UC Davis Researcher Advises ‘Opt Out of Olive Oil’

Summary

A University of California at Davis researcher argued in a blog post that peo­ple should opt out of con­sum­ing olive oil, claim­ing that fats should come from whole plant foods. However, crit­ics, includ­ing a Brown University researcher, pointed out that olive oil, espe­cially extra vir­gin olive oil, has numer­ous health ben­e­fits and that stud­ies sup­port­ing the neg­a­tive claims about olive oil were flawed. The debate high­lights the con­flict­ing views on the health ben­e­fits of olive oil within the sci­en­tific com­mu­nity.

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!”

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.

“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 the­ex­tra vir­gin olive oil 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 the­ex­tra vir­gin olive oil 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 the­ex­tra vir­gin olive oil 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, ​“asex­tra vir­gin olive oil 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 tha­tex­tra vir­gin olive oil 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 ownex­tra vir­gin olive oil 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.