Olive Oil Helps Reverse Damage of High-Fat Diets

Researchers in Chile found a compound in olive oil reduced the adverse effects on cholesterol and insulin caused by a high-fat diet.

Apr. 26, 2017
By Mary West

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While the car­dio­vas­cu­lar ben­e­fits of extra vir­gin olive oil are well known, its mech­a­nisms of action are cloaked in mys­tery to some extent. A new study pro­vided enlight­en­ment, as it showed a com­pound in the oil could reduce or reverse the neg­a­tive health con­se­quences of a high-fat diet.

Adding a rel­a­tively low dose of hydrox­y­ty­rosol was able to reverse oxida­tive stress, signs of fatty liver dis­ease and neg­a­tive effects seen in the other organs.- Rodrigo Valenzuela, University of Chile

Because of the lack of knowl­edge about the prop­er­ties by which olive oil works, researchers at the University of Chile set out to test the effects of a com­mon con­stituent that is sus­pected to be respon­si­ble for its health advan­tages — the com­pound called hydrox­y­ty­rosol. They found it reversed mark­ers of non­al­co­holic fatty liver dis­ease and insulin resis­tance in mice on a high-fat diet.

Hydroxytyrosol is a polyphe­nol found in extra-vir­gin olive oil, which is known to have antiox­i­dant prop­er­ties and may play a key role in its health ben­e­fits,” said lead author Rodrigo Valenzuela.

The researchers wanted to ascer­tain the action of hydrox­y­ty­rosol on cer­tain enzymes in the liver that are impor­tant in the syn­the­sis of long-chain polyun­sat­u­rated fatty acids. Some of these acids are needed for vas­cu­lar health. They dis­cov­ered mice on a high-fat diet had lower activ­ity of these enzymes, which was asso­ci­ated with an imbal­ance in the fat com­po­si­tion of the heart, liver and brain.

Yet when the high-fat diet of the mice was sup­ple­mented with hydrox­y­ty­rosol, the enzyme activ­ity and fat com­po­si­tion of the organs were com­pa­ra­ble to those of the mice fed the reg­u­lar diet. In other words, the ben­e­fi­cial com­pound found in extra vir­gin olive oil seemed to reverse the two harm­ful effects.


Our study found that mice fed on a high-fat diet had signs of non-alco­holic liver dis­ease which we believe has led to the notice­able reduc­tion in enzyme activ­ity in the liver and the neg­a­tive effects on fatty acid com­po­si­tion in this, and other, organs,” explained Valenzuela.

We also found that the liver showed signs of increased oxida­tive stress, which we know has links to fatty liver dis­ease. It is intrigu­ing that adding a rel­a­tively low dose of hydrox­y­ty­rosol to the diet was able to reverse these effects, reduce the signs of fatty liver dis­ease, and reduce neg­a­tive effects seen in the other organs.”

In the research, groups of mice were fed either a 60 per­cent fat diet or a 10 per­cent fat diet. Each of these mice sets was sub­di­vided into a group that was given hydrox­y­ty­rosol sup­ple­men­ta­tion and a group that was not. The inter­ven­tion period was 12 weeks. At the end of the study, blood and tis­sue sam­ples were col­lected to mea­sure enzyme activ­ity and fatty acid com­po­si­tion in mul­ti­ple organs.

Analysis of the blood tests showed increases in total cho­les­terol and LDL, or bad cho­les­terol, but no change in HDL, or good cho­les­terol, in mice fed the high-fat diet. The unhealth­ful effects on cho­les­terol were less­ened markedly with the hydrox­y­ty­rosol sup­ple­men­ta­tion.

The high-fat diet also raised mark­ers of insulin resis­tance, an action that was decreased by the hydrox­y­ty­rosol. However, the com­pound didn’t reduce the mark­ers to the lev­els found in the mice that were fed a reg­u­lar diet.

These find­ings strengthen the evi­dence that hydrox­y­ty­rosol may under­lie many of the health ben­e­fits of extra vir­gin olive oil, accord­ing to the researchers. The study was pub­lished in the jour­nal Lipids in Health and Disease.

In an inter­view with Olive Oil Times, natur­o­pathic can­di­date Rob Raponi explained that to receive the max­i­mum ben­e­fit from hydrox­y­ty­rosol, it’s best to avoid over­heat­ing the oil.

If some­one is want­ing to gain any ben­e­fit from this dis­cov­ery it is impor­tant to ensure that olive oil is con­sumed raw (prefer­ably) or lightly heated. If it’s heated past the smoke point, it begins to oxi­dize, an effect that reduces the amount of the hydrox­y­ty­rosol. My take-home mes­sage would then be to enjoy your olive oil, but take care not to destroy its del­i­cate bal­ance.”

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