The Skinny on Olive Oil 

Author: Lily Mazzarella

Truth about olive oilsThe right kind really IS that good for you

The health benefits of olive oil have been touted for millennia, and as with so many plant-based medicines, recent research confirms what the ancients (and my grandmother, Benigna Mazzarella, who died at the ripe old age of 108) knew.

Studies on high olive oil Mediterranean diets show benefit for bone density, cardiovascular health, brain health, degenerative joint disease and complications of type II diabetes. And that is just the beginning.

Extra Virgin Olive oil (EVOO) is rich in polyphenols—naturally occurring antioxidant and anti-inflammatory compounds which account for many of its health benefits and unique flavor characteristics. Polyphenol content in EVOO does vary. Very cool: the International Olive Council recently approved a method of measuring polyphenol levels which may end up on labels. According to Tom Mueller, author of Extra Virginity: The Sublime and Scandalous World of Olive Oil, numbers below 300 are considered low, above 500, high. The higher the rating, the stronger the taste— the bitter or pepper-y flavor many people are surprised to find is the hallmark of good quality olive oil.

Back of the throat bite

Gary Beauchamp, a biologist at the Monnell Chemical Senses Center teamed up with scientists at University of Pennsylvania to identify oleocanthal, a compound in EVOO that inhibits activity of the inflammatory enzymes COX1 and COX2, in a fashion similar to ibuprofen.

I love this story because it is an amazing example of organoleptics in practice: the science (and art) of using taste, smell and other senses to define drugs (or plants, in this case. The word “drug” comes from “droggen,” meaning “dried plant,” after all) and identify pharmacologically active constituents. As Beauchamp recounts: “I had considerable experience swallowing and being stung in the throat by ibuprofen from previous studies on its sensory properties…So when I tasted newly-pressed olive oil while attending a meeting on molecular gastronomy in Sicily, I was startled to notice that the throat sensations were virtually identical.”

A very useful oil indeed

A Better Brain:  Stress, infection, and exposure to chemicals all can cause inflammation in our brains. Turns out oleocanthal crosses the blood-brain barrier, scavenging free radicals and squelching inflammation where it counts. Diets high in olive oil also have been linked to a decreased risk of Alzheimer’s disease: in in vitro and in vivo studies, oleocanthal speeded clearance of the beta amyloid plaques associated with Alzheimer’s. Another compound in EVOO, hydroxytyrosol, has demonstrated protective effects against neurodegenerative diseases.

Anti-Cancer Effects?:  A recent study published in Molecular & Cellular Oncology shows rapid apoptosis (programmed cell death) of various cancer cell lines when exposed to oleocanthal. Other research shows it attenuates cell proliferation, invasiveness, and tumor growth in breast cancer models.  These exciting results are preliminary—meaning we have no idea if these effects hold in vivo, and when olive oil is consumed orally.

Mood Booster: Several studies have investigated the anti-depressant effects of high EVOO diets. Researchers believe that EVOO’s mood-enhancing effect may derive from a boost in BDNF (aka brain-derived neurotrophic factor, which is essentially an internally derived elixir of youth for our brain cells); BDNF plasma levels of which were higher in those consuming high EVOO diets. In a 12,000 person, 6-year study entitled Dietary Fat Intake and the Risk of Depression: The SUN Project, high trans-fat diets were associated with a 50% higher risk for depression, while high EVOO diets had an inverse relationship to depression. In a rat model of depression and anxiety, compounds in EVOO were shown to modulate serotonin and dopamine; rats consuming them showed improvements in various stress/anxiety/depression-related behaviors.

Liver/Gallbladder “Flush?”: The EVOO + lemon juice “liver/gallbladder flush,” in which up to a cup of each is ingested, has been popular in alternative health circles for decades. Is there anything to it? Both the presence of fat in the digestive tract and the sour flavor initiate strong signals to the gallbladder to contract, inducing full emptying of the little guy, which may be full of thickened and irritative bile (aka “sludge”). But be wary of internet claims regarding the flushing of “stones”: the yellow/green blobs in the toilet bowl people are raving about online aren’t “liver stones” or even “gallstones”—they are accretions formed by the physicochemical properties of olive oil, acids, and bile. See this article in the Lancet for photos and a proper debunking.

