Mouse experiment sheds light on the dietary benefits of extra virgin olive oil

April 10, 2017
Credit: martha sexton/public domain

Experiments carried out in mice have revealed that a compound commonly found in extra-virgin olive oil can reverse some of the negative effects of a high-fat diet. This compound, called hydroxytyrosol, was able to reverse markers of insulin resistance and non-alcoholic fatty liver disease in mice fed on a high-fat diet. The results are published this week in the open access journal Lipids in Health and Disease.

While there is substantial evidence that consuming extra- as part of a balanced can be beneficial to health, the biological and physiological reasons for this association have been unclear.

Dr Rodrigo Valenzuela, lead author from the University of Chile, said: "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. Our research shows that in mice fed on a high-fat diet, hydroxytyrosol exerts a protective effect in the liver."

The researchers were interested in looking at the effects of hydroxytyrosol on specific enzymes in the liver that are important for the synthesis of long chain poly-unsaturated fatty acids, some of which play an important role in vascular health. Mice fed on a high-fat diet were shown to have a reduction in these liver enzymes, which was linked to an imbalance in the fatty acid composition of the liver, brain and heart. Mice on a high-fat diet supplemented with hydroxytyrosol showed enzyme activity and fatty acid composition in these three organs which reflected that seen in mice fed a regular diet.

Dr Valenzuela explained: "Our study found that mice fed on a high-fat diet had signs of 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. 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 , and reduce seen in the other organs."

Four groups of 12-14 mice were fed on either a high-fat diet (60% fat) or a control diet (10% fat), with or without supplementation of 5mg hydroxytyrosol per kg body weight, administered orally, for a 12 week period. Blood and tissue samples were collected at the end of the experiment to study the dietary effects on oxidative stress, fatty acid composition and enzymatic activity in multiple organs.

Analysis of blood samples revealed an increase in levels of total cholesterol and LDL-cholesterol with no change in HDL-cholesterol in mice fed a HFD, which were all attenuated by hydroxytyrosol. HFD also increased markers of in the blood which were reduced by hydroxytyrosol, though not to the levels of mice fed a control diet.

The results of this study strengthen the evidence that many of the benefits associated with dietary consumption of extra virgin olive oil may be linked to its content of hydroxytyrosol, according to the researchers.

Dr Valenzuela added: "Our results indicate that hydroxytyrosol may be a key part of the health benefits of extra virgin olive oil. We have demonstrated that this compound may offer protection against and detrimental fatty acid composition in the , heart and brain caused by a . However, caution should be taken when extrapolating these findings to human consumption of hydroxytyrosol as our experiments have been conducted with in a controlled environment."

Explore further: Virgin olive oil, fish fatty acids help prevent acute pancreatitis

More information: Rodrigo Valenzuela et al, Hydroxytyrosol prevents reduction in liver activity of Δ-5 and Δ-6 desaturases, oxidative stress, and depletion in long chain polyunsaturated fatty acid content in different tissues of high-fat diet fed mice, Lipids in Health and Disease (2017). DOI: 10.1186/s12944-017-0450-5

Related Stories

Virgin olive oil, fish fatty acids help prevent acute pancreatitis

December 22, 2011
Scientists at the University of Granada have shown that oleic acid and hydroxytyrosol -present in a particularly high concentration in virgin olive oil- and n-3 polyunsaturated fatty acids -found in fish- relieve the symptoms ...

Blood fatty acids reveal your child's diet

March 23, 2017
Eating lots of sugary candy may strain the liver, alter the body's fatty acid metabolism and increase the risk of cardiometabolic diseases already in childhood. Children's blood fatty acid composition reflects their diet ...

Increase in coffee consumption could provide protective effect in non-alcoholic fatty liver disease

April 13, 2016
Adding coffee to the diet of people with non-alcoholic fatty liver disease (NAFLD) could help reverse the condition, according to a new study conducted in mice presented at The International Liver Congress 2016 in Barcelona, ...

A simple test to verify olive oil-related health claims

February 21, 2017
The fact that olive oil polyphenols contribute to the protection of blood lipids from oxidative stress—a physiological stress in the body that can cause DNA mutations and lead to diseases such as cancer, heart and blood ...

Changes in gut microbiota after unhealthy diet may protect from metabolic disease

March 17, 2017
An unhealthy diet changes the composition of the gut flora and it is generally assumed that this maladaptation called "dysbiosis" triggers disease. A study by Matteo Serino and his colleagues at the Université Paul Sabatier ...

Unveiling the biology behind nonalcoholic fatty liver disease

January 17, 2017
EPFL scientists have discovered a new biological mechanism behind nonalcoholic fatty liver disease.

Recommended for you

Researchers discover key signaling protein for muscle growth

November 20, 2017
Researchers at the University of Louisville have discovered the importance of a well-known protein, myeloid differentiation primary response gene 88 (MyD88), in the development and regeneration of muscles. Ashok Kumar, Ph.D., ...

New breast cell types discovered by multidisciplinary research team

November 20, 2017
A joint effort by breast cancer researchers and bioinformaticians has provided new insights into the molecular changes that drive breast development.

Brain cell advance brings hope for Creutzfeldt-Jakob disease

November 20, 2017
Scientists have developed a new system to study Creutzfeldt-Jakob disease in the laboratory, paving the way for research to find treatments for the fatal brain disorder.

Hibernating ground squirrels provide clues to new stroke treatments

November 17, 2017
In the fight against brain damage caused by stroke, researchers have turned to an unlikely source of inspiration: hibernating ground squirrels.

Age and gut bacteria contribute to multiple sclerosis disease progression

November 17, 2017
Researchers at Rutgers Robert Wood Johnson Medical School published a study suggesting that gut bacteria at young age can contribute to multiple sclerosis (MS) disease onset and progression.

Molecular guardian defends cells, organs against excess cholesterol

November 16, 2017
A team of researchers at the Harvard T. H. Chan School of Public Health has illuminated a critical player in cholesterol metabolism that acts as a molecular guardian in cells to help maintain cholesterol levels within a safe, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.