Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.4 October 2022
Smoking is directly responsible for 8 million deaths worldwide each year, mainly from cancer (30% of all cancers are due to tobacco) and cardiovascular and respiratory diseases. There is therefore clearly nothing worse than cigarettes for health, and quitting smoking remains, by far, the best decision a person can make to reduce their risk of premature death.
In recent years, electronic cigarettes have emerged as a valid alternative to tobacco cigarettes to reduce the harmful effects of smoking on health. This approach is based on a relatively simple concept: while tobacco addiction is due to nicotine, it is rather the tobacco combustion products present in cigarette smoke that are responsible for smoking-related health problems. If we can satisfy smokers’ nicotine needs while eliminating exposure to cigarette smoke, we can therefore substantially reduce the damage to their health. This is exactly what e-cigarettes do, as these devices allow nicotine to be inhaled, but without the approximately 7,000 chemical compounds found in cigarette smoke, and therefore expose users to much lower amounts of toxins. This marked decrease in toxic molecules in e-cigarette aerosols has been confirmed by several independent bodies (Public Health England, National Academies of Sciences, Engineering, and Medicine and the Committee on Toxicity of Chemicals in Food, Consumer Products, and the Environment), and it is for this reason that organizations such as Public Health England and the Académie nationale de médecine in France strongly recommend that smokers make the transition to vaping.
A study recently published in Circulation, the flagship journal of the American Heart Association, is a good illustration of the positive impact of this harm reduction approach. In this longitudinal study, approximately 32,000 American adults were followed for a period of 6 years (2013–2019) to assess the risk of cardiovascular diseases (heart attack, stroke, heart failure) in smokers compared to non-smokers, exclusive e-cigarette users, and dual users (tobacco and e-cigarette).
The researchers first observed, unsurprisingly, that smokers had a much higher risk of heart disease (almost 2 times) than non-smokers (see Figure 1).
Figure 1. Increased risk of cardiovascular disease in smokers, but not in e-cigarette users (vapers). Adapted from Berlowitz et al. (2022).
However, this increase is not observed for exclusive e-cigarette users (15% increase, statistically insignificant), consistent with two recent studies (here and here). In other words, the very strong and well-documented link between smoking and cardiovascular disease is simply not observed for vaping, confirming the much lower toxicity of these devices compared to cigarette smoke. It should, however, be mentioned that dual users (who smoke and vape) have a risk of cardiovascular disease of the same order as that of smokers, which indicates that the residual exposure to tobacco toxins, even if it is slightly reduced in these people, remains harmful and sufficient to damage the heart and blood vessels.
The superiority of e-cigarette use is also highlighted when directly comparing the risk of cardiovascular events between smokers and vapers, with a reduction of about 34% in the risk observed among exclusive vapers (Figure 2). Here again, the benefits provided by e-cigarettes are completely cancelled out in dual users, and it therefore seems clear that to be truly effective in terms of harm reduction, electronic cigarettes must be a substitute for tobacco and not simply a complement, for example to obtain a dose of nicotine when it is not possible to smoke a cigarette.
Figure 2. Decreased risk of cardiovascular disease in vapers, but not in dual users. Adapted from Berlowitz et al. (2022).
These results are extremely important, because even though we already knew that e-cigarettes were safer than tobacco cigarettes, this is the first time that we have been able to quantify the reduction in risk associated with the transition from tobacco to exclusive vaping. It goes without saying that a one-third reduction in the risk of cardiovascular events has major implications in terms of public health and should prompt governments to encourage smokers to adopt vaping to reduce their risk of chronic diseases and premature mortality.
Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.17 February 2021
- Cigarette smoke causes chronic inflammation that significantly increases the risk of lung and cardiovascular disease.
- Two recent studies show that this inflammation can be considerably reduced by replacing cigarettes with e-cigarettes.
- Smokers can therefore drastically reduce the damage caused by cigarette smoke and the risk of smoking-related illnesses by using e-cigarettes as a source of nicotine.
It is now well established that smokers have a reduced life expectancy of around 10 years compared to non-smokers. This dramatic increase in the risk of premature mortality is due to the repeated exposure of smokers to the thousands of toxic and carcinogenic substances that are generated during the combustion of tobacco leaves (polycyclic aromatic hydrocarbons and nitrosamines, among others). For example, it is estimated that each pack of cigarettes contains enough carcinogenic compounds to cause two mutations in the DNA of lung cells, so decades of smoking results in the accumulation of several thousand of these mutations and dramatically increases (about 40 times) the risk of lung cancer.
Another factor that contributes to the harmfulness of tobacco is the chronic inflammation caused by the many toxic compounds found in cigarette smoke. Locally, this inflammation damages cells in the airways and greatly increases the risk of developing chronic obstructive pulmonary disease (e.g. emphysema). But the damage caused by this inflammation is not limited to the lungs. Following inhalation of cigarette smoke, the toxic compounds rapidly diffuse into the pulmonary capillaries and can then spread throughout the body via the bloodstream. A climate of generalized chronic inflammation is then created, characterized by an increase in several inflammatory markers (IL-6, CRP, ICAM) and the recruitment of immune cells to the surface of blood vessels, two phenomena that contribute to the development of atherosclerosis.
