Research Finds Extra Virgin Olive Oil Safest, Most Stable for Cooking

Australian researchers found extra virgin olive oil to be the safest and most stable even when used at high temperatures, dispelling a common myth about cooking with olive oil.

By Mary West
May. 15, 2018 10:33 UTC

Australian researchers com­pared the effects of heat­ing on extra vir­gin olive oil (EVOO) and an array of other com­mon cook­ing oils in a pow­er­ful new study. They found EVOO to be the safest and most sta­ble even when used at high tem­per­a­tures. The inves­ti­ga­tion also dis­pelled sev­eral erro­neous beliefs asso­ci­ated with cook­ing oils.

Canola oil pro­duced more than 2.5 times the polar com­pounds of EVOO and just about dou­ble the polar com­pounds of even refined olive oil.- Mary Flynn, Research Dietician, Brown Univ.

In the study pub­lished in the jour­nal Acta Scientific Nutritional Health, sci­en­tists heated pop­u­lar cook­ing oils and per­formed a range of tests to assess para­me­ters con­nected to sta­bil­ity. Aside from EVOO, the oils tested included vir­gin olive oil, refined olive oil, canola, grape­seed, coconut, avo­cado, peanut, rice bran and sun­flower oils. One of the main find­ings was that EVOO pro­duced the low­est quan­tity of harm­ful sub­stances called polar com­pounds. The refined oils pro­duced much more.

Olive Oil Times sought the per­spec­tives of three experts: Sarah Gray, phar­ma­cist and nutri­tion­ist at the Olive Wellness Institute; Simon Poole, physi­cian, com­men­ta­tor and author of The Olive Oil Diet; and Mary Flynn, a research dietit­ian at The Miriam Hospital and Associate Professor of Medicine, Brown University.

When oil is exposed to heat, it breaks down and pro­duces a vari­ety of degra­da­tion by-prod­ucts such as polar com­pounds,” said Gray. Evidence shows that polar com­pounds may be detri­men­tal to health and have been linked to the devel­op­ment of neu­rode­gen­er­a­tive con­di­tions such as Alzheimer’s and Parkinson’s dis­ease.”

This supe­rior sta­bil­ity makes EVOO the safest oil to use in cook­ing. Lead author Florencia de Alzaa pointed out that the study’s test­ing tem­per­a­tures exceeded those used in com­mon cook­ing meth­ods.

This research looked at the chem­i­cal and phys­i­cal changes that occurred when heat­ing com­mon Australian super­mar­ket oils to 180℃/350℉ over 6 hours, and grad­u­ally (over 20 min­utes) from 25 to 240℃/475℉. In fact, this is much higher than stan­dard domes­tic cook­ing tem­per­a­tures such as 120℃/248℉ in stir-fry­ing (sautéing), 160 – 180℃/320 – 250℉ in deep fry­ing and 200℃/400℉ in oven bak­ing,” Gray said.

In recent years we have seen numer­ous unsub­stan­ti­ated claims that it is less safe to cook with extra vir­gin olive oil, despite fry­ing and roast­ing tem­per­a­tures being well below its smoke point,” said Poole. This research pro­vides unequiv­o­cal and defin­i­tive evi­dence that should finally dis­pel this myth. It shows that extra vir­gin olive oil is not only safe dur­ing heat­ing at reg­u­lar cook­ing tem­per­a­tures, but is the desir­able cook­ing oil when com­pared with oth­ers. The pro­duc­tion of poten­tially harm­ful polar com­pounds and trans fats was markedly lower in EVOO.”

Analysis of the results also showed that an oil’s smoke point doesn’t pre­dict its per­for­mance when heated. Instead, it found when com­bined with the total level of unsat­u­rated fats, oxida­tive sta­bil­ity and UV coef­fi­cients are more accu­rate pre­dic­tors. Interestingly, it is a com­mon thought if an oil has a high smoke point, it is pref­er­en­tial for higher-heat cook­ing despite lim­ited tech­ni­cal evi­dence to sup­port this. However, accord­ing to de Alzaa, the find­ings of this paper com­pletely debunk this very com­mon myth,” said Gray.

The study also dis­cred­ited the notion that the use of canola oil is ben­e­fi­cial for health. I found it most inter­est­ing how poorly canola oil per­formed, as the test­ing showed it to be the most unsta­ble com­pared to all the other oils, espe­cially in com­par­i­son to the three olive oils tested,” said Flynn. Canola oil pro­duced more than 2.5 times the polar com­pounds of EVOO and just about dou­ble the polar com­pounds of even refined olive oil.”

Some health pro­fes­sion­als inad­ver­tently make rec­om­men­da­tions that all olive oils and canola oil are equal in health ben­e­fits, as they all have high lev­els of monoun­sat­u­rated fat. If the monoun­sat­u­rated fat con­tent was the rea­son for the health ben­e­fits of olive oil, then stud­ies com­par­ing refined olive oil to extra vir­gin would show the same pos­i­tive effects, and they do not. The well­ness advan­tages of extra vir­gin olive oil are clearly due to its con­tent of phe­no­lic com­pounds,” said Flynn.

Increasing data shows the nutri­tional ben­e­fits of prepar­ing foods in EVOO and under­score its cen­tral role in the Mediterranean Diet,” Poole noted.

The new study builds on this wealth of research by show­ing that instead of lim­it­ing extra vir­gin olive oil for use in salad dress­ings, it can be used in all man­ner of cook­ing meth­ods.


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