Electronic cigarettes alter the composition of saliva, increasing the risk of oral diseases

Researchers from São Paulo State University and collaborators studied 50 young people with an average age of between 26 and 27. The goal was to find biomarkers that allow early detection of health changes.

By Fernanda Bassette  |  Agência FAPESP – The number of users of electronic cigarettes, also known as vapes, is increasing: it is estimated that at least 20% of young Brazilian adults have used these devices, originally developed with the aim of facilitating smoking cessation, at least once. But scientific research has shown just the opposite. These devices don’t help people quit smoking, and even significantly increase nicotine dependence and cause other health problems.

It is now known that electronic cigarettes can cause acute lung damage and are associated with diseases and risks similar to those of conventional cigarettes, such as asthma, COPD (chronic obstructive pulmonary disease) and emphysema, as well as causing changes in blood vessels that increase cardiovascular risk. Its compounds also contain carcinogens.

Now, a study conducted at the Institute of Science and Technology of São Paulo State University (ICT-UNESP) in Brazil, in collaboration with scientists from São Paulo affiliated with the University of São Paulo (USP) and scientists from Spain affiliated with the University of Santiago de Compostela, has found that vaping alters the composition of users’ saliva, increasing the risk of oral diseases such as caries, mucosal lesions and periodontal disease.

The results of the research, supported by FAPESP through four projects (20/10362-0, 20/10322-9, 22/16249-7 and 24/20063-1), were published in the International Journal of Molecular Sciences and are part of the results obtained during the doctoral studies of Bruna Fernandes do Carmo Carvalho.

To reach their conclusion, the researchers selected 50 young people with no visible clinical changes in the oral mucosa, with an average age of between 26 and 27 years: 25 regular and exclusive users of electronic cigarettes for at least six months, and 25 non-users for the control group. It is important to note that in Brazil, the use and sale of electronic cigarettes has been banned by the National Health Surveillance Agency (ANVISA) since 2009 – hence the difficulty in finding volunteers to participate in the study.

They all provided saliva samples for analysis, which included sialometry (saliva analysis), viscosity, pH and cotinine concentration – an important biomarker related to nicotine exposure. High doses of this substance in saliva, urine or blood are associated with higher levels of dependence. The volunteers also underwent clinical assessments that measured heart rate, oximetry, blood glucose, exhaled carbon monoxide (CO) concentration and alcohol consumption.

After analyzing the saliva, the researchers found a high concentration of cotinine among e-cigarette users. They also identified the presence of 342 salivary metabolites (compounds resulting from the metabolism of substances in saliva), but only those found in at least 70% of the samples were considered for analysis.

Of the total, 101 metabolites were included in the study: 61 were exclusive to the user group, while 40 compounds were shared between the two groups. From this, seven promising biomarkers were identified: four were specific and increased in the e-cigarette user group (stearic acid, elaidic acid, valine and 3-phenylacetic acid) and three were shared between the groups (galactitol, glycerol 2-phosphate and glucono-1,5-lactone).

“The identification of these metabolites is important because they could become potential biomarkers for the early detection of health changes. The impact of this alteration on health is not well established in the scientific literature, but we know that it’s related to inflammatory issues, the metabolism of chemical substances foreign to the body [such as drugs or toxins] and the effects of biomass burning,” explains dental surgeon Janete Dias Almeida, full professor at the Department of Biosciences and Oral Diagnosis at UNESP and coordinator of the study. This means that specific inflammatory pathways linked to periodontal disease, for example, can be induced by electronic cigarettes.

The results of these analyses were presented during the 17th Congress of the Spanish Society of Oral Medicine (SEMO) and the 18th Meeting of the Iberoamerican Academy of Pathology and Oral Medicine (AIPMB), held in Santiago de Compostela in 2023, and received an honorable mention.

Low salivary flow and higher CO

The study also found that the salivary flow of the e-cigarette users tended to decrease compared to the control group, which may be related to the presence of substances such as propylene glycol and glycerin in the flavorings – these substances irritate the upper airways and cause dry mucous membranes.

The results also showed that those who used vapes had lower saliva viscosity, which plays a crucial role in protecting and moisturizing the oral mucosa. “Reduced salivary flow favors the formation of biofilm, which is the film that forms when we don’t clean our teeth properly and favors the emergence of diseases related to the mouth, such as caries lesions,” warns the professor.

On physical examination, the vape users had higher levels of exhaled carbon monoxide and lower oxygen saturation than the control group. “This data is very important because the decrease in oximetry means that there’s less oxygen carried in the blood by the hemoglobins. And the increase in exhaled carbon monoxide is also a very important parameter,” she emphasizes.

The researchers also found that the young people who used e-cigarettes reported high rates of alcohol consumption: 76% of the participants reported using both products at the same time. In addition, 52% said that alcohol consumption increased their frequency of e-cigarette use. Alcohol consumption and smoking are known risk factors for several diseases, including oral cancer. “Alcohol acts on the cell membrane, making the mucosa more permeable and susceptible to the action of harmful substances,” says Almeida.

Also according to the study, only 24% of the participants were former conventional cigarette smokers; they had been using e-cigarettes for at least 2.13 years (52% used the devices daily and 60% seven to ten times a day); fruity/sweet flavored cigarettes were used the most, followed by menthol flavors.

Why analyze saliva?

According to Almeida, saliva is a fundamental biofluid that maintains oral balance. Its main functions include acting as a protective barrier against pathogens; initiating the digestive process and neutralizing acids from food or bacterial metabolism, preventing the demineralization of the teeth.

“Saliva is a very important protector. And we can assess many parameters related to various diseases using saliva. In addition, collecting the sample is a simple, non-invasive and inexpensive procedure. So this is a promising technique for identifying salivary biomarkers that may indicate the onset of problems,” explains the professor.

According to the researcher, the future is very worrying, especially when you think about public health and the problems that can arise as a result of this consumption.

“This study has confirmed that e-cigarettes are not harmless, as the industry wants to sell them. Young people tend to use these devices earlier and earlier, and the big problem is that they use nicotine salts that reach the brain much faster, causing greater dependence in a shorter time,” she says. “The devices are colorful, varied and have a pleasant taste. All designed to attract young people. We’re seeing more and more cases of heart attacks and strokes in younger people. It’s a compromising scenario,” she adds.

The article “Salivary Metabolic Pathway Alterations in Brazilian E-Cigarette Users” can be read at: www.mdpi.com/1422-0067/25/21/11750.