First of all "No harm". I suppose that the patient underwent gastrointestinal resection due to malignance. If yes, Vitamins are contraindicated. The latest supplement is MacuShield containing only lutein, zeaxanthine and the most important mesoxanthine.
MacuShield is a tab. In case of Chron's disease you can prescribe intramuscular injection of "B" -vitamins , containing Vit B1, B 6, B 12 for Optic nerve disease. Another IM injection of Vit E