Jilll,
     From my own personal breastfeeding experiences, both my children in the
first few months seemed more gassy (both burping & intestinal gas), when
breastfed vs. receiving a bottle of expressed milk.  It didn't seem to matter
whether I ate the blandest diet possible, or the spiciest foods I could find.
     I remember reading that foremilk is higher in sugars (lactose) than
hindmilk (which is higher in fat content).  Sometimes as sugars ferment
during the digestive process, they can cause a lot of gas cramping.  I see
this fairly often in hospital patients who are on a clear liquid diet --
consuming a lot of sugar from all the juices & gelatin.  I theorized that
 the higher lactose foremilk might be what was causing my kids to be so
gassy.  (They didn't get that way after being given a bottle of expressed
milk, only after nursing.)  Since  the bottle had the foremilk & hindmilk all
lmixed together, it might have been easier for their little stomachs to
tolerate.
     I have not seen any literature on this, and always figured that this was
a phenomenon unique to my children & me, but this might be what is happening
with the mom you are counseling.  It might also help her to know that it
seemed to resolve in both my children when they reached approximately 3
months of age.