Isn't there something about fiber tying up calcium, so that you may not get as much as you think you're getting? But one bowl of flaxseed isn't going to be a problem, for sure.

I do make a point of not taking fiber supplements at the same time as vitamins, but I figure an hour or two separation is good enough (and has to be good enough, as I'm taking supplements of one form or another five times a day).