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What breast milk is made of
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Breast milk is, above all, water: about 87%. The rest is fat, lactose, which is the sugar found in milk, and protein, each in much smaller proportions, plus vitamins, minerals, hormones, and immune factors.
What almost nobody expects is that it is not always the same milk. Shortly after delivery, what comes out is colostrum, a thick yellowish fluid loaded with antibodies and immune cells. It then turns into transitional milk, which is a mix of colostrum and mature milk, and later on mature milk comes in. It is a recipe that gets rewritten every week.
Colostrum and mature milk are nothing alike in composition. Colostrum has more protein and more immunoglobulins, which are antibodies; mature milk has more carbohydrate.
The change happens even within a single feeding: the milk at the start is bluer and lower in fat, and the milk at the end is creamy and rich in fat.
And there is no single recipe. The composition varies from one mother to another and within the same mother over time.
In brief
Breast milk averages 87% water, with fat, lactose, and protein in smaller proportions.
It is not always the same: first colostrum, then transitional milk, then mature milk.
A recipe that gets rewritten every week.
Colostrum carries more protein and immunoglobulins; mature milk carries more carbohydrate.
Within a single feeding, the milk at the start has less fat than the milk at the end.
Its composition varies between mothers and within the same mother over time.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Breast Milk, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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