I am currently 6 1/2 years out of gastric bypass surgery and have SEVERE IRON deficiencies as well as some other serious vitamin deficiencies. there is no way to take the required amounts of vitamins via oral suppliments or thru food intake.
I am currently getting 2 iron shots a week...dr is talking about switching to infusions (this has been going on since last september...and I have JUST reached the MINUMUN with my blood work)...am also suffering from osteo malasia (vitamin D deficiency)..which has me taking 200,000 units of vitamin d a day...and I take several individual suppliments and double multi's...
think a critical point is that we CANNOT eat enough to get our requirements, and suppliments are our lifeline...stop taking them....for any period of time (I had a 3 month slip....about 4 years ago...I cannot catch up or regain those levels)
You might want to take a look at the following: http://www.faqs.org/nutrition/A-Ap/Anemia.html. There can be a number of causes of iron deficiency so if she's had some blood work done and you have the results, you may be able to start to figure out where the 'lack' is, since there's a pathway that can lead to iron deficiency.
One big factor to look at is intrinsic factor. It's produced in the stomach along with the acid, and where a large portion of the stomach is 'gone,' it possible that intrinsic factor - which carries the B12 - can be compromised.
If she doesn't have intrinsic factor, eating all of the B12 foods in the world won't help since it won't get picked up and carried to the end of the small intestine and get picked up to function as it should in the pathway.