The blood vessels that supply the heart (coronary arteries) are particularly vulnerable to this inflammation. Since the heart is closely associated with the lungs, it is the first organ to receive blood that has been in contact with cigarette smoke and is therefore necessarily exposed to higher concentrations of toxic compounds.
The consequences of this proximity are disastrous. Studies show that people who smoke a pack a day have a 5 times higher risk of myocardial infarction compared to those who have never smoked, and smoking is estimated to be responsible for about 20% of all coronary heart disease deaths. So, even though we mainly talk about the major impact of tobacco on the risk of suffering from lung cancer, we must not forget that cardiovascular diseases remain the main cause of death associated with smoking. Of all the actions a person can take to improve their cardiovascular health (and overall health), quitting smoking is by far the most important.
The good news is that this damage of smoking on cardiovascular health can be reversed by quitting. Studies show that former smokers see their risk of cardiovascular accident decrease by 40% in the first five years after quitting and becomes similar to that of non-smokers after 10–15 years. Smoking cessation is beneficial at any age, but is particularly effective before the age of 40, with a 90% reduction in the risk of premature death from smoking.
Quitting smoking is difficult, with only 5% of people able to remain smoke-free after one year. However, several recent data show that this smoking cessation success rate can be considerably increased among smokers who opt for e-cigarettes. For example, a randomized clinical trial recently showed that e-cigarettes can double the effectiveness of smoking cessation compared to traditional approaches based on nicotine replacement therapy. A Cochrane review of 50 studies (including 26 randomized trials) with a total of 12,430 participants comes to a similar conclusion.
In addition to facilitating smoking cessation in the longer term, adopting e-cigarettes also has the advantage of immediately reducing the damage caused by tobacco. Remember that in an e-cigarette, a nicotine solution is heated to 80°C (compared to temperatures around 900°C in a cigarette), and therefore the vapour generated does not contain carbon monoxide, nor the thousands of toxic combustion products found in cigarette smoke. According to a recent study by the Institut Pasteur, the vapour emanating from e-cigarettes contains less than 1% of the toxins present in cigarette smoke, and consequently substantially reduce smokers’ exposure to these toxic compounds (see our article on this subject).
Two recent studies show that this drastic decrease in the amount of toxic compounds in e-cigarette vapour correlates with a significant decrease in inflammation normally observed in response to cigarette smoke. In the first of these studies, the researchers compared the levels of different inflammatory markers (hsCRP, IL-6, sICAM) or oxidative stress (urinary 8-isoprostane) present in non-smokers, vapers, cigarette smokers, and mixed users (vapers and smokers). As shown in Figure 1, while smoking causes a significant increase in the levels of all markers examined, these increases are much smaller, and in some cases (IL-6) even completely abolished, among exclusive e-cigarette users. Replacing tobacco cigarettes with an e-cigarette can therefore substantially decrease the inflammatory response and, in turn, reduce the risk of cardiovascular disease. However, the study clearly shows that this reduction in inflammation is not at all observed in vapers who continue to smoke cigarettes at the same time. To truly reduce the damage caused by smoking, e-cigarettes must therefore completely replace cigarettes and not simply serve to reduce the number of cigarettes smoked in a day.
Figure 1. Change in the levels of different markers of inflammation and oxidative stress in vapers and smokers. From Stokes et al. (2020). hsCRP: high sensitivity C-reactive protein; IL-6: interleukin-6; sICAM: soluble intercellular adhesion molecule.
The other study looked at the impact of e-cigarettes on the expression of inflammatory proteins by monocytes, a class of white blood cells involved in the innate immune response. Over-activation of these cells (by toxic compounds like cigarette smoke, for example) has been shown to trigger an inflammatory response that plays an important role in the initiation and progression of atherosclerosis.
Using blood samples taken from non-smokers, smokers, and vapers, the researchers examined by flow cytometry the profiles of inflammatory proteins (caspase-1, IL-6 receptor, TLR4) present in circulating monocytes in each category of volunteers. Unsurprisingly, they noted that the expression of all of these inflammatory proteins was higher in smokers, about 4 times higher on average than in non-smokers. However, this inflammatory signature was completely absent in vapers, suggesting once again that the elimination of cigarettes in favour of e-cigarettes leads to concrete health benefits for smokers. This is consistent with a recent randomized controlled trial that showed that the transition of smokers to e-cigarettes is accompanied by a rapid improvement (in just 1 month) in the health of the blood vessels.
This study shows once again how e-cigarettes allow smokers to significantly reduce their exposure to the many toxic substances in cigarette smoke and are therefore an extremely useful tool in the fight against diseases caused by smoking.
Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.18 September 2020
- Cigarette smoke contains more than 7,000 chemical compounds, of which at least 250 are well-characterized toxic substances and 70 are established carcinogens.
