Woman smoking an e-cigarette

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SAN DIEGO, Calif. — Many proponents of e-cigarettes claim they are a healthier alternative to traditional cigarettes, but research by a team at UCSD may make you think twice before your next puff. Scientists report that smoking pod-based JUUL e-cigarettes on a daily basis alters the inflammatory state across the majority of the human body, from the brain and heart to lungs and colon.

This is the first study ever to analyze the bodily effects of JUUL devices and their flavorants across multiple organs.

“These pod-based e-cigarettes have only become popular in the last five or so years, so we don’t know much about their long-term effects on health,” says senior study author Laura Crotty Alexander, MD, associate professor of medicine at UC San Diego School of Medicine and section chief of Pulmonary Critical Care at Veterans Affairs San Diego Healthcare System, in a university release.

Estimates show over 12 million Americans currently use e-cigarettes, with most of those users being young adults between 18 and 24. While plenty of earlier studies have looked at e-cigarettes, most of that research only examined short-term use, older devices such as vape pens or box mods, and e-liquids with much lower nicotine concentrations instead of the rechargeable, pod-based e-cigs in circulation today.

Inflammation highest in the brain

For this project, researchers focused exclusively on JUUL brand products, considered the most prominent e-cigarette brand on the market. The team analyzed the two most popular JUUL flavors: Mint and mango.

To recreate chronic e-cigarette use, study authors exposed a group of young adult mice to flavored JUUL aerosols three times a day every day for three months. Then, researchers waited for any signs of inflammation across the rodents’ bodies.

The most obvious changes appeared in the rodents’ brains, where several elevated inflammatory markers emerged. Additionally, the team discovered further changes in neuroinflammatory gene expression within the nucleus accumbens — a brain area scientists believe are critical for both motivation and reward-processing. This observation isn’t exactly a positive, researchers explain, as neuroinflammation in this region has a connection to anxiety, depression, and addiction, according to past studies.

“Many JUUL users are adolescents or young adults whose brains are still developing, so it’s pretty terrifying to learn what may be happening in their brains considering how this could affect their mental health and behavior down the line,” Crotty Alexander explains.

It wasn’t just the rodents’ brains either. Inflammatory gene expression increased in the colon, more specifically after one full month of e-cigarette exposure. Such a development in humans can increase one’s risk of gastrointestinal disease. Conversely, inflammatory markers actually declined in the heart after habitual e-cigarette exposure. While that may sound better than more inflammation, researchers explain such a cardiac state of immunosuppression could make cardiac tissue more vulnerable to infections.

Does the flavor really matter for your health?

Lungs, meanwhile, did not show tissue-level signs of inflammation. Still, researchers saw numerous gene expression changes in lung samples. Study authors say this warrants further research on the long-term impact of pod-based e-cigarettes on pulmonary health.

Finally, they also observed that the inflammatory response of each organ actually depended on which JUUL flavor users consumed. For instance, the hearts of mice inhaling mint aerosols were actually more sensitive to bacterial pneumonia than those inhaling mango aerosols.

“This was a real surprise to us,” Crotty Alexander adds. “This shows us that the flavor chemicals themselves are also causing pathological changes. If someone who frequently uses menthol-flavored JUUL e-cigarettes was infected with COVID-19, it’s possible their body would respond differently to the infection.”

Each one of the human body’s organs has its own ideal immune/inflammatory environment. The inflammatory changes, one way of the other, induced by e-cigarettes could have both long and short-term health effects.

“It’s clear that every e-cigarette device and flavor has to be studied to determine how it affects health across the body,” Crotty Alexander concludes.

The study is published in the journal eLife.

About John Anderer

Born blue in the face, John has been writing professionally for over a decade and covering the latest scientific research for StudyFinds since 2019. His work has been featured by Business Insider, Eat This Not That!, MSN, Ladders, and Yahoo!

Studies and abstracts can be confusing and awkwardly worded. He prides himself on making such content easy to read, understand, and apply to one’s everyday life.

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1 Comment

  1. mario says:

    Rodent studies aren’t always applicable to humans. This one in particular rests on oversuffocating mice (36x times the vapor amount humans would consume) to observe any effects (minor changes in cytotoxins mostly). It’s also not very timely, since both the observed products are off the market already. (But the paper took too long to revise before publication).
    It was also evidently just meant to feed into the anti-vaping FUD and prohibition campaigns. Otherwise it would have looked at artificial tobacco flavors, which are significantly more complex and concentrated. UCSD is not free from funding bias.