One of the problems with having Crohn's Disease (one of many), is the fact that you have problems absorbing the necessary vitamins and minerals your body needs. Over the years, and alot of trial and error, I was finally able to find a multi vitamin that does not cause me pain and discomfort. I think the Remicade (Infliximab) has alot to do with it. The over the counter multi's have too many "fillers" which I think was causing all the problems. Of course the one I find that works, I have to get from a doctor friend as they are only available through health practitioners. What I found interesting was that these multi's have zero fillers and are derived directly from fruits and vegetables.... that's it, which in a way, makes lots of sense. They are hard to get and cost more, but they work....for me. On top of the multi's, I also take other supplements. I take B50 complex, D, B12, Magnesium, Iron and Omega 3.
As a Crohn's patient, we need these supplements, but everyone is different so it will take a while to find what works for you. It's taken many many years to find what combination works. I dont take all of them at once, I take some one day and some the next day. I found that it I take them all each day, I get some pain and discomfort.
Even if you think they arent working, still take them, you never know.