- By allowing the absorption of nicotine without the combustion of tobacco, e-cigarettes are therefore an alternative to reduce exposure to these toxic compounds.
- According to an analysis by the Institut Pasteur, this reduction is very significant since the aerosols generated by electronic cigarettes contain less than 1% of the toxic compounds found in cigarette smoke.
There is nothing worse than smoking for heart and blood vessel health (and health in general), and quitting smoking is by far the best decision a person can make to lower their risk of developing cardiovascular disease. However, quitting smoking is very difficult for many smokers, and, for several years, I have recommended that my patients who are unable to quit by conventional means (patches, gum, etc.) use electronic cigarettes.
In an e-cigarette, a solution of nicotine is heated to around 80°C using an atomizer, which generates an aerosol that allows vapers to inhale a small amount of nicotine (like smokers) to satisfy their addiction, but which does not contain the multiple toxic molecules that are generated during the combustion of tobacco (at around 900°C). This last point is the most important: contrary to what many think (including the majority of doctors), it is the combustion products of tobacco cigarettes that cause health problems, not nicotine. The latter is a drug that creates tobacco addiction and encourages people to smoke, but it has no major health effects and is especially not responsible for cardiovascular disease or lung cancer that result from smoking. The advantage of the electronic cigarette is therefore that it allows smokers who are highly dependent on nicotine to considerably reduce their exposure to the many toxic substances of cigarette smoke. This is a classic example of what is called harm reduction.
In addition, not only is the e-cigarette less toxic than tobacco, but a randomized clinical study recently published in the prestigious New England Journal of Medicine shows that it can be very useful for smoking cessation, with twice the effectiveness of traditional approaches based on nicotine substitutes. These devices therefore represent a very interesting technological innovation that adds a new dimension to the fight against tobacco.
That being said, one of the most disconcerting aspects of the media coverage surrounding anything related to e-cigarettes is the negative, often even alarmist, tone that is used to report the latest research developments on these devices. Any study that claims to show a negative impact of e-cigarettes on health makes headlines, even those that are low-quality and published in second-rate journals, while studies that instead report a positive effect are simply ignored, even when they are very scientifically sound and published in prestigious medical journals. This imbalance means that the population is informed only of the potential risks associated with e-cigarettes, without knowing that there is also a whole body of literature showing that these devices have positive effects on the health of smokers.
Perhaps one of the best examples of this media bias is the coverage of a study claiming to show an increased risk of heart attack in vapers, a study that was widely circulated in the media around the world when it was published. However, a critical examination of the results revealed that the majority of the 38 patients in the study had suffered a heart attack on average 10 years BEFORE they started vaping and therefore that these heart attacks could not have been due to e-cigarettes. Since vapers are almost always ex-smokers, the increase in heart attacks observed in vapers is simply due to the fact that these people gave up smoking after being sick and now use e-cigarettes to avoid a recurrence. This is a blatant case of scientific misconduct that resulted in the retraction of the article, but the withdrawal of this fraudulent study was not reported by most media. It should be noted that the main author of this retracted article, Stanton Glantz, is one of the most committed researchers against the use of e-cigarettes.
This is all the more unfortunate because a randomized clinical study, which was very well done, showed that it is exactly the opposite phenomenon that occurs, i.e. that the transition of smokers to e-cigarettes is positive because it is accompanied by a rapid improvement (in only one month) in the health of the blood vessels. However, this important study has not been reported by the media, and the public therefore does not know that, far from being harmful to the heart, e-cigarettes are instead associated with concrete health benefits for smokers.
The immediate consequence of this misinformation is that fewer and fewer people see e-cigarettes as a less harmful alternative to tobacco, including smokers, and there is a risk that the number of smokers who make the leap to e-cigarettes will decrease. I see it already in my practice: patients who weaned themselves off tobacco through vaping have resumed smoking, while others are reluctant to try e-cigarettes to quit smoking. In both cases, the reason given is the same: if vaping is as bad as smoking, why make the switch? This shows that disinformation campaigns can have real consequences for people’s lives and even literally make the difference between life and death for some of them.
Yet no one can seriously argue that e-cigarettes are as bad for your health as cigarettes. Cigarette smoke contains more than 7,000 chemical compounds, of which at least 250 are well-characterized toxic substances and 70 are established carcinogens. Repeated exposure to these toxic emissions is directly responsible for 8 million deaths each year worldwide, making smoking the leading cause of preventable deaths, especially those caused by cancer (30% of all cancers are caused by tobacco) and cardiovascular and respiratory diseases.
Analyses by Public Health England, the American National Academies of Sciences, Engineering, and Medicine and the British Committee on Toxicity of Chemicals in Food, Consumer Products, and the Environment all show that aerosols from e-cigarettes contain a much smaller number and amount of toxic substances than cigarette smoke and are therefore less harmful to health than smoked tobacco. It is for this reason that organizations such as Public Health England and France’s Académie nationale de médecine strongly recommend that smokers do not hesitate and make the transition to vaping.
