World No Tobacco Day: What is tobacco and how does it affect our health?

Where does tobacco come from?

Tobacco, as we know it today, comes from a night-shade plant called Nicotiana tabacum. Indigenous to Mesoamerica and South America, its dried leaves are used to make tobacco found in cigarettes, cigars, etc.

Tobacco was first consumed by Indigenous Americans during religious rites and as a medicinal plant. Christopher Columbus, in his exploration of the New World in the 15th century, "discovered" tobacco smoking and consequently brought tobacco leaves and seeds back to Europe. The plant was initially used by Europeans medicinally, and only apothecaries could sell it. It was also later incorporated into the pharmacopoeia (a reference book of medicines and their uses) of many countries across Europe. In 1572, the publication of a treatise included tobacco as a medicinal plant confirmed its medicinal use. In the 19th century, medicinal cigarettes made of tobacco, datura, henbane, foxglove and belladonna even appeared.

From the 1600's in the New World, tobacco became a valued commodity fueling colonization and was often traded as money. Tobacco even helped to finance the American Revolution, serving as collateral for loans American revolutionaries borrowed from France. Later in France, the consumption of tobacco became democratized during the French Revolution and the military draft: "The soldier smokes, as others drink, to forget," wrote Marc Alyn, a French writer and poet.

Despite its popularity, tobacco's harmful effects were quickly suspected. Indeed, in 1610, Sir Francis Bacon observed that quitting tobacco was extremely difficult. Later, in 1642, Pope Urban VIII threatened all tobacco users with excommunication. Moreover, Guy-Crescent Fagon, personal physician of King Louis XIV of France, wrote a thesis entitled "Does frequent use of tobacco shorten life?" In 1842, Honoré de Balzac, a French novelist, wrote, "Tobacco, a tax a hundred times more immoral than gambling, destroys the body, attacks the intelligence; it dazes a nation." However, it was not until the second half of the 19th century that Claude Bernard, a French physiologist considered to be the founder of experimental medicine, described the toxic nature of tobacco as demonstrated in animals. 

It wasn't until the 1960s that awareness of tobacco's negative impact on health was truly raised in the United States, notably with the Surgeon General's Advisory Committee on Smoking and Health, spearheaded by then Surgeon General Luther Terry. Today, a distinction is made between "active smoking" (the act of smoking) and "passive smoking" (the involuntary inhalation of tobacco smoke in the presence of a smoker, secondhand smoke).

How does tobacco smoking affect our health?

When a cigarette is burned, the dried leaves that are burned turn into an aerosol. Thus, the 2,500 substances present in the unburned tobacco are transformed into 4,000 in the tobacco smoke. Of these, the majority are toxic and about 70 are carcinogenic.

First, the psychoactive substance responsible for addiction in tobacco is nicotine (an alkaloid). Nicotine addiction is very powerful: from the very first weeks of exposure and even with a low consumption of tobacco, the smoker can develop an addiction. Nicotine addiction entails a physical, psychological and behavioral dependence.

The physical dependence is due to the chemical effect of nicotine. Nicotine binds to the nicotine receptors in our nervous system, which results in the release of a hormone: dopamine. Dopamine gives the smoker a feeling of relaxation and well-being that he or she will associate with smoking.

The psychological dependence is also linked to the psychoactive effects of nicotine which provide the smoker with a feeling of relief, intellectual stimulation, and relaxation, and will allow the smoker to overcome his or her emotions. Nicotine acts as an anxiolytic (anxiety reliever) and an anorectic (appetite suppressant).

The behavioral dependence is related to the smoker's habits. The act of smoking itself, the places or people in which and with whom the individual used to smoke, all help to maintain the addiction.

In addition, substances such as tars, toxic gases like ammonia and carbon monoxide or heavy metals like cadmium and lead are inhaled by the smoker. It is also important to note that tobacco is toxic no matter how it is consumed (in cigarettes, cigars, in a pipe, etc.).

Tobacco is responsible for many health problems such as cancer, cardiovascular diseases and lung conditions. These morbidities are related to the quantity smoked but also to the time during which the person smoked, two factors calculated in pack years. Pack year is calculated as follows: the number of packs (taking as reference 20 cigarettes = one pack) per day, multiplied by the number of years the person has been smoking. So, one pack year (PY) is equal to 1 pack smoked per day for 1 year, two PYs is equal to 1 pack per day for 2 years or 2 packs per day for 1 year, and so on. Although there is no threshold beyond which the risk is more severe, the PY factor gives an indication of the severity of the patient's smoking.

Tobacco and cancer

One out of three cancers are thought to be caused by smoking. The most common is lung cancer (about 80% of cases are due to smoking). However, cigarettes are also implicated in other cancers such as those of the aerodigestive tract: lips, mouth, tongue, for which tobacco is responsible for 70% of cases. 

50% of bladder cancers are also caused by tobacco. 

Tobacco and other health conditions

Unfortunately, smoking is not only responsible for cancers but also for cardiovascular diseases such as myocardial infarction (heart attack), stroke, high blood pressure or peripheral artery disease (PAD) which can lead to amputation.

Tobacco is also the cause behind a number of respiratory diseases. Indeed, 85% of cases of chronic obstructive pulmonary disease (COPD) are linked to smoking. COPD multiplies one's probability of developing lung cancer by 2.

It has also been proven that smokers suffer from reduced fertility, longer conception times, reduced chances of successful fertility treatments and erectile dysfunction.

In addition, secondhand smoke increases the risk of asthma in children and infants.

How to quit smoking?

There are many ways to quit smoking. Some people can do it alone, others with the help of health professionals. In both cases, nicotine replacement therapies (NRT) are available over the counter (without a prescription) at the pharmacy or can be prescribed by a doctor.

NRTs serve as an aid in the withdrawal process. The goal is to reduce the dose of nicotine until total cessation is achieved. They exist in different forms such as patches, chewing gum, tablets or powders for inhalation. These treatments increase the chances of fully quitting by 50 to 70%. 

There are also non-nicotine smoking cessation aids such as varenicline (Chantix®) and bupropion (Zyban®), which are only available on prescription. These drugs are used as a second-line treatment when nicotine replacement therapy fails. They require strict medical monitoring and can have side effects such as nausea, dizziness, headaches, etc.

Your doctor or pharmacist can also help you to quit and offer your moral and psychological support, which is sometimes necessary. Your primary care doctor can also refer you to a tobacco specialist or an addictologist.

There are also organizations that help people who want to quit smoking: Both Smokefree.gov and the CDC provide a number of helpful resources to help you get and stay on your way to a smoke-free life.

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