Even twenty years ago, nicotine was so vilified (for good reason probally) scientists didn't do non-biased studies.

I remember Dr. Dean Edell always yacking about this.

(antidotally--I have know smokers, who didn't eat much, never seemed to get sick. My best friend of twenty years never got sick. I used to say, you smoke 4-5 packs/day. I don't get it. I even had him go in to check his Coronary arteries because I just assumed the worse. His arteries were clean. He practiced calorie restriction, but not on purpose. He just didn't eat much. And yes--at that much tobacco, how do you eat? He made it to 65. He died do to smoking. His lungs finally gave up one night. Now--smokers who ate a lot seemed like they were always sick.)