Recently there has been quite a stir in the electronic cigarette community regarding the chemical known as diacetyl in e-juices. This is due to the release of the recent Harvard study looking at diacetyl in e-cigarettes, and attracting a lot of headline in the process. The aim of this article is to give you all the information you need to make an informed decision about what you vape.

What is diacetyl?


V-Revolution Blog | Diacetyl Structure

Diacetyl is a naturally occurring chemical found in low-concentration in apples, artichokes, beans, butter, coffee, dairy, fruits, honey, tobacco and vinegar. Diacetyl is also a natural byproduct from the conversion of glucose to ethanol by yeast during the fermentation process when crafting beer. Diacetyl is used by chemical manufacturers to give butter, margarine, shortening, oil sprays, flavourings and other food products a buttery taste. Diacetyl has been used in microwavable popcorn, snack foods, baked goods and, more recently, flavorings found in e-liquids for use in electronic cigarettes and vaping devices.

Why is diacetyl used in ejuice?

The reason diacetyl is often found in e-juice is very simple: it tastes really nice. There is more to it than this, but there’s no getting away from this core point. Really, though, the use of diacetyl comes down to flavour chemistry. The main components of a buttery flavour are diacetyl and acetoin, and if you want something to have a buttery taste, there are only so many ways you can accomplish it.

Quite frankly, there are some flavors that would be very difficult to create without diacetyl.

How much diacetyl is in ejuice?

Dr. Farsolinos published results of his diacetyl research in electronic cigarette E-Juices. In his research, he took 159 eliquid samples from various vendors who have claimed to not have any diacetyl in their flavourings. The 159 eliquid samples came from 36 manufacturers from both the USA and Europe. His findings were troubling as over 74% of the ejuices he tested positive for both diacetyl and acetyl propionyl. 

Dr. Farsolinos’s study also measured the safety limits of the e-juices that contained diacetyl and acetyl propionyl. Using the NIOSH (National Institute for Occupational Safety and Health) guidelines, it was found that both diacetyl and acetyl propionyl were found to have more than double times the NIOSH safety guidelines.

The biggest criticism of the latest study is that the authors completely ignore the fact that diacetyl is present in cigarette smoke. So for a smoker switching to vaping, the most crucial comparison is between cigarette smoke and e-cig vapour. The levels of concentration in regular cigarettes are a 100 times more for diacetyl and ten times more for acetyl propionyl than the E-Juices that were tested.