Phenols More Important than MUFA Content for EVOO Health Benefits, Research Suggests

A research review pub­lished in the sci­en­tific jour­nal Nutrients con­firms that phe­no­lic com­pounds play a crit­i­cal role in the health ben­e­fits asso­ci­ated with extra vir­gin olive oil that are not asso­ci­ated with other olive oil grades.

“The sin­gle most impor­tant thing to under­stand is that extra vir­gin olive oil is a unique food,” Mary Flynn, the lead author and an asso­ciate pro­fes­sor of med­i­cine at Brown University, told Olive Oil Times.

“Compared to other oils, refined and non-extra vir­gin olive oil, or low-fat diet, daily use will improve sev­eral risk fac­tors for chronic dis­eases, such as decreas­ing blood pres­sure, blood glu­cose, oxi­da­tion, and LDL and increas­ing HDL,” she added. ​“There is no other food, or med­i­cine for that mat­ter, that can improve such a range of risk fac­tors.”

The researchers con­ducted a sys­tem­atic review of stud­ies pub­lished between 2000 and 2003 that com­pared extra vir­gin olive oil to low-fat diets, other oils and oils listed as ​‘olive oils’ in the stud­ies.

The nar­ra­tive review sys­tem­at­i­cally sum­ma­rized the lat­est evi­dence on the pro­tec­tive effects of extra vir­gin olive oil on dis­ease risk fac­tors.

A cri­te­rion included in this review was that the study had to state extra vir­gin olive oil was used. Most of the pub­lished stud­ies pro­vided lim­ited infor­ma­tion on the extra vir­gin olive oil used. Of 281 retrieved arti­cles, 34 arti­cles ful­filled the inclu­sion cri­te­ria for the study.

“Based on cur­rent test­ing in most coun­tries, an oil could meet a stan­dard for ​‘extra vir­gin,’ but it might not have phe­nols, and it is the phe­nols that pro­vide the health ben­e­fits,“ Flynn said.

Flynn, who is also the founder of The Olive Oil Health Initiative of the Miriam Hospital, added that one of the goals of the research was to sep­a­rate olive oil’s health ben­e­fits asso­ci­ated with phe­no­lic com­pounds and those that may come from its high con­tent of monoun­sat­u­rated fatty acids.

“I find it very hard to believe that there are still peo­ple who think it is the monoun­sat­u­rated fat con­tent that pro­vides the health ben­e­fits,” she said. ​“While there are no stud­ies that sup­port monoun­sat­u­rated fats pro­vid­ing any ben­e­fits, there are many stud­ies, some of which are in our review, that clearly show the [monoun­sat­u­rated fatty acid] con­tent is not the rea­son for health ben­e­fits.

“If it were, then both refined olive oil and canola oil would have health ben­e­fits, and they do not,” Flynn added.

Catherine Itsiopoulos, a co-author and pro­fes­sor at RMIT University in Australia, added that extra vir­gin olive oil is the key­stone ingre­di­ent behind the health ben­e­fits asso­ci­ated with the Mediterranean diet.

“Extra vir­gin olive oil is one of the most impor­tant sta­ples and a highly ranked dis­tinc­tive ingre­di­ent of a tra­di­tional Mediterranean diet,” she told Olive Oil Times. ​“Our study shows that extra vir­gin olive oil, due to its rich source of polyphe­nols with anti-inflam­ma­tory and anti-oxi­dant poten­tial, con­fers these health ben­e­fits and not just any type of olive oil.”

The researchers found extra vir­gin olive oil to be supe­rior for decreas­ing blood pres­sure, LDL‑c, LDL oxi­da­tion, fast­ing blood glu­cose, and improv­ing insulin sen­si­tiv­ity. Extra vir­gin olive oil also was deter­mined to increase HDL‑c and improve HDL func­tion.

“One of the more inter­est­ing find­ings was evi­dence of a dis­tinct advan­tage of extra vir­gin olive oil for weight loss,” said Flynn.

