Nicotine causes cancer.
That's just one of the misconceptions that surrounds nicotine. In fact, while not healthy in an absolute sense, nicotine is nothing like as bad as nicotine plus the tar, toxins and carcinogens that are in cigarette smoke. And in this post we aim to clear up some of the misconceptions.
1. Does Nicotine Cause Cancer?
Many people - including the majority of smokers - believe nicotine could give you cancer.
This is not true - or at least there is no proof that it does. Cancer is caused by all the other stuff in cigarette smoke, including about 70 chemicals known to cause cancer.
Actually studying this isn’t easy, though, because historically most people got nicotine through smoking. However, people using patches, gums or snus (Swedish smokeless tobacco) are exposed to nicotine without the huge number of nasty ingredients in smoke. Studies of both NRT and (high-quality) snus have shown no link with cancer.
The reason “high-quality” was specified is because nicotine products tend to contain small amounts of tobacco specific nitrosamines, which are a known cause of cancer. In studies of Swedish snus manufactured to minimise the amount of these chemicals, there is no increase in cancer risk, aside from a potential risk for pancreatic cancer (but still much less than the risk from smoking).
There is another issue which doesn’t have such a simple answer, though: does nicotine speed up the growth of cancer started by something else?
Studies have shown that nicotine has several effects which can promote the growth of tumours, like speeding the development of new blood cells. However, the studies showing this tend to look at either disembodied cells or animals, which don’t translate directly to humans. It’s possible that it will have the same effect, but this is far from established. Until there is relevant evidence in humans, we can’t really draw any conclusions.
There’s a good discussion of all of these issues in this paper.
(In an interesting aside, Christopher Snowden in his book Velvet Glove Iron Fist notes that while tobacco and nicotine have been in use for centuries, lung cancer was virtually unknown until the invention of the machine rolled cigarette in the late 19th century.)
2. Is Nicotine a Poison?
For nicotine, this was previously thought to be between 30 and 60 mg for an average adult. However, after looking in vain for where this figure actually came from, Bernd Mayer found out that it was derived from self-experiments from the 19th century.
These experiments really aren’t very reliable. Among many other claims, they said one of the experimenters had seizures for two hours after taking just 1 to 4 mg of nicotine, which is about the amount you’d absorb from 3 to 4 cigarettes or even less. Unless we’ve missed chain-smokers regularly falling into seizures, we can safely say this isn’t in line with day-to-day experience.
Based on other evidence, Mayer updates the estimate to between 500 and 1000 mg for an average-sized adult. It could also be even higher than that.
For smokers and vapers, the important point is that the nicotine absorbed from cigarettes or electronic cigarettes is not strong enough to poison you. (Remember the scientist’s adage – the poison is in the dose!)
Most of the nicotine in a cigarette is destroyed or burned, and e-cigarettes seem to deliver slightly less nicotine than a regular cigarette (see point 10). Most nicotine poisonings that have occurred have been caused by insecticide or by harvesting tobacco, or from nicotine gum handed out by anti-smoking clinics to children.
That said, here are a few points to bear in mind:
- Keep e-liquid and e-cigarettes away from your children, especially very young children and toddlers, who are more susceptible to nicotine poisoning
- Only use e-liquid from respectable suppliers – good suppliers batch test e-liquid and e-cig cartridges to ensure safety.
- Be careful around spills: nicotine can absorb through your skin (like it does in a patch), so clean up any spilled e-juice and wash it off your skin immediately.
3. What Else is Bad About Nicotine?
Finding out about the health effects of nicotine isn’t easy. Most nicotine users smoke, so it can be hard to separate the risks of nicotine from those of smoking. But surely nicotine on its own does have negative effects? Well, there is evidence from smokeless tobacco users and those of nicotine replacement therapies that suggest any negative effects are very, very minor.
Nicotine causes a temporary increase in blood pressure, an increase in heart rate, constricts blood vessels and increases the strength of the heart’s contraction. This might sound pretty bad, but when you study people consuming nicotine without smoke, the potential effects don’t appear to materialise. Studies of nicotine patch use in smokers with cardiovascular disease have found no increase in heart attacks, cardiac arrest and other related events, and the same is true for snus users.
Although nicotine isn’t advised during pregnancy because it may impact foetal development, it’s worth stressing that if the choice is between smoking and nicotine alone (from a safer source), nicotine alone is the better choice. This is something to discuss with your doctor, but generally it’s better to avoid all nicotine when you’re pregnant if possible.
Overall, while there are several potential harmful effects of nicotine, there is little evidence of risk when consumed outside of smoke. Nicotine has been called “no more harmful to health than caffeine,” and many of the short-term effects – such as increasing blood pressure and heart rate – are the same for both substances.
4. Is Nicotine Really Addictive?
Some scientists have maintained that nicotine is more addictive than heroin.
However, the science is really not clear cut here. Some studies found that when you have no chance of getting a cigarette, your nicotine cravings decrease. For example, when Jewish smokers observe the Sabbath and refrain from smoking, their urge to smoke a cigarette also decreases.
