So, why is smoke point important? For starters, low-level exposure to acrolein, the byproduct found in the smoke from burnt oil, can irritate your eyes, nose, and throat. And while that’s acutely unpleasant, the bigger issue is repeated exposure.
“Unfortunately, there is more harm to heating an oil past its smoke point than the irritating smoke it produces,” says Lindsay Wengler, M.S., R.D., CDN, CNSC, registered dietitian at Olive Branch Nutrition in NYC. “Not only can an oil heated beyond its smoke point catch fire, but the molecular breakdown of the oil can create pro-inflammatory free radicals and a carcinogenic compound, acrolein, which may be harmful to your health.”
Ferira explains the mechanisms of this problematic aldehyde compound further: “Acrolein is highly reactive and over time can mess with DNA by cross-linking it. It also has the potential to get in the way of essential detoxifying enzyme systems in the liver like cytochrome P450 and throughout the body by inhibiting glutathione pathways.”
Regular acrolein exposure has also been associated with heart disease and various other diseases. But the key words here are “regular exposure.” The occasional burnt oil isn’t a big deal, but you don’t want to make a habit of it.
And never reuse heated oil. Reheating oil can create various carcinogenic compounds, including polycyclic aromatic hydrocarbons (PAH), which have been linked to various types of cancer.