Cigarettes are addictive there is no doubt about it, but are substances added to ‎make them more addictive? And if ingredients are added to only “improve the ‎taste”, do they in actual fact only improve the taste?‎

The main ingredient in cigarettes is tobacco - a plant that contains, among other things, a relatively high concentration of a chemical called nicotine, which is the active and addictive chemical in cigarettes. But it is a mistake to consider cigarettes a ‘natural’ product. Since the 1950s, the tobacco companies, especially in the United States, initiated countless scientific studies that have led to many changes in the cigarette in order to increase its biological and pharmacological effect. In recent years, as a result of legislative changes in the United States and claims filed against the cigarette companies, companies have been forced to publish secret documents on the studies of smoking carried out over the years. It also forced companies to disclose the ingredients that are added to cigarettes.

Here we take a look at Philip Morris USA, manufacturer of Marlboro cigarettes, L & M, Parliament, etc. Below is a list of materials included in the tobacco mixture of Marlboro cigarettes (ingredients listed also represent other cigarettes):

Ingredients of Marlboro cigarettes | Screenshot from the website of Philip Morris USA

It should be noted that R.J. Reynolds, a competitor tobacco company, which manufactures, among other things, Winston, Camel, Pall-Mall and Lucky Strike, whose cigarettes contain exactly the same components. This is the list of ingredients in Camel Blue cigarettes:

Ingredients in Camel Blue cigarettes | Screenshot from the website of the tobacco company R.J. Reynolds

The tobacco companies argue that the components are designed to enhance the taste of the cigarette, but if you go through the list of ingredients you can see that many of the components that are added act on the human body or the nicotine itself to strengthen its effect, as explained in detail below. Is it a coincidence? Judge for yourself:

Sugar mixture – it is claimed they are added to change the taste in order to mask the bitterness of nicotine. However, when sugars are heated and burnt they emit a substance called acetaldehyde; cigarette smoke is rich in acetaldehyde. Studies show that when acetaldehyde is absorbed with nicotine it reaches the brain, and has a more powerful effect (synergy) - meaning one of the substances increases the activity of other, so when the two are combined, the effect is more powerful than just the sum of their effects alone:

Controlled studies conducted on rats (using an established animal model for addiction to tobacco) showed a mixture of nicotine with a small amount of acetaldehyde caused a much stronger addiction than nicotine alone; the rats consumed more nicotine compared to when they were give just ‘pure’ nicotine. In addition, the effect is in fact strongest in young animals. The most likely mechanism of action is based on inhibition of the enzyme called monoamine-oxidase (MAO), which is active in brain nerve cells and is responsible for breaking down neurotransmitters. The result is a prolonged activity of pleasurable substances that are released in the brain under the influence of nicotine, such as dopamine and serotonin.

Source no. 1: Acetaldehyde enhances acquisition of nicotine self-administration in adolescent rats.
Source no. 2: European Commission, Health and Consumer protection – Tobacco Additives.
Source no. 3: Abuse potential of non-nicotine tobacco smoke components: acetaldehyde, nornicotine, cotinine, and anabasine. Sales, Nicotine and Acetaldehyde Relationships. 
Source no. 4: From the documents forcibly published by studies done by Philip Morris, titled “Behavioral Pharmacology Annual Report - 1983” that evaluates the optimal relationship for the ratio of nicotine to acetaldehyde in cigarettes, according to sales.

Licorice extract – licorice is an herb with a typical flavor that also affects the taste of the cigarette. But one of the main components of the plant is a substance called Glycyrrhizin - which also acts as a bronchodilator, i.e. a chemical that expands the tubes in the lungs, allowing more smoke to penetrate into the lungs and beyond, and therefore increasing the effect of smoking.

The trachea and its split into two lungs. On the bottom are the bronchi | Illustration: Wikipedia

The importance of licorice and the extent of its use in modern cigarettes is proven by the fact that it occupies between 1 and 4 percent of the weight of the cigarette, and that 90 percent of the world's licorice is used for the cigarette industry.

