I found this website helpful:

http://mammary.nih.gov/reviews/lactation/Neville001/

This is of course a very complex process, going back to cellular
physiology. I do not pretend to fully understand all of the biology,
biochemistry, physiology, etc.

The way I explain it to myself, and the way I explain it to families if
some sort of question like this comes up is thus:

You eat and your body breaks down your food into proteins, carbs, fats, you
ingest vitamins etc. All of these tiny molecules flow through your
bloodstream and blood flows through your breasts which are like little
factories (at the cellular level). These cells or factories take in the raw
materials (I picture the simplest food particles being grabbed by little
hands as they flow by) and create or manufacture a special food product for
baby - breastmilk!

Hope this helps.
Laurie Wheeler RN MN IBCLC
MISSISSIPPI USA

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