“More research is needed to bet­ter under­stand which phe­nols are most pro­tec­tive and the amount of phe­nol needed in the olive oil to see the ben­e­fit,” she added.

In the mean­time, the researchers hope these find­ings can help inform pub­lic health pol­icy sur­round­ing nutri­tion, which they believe to be out­dated.

“I have been research­ing oil for the past 25 years,” Flynn said. ​“I’ve long been frus­trated that health guide­lines around the world do not dis­tin­guish the dif­fer­ent types of oils.”

“Extra vir­gin olive oil is the juice of the olive and pro­vides unique health ben­e­fits, espe­cially com­pared to other oils,” she added. ​“The con­sumer needs to know they are using extra vir­gin olive oil that has health ben­e­fits, mean­ing it has at least 150 mil­ligrams per deciliter of total phe­nols. Simply pass­ing the chem­i­cal tests is not suf­fi­cient.”

Itsiopoulos said more work also needs to be done to dis­pel com­mon myths about cook­ing with extra vir­gin olive oil.

“Extra vir­gin olive oil, due to its high antiox­i­dant nutri­ent con­tent, is highly sta­ble dur­ing cook­ing, dis­pelling the myth that you can­not fry with extra vir­gin olive oil,” she said.

Despite the work that still needs to be done, both researchers said the review gives con­sumers plenty of rea­sons to pre­fer extra vir­gin olive oil over other grades of olive oil and cook­ing oils.

“This review indi­cates that approx­i­mately two table­spoons per day for extra vir­gin olive oil can improve a range of chronic dis­ease risk fac­tors in as lit­tle as three weeks,” Flynn said.

From olive oil pro­duc­ers, Flynn would like to see phe­nol con­tent fea­tured promi­nently on label­ing and web­sites. The phe­nol con­tent of olive oil is high­est when first pro­duced. Fresher vir­gin olive oil has a higher phe­nol con­tent and there­fore offers more health ben­e­fits.

She added that pro­duc­ers should also men­tion har­vest dates on their olive oils and spec­ify the amount of time from the har­vest to the trans­for­ma­tion process. This infor­ma­tion would help con­sumers know which com­pa­nies are pro­duc­ing the fresh­est olive oil with max­i­mum health ben­e­fits.

“In many food-based dietary guide­lines around the world, extra vir­gin olive oil is cat­e­go­rized in the oils, spreads and added fats sec­tion with the rec­om­men­da­tion to con­sume spar­ingly,” Itsiopoulos added. ​“Given the evi­dence on the health ben­e­fits of extra vir­gin olive oil as pre­sented in this paper, its place in food pyra­mids or plate mod­els needs to be more promi­nent.”

Looking ahead at future stud­ies, Flynn said more research into the rela­tion­ship between extra vir­gin olive oil con­sump­tion and type 2 dia­betes should be done.

“I was sur­prised how few stud­ies there are test­ing the ben­e­fits of extra vir­gin olive oil for type 2 dia­bet­ics,” she said. ​“Studies have shown that lifestyle changes have more ben­e­fits for type 2 dia­bet­ics com­pared to med­ica­tions.”

“We reviewed some stud­ies show­ing extra vir­gin olive oil can improve insulin resis­tance (that is, the abil­ity of insulin to store nutri­ents includ­ing glu­cose), and insulin resis­tance is the root cause of type 2 dia­betes and meta­bolic syn­drome,” Flynn added. ​“If more stud­ies could con­firm this find­ing, that would be very impor­tant infor­ma­tion.”

Flynn pre­dicts future stud­ies could ​“test how quickly daily use of extra vir­gin olive oil could improve blood glu­cose con­trol.”

“Based on the cur­rently avail­able stud­ies, it is likely two table­spoons per day in as lit­tle as three weeks, but future stud­ies could exam­ine if the ben­e­fits increase over time,” she con­cluded.

• Clinical Nutrition and Metabolic Care