Nicotine
Nicotine is an alkaloid, a chemical compound that contains an amino group (with nitrogen in it) and is basic or alkaline, hence the name. Alkaloids typically have one or more phenolic rings. The position of the nitrogen in the structure determines their properties, which may be psychotropic (lsd and psyllocybin), narcotic (morphine, heroin, cocaine), or flat out poisonous (poison hemlock, belladonna and other plants in the nightshade family) Some alkaloids like nicotine and caffeine also have stimulant properties. Nicotine also has poisonous properties, in spite of the fact that millions of people inhale it every day. It can be used as an insecticide in strong enough concentrations. Nicotine comes from the tobacco plant, which was named Nicotiana after the 16th century French ambassador Jean Nicot, who distributed tobacco seeds to Europe after their discovery in the new world. Nicotine is not related to niacin, the B vitamin.
You can absorb nicotine through your skin or mucous membranes, but most people inhale it and absorb it through their lungs. It is readily absorbed into the bloodstream, and carried to the brain where it passes the blood-brain barrier. Nicotine is a stimulant, but also can relax a smoker, depending on how much you smoke. It initially causes a rapid release of adrenaline, which increases blood pressure, breathing rate and heart rate. Adrenaline tells the body to dump glucose stores into the bloodstream for instant energy. It blocks release of insulin, which would move that sugar back out of the blood. This is why people feel that smoking helps curb the appetite - with sugar in your bloodstream you will feel less hungry. Nicotine stimulates pathways in your brain which causes the release of several chemicals. Acetylcholine improves your reaction time and ability to pay attention, dopamine is a "reward chemical" that makes you feel happy, and enhances memory, reinforcing the good feelings that you have from using nicotine. Endorphins can give you feelings of euphoria while acting as a natural pain killer. All of this sounds wonderful, right, so why don't we all just smoke cigarettes?
All of the "feel good" chemicals released by nicotine reinforce the addiction that people feel, which makes it difficult to quit smoking. When you deprive your body of nicotine you will experience all the opposite symptoms - irritability, difficulty concentrating, depression, increased appetite, anxiety, impatience, decreased heart rate, etc. The reward pathways activated by dopamine cause the intense addiction which can be even stronger than cocaine or heroin. While nicotine is working to keep you using tobacco, many other chemicals in the tobacco plant are damaging your body. Tobacco contains over 60 chemicals that are known to cause cancer, and thousands of other substances that are bad for your health.
Nearly nine out of ten lung cancer cases are caused by tobacco, and it also causes emphysema and chronic bronchitis, and makes asthma worse. Smoking 15 cigarettes a day doubles your risk of having a heart attack. Smoking can also cause cancers of the esophagus, larynx, throat and mouth and also is related to cancer of the bladder, pancreas, kidney, cervix, stomach, and some leukemias. Chemicals in tobacco smoke cause premature aging and wrinkling of the skin, and will make your teeth yellow. It increases chances of infertility and impotence, and can damage a pregnancy and result in premature or low birth weight babies. Smoking tobacco increases insulin resistance, which can put you at a risk for diabetes. Smokers are more prone to respiratory infections, and people who simply live with smokers, especially children, are also at increased health risk.
While many of these health hazards are caused by other chemicals in tobacco, nicotine itself can be an extremely toxic poison. Excessive amounts of nicotine cause a buildup of acetycholine which overstimulates neurons, and causes vomiting, nausea, headaches, difficulty breathing, stomach pain and seizures. People who are poisoned by insecticides exhibit the same symptoms. There is enough nicotine in a cigarette to make a child very ill, as they sometimes eat cigarettes or cigarette butts.
Nicotine may be protective for a number of diseases. Studies have shown that smokers tend to have less Alzheimers and Parkinsons disease. The acetylcholine stimulated by nicotine appears to have a protective effect, and people who come down with Alzheimers have lower levels of this chemical in their brains. Nicotine also may protect against ulcerative colitis, Tourettes Syndrome and rheumatoid arthritis. It is being studied as a possible treatment for Schizophrenia. However, taking up smoking is NOT the answer for someone worried about these diseases. The health risks associated with smoking are too great. The treatment would need to administer nicotine without all the other harmful chemicals in tobacco, for example as a nicotine patch.
The information on this page is not meant to be used in treatment of medical conditions. Please seek the advice of a physician about any medical condition or symptom. Those with medical conditions should consult a medical professional about the appropriateness of taking dietary supplements or diet therapy, and how these methods will interact with their medications.
LINKS
Mayo Clinic information on nicotine dependence.
More about nicotine research.