Tobacco chemical blamed for disease
Scientists have discovered a chemical in tobacco that may be partly responsible for causing diabetes, cancer, Alzheimer's disease and accelerating the ageing process.
The chemical - nornicotine - is naturally present in tobacco, and is also produced when nicotine is broken down in the body.
A team from Scripps Research Institute in the US has discovered that it reacts with proteins in the body, damaging their ability to perform their proper function.
The process is the chemical equivalent of cooking and is the same reaction that browns seared sugars and caused food to age and spoil.
The researchers have also discovered that nornicotine can have a second damaging effect - it reacts with commonly prescribed steroids, like cortisone and prednisone, potentially making them unsafe to use.
Nornicotine attaches itself to steroids and to certain amino acids on the surface of proteins.
These modified steroids and proteins can then interact with other chemicals in the body to form a varity of compounds known as advanced glycation endproducts (AGEs).
These compounds have previously been implicated in numerous diseases including diabetes, cancer, atherosclerosis, and Alzheimer's disease.
Researcher Dr Tobin Dickerson said: "These advanced glycation endproducts are not supposed to be present in your body naturally.
"Your body is not prepared for them."
The researchers found that smokers had higher levels of nornicotine-modified proteins - and AGEs - than non-smokers.
Nornicotine appears to linger in the bloodstream for a lot longer than nicotine, which quickly disappears when somebody stops smoking.
For this reason, the researchers believe it may also help to explain why smoking is physically adictive.
Lead researcher Professor Kim Janda told BBC News Online that AGEs appeared to increase the rate of mutations among the body's cells, raising the risk of cancer.
They also appeared to stimulate the formation of protein plaques in the brain - thought to be a major cause of Alzheimer's disease.
Professor Janda said: "Only the future will tell us whether what we see are truly devastating events to the body.
"However, the public should be made well aware that there is a now another component in tobacco products - and for that matter any product that has nicotine - that can cause aberrant modification of proteins and prescription drugs."
The research is published in the Proceedings of the National Academy of Sciences.