This does not mean that e-cigarettes are completely safe, but they are undeniably much less harmful than the product they replace (which is the principle of harm reduction). By focusing only on identifying the potential harmful effects of vaping, we come to forget that the basic principle of vaping is to reduce the harms of smoking in smokers who are repeatedly exposed to toxic substances from tobacco.
A recent study by the Institut Pasteur provides a clear view of this potential for harm reduction. In this study, scientists compared the presence of two major classes of toxics (carbonyl compounds and aromatic hydrocarbons) in aerosols from smoked cigarettes, heated tobacco products (IQOS) and e-cigarettes. The results are really impressive: for the 19 carbonyls and 23 aromatic hydrocarbons tested, the e-cigarette chosen for the study (high-capacity tank device, used at maximum power) reduces these toxic compounds by 99.8 and 98.9% compared to tobacco cigarettes (Figure 1). IQOS (heated tobacco product) is also less toxic than cigarettes, with reductions of 85% and 96% in the concentration of these toxic compounds, but these reductions nevertheless remain lower than those observed with e-cigarettes, in line with previous studies.
Figure 1. Content of carbonyl compounds (A) and polycyclic aromatic hydrocarbons (PAHs) (B) in aerosols produced by a cigarette, a heated tobacco product and an e-cigarette. Note the drastic reduction of these two classes of toxics in e-cigarette vapour compared to tobacco smoke. From Dusautoir et al. (2020).
The researchers then compared the toxicity of different types of cigarettes by measuring the viability of bronchial epithelial cells following repeated exposure to aerosol puffs generated by cigarettes, heated tobacco products and e-cigarettes. As shown in Figure 2, exposing the cells to only 2 puffs from a cigarette is enough to kill half of the cells, and no residual cells are detectable after coming into contact with 10 puffs of smoke. Heated tobacco products significantly reduce this toxicity (40 puffs are necessary to kill half of the cells and a hundred to eliminate them completely), but it is here again that e-cigarettes are by far the least toxic, with all cells remaining alive even after exposure to 120 puffs of aerosols.
Figure 2. Viability of bronchial epithelial cells after repeated exposure to aerosols from a regular cigarette, a heated tobacco product or an e-cigarette. Note the high toxicity of cigarettes, which cause 50% mortality after cells are exposed to just 2 puffs of smoke, while cells remain viable even after being in contact with 120 puffs of aerosols from an e-cigarette. From Dusautoir et al. (2020).
Another study shows that this very significant reduction in toxicity is also observed for Juul, the e-cigarette which has recently captured the majority of the e-cigarette market (see our article on this subject). Compared to traditional cigarettes, the vapour generated by Juul contains almost 100% less carbon monoxide and carbonyl compounds like acetaldehyde, formaldehyde, and acrolein (a major irritant in cigarette smoke) (Table 1). Similar results were also reported in another study. These data are important because Juul is particularly popular among young vapers. Contrary to what we often hear, the vast majority of young people (> 99%) who regularly vape are occasional or regular smokers and these people can therefore substantially reduce their exposure to tobacco toxins by vaping. In addition, recent data indicates that nicotine absorbed through e-cigarettes is less addictive than when it comes from burning tobacco, which decreases the risk of developing longer-term dependence.
Table 1. Concentration of certain toxic compounds present in cigarette smoke or in the vapour generated by the Juul e-cigarette. From Son et al. (2020).
It is worth remembering that the ultimate goal of tobacco control is to reduce the incidence of smoking-related diseases, especially cardiovascular disease and lung cancer. To achieve this, total abstinence is desirable, but the large number of people who are unable to quit smoking on their own or by using current cessation tools and therefore remain at risk of dying prematurely must be taken into account. In my clinical experience over the past ten years, the electronic cigarette is the most popular nicotine replacement for smokers and for many of them represents the only approach that allows them to successfully quit smoking. Instead of constantly seeking to discredit these devices, as is currently the case, they should instead be seen as a technological innovation that can greatly contribute to the fight against diseases caused by smoking, and we need to clearly inform smokers of the benefits associated with the transition to vaping.
Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.30 June 2020
- The percentage of young Canadians aged 16–19 who smoke cigarettes on a regular basis continued to decline between 2017 and 2019, from 3.8% to 2.3%.
- This decrease in youth smoking is correlated with an increased use of electronic cigarettes, with the proportion of young people having vaped at least once in their lives increasing from 29 to 41% during this period.
- These vapers are, however, mostly occasional or regular smokers, which suggests that the electronic cigarette represents an alternative to traditional cigarettes and contributes to the decline in smoking observed among young people.
One of the greatest successes of tobacco control in the last 20 years has been the dramatic decline in smoking among young adolescents. As we mentioned in another article, while nearly 25% of teens in grade 12 smoked cigarettes daily in the early 2000s, this proportion is now around 2%. This drastic drop in youth smoking is of paramount importance, as more than 90% of regular adult smokers started smoking before the age of 18, during the experimentation period of adolescence. Such a low rate of smoking among young people will therefore necessarily translate into a significant reduction in the number of adult smokers over the next few years and a decrease in the incidence of the many diseases caused by tobacco, which is the ultimate goal of tobacco control.
