How much you know about Nicotine & Nicotine Addiction?
What Is Nicotine and Does Nicotine ONLY Exist in Tobacco?
Nicotine is a stimulant and potent parasympathomimetic alkaloid that is naturally produced in the nightshade family of plants. The word parasympathomimetic simply means that it affects the parasympathetic nervous system – the part of our brain that is responsible for involuntary actions (also referred to as feed-and-breed and rest-and-digest actions).
A common misconception is that nicotine is only found in the tobacco plant when, in fact, it’s pretty widespread. The nightshade family of plants (various tobacco cultivars) will usually contain relatively high amounts of it, but it’s easy to detect nicotine in other fruits, vegetables, and herbs, such as tomatoes, potatoes, eggplants, peppers, cauliflower, papaya. In fact, we’re all exposed (and ingest) nicotine on a daily basis. Some research indicates that the contribution of nicotine obtained from food is substantial in comparison to inhalation of second-hand smoke. Others consider nicotine obtained from food to be trivial unless exceedingly high amounts of certain vegetables are eaten.
Is Nicotine Toxic?
Before Columbus discovered The America, tobacco has been popular among the indigenous people of the Americas for at least 2000 years. Soon afterwards, tobacco spread rapidly around the world. In 1560, French Ambassador to Portugal Jean Nicot sent several reports on the “medicinal value of tobacco” to Paris, as well as tobacco and seeds that others brought back from Brazil. Queen France II, Catherine de Medici used tobacco to treat her migraine headaches under Jean Nicot’s suggestion, and she recovered successfully. After that, tobacco use increased greatly and it was regarded as a “sacred plant”. Nicotine, the main ingredient in tobacco, is also named after Jean Nicot. During the 16th – 17th century, most doctors in Europe agreed that tobacco has multiple medical effects.
Early researches on nicotine toxicity was closely related to the studies of tobacco hazard. In 1809, Louis-Nicolas Vauquelin, a professor of chemistry at the Paris Medical School, published his research on the juice of tobacco. He found this plant contained a nitrogenous alkaline substance, and pointed out that this substance might be highly toxic. The Dictionnaire des sciences medicales published in 1821 indicates, that “According to the medical use report of tobacco, the substances contained in tobacco plants are too active and may have certain corrosiveness to human tissues.” In 1928, the German doctor W. Posselt and the chemist L. Reimann successfully separated this active substance from tobacco and named it “nicotine.”
Before people found out nitrosamines and benzoquinones in tar were the major carcinogens in tobacco, Nicotine has been misunderstood for a long time as the main harmful substance in tobacco. But as more researches progressed, nicotine gradually began to be correctly recognized by people.
In the famous report Smoking and Health-Report of the Advisory Committee to the Surgeon General of the Public Health Service published in 1964, is was concluded that “There is no acceptable evidence that prolonged exposure to nicotine creates either dangerous functional change of an objective nature or degenerative disease.” After that, nicotine even began to be used to quit smoking. The median lethal dose of nicotine in humans is still unknown, but it is unlikely that a person would overdose on nicotine through smoking alone. The US Food and Drug Administration stated in 2013 that there are no significant safety concerns associated with the use of more than one form of over-the-counter (OTC) nicotine replacement therapy at the same time, or using OTC, NRT at the same time as another nicotine-containing product, like cigarettes.
How We Get Addicted to Nicotine?
The pathophysiology of Nicotine addiction was explained by the Report of the Surgeon General 2010: How Tobacco Smoke Causes Disease, The Biology and Behavioral Basis for Smoking-Attributable Disease, that the mechanism of nicotine addiction is mainly due to its “Reward Effect”.
Nicotine is an agonist at the nicotinic acetylcholine receptors (nAChRs) expressed both in the peripheral nervous system and the central nervous system. It is fat-soluble, by which it can quickly penetrate the alveolar membrane into the blood of the pulmonary capillaries, and reach the central nervous system within 10 seconds, then combine with presynaptic nAChRs in the brain to activate dopamine neurons, release dopamine, the excitatory neurotransmitter, then give the smokers a “pleasant” feeling. At the same time, nicotine promotes the release of epinephrine and norepinephrine from the adrenal medulla and terminal nerve endings, resulting in increased heart rate, rapid breathing, vasodilation, and elevated blood pressure, which make smokers feel excited.
This pleasure and excitement can last for about 2-3 hours. If the intake is reduced or stopped, the concentration of nicotine in the brain will decrease rapidly, and the “pleasure” will disappear, which will lead to the nicotine withdrawal symptoms, which include depressed mood, stress, anxiety, irritability, difficulty concentrating, and sleep disturbances. Therefore, nicotine addicts need to maintain the level of nicotine in the brain in exchange for physical and mental relaxation.
Nicotine addiction depends on the amount of nicotine delivered and the way in which it is delivered, which can either enhance or reduce its potential for abuse: the faster the delivery, rate of absorption, and attainment of high concentrations of nicotine, the greater is the potential for addiction.
Those nicotine withdrawal symptoms might look intimidating, but luckily the Nicotine Replacement Therapy(NRT) was first proposed as early as 1978. In 1995, the FDA agreed that nicotine preparations were “safe and effective when used according to the instructions.” In 1996, the World Health Organization recommended the use of NRT to quit smoking in countries around the world. At present, there are a lot of conventional nicotine replacement therapies available, such as nicotine patches, gums, lozenges, nasal spray and inhalers. Nicotine is used for the treatment of tobacco use disorders as a smoking cessation aid and nicotine dependence for the relief of withdrawal symptoms. Although the effectiveness of conventional NRTs is still widely debated, but some studies confirm that they can lead to increased quit rates.
Is Vape Safer?
In the past decade, more and more people have tried to quit smoking by using vapes, but there still has skeptical voices about the safety of e-cigarettes. Just how much less harmful are vapes than cigarettes is a matter of scientific assessment and science communication.
Two landmark reviews brought the evidence together on e-cigarettes and have been published in the UK, from Public Health England and the Royal College of Physicians. The first key point is that there are no circumstances in which it is safer to smoke than to use e-cigarettes. The more cautious and conditional evidence review from the US National Academy of Sciences, The Public Health Consequences of E Cigarettes (2018), stated nonetheless: “There is conclusive evidence that completely substituting e-cigarettes for combustible tobacco cigarettes reduces users’ exposure to numerous toxicants and carcinogens present in combustible tobacco cigarettes”.
And while opposed to safer nicotine products, the WHO briefing on e-cigarettes conceded that “it is very likely that average ENDS use produces lower exposures to toxicants than combustible products”. Public Health England has asserted that “based on current knowledge, stating that vaping is at least 95% less harmful than smoking remains a good way to communicate the large difference in relative risk unambiguously…”. This means that e-cigarettes are not totally harmless, but that the appropriate scientific approach is to compare their safety relative to combustible cigarettes, rather than examine the absolute safety of the products in isolation. In other words, harm reduction, not harm eradication.
As the Royal College of Physicians states, “In normal conditions of use, toxin levels in inhaled e-cigarette vapour are probably well below present threshold limit values for occupational exposure in which case significant long-term harm is unlikely. Some harm from sustained exposure to low levels of toxins over many years may yet emerge, but the magnitude of these risks relative to sustained tobacco smoking is likely to be small”. Most reviews raising concerns about constituents, were related to their presence rather than absolute levels which are “generally the more important determinant of toxicity”. They commented that all the constituents identified were at lower levels than in cigarette smoke, but that long-term use even at these low levels could be problematic, although “the magnitude of these risks relative to those from sustained tobacco smoking is likely to be small.”