Scientists say adding more olive oil to your diet can positively impact your health in many ways, from alleviating high blood pressure to helping with weight loss.
Most people know that the Mediterranean diet is one of the healthiest eating plans because it’s chock full of fruits and vegetables. But many experts say the under-appreciated secret sauce in the diet is its liberal use of extra virgin olive oil as the primary added fat.
While every fruit and vegetable has health-promoting compounds, the ones unique to olive oil, called phenols, are especially powerful, says Mary Flynn, a nutrition researcher and founder of the non-profit Olive Oil Health Initiative at Brown University. The nutrients in extra virgin olive oil have been found to benefit numerous health conditions, including heart disease and diabetes.
“I call the Mediterranean diet a plant-based olive oil diet,” says Flynn, who recently published a review of the science behind the oil and found dozens of high-quality studies supporting its healthful effects. “We have no food or medicine that can do what olive oil can do,” she says.
The phenols in extra virgin olive oil are antioxidants, capable of protecting the body’s cells from dangerous molecules, and they also have antimicrobial properties, says Selina Wang, a food science researcher at the University of California, Davis and former research director of the school’s Olive Centre, which has received funding from the state’s olive oil growers and processors.
Like orange juice, extra virgin olive oil is simply the juice of the olive fruit, albeit juice that is tested to meet quality standards such as not having a musty or rancid smell or taste—an indication that compounds delivering the health benefits have degraded.
“Olive oil is one of the very few foods that has a sensory component in its quality standards,” Wang says.
In Greece, Italy, and other parts of the Mediterranean where olive trees have grown for thousands of years, oils were once extracted with hot water, applied after the fruit has been picked and crushed, a process that damaged some of the phenols. In the modern era, manufacturing protocols were revised as it became clear that a way to economically extract the oil from the fruit while keeping the phenols intact was by spinning it in centrifuges using ambient temperatures (and no chemical solvents, as was sometimes used). Oils processed this way bear the “extra virgin” label.
Olives’ most well-studied phenols, called secoiridoids, include their natural derivatives oleocanthal, oleacein, oleuropein aglycone, ligstroside, aglycone, and oleomissional. But it’s likely the combination working synergistically is what really matters.
A tasty and powerful medicine
In locations where the Mediterranean diet has long been a staple, rates of many diseases are lower, and many experts think that the extra virgin olive oil is a big reason why.
Heart disease
During a ten-year study of more than 12,000 people in Spain, researchers discovered that the risk of dying from cardiovascular disease was half as high in people consuming one-and-a-half teaspoons of extra virgin olive oil daily. The researchers noted this was not the case for “refined” olive oil that was not extra virgin.
The high blood pressure that contributes to heart disease specifically benefits from extra virgin olive oil, with one study finding systolic BP dropped after three week of two daily tablespoons.
“So many people could lower or get off their blood pressure meds” by increasing consumption, Flynn says.
Breast cancer
When 4,000 women in Spain were randomly assigned to one of three forms of a Mediterranean diet—a fat-restricted plan or one supplemented with extra nuts (another healthy fat) or one with extra virgin olive oil—the women who consumed the extra virgin olive oil reported the lowest rates of breast cancer during the five-year study period.
A separate study compared the eating habits of more than a thousand Spanish women who had invasive breast cancer with a similar group without the disease and concluded that consuming more than two tablespoons of virgin olive oil daily during meals offers the most protection.
Diabetes
More than a dozen randomized trials have documented the oil’s ability to decrease blood glucose, Flynn’s review found. Some researchers believe it does this by reducing damage to the pancreas’ insulin-producing cells.
Cognitive impairment
Studies in mice and one small randomized clinical trial in people
with mild cognitive impairment have linked consumption of extra virgin olive oil to the clearing of some amyloid plaques and improved cognitive functioning, although experts emphasize larger studies are still needed.
Weight loss
It seems counterintuitive because oils are calorie dense, but several dozen women randomised to either a low-fat plant based diet or one adding more than three daily tablespoons of extra virgin olive oil found the latter were significantly more likely to lose more than five percent of their body weight after eight weeks. When asked if they would continue their given plan, many more in the oil group said yes. “Compliance is the biggest issue with diet, so this is significant,” says Flynn, the study’s lead author.