However, this good news is rarely mentioned: instead of celebrating this decline in youth smoking, much more attention has been paid to the recent emergence of a new trend, namely the increase in the number of young people who have experimented with electronic cigarettes in recent years. According to a recent study by Dr. David Hammond’s group, e-cigarette use is indeed on the rise among young Canadians, with about 41% of 16-19-year-olds having tried these products at least once, compared to 29% in 2017 (Figure 1). This increase is correlated with the appearance on the market of e-cigarettes of the Juul type, extremely attractive and easy-to-use devices, which allow the absorption of a significant amount of nicotine (see our article on the subject).
Figure 1. Frequency of use of electronic cigarettes by 16-19-year-olds. Adapted from Hammond et al. (2020). Note that non-smokers represent less than 1% of total vapers.
However, it is important to note that the vast majority of this vaping is experimental in nature. While almost half of young people have used these products at least once in their life, this proportion decreases to 18% in the last month, 12% in the last week, eventually reaching just over 5% of regular vapers (20 or more times in the last month). Daily use of electronic cigarettes is therefore still a relatively uncommon phenomenon among young people and certainly does not reach “epidemic” proportions, as is often said. Not only do regular vapers remain a very small minority, but most (over 85%) of these young people already smoke cigarettes occasionally or regularly. Young people who have never smoked cigarettes represent less than 15% of regular vapers, which corresponds to less than 1% of all vapers (Figure 1, red rectangle).
Overall, these results paint a much more nuanced picture of the phenomenon of vaping among young people than what we regularly hear in the media: the vast majority of those who want to experience the effect of tobacco are now turning to new forms of nicotine such as electronic cigarettes, but even then the regular users of these products remain relatively few, and are mostly young people who are primarily attracted to tobacco.
Initially, the main concern raised by the increased use of electronic cigarettes by young people is that it could lead to an increase in smoking in this population. This is clearly not the case as the number of young smokers continues to decline each year, even since the introduction of the electronic cigarette, and studies even indicate that these products have led to an acceleration of this decline in the smoking rate. The study mentioned earlier observes the same phenomenon, i.e. that the increase in vaping observed over the past two years in Canada is directly correlated with a significant decrease (40%) in smoking among young people (Figure 2).
Figure 2. The increase in the percentage of young vapers is correlated with a decrease in the percentage of young smokers. From Hammond et al. (2020).
Instead of being a gateway to tobacco as was initially feared, the electronic cigarette therefore seems to represent more of an alternative to traditional cigarettes. The abandonment of cigarettes by young people in favour of this new technology is not so surprising when you consider the unpleasant smell of cigarettes, the exorbitant prices of tobacco, and the ban on smoking in almost all public places. In such a context, it is difficult to conceive why a user of electronic cigarettes might be tempted to turn to conventional tobacco products.
Obviously, everyone agrees that it would be better if young people did not use either electronic cigarettes or tobacco. But if we assume that adolescence is an intense period of experimentation, it is vastly preferable that this experimentation with the effects of nicotine be done in the form of vaping rather than of tobacco cigarettes.
It should be noted that with an electronic cigarette, the vaper inhales an aerosol containing nicotine, but without the multiple carcinogenic molecules, carbon monoxide and fine particles that are generated during the combustion of tobacco (at around 900 °C). This last point is the most important: it is the combustion products of tobacco cigarettes that cause health problems, not the nicotine. The latter is a drug that creates addiction to tobacco and pushes people to smoke, but it has no major effects on health and is especially not responsible for cardiovascular diseases or lung cancer that result from smoking. According to the British public health agency, Public Health England, the vapour generated by electronic cigarettes is much less toxic than the smoke produced by the combustion of tobacco, and therefore vaping presents considerably less risk to health than smoking.
It is also important to remember that while there is great concern about the increase in vaping among young people, electronic cigarettes are certainly not the main threat to their health. For example, surveys in the United States indicate that more than 15% of high school youth regularly drink large amounts of alcohol (binge drinking), an extremely harmful behaviour that is associated with an increased risk of accidents, violence and several serious diseases (stroke, cirrhosis, cancer). Although the consumption of alcohol is more socially acceptable than that of electronic cigarettes, it should be kept in mind that excessive alcohol consumption represents one of the main causes of death on a global scale and is therefore much more harmful to the health of youth than electronic cigarettes. Before considering banning vaping products under the pretext of “protecting our young people”, as is sometimes argued, we must take into account these relative risks and avoid any form of prohibition that could have the effect of leading them towards combustible tobacco products, which are much more harmful to health. Despite the often very alarmist reports, the transition from tobacco to e-cigarettes is a less worrying trend than it might appear at first glance and represents a typical example of harm reduction in public health.
Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.26 November 2019
- 141 regular smokers were subjected to three different treatments: 1) tobacco cigarette (control group), 2) e-cigarette containing nicotine, and 3) e-cigarette containing no nicotine.
