UC Davis Researcher Advises ‘Opt Out of Olive Oil’

A faculty member at the University of California, Davis School of Medicine wrote a post on her department's blog urging people to avoid the use of olive oil.

May. 19, 2016
By Olive Oil Times Staff

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A Uni­ver­sity of Cal­i­for­nia at Davis researcher and a fac­ulty mem­ber of its Med­ical Cen­ter urged read­ers in a blog post for the school’s Inte­gra­tive Med­i­cine depart­ment to opt out of olive oil,” argu­ing, fats we need should come in nature’s orig­i­nal pack­age.”

Rosane Oliveira, a vet­eri­nary doc­tor from Brazil and the found­ing direc­tor of Inte­gra­tive Med­i­cine at UC Davis, wrote: the Mediter­ranean diet is health­ful in spite of olive oil — not because of it!”

Bot­tom line is that the fats we need should come in nature’s orig­i­nal pack­age – whole plant foods!- Rosane Oliveira, UC Davis

To sup­port her posi­tion, Oliveira drew selec­tively from stud­ies that she said showed olive oil plays a role both in dam­ag­ing blood ves­sels as well as form­ing ath­er­o­scle­rotic plaques.”

If you want some nutri­tional value, you will find it by eat­ing the whole olive — not by con­sum­ing it in its almost unrec­og­niz­able extracted oil form,” Oliveira wrote, dis­miss­ing count­less stud­ies that have shown that not to be the case. Like any other oil, olive oil is a processed, con­cen­trated fat extract and thus has lost most of the nutri­tional value of its orig­i­nal form (the olive itself).”

Extra vir­gin olive oil, mean­while, is no more processed than the juice of any other fruit. Brown Uni­ver­sity researcher and asso­ciate pro­fes­sor of Clin­i­cal Med­i­cine, Mary Flynn, told Olive Oil Times, extra vir­gin olive oil, by def­i­n­i­tion, con­tains phe­no­lic com­pounds, which have been shown to have numer­ous health ben­e­fits.”


In lay­ing out her case for eschew­ing olive oil, Oliveira cited a 1999 study mea­sur­ing FMD (flow medi­ated dila­tion) after the inges­tion of high-fat meals reported a 3‑hour decline in FMD after sub­jects ingested a tra­di­tional meal of a ham­burger and fries or cheese­cake. Olive oil was found to have the same impair­ment to endothe­lial func­tion as the rest of these high-fat meals.’ ”

The cita­tion is not a study, but an arti­cle on Brachial Artery Ultra­sound and endothe­lial func­tion,” Flynn argued. And while researchers found olive oil to have the same impair­ment to endothe­lial func­tion as other high-fat meals, the impair­ment was totally elim­i­nated when vit­a­mins C and E were given. As with antiox­i­dant vit­a­min sup­ple­men­ta­tion, olive oil, eaten with vine­gar on a salad, for exam­ple, did not impair endothe­lial func­tion.

Oliveira also cited the land­mark PREDIMED study, where 7,447 peo­ple at risk for car­dio­vas­cu­lar dis­ease were placed into groups. One group was told to eat a Mediter­ranean diet with extra vir­gin olive oil, another ate a Mediter­ranean diet with nuts, and the third was told to reduce fat intake.

Dr. Rosane Oliveira

After five years,” Oliveira wrote, the con­clu­sions were stun­ning; there were no dif­fer­ences between groups. No dif­fer­ences in weight, waist cir­cum­fer­ence, sys­tolic and dias­tolic blood pres­sure, fast­ing glu­cose, or lipid pro­file. And no dif­fer­ence in the num­ber of heart attacks or deaths from car­dio­vas­cu­lar dis­ease; those in the EVOO group suf­fered just as many heart attacks and car­dio­vas­cu­lar dis­ease as those in the con­trol group.”

To that argu­ment, Flynn coun­tered: There is no men­tion of change in these vari­ables over the study period so this author is say­ing all groups were alike at base­line,’ but mak­ing it sound like there were not changes with the inter­ven­tions.”

