What is nicotine?
Nicotine is a chemical that occurs naturally in tobacco. It is addictive and is not risk-free. However, as opposed to what many people mistakenly believe, it is not the primary cause of smoking-related diseases. These are principally caused by the chemicals released when tobacco is burned.
Nicotine constitutes around five percent of the tobacco plant by weight. It can also be found in significantly lower levels in other plant varieties of the nightshade family, including tomatoes, potatoes, and eggplants. It takes its name from French ambassador Jean Nicot, who sent tobacco seeds back to Paris in the 16th century. In its pure state, it is a colorless, odorless liquid with an oily consistency.
How is nicotine absorbed and how does it move through the body?
Products that provide nicotine include cigarettes and smoke-free alternatives. Some smoking-cessation aids also provide nicotine (nicotine replacement therapies) and include chewing gums and nicotine patches. Nicotine can be absorbed into the body through the lungs, mouth, or skin.
The way nicotine is absorbed determines the speed and intensity of its delivery. When tobacco smoke is inhaled via cigarettes, nicotine is absorbed through the lungs into the bloodstream and reaches the brain in 10 to 20 seconds. When absorbed through the skin via a patch—or through the mouth and stomach when chewing nicotine gum—nicotine is absorbed more slowly and therefore takes longer to reach the brain.
Once nicotine has entered the bloodstream, it modulates the reward systems, and is distributed to all tissues and organs, including the brain. There, it binds to specific receptor molecules, mimicking the actions of a naturally occurring brain chemical, acetylchorine. Nicotine is metabolized primarily by the liver and is constantly cleared by the body. Once it leaves the brain, it can lead to withdrawal symptoms. These withdrawal symptoms—which may include difficulty concentrating, anxiety, and dysphoria (commonly understood as distress and/or discomfort with life)—can affect many people when they initially quit smoking.