- A month later, researchers measured arterial stiffness and dysfunction of blood vessels, two major risk factors for cardiovascular disease.
- The results show that the transition to e-cigarettes rapidly improves the function of blood vessels, regardless of its nicotine content, confirming the usefulness of these devices for reducing cardiovascular damage caused by tobacco.
A study recently published in the Journal of the American College of Cardiology confirms the enormous potential of e-cigarettes to reduce cardiovascular damage caused by combustible tobacco. In this randomized clinical study, researchers recruited 141 regular smokers (15 or more cigarettes per day for at least two years) and randomly separated them into 3 distinct groups: 1) a control group, in which participants continued to smoke tobacco cigarettes; 2) a group where participants replaced tobacco cigarettes with e-cigarettes containing nicotine (16 mg); and 3) a group where participants replaced tobacco cigarettes with e-cigarettes not containing nicotine. To measure the impact of different treatments on cardiovascular health, the researchers measured, at the start of the study and 1 month later, arterial stiffness and dysfunction of blood vessels, two important risk factors for cardiovascular disease.
This approach measured 5 major positive changes associated with the substitution of tobacco cigarettes by e-cigarettes:
1) The transition to e-cigarettes quickly improves the function of blood vessels. The function of the endothelium (the thin layer of cells lining the inside of blood vessels) was assessed by flow-mediated dilatation, a technique that measures the ability of these vessels to dilate. An increase in vasodilation allows a better supply of oxygen to peripheral tissues and is considered an excellent marker of the health of blood vessels.
The researchers observed that flow-mediated vasodilation is increased significantly only 1 month after the substitution of tobacco cigarettes by e-cigarettes, independently of the presence of nicotine (Figure 1). The increase observed (about 1.5%) may seem minimal at first glance, but several studies have shown that an increase of only 1% in flow-mediated vasodilation is associated with a 13% decrease in the risk of cardiovascular events. According to the authors, the observed vasodilation values are even close to those of healthy non-smokers, which shows how quickly the transition to e-cigarettes had beneficial effects on the cardiovascular health of smokers.
Figure 1. Change in mean flow-mediated dilatation among tobacco cigarette smokers and e-cigarette users.
2) Arterial stiffness is reduced as a result of the transition to e-cigarettes. Arterial stiffness was assessed using pulse wave velocity, a technique that measures the speed at which the pulse travels along the arteries. The stiffer the arteries, the less ability they have to contract and expand as a result of changes in blood volume and therefore the higher the speed of pulse wave propagation. A reduction in velocity should thus be considered as a sign of improved vessel health.
This is what has been observed in smokers who have smoked the equivalent of a pack of 20 cigarettes per day for less than 20 years (20 packs-years): the measurement of pulse wave velocity in these people indicates a significant decrease in artery stiffness following the transition to e-cigarettes (with or without nicotine). However, this phenomenon is not observed in smokers who have been smoking longer (>20 pack-years), which could suggest that in these people, the damage caused by tobacco to the elasticity of the arteries is more pronounced and could not be mitigated in just one month of intervention.
3) Women can particularly benefit from the transition to e-cigarettes. An analysis of the results by sex of smokers indicates that the improvement in vasodilation mediated by the flow obtained following the adoption of e-cigarettes appears to be more pronounced among women smokers than men smokers. This is very important because women who smoke are much more at risk of developing smoking-related health problems than men, with almost 3 times more risk of developing lung cancer and 2 times more risk of having a myocardial infarction. With approximately 200 million women currently smoking cigarettes worldwide, the potential for harm reduction by e-cigarettes in this population is therefore considerable.
4) The more complete the transition to e-cigarettes, the better its impact on the health of blood vessels. An easy test to determine if a person has recently smoked a tobacco cigarette is to measure the level of expired carbon monoxide (CO). The authors observed that participants with the lowest CO levels also had the strongest improvements in blood vessel function, suggesting that the positive effects observed in the study would have been even more pronounced if all smokers had used e-cigarettes exclusively. Nevertheless, the significant improvement in vessel health, even among those who “cheat” from time to time, indicates that any reduction in tobacco use, even if not total, is positive for health.
5) The presence of nicotine has no influence on the benefits of e-cigarettes. No difference in cardiovascular benefits could be observed between e-cigarettes containing nicotine or not, which is consistent with several observations showing that it is tobacco combustion products, not nicotine, that are responsible for the negative effects of smoking. Of course, nicotine is the drug that creates tobacco addiction and encourages people to smoke, but it has no major health effects and is not responsible for cardiovascular disease or lung cancer that results from smoking.
Overall, this study, which stands out from many others, must be commended for its scientific rigour and its clinical relevance. Recently, there have been many reports in the media about studies that claim to show that the vapour generated by electronic cigarettes has harmful health effects, with some going as far as to say that they are as harmful as cigarettes. What the media reports do not say, however, is that these studies often have serious methodological flaws that completely invalidate their conclusions. For example, a few days before the publication of the article described here, a summary presented at the American Heart Association’s annual conference reported that e-cigarettes had an adverse effect on blood vessel function, i.e. they decreased flow-mediated vasodilation. However, these parameters were measured immediatelyafter the inhalation of the vapour, which makes no such conclusions possible: just about anything that is stimulating (coffee, sex, alcohol or even certain foods) elicits this type of acute response in the short term, but this effect is transient and has no longer-term impact. It is only when abnormalities in blood vessel function occur over long periods of time (as in the study described earlier) that they can serve as a marker of risk of future cardiovascular events.
