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Is this the magic ingredient that makes olive oil so healthy?


A new study in mice may shed light on the often-claimed health benefits of olive oil, writes Andrew Masterson.


An artificially fattened mouse and a control mouse.
Oak Ridge National Laboratory

A compound found in extra virgin olive oil reduces symptoms of insulin resistance and non-alcoholic fatty liver disease – at least in mice.

The finding – published in the journal Lipids in Health and Disease – provides a tantalizing insight into why olive oil has been consistently identified as a valuable part of healthy eating regimes.

The mouse study, conducted by researchers led by Rodrigo Valenzuela of the University of Chile, focused on hydroxytyrosol, a polyphenol found in extra virgin olive oil.

In an elegant experiment, Valenzuela’s team set up four small cohorts of mice. Over a 12-week period, two groups were put on a diet comprising 60% fat, with the others enjoying a “normal” 10% fat regime. One group from each pair was also given daily oral doses of hydroxytyrosol.

The high-fat cohort without the supplement was found to have decreased levels of enzymes in the liver, which, in turn, negatively affected the production of long-chain polyunsaturated fatty acids – critical for vascular health.

The cohort enjoying the added hydroxytyrosol, however, showed enzyme production on a par with the mice on the lower-fat diets.

The results illustrate at least a partial mechanism to explain why olive oil appears to have a positive and protective effect on health. They also suggest that it might also ameliorate the adverse health consequences of high fat diets.

“However, caution should be taken when extrapolating these findings to human consumption of hydroxytyrosol as our experiments have been conducted with mice in a controlled environment,” warns Valenzuela.

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Andrew Masterson is news editor of Cosmos.
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