Extra virgin olive oil (EVOO) is rich in plant chemicals called polyphenols, which combat the oxidative stress and inflammation that are typical in cancer. EVOO has powerful effects against several cancers including breast, prostate, liver, colon, and pancreatic cancer, multiple myeloma, myeloid leukemia, cutaneous squamous cell carcinoma, and melanoma.

Does your EVOO “burn” going down?

EVOO’s most important polyphenols for killing cancer cells are oleocanthal and hydroxytyrosol, which create the slight burning sensation you feel in your throat when you swallow it.

Not all olive oils are created equal when it comes to the level of the polyphenol oleocanthal. A recent study that compared the cancer killing power of several brands of olive oil on breast cancer cells and prostate cells showed that the oils with the most oleocanthal had the greatest cancer-killing power. Another study showed that oleocanthol in EVOO increased the effects of Tamoxifen in breast cancer treatment.

How do you find EVOO that’s high in oleocanthal?

Most supermarket olive oils are either too old, stored improperly, or cut with cheap and unhealthy vegetable oils. If you are going to use EVOO as part of your cancer toolbox, it's important to invest in a quality product.

Choose "Extra Virgin” and avoid "Refined or Pure" olive oil, which means the oil has been treated with solvents.
Next, look for a dark glass bottle that has printed the “Harvest date” on the back (not a “Best By’ date as that could be misleading). EVOO has optimal oleocanthal content within a year of harvest.
And know who is bottling your olive oil: Are you buying it from a small farmer who puts his family name on the bottle or from a large conglomerate that likely sources from many different farms, possibly adds GMO soybean or canola oil, and stores and sells oils that are too old?

How much EVOO should you consume?

There are few controlled human studies to determine optimal EVOO consumption, but one study did look at the reduced risk of developing breast cancer from adding 4 tablespoons of EVOO daily to a Mediterranean diet for nearly 5 years. The added EVOO reduced relative breast cancer risk by 68% compared with women who just consumed a Mediterranean diet.

Does cooking with EVOO ruin its health-promoting properties?

EVOO is well known for its ability to improve heart health by reducing LDL oxidation as well as reducing risk and possibly improving outcomes of breast cancer. But many in the health space caution against cooking with EVOO. Does cooking damage the oil? Does it reduce the health promoting properties? Researchers in Spain tested EVOO in a real-world cooking situation, with the oil added to a pan directly over a heating element. They found that while sautéing at a low temperature changes the polyphenolic profile of EVOO by causing some oxidation and depleting other compounds, the cooked oil still had the amount of hydroxytyrosol, tyrosol, or the derivates necessary to inhibit LDL oxidation. However, the amount of hydroxytyrosol diminished greatly at high temperature—about 60 percent lower hydroxytyrosol concentration in the EVOO cooked at a high temperature compared to the EVOO cooked at a low temperature. So if you cook with olive oil, rest assured that you will still derive health benefits. But to get the maximum benefit with all the cancer-fighting hydroxytyrosol and oleocanthol, consider steaming vegetables and adding raw EVOO.

Make sure your EVOO is genuine

In the US, unfortunately there is no FDA standard to ensure you are getting EVOO when it is marketed as such. When buying oil from California, I recommend choosing a smaller, single-source grower you trust; for larger brands, look for the California Olive Council (COC) certification, which ensures you are getting EVOO. Find out if your grower uses non-toxic methods for pest control. Becoming certified organic or COC certified can be an expensive process for smaller growers but they are likely to use natural farming methods. In Europe, EVOO marked DOC DO ensures that it has been made according to specific regulations.

Investigative journalist Tom Mueller, author of the revealing book Extra Virginity about the world of olive oil manufacturing, gives some tips and tricks for buying high-quality EVOO.

Buying EVOO in the US

I’m fortunate to live in California where we have access to fresh, high quality olive oil at our neighborhood specialty grocery store. We even have a few trees on our own property that yield some delicious olive oil every year, though it certainly isn’t “free” after all the money spent on maintaining the trees and bringing the olives to a commercial press.

If I do need to buy EVOO, I have a great source who happens to be related to me. My brother’s boutique olive oil company offers an economical monthly mail order subscription in the US. (Canadian shipping is also available for larger one-time orders.) He uses only natural and organic fertilizers and organic pest control–never any cancer-causing Roundup or malathion. (Unavailable in 2023 due to poor 2022 yield.)

In 2023, ConsumerLab.com tested commercially available extra-virgin olive oils for purity, rancidity, and polyphenol content as well as taste. Of the organic options, one that tested well for all was Lucini Organic Extra-Virgin Olive Oil. Look for the harvest year just before the current year, or no more than 18 months before the date you’re consuming it. For a very high polyphenol content and reasonable taste, Life Extension California Estate Extra Virgin Olive Oil could be a good choice, but it’s not organic. Costco got some high marks for its Kirkland Organic EVOO, but the reviewers described its flavor profile as having undesirable traits.

The North American Olive Oil Association tests and certifies olive oils for purity and quality standards set by the International Council. They have created a master list of certified olive oils that you can find here. Remember, however, freshness is also important. Your best choice is an olive oil brand that provides the harvest date on its label rather than the sell by date. Unfortunately, the larger olive oil brands typically don’t provide the harvest date with. You can check the freshness yourself by trying the oil. If you feel a tickle in your throat then it is probably less than 18 months past harvest when you get the freshest oil. If you don’t feel the tickle then look for another one.

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