Another study found that the physiological act of lifting the cigarette to your mouth and taking a puff has been vastly underestimated - perhaps deliberately, as most cessation studies are funded by pharmaceutical companies who sell nicotine cessation aids.
David Kroch, in his book Smoking, The Artificial Passion, has another interesting point to make. Whereas morphine and cocaine were rapidly adopted as drugs of 'abuse' when produced in a pure form, nicotine, stripped from tobacco, has rarely been popular.
The reason is that nicotine is not the only thing in tobacco that contributes to its addictiveness. Monoamine oxidase inhibitors, other tobacco alkaloids, acetaldehyde and nitric oxide all increase the addictive potential of the nicotine in cigarettes. Aside from much lower levels of acetaldehyde, these are all absent from e-cigarettes.
Things are generally more addictive if they reach your blood-stream quicker, and smoking gives a much quicker hit of nicotine than other delivery methods. This includes e-cigarettes, particularly earlier models (more on this in point 10).
These points, taken together, explain the problems researchers have had finding never-smokers who’ve become addicted to nicotine. It took a study specifically looking for some to identify just two people who could be seen as addicted to nicotine gum without having ever used tobacco in any form. The researchers note that other studies trying to do the same thing had completely failed.
The short version is that while it is possible to become addicted to nicotine without smoking or using tobacco, it’s not very likely at all. Without the extra addictiveness-boosting chemicals found in smoke and the rapid dose it provides, nicotine really isn’t very addictive at all.
With that in mind, it’s not surprising that 67% of e-cig users believe electronic cigarettes are less addictive than cigarettes.
5. A Stimulant - AND a Relaxant!
Nicotine is biphasic – it both stimulates and relaxes you. Take a little and it stimulates you – more than that, it can accentuate the mood of the moment, heightening your awareness of pleasure.
Take a lot, though, and it can help calm and relax you in stressful situations. When you smoke a cigarette, short, sharp inhalations produce the stimulant effect, whereas longer, deeper inhalations produce the relaxant effect.
However, the effect smoking has may also differ according to the situation you’re in. The relaxant effect occurs during stressful situations, when the same dose in other situations would have a stimulating effect.
The difference in effects depending on the dosage taken should be the same for vaping. However, because vaping doesn’t provide nicotine as effectively as smoking, the relaxing effects probably aren’t as easy to obtain, unless you’re in a stressful situation.
6. Does Nicotine Cause Brain Damage?
There are a few studies looking at nicotine and brain damage, but these tend to involve mice and rats rather than humans. For example, one study suggests that nicotine can actually stimulate recovery from brain damage, and others suggest that cotinine, the metabolite of nicotine (what your body turns it into), has a protective effect for the brain against diseases like Alzheimer’s and Parkinson’s.
However, there are other studies which suggest it kills brain cells and stops new ones from forming in the hippocampus, which is involved in memory. This is in contrast with the evidence on the effects of nicotine on memory (see point 7), though, so it’s hard to draw conclusions based on it.
One of the most common claims about nicotine’s effect on the brain is the oft-repeated line (especially in the US) that it may have lasting consequences for adolescent brain development. The research backing up this claim is summarised in the Surgeon General’s report on smoking (pages 150 to 152), and largely consists of studies on rats. There is some evidence on human teens, but this relates to smoking rather than nicotine alone.
In a nutshell: it’s hard to be sure about brain damage and nicotine in teens and adults, but animal studies suggest it may be a concern for teens. However, there is also plenty of evidence showing a benefit of nicotine for brain functioning, as the next two points address.
7. Nicotine and Memory
Nicotine may also help your memory. This is a controversial area, but there are several suggestive results that support the benefits of nicotine for memory.
For Alzheimer’s sufferers, the situation is a little uncertain, but there is some promise for nicotine. Researchers have found that there is a negative association between Alzheimer’s disease and smoking, meaning that smokers are less likely to suffer from Alzheimer’s than non-smokers. The reason appears to be that the receptors which nicotine acts on in the brain are crucial for maintaining performance on a wide range of tasks.
In Alzheimer’s sufferers, there are fewer of these receptors, and some studies show that providing them with nicotine can minimise the effect the disease has on their mental functioning. There is some disagreement on the benefits of nicotine for Alzheimer’s, though, with some arguing that nicotine could actually make things worse. However, this last study was conducted on rats, so it can’t be directly applied to humans.
For memory overall, the evidence suggests some benefit from nicotine. A review of the relevant studies suggests that nicotine can help improve the accuracy of short-term memory and improve the speed of recall for working memory. Working memory is basically the mental “workspace” you have to remember important facts as you’re performing a task.
When nicotine users are deprived, though, their performance on various tasks generally gets worse. This has led many to assume that the positive effects of nicotine on memory, attention and many other areas of brain functioning is more to do with alleviating these withdrawal symptoms than an actual positive effect. But this review focused on benefits of nicotine unrelated to withdrawal, so it does show that nicotine genuinely has a positive effect on some aspects of memory, even for non-users of nicotine.
