I use the microwave analogy to explain the radiation and also the sunburn analogy (coming out of the sun doesn't stop the burn from feeling worse!).

I personally don't buy into the rationale that ONLY natural vits are good; granted, there may be a few vits that are ineffective or less effective when taken "out of context" because they need something else to work properly, but not all will be that way.

And, one must factor in that some people have an almost religious faith in diets, vitamins, etc. that goes beyond the chemistry.