Addictive, yes, but nicotine was until recently considered the least harmful ingredient in tobacco.
Now some experts are beginning to question whether nicotine is really as benign as thought, or whether its adverse effects are simply masked by the fact that other toxins in cigarettes are so much worse.
And this also raises questions about vaping – the 'safer' alternative to cigarettes – because they also often contain nicotine.
Scientists have started looking at nicotine because although smoking levels are at their lowest since records began (in the 1940s), vaping is on the rise.
More than 270 people die in Britain every day from smoking-related conditions such as heart attack, lung disease and cancer.
This toll is largely due to a toxic brew of harmful chemicals in cigarettes.
Nicotine was until recently considered the least harmful ingredient in tobacco (stock image)
These include 1,3-butadiene (used to make rubber and which can cause some blood cancers); cadmium (found in batteries and linked to lung cancer); and chromium VI (used to make paints and dyes, also linked to lung tumors).
In fact, there are thousands of harmful chemicals in cigarettes – some occur naturally in the tobacco plant, others are added during production to enhance the flavor or increase the absorption of smoke into the lungs (to release more into the bloodstream and then into the brain). better 'hitting').
But the innocent party in tobacco's deadly effect on human health has always been thought to be nicotine – the addictive ingredient that produces the 'high' that smokers crave but is considered relatively safe.
However, it is coming into the spotlight due to the increasing popularity of e-cigarettes, which give users the same nicotine hit as tobacco, but without exposure to harmful chemicals – although there are separate concerns about the possible carcinogenic effects of gases called volatile organic substances. , in vapours.
More than four million people in Britain now vape and according to the latest estimates, e-cigarette users will surpass smokers in the coming years.
As a means of quitting smoking, vaping is supported by charities such as the British Heart Foundation and Action on Smoking and Health, while the NHS website says vaping doubles the chance of quitting smoking compared to nicotine gum or patches.
Nicotine occurs naturally, but in small amounts, in many plants, including tomatoes, potatoes and eggplant. But in tobacco plants, where it acts as a built-in insecticide, levels are highest.
Its effect on the brain is well known: within 20 seconds of inhalation, it causes the release of chemical messengers such as dopamine, which are associated with reward and pleasure. But it also increases heart rate and blood pressure and causes blood vessels to constrict. This is because nicotine causes the release of the hormone adrenaline. The big question is whether there is a long-term effect.
“Nicotine does have physiological effects on the body,” says John Britton, professor of epidemiology at the University of Nottingham and former chairman of the Royal College of Physicians' Tobacco Advisory Group. 'It changes blood pressure and heart rate and has similar effects to caffeine.'
The problem was a lack of evidence for nicotine alone.
Professor Britton says one of the few large-scale studies to specifically reveal the effects of nicotine was led by scientists at the Karolinska Institute in Sweden, who looked at data from more than 130,000 men who were regular snus users.
This is a teabag-style tobacco product that is placed under the upper lip to allow the nicotine to seep into the bloodstream through the small blood vessels on the inside of the mouth. (Snus is very popular in Scandinavia and although it is illegal to use it in Britain, it is not illegal to use it.)
The study results showed that regular users of snus were no more likely to have a heart attack than non-users, the European Journal of Epidemiology reported in 2012.
But now more recent research – by another team of scientists from the Karolinska Institute – is casting doubt on these findings.
The researchers looked at the effect of snus on the arteries of otherwise healthy men. They did this by temporarily cutting off the blood supply to the forearm after the snus was ingested and then measuring how much the arm 'shrank', before allowing blood to flow again to see how quickly the arm returned to its original diameter. The faster this happens, the more elastic the arteries are.
The researchers found that the nicotine from snus made arteries much stiffer, reducing blood flow and possibly increasing the risk of heart disease over time, according to results published last June in the journal PloS One.
Some experts are beginning to question whether nicotine is really as benign as thought, or whether its adverse effects are simply masked by the fact that other toxins in cigarettes are so much worse.
Other studies suggest that rates of peripheral arterial disease – restricted blood flow in the legs and feet – resulting from nicotine exposure through snus are similar to those from cigarette smoking.
In September, the British Professional Footballers' Association announced an investigation into reports of the increasing use of snus (top footballers have reportedly been spotted using it) and warned that it has been linked to heart problems and reduced physical performance.
In addition, research presented last October at the American Heart Association conference found that e-cigarette users who were regularly exposed to nicotine consistently performed worse than non-vapers on treadmill tests designed to reduce the risk of cardiovascular disease. predict cardiovascular disease – with harmful effects comparable to those of cigarettes. .
Laboratory studies have also suggested a possible link with some types of cancer.
For example, nicotine has been shown to stimulate the growth of pancreatic cancer cells in mice, while a 2021 study at the Wake Forest School of Medicine in the US found that nicotine promotes the spread of breast cancer cells to the lungs, changing the environment in the lungs. airways so that they are more conducive to tumor growth, the journal Nature Communications reported.
Dr. Marina Picciotto, a neuroscientist at Yale University, has studied the effect of nicotine on the brains of young adults and is particularly concerned about the exposure of young vapers during their crucial years of neurocognitive development.
She told Good Health: 'We know from both preclinical and human studies that nicotine disrupts normal activity in the brain' – particularly in areas related to memory, learning, attention and arousal.
Nearly one in 20 children in Britain between the ages of 11 and 15 vape regularly, rising to around one in six older teenagers, according to Action on Smoking and Health.
Campaigners fear that the fact that some vapes are designed to appeal to young palates, with flavors such as blackberry acid, means a new generation is being exposed to nicotine.
Dr. Picciotto says that while nicotine is potentially less harmful than other toxins in tobacco, “my concern is that we will only learn more about the effects of nicotine vaping in the coming years – just as it may take decades for the effects of smoking to become apparent.” become'. .
But Professor Britton says the risks are minimal.
'Being addicted to nicotine all your life is probably comparable to drinking coffee every day. The evidence linking it to serious illness is scant and is still made worse in people by tobacco and the many things in smoke.
'The real harm comes from the things you have to take with you to get the effect: toxins in tobacco and the other chemicals in e-cigarettes.
'If one of my kids said they were going to vape, I'd say 'no, over my dead body' – why would I needlessly become addicted to something? But if they said they were going to vape instead of smoking, I'd say yes, absolutely; that's a no-brainer.'
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