While these aids are a much safer alternative to smoking, new evidence suggests that nicotine, in whatever form, significantly alters blood circulation through the arteries.
A research team from the Centre for Biological and Medical Systems at Imperial College, London, gave nicotine chewing gum and a dummy version to healthy young volunteers.
Ultrasound scans of the main artery of the thigh showed significant short- term changes in blood flow pattern and stiffening of the artery wall soon after the volunteers started chewing the gum. These changes were similar to those brought on by cigarette smoking.
Professor Colin Caro, a member of the research team, said the changes included a speeding up in the rate of blood flow. This could increase the risk of stagnant areas forming along one 'bank' of the artery. Fatty deposits could then start building up, increasing the risk of arterial disease.
A larger study, funded by the Tobacco Products Research Trust, was now planned to confirm the findings, he said.
Professor Caro emphasised that short-term use of nicotine replacement therapy was safe. 'However, there is concern in the case of people who become addicted to the gum, particularly if they already have a heart condition or angina.'
Researcher Chris Rees said gases such as carbon monoxide, absorbed during smoking, were widely believed to be responsible for the known link between smoking and arterial disease.
The new findings suggest that nicotine might be at least as important, if not more so.