Another good example of disinformation about the effects of e-cigarettes is a study that claims to show an increased risk of heart attack in vapers: a close examination of the data indicates that the majority of the infarctions reported in the study occurred before the adoption of vaping by participants and therefore cannot be due to e-cigarettes! Since vapers are generally ex-smokers, the increase in infarction observed among vapers is simply due to the fact that these people have given up smoking after being sick and are now using e-cigarettes to avoid a recurrence. It is therefore appalling that this type of study, which does not even respect the basic rules of the scientific approach, is currently being used as a pretext to claim that e-cigarettes are as dangerous as tobacco cigarettes, and at the same time create a climate of mistrust towards these devices.
The main danger of the current anti-vaping climate is to reduce the number of smokers who make the leap to e-cigarettes. I can already see it in my practice: patients who had quit smoking thanks to vaping have started smoking again, while others are reluctant to try e-cigarettes. In both cases, the reason given is the same: if vaping is as bad as smoking, why make the transition? So, we can see that disinformation campaigns can have real consequences for people’s lives and even literally make the difference between life and death for some of them.
It is worth remembering that the ultimate goal of tobacco control is to reduce the incidence of smoking-related diseases, particularly cardiovascular disease and lung cancer. Although in theory total abstinence is desirable to achieve this goal (one cannot be against virtue), the reality remains that many people are unable to quit using current smoking cessation tools and therefore remain at risk of dying prematurely. The value of e-cigarettes is that they allow these people to considerably reduce their exposure to the many toxic substances of cigarette smoke, with immediate positive effects on their health. Moreover, not only are e-cigarettes less toxic than tobacco, but a randomized clinical study recently published in the prestigious New England Journal of Medicine shows that they can be very useful for smoking cessation, with twice the effectiveness of traditional nicotine substitute approaches. Instead of trying by all means to “demonize” e-cigarettes, these devices should instead be seen as a very interesting technological innovation that adds a new dimension to the fight against tobacco.
We must therefore hope that serious studies, such as the one described here, will succeed in putting an end to current disinformation campaigns and remind smokers that e-cigarettes are much less harmful than tobacco and can greatly help them quit smoking definitively.
I want to make it clear that I do not receive any compensation from companies and shops that sell e-cigarettes. I also do not receive fees as a speaker or consultant from pharmaceutical companies, especially those that make products to quit smoking, unlike many doctors and scientists who are very critical of e-cigarettes.
Dr Martin Juneau, M.D., FRCPCardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.16 July 2019
In recent years, there has been much mention of the marked increase in the use of e-cigarettes by young people, a trend that has recently increased with the arrival of Juul (see our article on this topic). The often alarmist tone that accompanies the reports of these studies suggests that vaping currently reaches “epidemic” proportions and poses a serious threat to the health of young people by pushing them towards the traditional cigarette.
These fears are no doubt in good faith, but they are not at all consistent with the results of the serious surveys that have been conducted in recent years, particularly with regard to smoking rates among young people.
Smoking rates continue to plummet among young people.
Very little is said about it, but one of the most encouraging trends in tobacco control is the marked decline in youth smoking seen in recent years. One of the best examples of this reduction is provided by the “Monitoring the future” survey, a large epidemiological study conducted since 1975 by researchers at the University of Michigan, which annually measures the prevalence of users of different drugs among American high school students. As shown in Figure 1, while youth smoking peaked in 1997 with 37% of 12th grade youth who smoked occasionally and 25% who smoked daily, these proportions have since significantly fallen to 7.6% and 2%, respectively, in 2018. A similar trend is observed in Canada, with approximately 3.5% of 12–17-year-olds who were smokers (casual or regular) in 2017, a 25% decrease compared to 2013 (4.6%). It should also be noted that according to the latest data from Statistics Canada, the proportion of Canadians aged 12–17 who smoked cigarettes daily was only 0.9% in 2018.
Figure 1. Changes in the proportion of smokers among 12thgrade American high school students from 1975 to present day. From Bates (2019).
Can the introduction of e-cigarettes reverse these trends, as many fear? There has been a lot of evidence from studies (here, here and here, for example) that teens who have tried e-cigarettes are more likely to smoke a tobacco cigarette than those who have never been in contact with the electronic cigarette. But as several experts have pointed out, this interpretation is not scientifically valid, because it is impossible to establish a causal link between the two phenomena: a young person attracted by tobacco will experiment with several forms available, without necessarily meaning that trying one will lead to testing another.
