In the New World, tobacco was both thought of as a panacea for all that could ail you and as a spiritual conduit.
Using it cured you, kept you safe, and gave you visions. And it also helped with what was more common in those days: a less reliable food supply.
In other words, more people were more hungry more of the time.
Tobacco, and the nicotine it contained, was an effective appetite suppressant and a food substitute. When you smoked, it both distracted you from thinking about food as well as suppressing the cravings.
Historically it appears that many psychoactive substances were adopted precisely because they helped alleviate hunger.
Hallucinations were much more common in those days. Tobacco had a much higher nicotine content, – both because of the use of tobacco (which had a much higher nicotine content) and many other suppressants with similar side effects, and because extreme hunger caused people to eat almost anything to fill their stomachs and quite often those substances had side effects.
Choosing nicotine over food
James Dunworth – Ashtray Blog – 2012-01-20.