Forceval are available on prescription only, and advocated by a lot of surgeons. They have a higher concentration of vitamins and minerals than OTC ones, and are easily broken down by the new pouch and intestines as they are a gelcap instead of a tablet.
On top of that, you'll need Calcium, Iron and B12 injections. Again, all available on prescription. If you start to suffer with hair loss, add selenium and zinc.