*That said, there can be benefits to the flush, especially for people with a tendency towards thickened bile. I recommend 2 TBSP of each upon rising to start—Mark Hyman, MD recommends this in his UltraSimple Diet cleanse, which I have guided several hundred people through. Many people feel lighter, brighter, and less irritable and constipated after doing this. If you have biliary distress, proceed with the guidance of your health care practitioner. Be aware that if you DO have gallstones, this therapy can mobilize them, and possibly cause a bile duct obstruction!

Antibacterial, antifungal, and antiviral compounds: Naturally occurring compounds in EVOO that protect the olive tree from herbivory, disease, and radiation also protect us from potential pathogens.

Can I Cook With It?

This has been a subject of much debate. But after a good amount of research, I feel comfortable saying: Yes, you can. Sauté or bake with EVOO up to 400 degrees and you’re in the clear. One study showed that there was minimal change to the phenolic compounds after 36 hours of heating at 180 Celsius (356 Fahrenheit). The smoking point is approximately 400 degrees, so avoid frying, broiling, or grilling on high flame with EVOO.

How Not to Get Duped by the Olive Oil Thugs

You probably have heard about the super shady worldwide olive oil racket, exposed in this country by Tom Mueller in a 2007 New Yorker article, that evolved into his bestseller Extra Virginity. If you’ve missed out on this greasy topic, check out this excellent NYT magazine infographic that says it all: Olive oil exported from Italy is often cut with cheaper oils like soy and canola, doctored with industrial beta carotenes and chlorophyll (and who knows what else) to approximate color and flavor, and then shipped out as “Italian origin” EVOO. Some of our most common supermarket brands—Colavita, Filippo Berio, Bertolli, etc, failed to pass the standards of a true EVOO screen at UC Davis (In October of 2014, class action suits were filed against Bertolli and Filippo Berio).

These common brands did NOT pass muster:

  • Carapelli
  • Colavita
  • Filippo Berio*
  • Mazzola
  • Mezzetta
  • Newman’s Own
  • Pompeian
  • Rachel Ray
  • Safeway
  • Star
  • Whole Foods (except for 365 California varietal)

Become an Organoleptics Expert:

You can learn to taste for the characteristics of a real—and great—EVOO. You’re first checking for rancidity—the oil should never taste flat, “cardboard-y” or fishy.  Next, you’re detecting the presence of polyphenols, which will arrive with a spicy, pungent “bite” at the back of your throat. Good olive oil is spicy, grassy, bitter and complex–not buttery or round. Tom Mueller says not to worry about color—as good olive oil comes in many hues. For more tips on how to evaluate and buy great olive oil, see Mueller’s blog.

Do I Need to Buy Organic?

Many agrochemicals are fat soluble. Pesticide residues are higher in non-organic EVOO, but unfortunately still present in organic. Here in Northern California, some local producers are using biodynamic practices, which further reduce organic pesticide burden. We love the magical Preston Farms in Healdsburg, CA, and Sunhawk in Hopland CA.

Which common brands pass muster? (Sources: Consumer Reports, Tom Mueller, and UC Davis)

If you shop at…

Trader Joe’s: California Estate, Premium 100% Greek Kalamata, Premium Extra Virgin (all others failed)

Whole Foods: 365 California (all other types notably failed)

Costco:  Kirkland Organic

Other standouts: McEvoy Ranch (local fave!); Corto Olive; Lucero. California Olive Ranch has an iffy track record, passing the stringent tests some years, and not others.

If you’re in NorCal go local: we are lucky enough to have some of the best EVOO producers in our backyards, with a lower carbon footprint (think of all the container ships, refrigeration and air travel that go into imported oils).  We love McEvoy Ranch (I pass their beautiful organic farm on my way out to Pt. Reyes), Preston Farms in Healdsburg, and SunHawk in Hopland CA. 



  1. My wife barely made it through the second line chemo for recurrent endometrial stage 4 serous type. I read about oleocanthal in Google news too late to test it earlier. Now it has been 5 months of weekly EVOO 4 hour application all over and her endometrial appropriate cancer marker called CA125 is lowest in 2 1/2 years at 5.9. Sure, we did everything else regarding best practices. We had the best doctors. But I am a mechanic. I need tools. God does he ever provide.

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