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

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.

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.

• Acta Scientific Nutritional Health


• Olive Wellness Institute