Here's another perspective on the whole nightshades issue:
THERE'S A CHEAP, COMMON, and mostly safe drug, in daily use for centuries by hundreds of millions of people, that only lately has been investigated for its therapeutic potential for a long list of common ills.
The list includes Alzheimerís disease, Parkinsonís disease, depression and anxiety, schizophrenia, attention deficit hyperactivity disorder (ADHD), and even pain and obesity. Why has interest in this potential cure-all been slow to develop? One reason: in its current forms the drug offers pharmaceutical companies no possibility of substantial profit. Another, perhaps more important: the drug is reviled as the world's most addictive. The drug, of course, is nicotine.
I will probably still try to minimize my consumptions of nightshades as a whole, but this article provides a nice rationalization for my occasional visit to the hookah bar.