Nicotine By-Product 'Cooks' Proteins

Substance May Contribute to Diabetes, Cancer, and Other Diseases

From the WebMD Archives

Oct. 28, 2002 -- A substance found in tobacco and produced as a by-product of nicotine may increase smokers' risk of diseases such as diabetes, cancer and Alzheimer's, as well as intensify the negative effects of aging. Researchers say they've discovered a new way in which the chemical, known as nornicotine, reacts with proteins in the body.

"Nornicotine permanently and irreversibly modifies proteins, which can affect their overall function," says study author Kim Janda, PhD, a researcher at The Scripps Research Institute in La Jolla, Calif., in a news release.

The study shows that the process by which nornicotine changes proteins is the chemical equivalent of cooking and is the same process that browns sugars under heat and causes foods to age and spoil.

The findings appear in the Oct. 28 online edition of the Proceedings of the National Academy of Sciences.

But the authors say this "cooking" of the body's proteins may just be the tip of the iceberg in terms of what damage the chemical can cause. The study also shows that nornicotine reacts with commonly prescribed steroids, such as cortisone and prednisone, which may cause dangerous drug reactions or may make the steroids less effective. These steroids are used to treat a variety of illnesses such as arthritis, lupus, severe psorisasis, asthma, ulcerative colitis, and Crohn's disease.

The chemical attaches itself permanently to these steroids as well as amino acids found on the surface of proteins in the body. These altered steroids and proteins then interact with other substances in the body and may form compounds known as advanced glycation endpoints, which the body isn't prepared to deal with.

Previous studies show that these compounds have been linked to many diseases, such as diabetes, heart disease, cancer, and Alzheimer's.

The study authors say this study is the first to show a direct link between tobacco use and the creation of these dangerous compounds. They tested the blood of smokers and nonsmokers and found that the smokers had higher levels of these "cooked" proteins than nonsmokers. The smokers also had higher levels of the advanced glycation endpoints.

Researchers say the findings show that nornicotine has a lasting effect on the body, as opposed to the short-term effects of nicotine, which might contribute to the development of tobacco addiction, and more research is needed to examine the effects of exposure to this and other nicotine by-products.

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