It’s more than the monounsaturated
The polyunsaturated seed oils many cooks have turned to, however, including safflower, sunflower, corn, and soy, have problems of their own, she says. Most notably, they are subject to higher rates of chemical reactions—known as oxidation—that degrade their quality compared with extra virgin olive oil.
And, as other monounsaturated cooking fats like canola oil do not pack the same health punch, attributing all the health benefits of extra virgin olive oil to its monounsaturated fats rather than its phenol content is wrong, Flynn says.
Another misconception is that you can’t cook well with extra virgin olive oil because the oil smokes at a low temperature, but it actually produces fewer unhealthy by-products when heated compared with other oils, researchers have found.
Choose your olive oil carefully.
Health isn’t the only reason to boost your olive oil consumption. High quality, well stored olive oil also tastes great.
“We call olive oil liquid gold” because of its flavour and versatility along with its healthfulness, says Joy Pierson, a chef and restaurateur who, with her husband Bart Potenza, founded the famous vegan Candle 79 restaurant and others in New York City and now serves as a mentor to other chefs specialising in vegan cuisine.
The couple use extra virgin olive oil for seasoning and cooking everything from dressings, marinades, and pesto’s to sautés, pan fries, roasted and grilled vegetables, and even cakes.
Many people grab whatever extra virgin olive oil they find in their local supermarket but that is a mistake, Pierson says. The oils have unique flavours depending on the company, the growing region’s climate and soil, and numerous other parameters, which are especially important when the oil is not cooked. She also prefers organic varieties.
Pierson recommends going to a local farmers’ market or gourmet shop where they let you taste various brands. She also suggests buying more than one, with a mild-flavoured product for stir fries or cakes and one with more bite for a food like polenta.
“If we cared about olive oil the way we care about wine, we might shop for them similarly,” Wang says.
Potenza recommends perusing the websites of extra virgin olive oil producers before settling on preferred brands. “They’ll use descriptors like mild or grassy notes, similar to discussions of the flavour profiles of fine wines. It’s exciting,” he says.
Another important fact you can find on many websites is how quickly their olives go from plucking to oil production, something experts say should happen within hours to keep products fresh and phenols high. California, which has been producing extra virgin olive oil at scale only for a few decades, uses a modern method where special dwarf trees are planted close together to allow for speedy machine harvesting.
But high-quality boutique oil companies that pick by hand also aim for that timetable, says Kiara Koutoulakis, the communication and sales manager at olive oil manufacturer Koronekes on the Greek Island of Crete. “The fresher they are, the better,” she says. “Olives are a very fragile fruit.”
Koronekes also picks its olives early in the harvest, before they turn black, when their phenols have been shown to be at their highest, she says.
Because the large manufacturers extract the oil via centrifuge, you won’t see the term “first cold press” on major brands. But small companies like Koronekes that still press their olives use that language to distinguish the initial, most flavourful batch.
How to store your extra virgin olive oil
Once you bring the bottle home, the clock is ticking.
“I always say extra virgin olive oil loses its extra virginity with time,” Wang says. The product may have a two-year use-by date on it, but once opened you need to view extra virgin olive oil as a perishable item and consume it within four months, she says.
Never store the oil near heat—which includes next to or over your oven, as many people mistakenly do—Flynn says. And don’t leave the lid off too long during meal prep because oxygen is the enemy of its phenols.
The bad news about extra virgin olive oil is that the price is poised to rise substantially, thanks to floods, wildfires, droughts, freezes, and other problems with olive crops around the world. While it’s best to buy fresh, if you do want to stock up while costs are lower store the product in a cool, dark place or, if you won’t be opening it for several months, in the freezer or refrigerator, Wang recommends.
But don’t take it out until you’re ready to use it and avoid re-refrigeration. “If the oil has to keep coming to room temperature repeatedly, that may change its taste and appearance,” she says.