A fairly recent study also found that nicotine patches helped patients with mild cognitive impairment gain 46% of normal performance, while a test group who did not receive nicotine declined by 26% in the same period.
8. Nicotine, Attention and Concentration
Although nicotine has moderate effects on memory, it does appear to be effective for improving concentration and the ability to pay attention.
The issue was covered by the meta-analysis (where the results of several experiments are combined and analysed together) from the previous section, which found numerous positive effects of nicotine on attention.
The benefits for attention primarily come in the form of more accurate and faster “alerting attention.” As the name suggests, this is to do with transitioning to an alert state and remaining in it.
This is tested using things like rapid visual information processing tasks. Participants are shown a series of numbers on a screen, one at a time, with each number being shown for less than a second. The task is to identify when three odd or even numbers is shown consecutively. This example comes from one of the studies used in the analysis, but other studies either used different target sequences (e.g. looking for the sequence 2, 4, 6) or other tests of the same basic skill.
The results showed that nicotine improves the number of accurate responses (correctly identifying a series of three even numbers, for example) and speeds up response time. The improvement in accuracy is stronger in smokers, but it was almost significant in non-smokers too. For response time, non-smokers improve more than smokers after consuming nicotine.
“Orienting attention” relates to paying attention to relevant factors while ignoring irrelevant ones, and is tested in a similar way to alerting attention. In these tests, people are given some target letters, and presented with a series of 20 letters. They have to scan the letters for the given target letters and state whether one, both or neither of the letters appears. Nicotine increases response time on these tasks, but it didn’t have any impact on accuracy.
There are also other results suggesting benefits in attention and concentration from nicotine, with two examples in simulated driving and flying suggesting that nicotine improves the ability to perform both of these tasks.
(See Are you smarter when you vape? for more information.)
9. Does Nicotine Make You Feel Less Hungry?
Nicotine can make you feel less hungry. In fact, as Paul Bergen has argued on this blog, this may have been one of the reasons why tobacco originally became so popular at a time when people were often hungry. (See Nicotine and Hunger: Closer than you think.)
In general, smokers weigh less and have lower BMIs (body mass indexes) than non-smokers, and the effect appears to be related to nicotine. Also, as you probably know, quitting smoking is commonly accompanied by weight gain.
There are many possible explanations for this, but the most widely-supported are that nicotine increases your metabolism and reduces your appetite. For example, one study found that increasing doses of nicotine decreased hunger and food consumption and increased feelings of fullness. This study also found that caffeine increased this effect – so vaping and drinking tea is probably a good approach to eating less! Another study has looked at the specific nicotine receptors (in mice) related to the decrease in appetite smokers report, which could even lead to new appetite-suppressing medicines in future.
However, the relationship between nicotine and weight isn’t as simple as it might seem. Although smokers weigh less than non-smokers overall, heavy smokers (no pun intended) are a different matter. Those who smoke are more likely to be overweight or obese, and some results show that heavy smokers have higher BMIs than both non-smokers and lighter smokers. The reason for this is that smoking – especially heavy smoking – is usually accompanied by a lot of other behaviours that lead to weight gain. For example, smokers tend to exercise less, eat less fruit and vegetables, and drink more alcohol, and this could be especially true for heavy smokers.
There are many other findings that show things are a bit more complicated than “smoking helps you lose weight.” For example, studies looking at what happens to weight when people start smoking have found conflicting results: sometimes new smokers seem to lose weight, other times they put it on or stay the same.
The overall conclusion is still that nicotine appears to help reduce appetite and facilitate weight loss, but it doesn’t appear to be as effective an approach as we might hope.
10. Electronic Cigarettes and Nicotine Delivery
Early studies found that electronic cigarettes did not deliver as much nicotine as cigarettes do. A follow-up study from the same author found that longer periods (up to an hour) of vaping with experienced users provided a similar amount of nicotine to a cigarette, but still a bit less.
The most well-known and informative study on nicotine delivery from vaping comes from Dr. Farsalinos, who compared first-generation devices with a (now quite old) mod. The results showed that the cigalike device didn’t get users the amount of nicotine they would obtain from a cigarette even after an hour and five minutes. However, newer-generation devices got vapers to cigarette-like blood-nicotine levels after 35 minutes of vaping.
A later study from the same team again showed that experienced vapers manage to obtain more nicotine from vaping than inexperienced smokers. This appeared to be related to the length of the puffs taken: smokers tend to puff quickly and sharply, while vapers take longer, more gradual and gentle puffs.
Although we don’t have evidence on this yet, it would be assumed that higher-wattage vaping with sub ohm tanks would be even more effective for getting you nicotine. However, it’s still likely that even modern vape mods will deliver rather less nicotine than regular cigarettes, so we always advise smokers to use higher nicotine strengths when they first get started with vaping.
Over to you
This is a huge subject, and I haven't covered everything. (I had to cut down the scope of this post or I would never have finished it!) What else would YOU include in a list like this?
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