Dear Rob,
One of the mothers in my hospital had black milk in her early days of
lactation.  As we did not know what could be the cause at that time, we
told her to discard the milk until we could confirm the cause of the
colour.  Later, we found that it was the multivitamin that she was taking-
it was supposed to be of plant origin.  Once she stopped taking the
multivitamin, her milk was no longer black.  She resumed feeding her baby
breastmilk.
Doris Fok,
lactation consultant in Singapore