> [Snus] In old people, a little nicotine can have a balancing effect, improving alertness, and probably protecting nerves, for example in the negative association with Parkinson's disease. But in younger people, its vasoconstrictive effect tends to promote the development of wrinkles in the [[skin]], and I think it's likely to contribute to periodontal disease. > [Niacinamide for quitting smoking] After middle age, nicotine isn't likely to become addictive, and in small amounts it has nerve protective effects. Some of those effects probably overlap with the nerve protective effects of niacinamide. I haven't experimented with nicotine or tobacco, but I think transdermal application is preferable to smoking; carbon monoxide and other serious toxins are produced by burning the tobacco.