Anything over 100% daily value is probably too much, regardless of the decisions of the manufacturer to put more in the vitamin. b12 may be an exception, in general more is not always better.
I have had weird experiances with niacin, too much niacin can inhibit a process called autophagy which is a backup defense our body uses to get rid of bacteria that have invaded a human cell, supresses this process can make IBD worse specifically crohn's, where intracellular bacteria are suspected to play a large role in our disease.
Just watch out for niacin I guess.