When choosing a cooking oil, most health-conscious people obsess about smoke point. That's the temperature at which a trail of blue smoke wafts upward and triggers the kitchen smoke alarm, causing your poodle and similarly high-strung humans to wet themselves.
Smoke point has always been a concern for two main reasons, one taste related and one health related. An oil that's been pushed to its smoke point and beyond will make whatever food you're cooking taste like the charred hot dog that your uncle pulled out of the campfire last fourth of July picnic.
An oil that's reached its smoke point was also believed to be well on the way to turning your cooking oil into a toxic stew, full of inflammatory, cell-damaging, and potentially cancer-causing chemicals.
A lot of physical factors can determine smoke point, things like the amount of oil being used, the size of the frying pan, the air currents, the altitude, the type and source of light, and, most prominently, the amount of free fatty acids (FFA) the oil or fat contains.
The more FFA, the quicker it breaks down and starts smoking, but since FFA usually make up less than 1% of the total oil, smoke point is now regarded as a poor indicator of the ability of a fat or oil to withstand heat.
What's of more concern is the production of 4-hydroxynonenal (HNE), which has been implicated in cardiovascular disease, neurodegenerative diseases, and even influencing factors that affect the life and death of cells.
HNEs are created when highly unsaturated oils like grapeseed, safflower, sunflower, and rice bran oil are heated, but not necessarily to their smoke point. To make matters worse, you can't really tell when HNE is being formed as it's odorless, flavorless, and invisible.
That's why we need to cook with oils with a low level of polyunsaturated fatty acids. Enter, or re-enter, an old favorite, one that's long been judged to be too "delicate" for frying: extra virgin olive oil (EVOO).
Last year, Australian scientists subjected a number of oils to rigorous testing to see which ones could best withstand the challenges of heat.
Their goal was to examine the formation of nasty byproducts like HNE, along with gauging the propensity of these oils to form free radicals. It turns out extra virgin olive oil fared the best, failing to produce a significant quantity of harmful compounds. It also showed an admirable resistance to oxidation. Granted, it didn't have the highest smoke point, but that didn't appear to matter.
The high smoke-point award went to the second-place finisher: coconut oil. Aside from being the smoke point champion, it also failed to produce a significant amount of harmful compounds. It didn't do quite as well in the oxidation department as EVOO, though, as it was slightly less resistant to this chemical reaction.
The authors wrote:
"Reasonable predictors of how an oil will perform when heated have been oxidative stability, secondary products of oxidation, and total level of PUFAs, EVOO has demonstrated to be the most stable oil when heated, followed closely by coconut oil and other virgin oils such as avocado and high oleic seed oils."
When sautéing or frying, choose extra-virgin olive oil, but if you want to save your EVOO – which is usually more expensive – for drizzling atop your food, opt for coconut oil.
You can also use other "virgin" oils (those that were derived by old-fashioned pressing instead of chemical extraction) like avocado oil, those that are high in oleic acids (monosaturated fats) like canola, or those normally non high-oleic cooking oils that have been selectively bred to contain higher amounts of oleic acid than is typical for their species. Examples include high-oleic sunflower oil, high-oleic soybean oil, and high-oleic safflower oil.
- de Alzaa F et al. Evaluation of Chemical and Physical Changes in Different Commercial Oils During Heating. Acta Scientific. 2018;2(6):2-11.
- Csala M et al. On the role of 4-hydroxynoneal in health and disease. Biochim Biophys Acta. 2015 May;1852(5):826-38. PubMed.