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.

Pro-inflammatory smoke
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.

Reversible damage
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.

Reducing damage
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.

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.

Large-scale misinformation
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.

Toxics reduction
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.

OVERVIEW

• 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.