In this community request, we look at diacetyl, a compound that’s caused safety confusion.
Top Takeaways:
- Diacetyl is safe for ingesting in food and beverages.
- Some vape and e-cigarette liquids contain diacetyl.
- You should avoid inhaling diacetyl in all forms.
What is diacetyl?
Diacetyl (chemically known as 2,3-butanedione) is a naturally occurring compound that gives foods a rich, buttery flavor.
It belongs to a group of chemicals called diketones and is found in many fermented foods and drinks, like butter, cheese, yogurt, beer, and wine.
Where is diacetyl found?
We encounter diacetyl in everyday foods like:
- Baked goods
- Butter-flavored popcorn
- Candy, tea, and coffee
- Beer, wine, and other fermented beverages
- Dairy products like cheese, milk, and yogurt
- Fruits and vegetables such as raspberries, tomatoes, peas, and cabbage
- Meats like chicken and beef
We also find diacetyl used as a flavoring in some vaping and e-cigarette products.
Why is diacetyl used in vapes and e-cigarette liquids?
Some manufacturers have added diacetyl to their vape liquids to create dessert-like or creamy flavors, such as custard, vanilla cream, or butterscotch. This helps replicate the rich, buttery taste that diacetyl is known for in food.
Is diacetyl considered safe?
Diacetyl is considered safe as a food ingredient only.
The FDA classifies diacetyl as “Generally Recognized as Safe” (GRAS), but that designation only applies to ingestion, not inhalation.
So, while diacetyl is safe to eat in small quantities (like found in candies), we don’t have the same level of safety data for inhaling diacetyl as part of a vape or e-cigarette, especially over time.
Does it matter how we’re exposed?
Yes, the exposure route (how a substance enters our body) matters a lot.
Our bodies handle substances differently depending on whether we eat, inhale, or touch them.
- When we ingest small amounts of diacetyl in food or a beverage, it’s broken down safely by our digestive system.
- When we inhale diacetyl, such as in manufacturing settings or through vaping, it can cause significant harm, especially with long-term or high-concentration exposure.
We know inhaling diacetyl in industrial settings has been linked to the chronic and irreversible lung disease bronchiolitis obliterans (informally known as “popcorn lung”), which led to regulations and protective gear requirements for workers.
Additionally, there is evidence of people developing bronchiolitis obliterans (“popcorn lung”) due to repeated vaping and e-cigarette use.
Are vapes and e-cigarette liquids regulated? If so, why is diacetyl allowed?
Yes, in the U.S., the FDA regulates e-cigarettes and vape liquids. Manufacturers must:
- Submit a Premarket Tobacco Product Application (PMTA)
- Provide a full ingredient list
- Report any harmful or potentially harmful constituents (HPHCs)
However, diacetyl isn’t specifically banned. While many companies voluntarily avoid it, others still use it. Even with regulations in place, unapproved or illegal products still find their way to the market.
And since vaping is still relatively new, research and regulation are still evolving.
Is it safe to vape diacetyl?
We don’t recommend smoking, vaping, or using e-cigarette devices at all.
We can’t say for certain how much or how often you’d need to be exposed to diacetyl through vaping to experience harm. However, we do know that in workplace settings, high or prolonged inhalation exposure to diacetyl can damage the lungs.
If you’re vaping, you’re potentially inhaling substances in ways your lungs aren’t built to handle, and the long-term health consequences of that aren’t fully understood.
The good news.
Despite the concerns, there’s good news about diacetyl. It’s safe at the levels typically found in food and beverages and doesn’t pose a health risk when ingested.
As awareness around inhalation risks grows, many responsible companies are choosing to formulate diacetyl-free vape products. And, regulation is evolving as science continues to catch up with this relatively new product.
If you have any questions about ingredients or ideas for a blog post, please send us an email or submit your idea to us at go.msu.edu/cris-idea.
Learn more: citations and further readings.
Academic Papers
Allen, J. G., Flanigan, S. S., LeBlanc, M., Vallarino, J., MacNaughton, P., Stewart, J. H., & Christiani, D. C. (2016). Flavoring chemicals in e-cigarettes: Diacetyl, 2,3-pentanedione, and acetoin in a sample of 51 products, including fruit-, candy-, and cocktail-flavored e-cigarettes. Environmental Health Perspectives, 124(6), 733-739. https://doi.org/10.1289/ehp.1510185
Cao, D. J., Aldy, K., Hsu, S., McGetrick, M., Verbeck, G., De Silva, I., & Feng, S. (2020). Review of health consequences of electronic cigarettes and the outbreak of electronic cigarette, or vaping, product use-associated lung injury. Journal of Medical Toxicology, 16(3), 295-310. https://doi.org/10.1007/s13181-020-00772-w
White, A. V., Wambui, D. W., & Pokhrel, L. R. (2021). Risk assessment of inhaled diacetyl from electronic cigarette use among teens and adults. Science of the Total Environment, 772, 145486. https://doi.org/10.1016/j.scitotenv.2021.145486
CRIS Information
Everyday toxicology – exposure. (2024, June 10). Center for Research on Ingredient Safety. Retrieved March 31, 2025, from https://cris.msu.edu/news/everyday-toxicology/everyday-toxicology-exposure/
Everyday toxicology – exposure-based risk assessment. (2024, June 17). Center for Research on Ingredient Safety. Retrieved March 31, 2025, from https://cris.msu.edu/news/everyday-toxicology/everyday-toxicology-exposure-based-risk-assessment/
Everyday toxicology – exposure to ingredients. (2020, February 10). Center for Research on Ingredient Safety. Retrieved March 31, 2025, from https://cris.msu.edu/news/everyday-toxicology/everyday-toxicology-exposure-to-ingredients/
What are GRAS ingredients? (2019, June 10). Center for Research on Ingredient Safety. Retrieved March 31, 2025, from https://cris.msu.edu/news/summer-staple-ingredients/what-are-gras-ingredients/
Government Resources
E-Cigarettes, vapes, and other electronic nicotine delivery systems (2024). U.S. Food and Drug Administration. Retrieved March 31, 2025, from https://www.fda.gov/tobacco-products/products-ingredients-components/e-cigarettes-vapes-and-other-electronic-nicotine-delivery-systems-ends
Premarket tobacco product applications. (2024). U.S. Food and Drug Administration. Retrieved March 31, 2025, from https://www.fda.gov/tobacco-products/market-and-distribute-tobacco-product/premarket-tobacco-product-applications