Health

EVOO Absorbs Polyphenols From Veggies When Cooked Together, Study Finds

Researchers found that polyphenols are exchanged between vegetables and olive oil during the sofrito preparation, becoming more accessible and easier to absorb after this type of preparation.

Rosa Maria Lamuela-Raventos led the research team.
Sep. 5, 2019
By Costas Vasilopoulos
Rosa Maria Lamuela-Raventos led the research team.

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Researchers from Spain and Brazil have found that cook­ing veg­eta­bles with extra virgin olive oil can improve the extractabil­ity of their polyphe­nols, increas­ing the amount of the com­pound that is absorbed by the oil.

The study exam­ined the inner work­ings of the tra­di­tional meth­ods of Mediterranean cook­ing, attempt­ing to shed light on how extra virgin olive oil inter­acts with the ingre­di­ents of the local cuisines. Along with polyphe­nols, var­i­ous other bioac­tive com­pounds from the veg­eta­bles were also found to be absorbed by the oil when cooked.

There is an exchange of polyphe­nols during cook­ing, some more apolar from veg­eta­bles go to the oil frac­tion, while some from the oil are absorbed by the veg­eta­bles.- Rosa Maria Lamuela-Raventos, lead author of the study

The researchers focused on the sofrito method, a pop­u­lar Mediterranean cook­ing tech­nique for prepar­ing a light sauce with tomato, onion and garlic. Sofrito report­edly con­tains 40 dif­fer­ent phe­no­lic com­pounds and a high con­tent of carotenoids, while its con­sump­tion is asso­ci­ated with reduced car­dio­vas­cu­lar risk and insulin sen­si­tiv­ity.

After the cook­ing process, an analy­sis of the olive oil showed that it was infused with polyphe­nols from the veg­eta­bles in the sofrito sauce; specif­i­cally with narin­genin, fer­ulic acid, quercetin and Z‑isomer carotenoids, none of which are typ­i­cal com­pounds of extra virgin olive oil.

See more: Olive Oil Health Benefits

The migra­tion of bioac­tive com­pounds such as polyphe­nols and carotenoids from the tomato to the olive oil also explained the find­ings of pre­vi­ous work of the researchers, which had con­cluded that the spe­cific type of sauce demon­strated increased anti-inflam­ma­tory prop­er­ties.

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“In inter­ven­tion nutri­tional stud­ies we have observed that polyphe­nols from toma­toes were better absorbed when the tomato was cooked as a sauce with extra virgin olive oil,” Rosa Maria Lamuela-Raventos, a food sci­ence pro­fes­sor at the University of Barcelona and a researcher at Ciberobn (the research center for obe­sity and nutri­tion of Spain), told Olive Oil Times.

“For this reason, we wanted to eval­u­ate why this was hap­pen­ing, so we per­formed an in vitro assay where we sep­a­rated sofrito in three frac­tions or parts: solid (insol­u­ble part), water frac­tion and oil frac­tion,” she added. “In this paper we observed that some of the polyphe­nols from the tomato, onion and garlic were moving to the oil frac­tion, being more bio-acces­si­ble, so easier to be absorbed.”

Additionally, the researchers noticed that the polyphe­nols in the olive oil were also reduced, by degrad­ing or by migrat­ing to the food matrix.

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“There is an exchange of polyphe­nols during cook­ing, some more apolar from veg­eta­bles go to the oil frac­tion, while some from the oil are absorbed by the veg­eta­bles,” Lamuela-Raventos, who was also the main author of the study, said. “However, the tem­per­a­ture is impor­tant while cook­ing, because high tem­per­a­tures over 100 degrees Celsius (212 degrees Fahrenheit) oxi­dized polyphe­nols.”

Having used sci­ence for years to assess the qual­i­ties of dif­fer­ent edi­bles and food ingre­di­ents, Lamuela-Raventos regards the Mediterranean diet as one of the health­i­est.

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“[The Mediterranean diet] is one of the health­i­est diets in the world,” she said. “As a sci­en­tist, I observe that the results with the tra­di­tional Mediterranean foods and dishes – such as extra virgin olive oil, sofrito, wine and more – give really very good results in inter­ven­tion nutri­tional stud­ies.”

However, sci­ence and good health are not the only para­me­ters to be taken under con­sid­er­a­tion when it comes to the Mediterranean diet, Lamuela-Raventos added.

“As a con­sumer, I try to follow a Mediterranean diet not only for health rea­sons but also because of the way cook­ing and eating habits with family and friends are good not only for health but also for socia­bil­ity and hap­pi­ness,” she said.

“We are con­tin­u­ing our research about cook­ing with extra virgin olive oil with other food rich in pro­teins such as chicken or in car­bo­hy­drates such as pota­toes,” Lamuela-Raventos added. “We want to eval­u­ate if extra virgin olive oil polyphe­nols are absorbed in these foods while cook­ing.”

The health effects of the Mediterranean diet have been dif­fi­cult to repro­duce in non-Mediterranean pop­u­la­tions, the researchers noted, in all like­li­hood due to the dif­fer­ent cook­ing tech­niques used.

The researchers’ work estab­lished that, apart from con­sum­ing the ingre­di­ents and staple foods of the regime, tra­di­tional cook­ing from the Mediterranean can also play an impor­tant role in taking full advan­tage of the ben­e­fits of the Mediterranean diet.

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