There has been some cause for concern due to the fact some manufacturers
put "little extras" in there collodial vitamins.  Things such as silver
and other minerals not normally found in the body.  The U.S. government
has listed silver as an insecticide.  There is also the problem of
minerals building up to a toxic level.   As Frank mentioned as long as
the minerals listed meet the dietary allowance there should be no
problem, but what I have found is that many brands list various
percentages.  Some allowances are  too high and some too low.   What this
might mean to a breastfeeding couplet?  I don't know.  Maybe someone out
there could fill in the blanks for me.  I would recommend she read the
label and be sure  the amounts match the daily recommended value for a
lactating mother and watch out for the "extra" minerals.
Monique