Niacin is also called nicotinic acid. Given that nicotinic acid sounds similar to nicotine, it's easy to understand why the Linus Pauling Institute has to explain that they are unrelated compounds. While both niacin and nicotine are both found in plants, the similarities end there. Given their comparative chemistry and effects on the body, it's hard to imagine two more different substances.
3DChem.com explains that nicotine is an organic compound. This alkaloid has a molecular weight of 162.26 g/mol. It is synthesized in the roots of the tobacco plant and found concentrated in the leaves. Nicotine constitutes 0.3 to 5.0 percent of the dry weight of the plant. Chemically, it contains a pyridine ring bound to a five-membered heterocycle containing four carbon atoms and one nitrogen atom.
Effects of Nicotine
Although most of the nicotine is destroyed as the cigarette burns, a significant amount makes it through to the body intact. The National Institute on Drug Abuse explains that nicotine is one of the most commonly used addictive drugs in the U.S.. It causes "increased blood pressure, and heart rate/chronic lung disease; cardiovascular disease; stroke; cancers of the mouth, pharynx, larynx, esophagus, stomach, pancreas, cervix, kidney, bladder, and acute myeloid leukemia; adverse pregnancy outcomes and addiction."
Niacin, or nicotinic acid, is also called vitamin B-3. Chemically, it contains a pyridine ring bound to a carboxyl group and has a molecular weight of 123.1094 g/mol. This molecule acts as a cofactor in enzymatic reactions involved in the synthesis of RNA, DNA and ATP, otherwise known as adenosine triphosphate. A cofactor allows an enzyme to catalyze a reaction more efficiently.
The daily requirement of niacin for men and women over 19 years is 16 and 14 mg of niacin, respectively. Getting the required niacin from dietary sources is fairly easy. The Linus Pauling Institute reports that the average dietary intake of niacin in the U.S. is between 20 and 30 mg/day for young adults. A 3-oz. serving of chicken cooked without skin provides 7.3 mg. Three ounces of tuna provide 11.3 mg. Even a 1 cup serving of coffee provides 0.5 mg.