Nicotine is the most natural of all consumer stimulants and stress relievers as it is part of the diet and everyone tests positive for it. If you take 800 people and test them, they all test positive for nicotine [2]. It is present in many vegetables and is co-located with the vitamin nicotinic acid (niacin or vitamin B3), which is also a metabolyte of nicotine in some circumstances (the literature is extremely sparse here). This means that trying to remove nicotine from the diet would likely also remove vitamin B3 and lead to sickness. Nicotine is a natural part of the diet and it is unhealthy to avoid it. On the other hand, nobody tests positive for coffee, alcohol or chocolate (unless they have consumed it very recently). Nicotine is the most natural and normal of all the consumer products in this class - everybody has some, it is healthy to consume it, and unhealthy to avoid it. Like all such materials, the dose makes the poison (the only difference between a nutrient or medicine and a poison is the dose).