Substance May Contribute to Diabetes, Cancer, and Other
By Jennifer Warner
WebMD Medical News
Reviewed By Brunilda Nazario, MD
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
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.
© 2002 WebMD Inc. All rights reserved.