liquid and will even change within one feeding. Thinner in the beginning, and fattier and thicker as the breast is emptied (the so-called hindmilk).

Later in the article, you can see the change of breastmilk over time – from the colostrum when your baby is newborn, the regular breastmilk.

The list of known breast milk components not present in formula is long and includes hormones, enzymes, growth factors, and substances that fight infection and help develop the immune system.

Below you’ll learn a bit of the most important components of breast milk so you know what you are feeding your baby when nursing.

The (Known) Components of Breast Milk

Proteins that promote health

One large component of breastmilk is protein. In fact, there are two types of proteins found in human milk, called “whey proteins”, and “casein proteins”. This is one of the things that formula companies try to reproduce.

However, breast milk is much easier for the baby to digest. The more casein protein found in the formula, the harder it is for the baby to digest. Mother’s milk is around 60 to 80 percent whey protein. These proteins are great for preventing infection in your baby.

Here are some of the important specific proteins found in breast milk:

One specific protein found in breastmilk is Lactoferrin. This protein is great for your baby’s intestinal tract. It prevents the growth of bacteria and yeasts which need iron to live. Those things can cause infections and physical problems for the baby. There is little to no Lactoferrin found in formula.

Lysozyme, which is an antimicrobial enzyme, is found in mother’s milk, but not in formula. This substance has an important effect on which type of bacteria can survive in the intestinal tract. Interestingly, the level of lysozyme in breast milk is not affected by what mom eats – probably because it is so important for the baby. There is no or very little Lysozyme in formula.

The Bifidus factor in human milk supports the growth of Lactobacillaceae, which are beneficial bacteria that protect the baby against harmful bacteria and parasites. In fact, there is a huge difference between the bacteria found in the guts of the breast- and formula-fed infants. Breastfed babies have a level of lactobacillus that is as much as ten times greater than that of formula-fed infants.

Fats for brain development

Breastmilk also contains some very beneficial fats. Mainly, Omega 3 fats such as DHA and AA. These fats are there to help the baby’s brain work, ensure that his immune system is functioning, and helps him take in fat-soluble vitamins. The fats that are found in formula are not digested completely by the infant, and formulas also don’t contain DHA.

The fat level in mature breastmilk is around 4% or a bit less and is independent of what mom eats. However, the type of fats can be affected by the maternal diet.

Carnitine for fatty acids

While carnitine is present in both breast milk and formula, the carnitine in human milk is easier for the baby to take up. Breastfed babies have significantly higher carnitine levels than their bottle-fed counterparts. Carnitine is necessary to make use of fatty acids as an energy source.

Immunoglobulins for disease protection

Breast milk is also rich in immunoglobins, and while formula does contain these, it’s not the same kinds that are found in human milk.

One important type of immoglubin is called secretory immunoglobulin A (sIgA) and has the ability to bind to foreign substances (including harmful bacteria) so they can be eliminated from the body. sIgA particularly protects the throat, nose, and ears as well as the gastrointestinal tract.

Colostrum, the thicker milk that a mother’s body produces in the first few days, is especially high in sIgA.

Lactose for growth

Lactose, which is a very important carbohydrate, is supplied richly from breast milk. This component is wonderful for brain function and growth. Lactose helps to decrease the number of unhealthy bacteria in the stomach and improves the uptake of calcium, phosphorus, and magnesium. Lactose concentration in breastmilk increases over the duration of breastfeeding.

White blood cells fight infections

Leukocytes are the white blood cells that are only found in breast milk (not in formula). They help fight infection. It is the antibodies, enzymes, and hormones that make breastmilk ideal. These cannot be added to formula.

Vitamins and minerals

The vitamins in mom’s milk are dependant upon the vitamins the mother is getting. This is one reason that it is so important that Mom gets the vitamins she needs. She will be sharing them. The vitamins and minerals in mother’s milk, for instance, iron, are absorbed readily and better by the baby. While a baby will only absorb around 5 to 10 percent of the iron in formula, she will absorb 50 to 75 percent of the iron in mother’s milk.

Learn more about what to eat while breastfeeding here.

Changes as your baby grows

from colostrum to breastmilkThe greatest thing about breast milk is that as your baby grows, the components automatically change to supply your child with what is needed most as she grows.

The very first milk, the colostrum (seen to the left in the above picture) is much thicker, more yellow and sticky and contains a very high concentration of immunoglobulins sIgA, to protect the newborn baby from infections.

A newborn infant tends to eat very little. Just a teaspoon is a typical feeding and enough colostrum to provide large amounts of immunoglobins.

Studies have shown that the immunoglobulin sIgA is found in high concentrations in the breastmilk during your baby’s whole first year, but the very highest concentration is in the colostrum. (So at least breastfeed during those first few days of your baby’s life!)

The same is true with lactoferrin, a protein that for example has antibiotic effects.

Also, the components of breast milk vary with the time of the day as well as whether it is at the beginning or at the end of the feeding. Fats are particularly high at the end of the feeding (hindmilk), which is why it is so important to let our baby empty one breast before changing sides.

Isn’t all this simply amazing? Put quite simply, Mother Nature knows her stuff! :-)

Are you still awake? So much complicated and healthy stuff packed in perfect containers…

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Image Courtesy: Standford School Of Medicine

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  1. stephen987

    Thanks for this great article .Breast milk is very helpful it can help your baby fight off viruses and bacteria.