Source no. 1: Cigarettes: Some things you probably didn't know were in there (including licorice)
Source no. 2: Seeing Through the Smoke -- The Secrets In a Cigarette
Source no. 3: Toxicologic evaluation of licorice extract as a cigarette ingredient

Di-ammonium phosphate and ammonium hydroxide - These two chemicals release ammonia gas (NH3(g)). Ammonium phosphate ((NH4) 2HPO4 (s)) releases ammonia when heated, according to the following reaction:

(NH4)2HPO4 (s) → NH3 (g) + NH4H2PO4 (s)

Ammonium hydroxide is simply a solution of ammonia gas in water. What helps release ammonia into the smoke mixture? Well since ammonia is chemically a base, it helps release other bases into their pure state.

An explanation is needed here: nicotine, like other natural substances (e.g. cocaine) is a base. Bases tend to react with acids to form salts. Indeed, in dry tobacco, the nicotine composition includes acid as “nicotinic acid”. When nicotine is in the salt form it is more difficult for absorption into the body. The ammonia releases it by replacing it in the salt compound, and therefore allowing it to be absorbed and act more strongly and more quickly.

So when the drug is working faster on the brain, dependence is developing stronger. This is exactly the difference between crack and cocaine - the drug is the same drug, but the first contains baking soda (a base) that causes it to be much stronger. By the same token you could say that adding ammonia to tobacco changes the nicotine to “crack” nicotine whose power is much stronger than normal nicotine.

Source: Brand differences of freebase nicotine delivery in cigarette smoke: the view of the tobacco industry documents.

Cocoa and cocoa products - even this seemingly innocent material, apparently designed to improve the taste, also has a pharmacological chemical that affects the lungs: Theobromine.

The chemical structure of Theobromine,  relaxes the bronchi and reduces cough | Illustration: Wikipedia 

Theobromine has a dual effect on the human body - it expands the bronchial tubes, just like the material in licorice (in fact this is its medicinal use), and can also act as a powerful cough suppressant (a study in 2004 found that it was stronger than codeine - the active ingredient in cough syrups) by inhibiting the activity of the vagus nerve. In other words, adding cocoa to cigarettes suppresses the body's natural response to smoke - coughing - and thus enables the smoker to feel healthy and hold the smoke for longer without irritation or the need to cough. Indirectly, this also increases the effect of nicotine on the body, by increasing the feeling of respiratory health, so that one can smoke for longer and thus increase the absorption of nicotine from the lungs into the blood.

Source: Theobromine inhibits sensory nerve activation and cough.

Natural and artificial flavors - the tobacco companies do not publish individual components where their concentration in a cigarette is less than 0.1 percent, but instead collectively mark all other ingredients they add under this name. This includes a long list of chemicals, and as we have seen it is likely that the activity of some are not so innocent and do not only cause a change in taste or smell, but also have a pharmacological activity on the body: a book recently published in the United States, based on hundreds of documents from US tobacco companies that were forcibly published, found that in addition to all of the above, they add a substance called levulinic acid that increases the binding of nicotine to receptors in the brain.

Thus, tobacco cigarettes contain a mixture of many substances, in addition to tobacco, that operate on many aspects to strengthen the biological addictive effects of cigarettes. They enhance the activity of nicotine, increase its concentration, shorten the time it takes for it to become available, expand the airways and inhibit the cough reflex. These ingredients were added to the mix after a long process of years of research and scientific development initiated by the cigarette companies.

Beagles used in research for developing a new type of cigarette. The photograph shocked the nation when it was first published in 1975 | Photograph by Mary Beith, Bournemouth Times

In other words, cigarettes are an adapted product (in the negative sense of the word), while exploiting research tools and scientific knowledge to be stronger and more addictive than in its natural state. New studies show that 10-25 percent of people will develop symptoms of cigarette addiction after smoking even just one cigarette.

Given the many health dangers of smoking and the high chances of developing addiction, which the tobacco companies have apparently acted to further increase with the means mentioned above. Bottom line is, it is highly recommended to not try smoking - even once.