Off that, they did fine.
I question the claim of "most or those children or their mothers . . ." because I do not believe there is any case studies to back that.
Look, I founded and ran a Food Bank for over 26 years, and I know the best thing for infants is their own mother's breast milk. I know a lot about nutrition. I would have heard about such a problem if it were a major issue. I've been out of that field for over 15 years, but I still don't see it.