E-cigarettes can cause a ‘leaky gut,’ trigger harmful stomach inflammation

SAN DIEGO, Calif. — In another blow to e-cigarettes’ supposed status as a “safer alternative” to smoking, a new study finds these vaping devices contain chemicals capable of disrupting the gut barrier. This causes excessive amounts of bodily inflammation which can lead to numerous health issues.

Researchers from the University of California, San Diego say chronic use of nicotine-free e-cigarettes can cause a “leaky gut;” meaning microbes and other molecules continually escape from someone’s gut. This eventually results in chronic inflammation.

Study authors say the condition can contribute to many ailments, such as dementia, IBD, some cancers, diabetes, and arthritis.

“The gut lining is an amazing entity. It is comprised of a single layer of cells that are meant to seal the body from the trillions of microbes, defend our immune system, and at the same time allow absorption of essential nutrients,” says Pradipta Ghosh, MD, a professor of cellular and molecular medicine, in a university release. “Anything we eat or drink, our lifestyle choices in other words, has the ability to impact our gut microbes, the gut barrier and overall health. Now we know that what we smoke, such as e-cigarettes, negatively impacts it as well.”

What’s causing the ‘leaky gut’

Study authors report that two chemicals which are base ingredients in all e-cigarette liquid vapor are to blame for this inflammation: propylene glycol and vegetable glycerol.

smoking chemicals gut lining
In the bottom frames, burst cell junctions in the gut lining can be seen after being exposed to e-cigarette chemicals as compared to healthy cells in the top frames. (Credit:
HUMANOID Center of Research Excellence)

“Numerous chemicals are created when these two are heated to generate the fumes in vaping that cause the most damage, for which there are no current regulations,” Ghosh explains. “The safety of e-cigarettes have been debated fiercely on both sides. Nicotine content, and its addictive nature, has always been the major focus of those who argue against its safety, whereas lack of chemicals in the carcinogens that are present in the cigarette smoke has been touted by the makers of e-cigarettes when marketing these products as a ‘healthy alternative.’ In reality, it’s the chemicals making up the vapor liquid that we should be more concerned about as they are the cause of gut inflammation.”

Generated via patient cells, researchers used a series of 3D models depicting human intestinal tracts to recreate what happens when e-cigarette vapor makes contact with the gut lining. The team confirmed their findings using lab mice.

Vaping overwhelms the cells

Upon exposing the animals to vaping smoke, researchers immediately noted that epithelial tight conjunction markers began breaking down and loosening. These are zipper-like proteins that make up the stomach’s first physical barrier. With the barrier weakened, pathogens from the vapor to easily seep into the surrounding immune system, eventually inflicting damage to the protective epithelial cells underneath.

Epithelial cells usually function as a primary means of defense against infections by clearing pathogenic microbes and jumpstarting immune responses. After being exposed to vape smoke however, the cells quickly became “overwhelmed” and unable to perform their bodily duties.

“This is the first study that demonstrates how chronic exposure to e-cigarettes increases the gut’s susceptibility to bacterial infections, leading to chronic inflammation and other health concerns,” Soumita Das, PhD, associate professor of pathology, concludes. “Given the importance of the gut barrier in the maintenance of the body’s immune homeostasis, the findings provide valuable insight into the potential long-term harmful effects chronic use of e-cigarettes on our health.”

Study authors say damage to the stomach lining itself is likely reversible if an individual stops vaping. The damage already done to other organs such as the heart or brain, however, may be permanent.

The study is published in iScience.