Smoking is associated with a lot of things, and in many cases, such as depression, the causation is very confused. It's possible people were self-medicating for these problems with cigarettes. Personally, I've switched from nicotine-and-flavoring-only e-cig juice to WTA juice following a comment in a Slate Star thread talking about the MAOI in tobacco, and the slow decline I've experienced with the effectiveness of vitamin D in correcting my emotional deadness seems to have largely, although not entirely, reverted. I hesitate to declare it a success, placebo effect and everything, but I certainly started smoking in a particularly deep depression, and my recovery, in retrospect, stalled out when I switched to e-cigs. (Which I was entirely not expecting, since I moved at the same time from a Northern state to a Southern one, explicitly for the increased hours of sunlight.)

Gwern might have data on peak iodine consumption somewhere on his site. I feel like the sodium scare happened later, but that's hard to pin down.

ETA: I'm also on absurd doses of iodine (usually used by paranoid people to flush out radiation or something), personally, because with a normal consumption level, iodine (which I have long used as a general-purpose antiseptic) would -visibly- absorb into my skin, which is apparently a sign that my levels are low.