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Food, Health, and Eco-news
Antioxidant Unique to Extra Virgin Olive Oil Protects Mouse Brain Cells
Studies in mice and test tubes find EVOO antioxidant guards against damage associated with Alzheimer's and age-related mental decline
by Craig Weatherby

Extra virgin olive oil (EVOO) is the only common food rich in a potent antioxidant called hydroxytyrosol.

This probably explains why, as we're reported, EVOO appears to offer health benefits far exceeding those of any other kitchen oil.

(See “Extra Virgin Olive Oil Undermines Bug Behind Ulcers and Stomach Cancer,” “Olive Oil Earns More Cardiovascular and Anti-Cancer Kudos,” and “Extra Virgin Olive Oil Confirmed as Best Cardiac Prevention Choice.”)

So-called “pure” grade olive oil (labeled simply “olive oil”) contains virtually no hydroxytyrosol, while “virgin” grade olive oils contain much less than EVOO does.

This nearly unique food factor surpasses virtually all other food-borne antioxidants when it comes to neutralizing the damaging oxygen compounds called free radicals.

Free radicals are byproducts of normal metabolism, the body's immune responses, and the low-level inflammation caused by sugary, starchy diets.

If the body's own antioxidant defenses can't control them efficientlya common problem in middle age and beyondfree radicals can promote and exacerbate the brain-cell damage associated with Alzheimer's and the garden variety age-related cognitive decline (ARCD) that produces memory loss and “brain fog”.

People in Mediterranean countries have lower rates of Alzheimer's disease, and researchers have suspected that the hydroxytyrosol in EVOO may hold part of the answer to this riddle.

A study from Germany supports that suspicion, and offers hope that diets high in extra virgin olive oil may help reduce brain damage from free radicals (Schaffer S et al 2007).

What the study showed

Researchers at the University of Frankfurt experimented with mouse brain cells and living mice to gauge the brain-protective effects of hydroxytyrosol from olives.

Their methods were twofold:

  • They exposed isolated mouse brain cells to chemicals that generate free radicals—so-called “oxidative stressors”—after first bathing some of the brain cells in a hydroxytyrosol solution.
  • They fed some mice hydroxytyrosol for 12 days, and then exposed parts of their brains to oxidative stressor chemicals. (A control group got no hydroxytyrosol.)

When the German team exposed isolated mouse brain cells to oxidative stressor chemicals, levels of lipid oxidationa measure of free radical damagewere 25 percent lower in brain cells that had been previously bathed in the hydroxytyrosol solution.

They also found that the EVOO antioxidant protected brain cells' energy producing capacity: a key factor in Alzheimer's and regular forms of senility.

Brain cells exposed to the oxidative stressors lost 40 percent of their adenosine triphosphate (ATP), which is the chemical that our cells use to store energy.

But when the rodent brain cells were pre-exposed to the EVOO antioxidant before being exposed to oxidative stressors, they lost only 15 percent of their ATP.

Their experiments also proved that eating hydroxytyrosol is an effective way to gain brain protection.

They fed mice 100 mg of hydroxytyrosol per kilogram (2.2 pounds) of body weight, for 12 days, and exposed cells in the living animals' brains to oxidative stressors.

The Germans found that the brain cells of the mice fed hydroxytyrosol showed enhanced resistance to oxidative stress, and less damage to the crucial membrane surrounding the cells' mitochondria (energy factories).

As they wrote, their findings “…provide the first evidence of neuro-protective effects of oral hydroxytyrosol intake.” The researchers came to an overall conclusion that should be very encouraging to the EVOO lovers among us:

“This study indicates that hydroxytyrosol and extra-virgin olive oil afford neuroprotection and might contribute to the lower incidence of neuro-degenerative diseases, as observed in the Mediterranean area” (Schaffer S et al 2007).


  • Schaffer S, Podstawa M, Visioli F, Bogani P, Müller WE, Eckert GP. Hydroxytyrosol-rich olive mill wastewater extract protects brain cells in vitro and ex vivo. J Agric Food Chem. 2007 Jun 27;55(13):5043-9. Epub 2007 May 27.
  • Fki I, Sahnoun Z, Sayadi S. Hypocholesterolemic effects of phenolic extracts and purified hydroxytyrosol recovered from olive mill wastewater in rats fed a cholesterol-rich diet. J Agric Food Chem. 2007 Feb 7;55(3):624-31.