Why do you not eat multivitamins?

I spoke with a physiochemist once at a small roundtable about the reactive nature of the oxygen in the body, and she mentioned a lot of the potential dangers inherent in taking something that does not seem to provide a lot of benefit to health over time. Then we talked about lobster circulatory systems. The book "Denialism" discusses about the same thing I think. Other dietary supplements may be even worse