This was a fairly widely reported study so for (Oliveira) to miss this one is a bit sus­pect,” Flynn said, call­ing the over­sight down­right bizarre.” The study showed a 30 per­cent decrease in pri­mary major car­dio­vas­cu­lar events for the EVOO group com­pared to the low-fat con­trol group (the group receiv­ing nuts had a sim­i­lar decrease in CVD events). To imply there were no dif­fer­ences after the inter­ven­tions, is prob­a­bly the most egre­gious false state­ment in (Oliveira’s post), and the author has an appalling inabil­ity to read a jour­nal arti­cle,” said Flynn.

In sup­port of her state­ment that stud­ies to mea­sure the effects of the Mediter­ranean diet on endothe­lial func­tion showed FMD impair­ment after meals rich in olive oil,” Oliveira cited a sin­gle study with 10 par­tic­i­pants.

But the results of the study did sug­gest that the EVOO meal reduced FMD by 31 per­cent, while the oth­ers did not. In fact, as Flynn pointed out, the author of the study had stated that the mech­a­nism appeared to be oxida­tive stress because the decrease in FMD was reduced 71 per­cent by the con­comi­tant admin­is­tra­tion of vit­a­mins C and E. So, this could not have been extra vir­gin olive oil used,” Flynn sug­gested, as EVOO is rich in antiox­i­dants and adding vit­a­min C and E would there­fore not improve antiox­i­dant abil­ity.”

Yet Oliveira per­sisted, These results were con­firmed in another study show­ing that adding veg­eta­bles to a fatty meal may restore (at least par­tially) arte­r­ial func­tion and blood flow,” cit­ing research that looked at par­tic­i­pants after a meal of 2 sausages (80 g), 6 bread slices (90 g), a small egg (40 g), but­ter (15 g), and olive oil (5 g).

I drill into my stu­dents that no study con­firms any­thing. It may sup­port, add evi­dence, but it can­not con­firm,” Flynn cau­tioned. This would not be used to sup­port the argu­ment that EVOO reduces endothe­lial func­tion with or with­out veg­eta­bles added.”

Finally, Oliveira looked back to a 26-year-old study that showed that reduc­ing all fats stopped the growth of coro­nary lesions.

Flynn said that study did 24-hour recalls at time points, ana­lyzed them for nutri­ents, and used the nutri­ents to com­pare to changes in angiograms. They looked at polyun­sat­u­rated, monoun­sat­u­rated, and sat­u­rated fat.


The main source of monoun­sat­u­rated fat in the US diet is red meat, Flynn noted. So, if you are look­ing at nutri­ents, monoun­sat­u­rated fat intake would reflect red meat intake cer­tainly in the 1980’s (when the study took place), but even now it is an issue, and not olive oil. Inter­est­ingly, the odds ratio for PUFA was 3x the OR for MFA so the peo­ple with higher veg­etable seed oil intake (rich in PUFA) did even worse than the other groups.”

The seem­ingly extreme view to opt out” of what is con­sid­ered among the world’s most ben­e­fi­cial foods caused sur­prise among some read­ers of Oliveira’s blog and this page, espe­cially under the logo of the Uni­ver­sity of Cal­i­for­nia at Davis, which is the home of the UC Davis Olive Cen­ter, an inter­na­tion­ally renowned research cen­ter which pro­duces its own EVOO from trees grown on its Cen­tral Val­ley cam­pus.

Olive Cen­ter exec­u­tive direc­tor Dan Flynn said his col­league’s blog post needed to be weighed against the body of research that has sup­ported the inclu­sion of olive oil in a health­ful diet. Uni­ver­si­ties accom­mo­date a wide range of inde­pen­dent thinkers, and we wel­come the dia­logue. The sci­en­tific evi­dence in favor of the health ben­e­fits of olive oil is far stronger than the cita­tions offered in the blog,” he noted.

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