Here's the catch. The FDA emphasized in its JUUL2 announcement that the health benefit comes from complete switching, not dual use. A July 2026 narrative review published in the journal Cureus explains why.
The review examined laboratory, clinical, and population evidence on vapes, heated tobacco, and oral nicotine pouches. Key findings:
- Adults who switched completely to vaping showed substantial reductions — often 90% or more — in biomarkers of exposure to tobacco-specific carcinogens (NNAL and NNN) compared with continued smoking. These reductions can approach levels observed in non-users.
- Smokers who switched completely showed favorable changes in markers linked to inflammation, blood clotting, cholesterol, and blood-vessel health.
- Dual users — those who continued smoking while also vaping — frequently had biomarker levels and cardiovascular risk similar to exclusive smokers. In some studies, their estimated risk was higher.
This is because cardiovascular risk does not fall in direct proportion to the number of cigarettes smoked. Even low-level smoking carries a surprisingly large share of smoking-related heart disease and stroke risk. Simply cutting down may deliver less protection than smokers expect.
Real-World Consequence: The South Korean Evidence
Two recent South Korean observational studies provide real-world confirmation:
- A 2025 study followed 17,973 smokers who had undergone coronary artery treatment. Over 2.4 years, major adverse cardiac events occurred in 10.8% of switchers vs 17% of continued smokers — an 18% lower risk. Complete switchers also had a 29% lower risk than dual users.
- A 2026 study followed 23,262 adults who smoked when diagnosed with COPD. Those who switched to vapes had a 20% lower adjusted risk of major adverse cardiac and cerebrovascular events than those who continued smoking. However, the study did not find comparable reductions in lung cancer or COPD exacerbations.
Both studies are observational — they cannot prove causation. But they align with the biological evidence: eliminating combustion is where the harm reduction happens.
