Breast Milk Composition

Composition of Milk (compare breast milk/formula and cows milk)

Breast milk is alive! It also changes from time to time and month to month to adapt to the needs of a growing child. All mammals produce milk for their young, but not all mammal milk composition is the same. For example: A mother seal will produce milk much higher in fat to fit the needs of her young.

Breast Milk Composition Compared to Formula and Cow's Milk

  • Breast milk contains more calories than formula or cow's milk.
  • More lactose than cow's milk and formula does not contain lactose.
  • Breast milk contains much less protein than formula and cow's milk. Cow’s milk contains the most protein.
  • Breast milk contains more fat than formula and cow's milk.
  • Breast milk contains less Cholesterol than formula, but more cholesterol than cow’s milk.
  • Formula and breast milk contain about the same amount of Vitamin A; cow's milk contains half this amount.
  • Breast milk contains Beta carotene, which formula does not. Cow’s milk contains small amounts of beta carotene.
  • Breast milk contains Vitamin D, formula does not contain any vitamin D. Cow's milk is high in Vitamin D.
  • Formula contains three times more Vitamin E than breast milk. Cow’s milk contains less Vitamin E than breast milk. (The higher levels of certain elements are needed in formula, because they are not digested as easily)
  • Vitamin K is high in formula, low in breast milk and even lower in cow’s milk.
  • Low levels of Thiamine in breast milk, high in formula and very little in cow’s milk.
  • Highest levels of Riboflavin in cow’s milk, then formula then breast milk.
  • More than three times Niacin in formula than in breast milk and even less in cow's milk.
  • Half the amount of Folic acid found in breast milk and cow’s milk compared to formula.
  • Vitamin B6 is nonexistent in formula and higher in cow’s milk than breast milk.
  • Vitamin B12 is highest in breast milk and very low in formula.
  • There is much more Vitamin C in formula than breast milk and none in cow’s milk.
  • Cow’s milk contains the most Calcium, then formula and then breast milk.
  • Breast milk contains half the amount of Sodium as formula. Cow’s milk contains more sodium than formula. Colostrum contains even more sodium than cow’s milk.
  • There is half the amount of Potassium in breast milk compared to formula and the most potassium in cow’s milk.
  • Breast milk contains a little more Iron than cow's milk, but formula contains a lot more iron than breast milk.
  • Breast milk contains less Zinc than formula, with cow’s milk somewhere in-between.
  • Most importantly breast milk contains many Immune factors that cow's milk and formula do not contain. Read more on the immunity that breast milk provides. 

These amounts are estimated according to full cream fat cow’s milk and Nestle Good Start formula with iron (ready to feed).

Other Components of Breast Milk


Breast milk is over 80% water and contains all the water a newborn needs. Babies do not need water supplements. Water supplements will also not help clear of prevent jaundice; supplementing with water will just cause breastfeeding problems.

Fats (lipids):

About half the calories in breast milk are fat, including DHA and AA, which are needed for brain development. Formula manufacturers have started adding these fats to their formula via fermented algae and fungus from the soil, but the addition of these have not been monitored or researched for safety. The concern is that the addition of these ingredients to formula may alter growth patterns in infants.


Protein is high in colostrum and about 1% in mature breast milk. The two types of protein found are namely Whey protein and Casein protein. Whey protein is higher in colostrum and starts to even out later on. Mature milk contains 50% Whey and 50% Casein protein.

Some babies may have allergies towards cow proteins, and these allergies are triggered through formula, that are made from cow protein!


The main carbohydrate in breast milk is Lactose. Lactose is essential for brain development, enhances absorption of calcium and iron and is needed for micro flora in a baby’s gut.

Lactose intolerance is very rare. It is more likely that a baby struggles with a cow milk protein allergy in formula or via something in the mother's diet, which is transferred through her milk.

Vitamins and minerals

Water soluble vitamins like B, C and folate are drawn from Mom's blood supply. Fat soluble vitamins such as Vitamin A, D, K and E are drawn from a mother's stores. Taking supplements will not affect the vitamins in breast milk, unless a mother is very malnourished.

Minerals in breast milk are absorbed much easier than minerals in formula, because of the lactose that helps for easier digestion; this is why formula contains larger amounts of certain vitamins and minerals.

Other Interesting Factors


Breast milk is much easier for a baby to digest. A portion of breast milk is half digested in 48 minutes, but it takes 78 minutes to digest the same size portion of formula milk. (that’s a whole 30 minutes extra) A breastfed baby’s tummy does not need to work half as hard to eliminate waste, because there hardly is any.

Changes of milk composition during a feed:

The milk that a baby receives the first few minutes whilst breastfeeding, is called the watery foremilk. As baby drinks, the milk becomes fattier. This is because the milk at the back of the “milk producing alveoli cells" are fattier. This milk is called the hind milk. Read more on foremilk/hindmilk here

Breast Milk composition, changes during the day:

The longer the periods between breastfeeding sessions, the less fat a mother will have in her milk. If she drains her breasts more often, the milk will have more fat in it.

Milk changes over a few months:

Colostrum is much higher in protein and minerals and lower in fat and carbs compared to mature milk. Milk changes as the baby gets older.

Quality of milk:

A mother’s diet does not influence the quality of her breast milk. A good diet is essential for the mother’s health though, because the body will derive all needed in breast milk from her body, whether she has extra or not.

Tracy Behr CBC, CLD (CBI)


Course on breast milk composition through Child Birth International

What makes Breast Milk so Healthy?

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Other pages on breastfeeding problems in connection with breast milk composition.

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