Here's what I say in response to being told it kills brain cells:

I tell them, well, it kills glioma cells, but glioma cells cause brain cancer so that's not really a bad thing. As for any other brain cell, the only study I've seen was the glioma one and that was on rats, so unless you can show me your proof I'm not interested.

<_< That last part generally ticks a few people off :thumbsup: