>Is lactose able to pass through the breastmilk?<
It's pretty highly unlikely that any intact molecules of lactose
would make it through the villi of the intestine to enter into the
bloodstream in the first place. But since human milk contains
the highest percentge of lactose in the animal kingdom
(about 7.0% on average), I don't think it really matters much
if a few molecules do slip by.
Steve Carper