To determine the impact of the e-cigarette, the best measure remains to examine the evolution of youth smoking. And in this regard, the results are reassuring: although these products have appeared relatively recently (around 2010), the available data suggest that they have not had negative impacts on the adoption of cigarettes by young people: in the United States, for example, the smoking cessation rate is 3 to 4 times higher between 2010 and today than between the period from 1975 to 2010, suggesting that e-cigarettes have instead accelerated the reduction of youth smoking (Figure 1). It should also be noted that Juul has been available since 2015 in the United States and has since conquered most of the e-cigarette market, but this has not resulted in a resurgence of youth smoking. The data are also reassuring for England, where e-cigarettes have been available for several years: the smoking rate has been steadily decreasing since 2011 and the largest decrease is observed among 18–24-year-olds.
According to the data currently available, the fear that vaping leads to smoking therefore seems totally unfounded. On the contrary, it seems that vaping represents an increasingly popular alternative to traditional cigarettes and could even replace conventional tobacco products in the short and medium term. This is very encouraging, since it is clearly established that e-cigarette vapour is much less harmful than cigarette smoke, particularly because of a very significant decrease in the presence of carcinogenic compounds.
Regular vapers are usually smokers.
A recent study found that the proportion of young e-cigarette users has increased significantly in Canada from 29% to 37%. At first glance, this may actually seem enormous, and it is this type of statistic that is at the root of the concerns raised by vaping critics.
However, it is important to know that in this type of study, individuals are considered smokers or vapers if they have used these products at least once in a given period (in the last month, for example) or during their lifetime. This approach fails to distinguish occasional users from those who regularly smoke or vape. To make a simple analogy, it is as if a study of pathological gambling considered that people who buy a lottery ticket from time to time belong to the same category as those who go to the casino every day. This is obviously not the case: it is the development of a dependence on a substance (tobacco, alcohol, drugs, opiates) or an activity (excessive gambling, for example) that poses risks, whereas occasional use is much more like an experiment, a phenomenon that is particularly common among young people.
In fact, when we take into account the frequency of vaping and smoking habits, the situation is much less worrying. As shown in Figure 2, the vast majority of young people only vape occasionally (only 3.6% of 16-19-year-olds were vaping more than 15 days per month according to the latest estimates); 2) it is mainly young people who smoke cigarettes (regularly or occasionally) who are attracted to these products; and 3) only a tiny proportion of non-smokers (less than 1%) vape regularly.
Figure 2. Distribution of vapers according to the frequency and habits of tobacco use. Note the very low percentage of non-smoking youth who regularly vape (arrow). From Hammond et al. (2019).
The situation is not “out of control”, as we hear regularly, but rather reflects a new reality: the traditional cigarette is no longer popular with young people, possibly because of the exorbitant prices and smoking bans in almost all public places. The vast majority of those who want to experiment with the effect of tobacco are turning to new forms of nicotine such as e-cigarettes, but even then, regular users of these products remain relatively few, and are for the most part young people who are primarily attracted to tobacco or inclined to adopt higher-risk behaviours in general. This last point is well illustrated by a study in Colorado, where researchers have found that vapers are 5 to 10 times more likely to have previously tried hard drugs such as cocaine or regularly drink excessive amounts of alcohol than non-vapers (Table 1).
Table 1. Comparison of the prevalence of risky behaviours between vapers and non-vapers. From Ghosh et al. (2019).
Overall, and despite the sensationalist headlines in recent years, we must consider that e-cigarettes do not pose a threat to the enormous progress we have made in tobacco control. On the contrary, regular vapers are mostly smokers, and the adoption of these products can substantially reduce the risks associated with cigarette smoke. Based on the very low percentages of non-smokers who regularly vape, it also seems that nicotine vapour is less addictive than traditional cigarettes and it is very unlikely that it can be used as a gateway to tobacco.
It should also be remembered that the main utility of e-cigarettes remains one of the best ways to quit smoking, with twice the effectiveness of nicotine replacement therapy. The British have long recognized the usefulness of e-cigarettes in tobacco control and, hard to imagine here, have even made these products the emblem of anti-smoking campaigns (see photo).
(Public Health England advertising promoting e-cigarettes to quit smoking)
An extremely damaging collateral effect of the current “hysteria” towards e-cigarettes is to make smokers suspicious of these products and at the same time to deprive them of a valuable aid to quit smoking. The latest surveys also show a sharp increase in the number of smokers who think that the e-cigarette is as, if not more, damaging than the traditional cigarette. This is a very unfortunate situation, which shows how the best is sometimes the enemy of the good: by wanting at all costs to prevent vaping among young people, we are creating a climate which discourages the use of alternatives to tobacco that are infinitely less dangerous and would have a very positive impact on the health of smokers.
Of course, we must remain vigilant about the use of these products by young people and I will be the first to question the regulatory framework surrounding their marketing if it turns out that modern e-cigarettes (Juul, for example) lead to an upsurge in smoking among this population. With the current state of knowledge, on the other hand, there are many reasons to be optimistic and consider the electronic cigarette as a very promising tool to reduce smoking and even, hopefully, ultimately lead to the complete disappearance of the traditional cigarette.