Olive oil, known as “the great healer” of various ailments in Ancient Greece, has been used medicinally for centuries. Today, olive oil is known by health-conscious consumers and scientists alike to have medicinal properties ranging from heart health to cancer treatment. Yet when it comes to purchasing olive oil, the options seem endless – extra virgin, virgin, high-phenolic, early harvest, refined, premium, pure – leaving consumers perplexed. While taste may seem like an easy way to choose a condiment, this is not the most surefire way to choose a health supplement with proven results. In this article, we have gathered the most compelling, peer-reviewed and published scientific studies on olive oil’s health benefits to remove some of the guess work when choosing a healthy olive oil.
The Composition of Olive Oil
In the 1960s, the Mediterranean Diet, vegetable-heavy, low in sugar, and high in fat, became popular as it came to be known that people from Greece and Italy had lower rates of heart disease than those from northern Europe or the United States. Yet, recent data has indicated that many of the health effects of the Mediterranean diet actually stem from the increased consumption of olive oil.
Olive oil is made up of nearly 99% triacylglycerides (ie, fats; most of which are oleic acid) . However, many of the health effects of olive oil are attributed to the remaining 1%, which consists of ~30 known phenolic compounds . These phenolic compounds are naturally occurring in the flesh of olives, and have anti-inflammatory and antioxidants properties . The phenolic content of olive oil is highly dependent on the production and storage of the oil and can range anywhere from 50 to 1000 mg or more of phenols in each kg of oil .
The time of harvesting the olives is considered the most influential factor when producing oil with high phenol levels . The phenolic content of the olive fruit increases in the early stages of ripeness and then declines rapidly as the olive matures . Therefore, early harvest olive oil containing high phenol levels is pressed from olives that are harvested earliest in the season, when the olives are unripe and bright green in color. While pressing unripe olives yields less olive oil (and consequently, a higher price tag), it preserves the natural phenols and thus, produces olive oil with superior health benefits.
In addition to the medicinal properties, early harvest olives tend to deliver a more robust aroma and flavor, and a more green-golden colored olive oil due to the higher concentration of chlorophyll in the unripe olives at the time of pressing. Moreover, the phenolic content of olive oil is directly related to the stability of the oil; these phenols prevent the oxidation of olive oil in the presence of air or light that would result in the oil turning rancid. Accordingly, early harvest, high phenolic extra virgin olive oil has been found to be an extremely stable oil, producing less harmful chemicals under heat than any other cooking oil.
Additional factors that influence the phenol content of olive oil include the olive fruit’s genetic origins and the duration and temperature during the malaxation, or churning, of the crushed olive paste prior to oil extraction . Overall, higher phenol content is found in extra virgin olive oil (EVOO) than refined or virgin olive oil.
Specific Health Benefits of High Phenolic EVOO
High phenolic olive oils, acquired through an early harvest and precise extraction and manufacturing process, are naturally rich in anti-inflammatory and antioxidant molecules such as tyrosol, hydroxytyrosol, oleocanthal, and oleuropein. The scientific community has published thousands of studies connecting the dots between daily intake of EVOO and numerous health benefits. Decreased inflammation, lower incidence of diabetes, improved cardiovascular health, and improved cognitive function have all been associated with the consumption of high quality EVOO.
1) Improve brain function
Researchers found that replacing all vegetable oils in the diet (such as safflower, canola, or low-quality olive oil) with high-quality extra virgin olive oil had improved cognitive function in elderly study participants just 1 year later . Another study demonstrated that high phenolic early harvest EVOO and, to a lesser degree, moderate-phenolic EVOO, significantly improved cognitive function compared with a Mediterranean diet alone, even in participants with a genetic predisposition to Alzheimer’s disease . Further studies of Alzheimer’s disease demonstrated that mice fed EVOO for six months displayed less Alzheimer’s disease-causing protein aggregates in their brain, resulting in improved memory and cognitive function .
2) Manage diabetes
Researchers have shown that olive oils high in phenolic compounds can be used for the management of diabetes . They extracted the active phenolic compounds from high-quality olive oil and found that these EVOO extracts were more effective at inhibiting diabetes-related enzymes than Acarbose, a common drug prescribed to diabetics .
3) Control inflammation
High-quality EVOO has a repertoire of medicinally active compounds that keep inflammation in check and protect against developing chronic inflammatory diseases. Various phenolic compounds, inclduing oleuropein, oleocanthal, and hydroxytyrosol, and triterpenic compounds, such as oleanolic acid and maslinic acid, have been credited with the antioxidant, anti-inflammatory, and immune-boosting properties of EVOO. In fact, a recent human study demonstrated the importance of consuming olive oil that is high in both phenols and triterpenes for reducing inflammation and DNA oxidation .
4) Fend off cancer
Regular EVOO consumption has been linked to decreased cancer risk . In fact, people in the Mediterranean region have decreased rates of cancer and decreased cancer mortality , possibly due to higher EVOO consumption than the rest of the world. Studies have linked the polyphenols found in EVOO to its cancer-fighting abilities; these polyphenols can kill cancer cells, but not non-cancerous cells , eliminating many of the side effects seen with classic chemotherapy, and can reverse acquired resistance to standard-of-care breast cancer treatments . Additional studies have shown the therapeutic potential of EVOO and/or its phenolic compounds against colorectal cancer , glioblastoma , malignant bone diseases , hepatocellular carcinoma , and melanoma .
5) Boost heart health
Studies have demonstrated that phenolic compounds in isolation or within olive oil can improve cardiovascular health by reducing blood pressure and “bad” cholesterol, and preventing plaque formation. One study conducted in Spain followed participants over a 5-year period and found that those that supplemented their diets with high-phenolic OO had significantly lower incidence of heart disease . Another study demonstrated that high-phenolic olive oil, but not low-phenolic olive oil, improves both blood pressure and endothelial function . And just 3 weeks of consuming 2 tablespoons of high-phenolic olive oil a day improved cholesterol levels, whereas low-phenolic olive oil consumption actually worsened cholesterol levels . The negative effect of low-phenolic olive oil strengthens the importance of using high-quality EVOO. Furthermore, higher than average phenolic content qualifies an olive oil to be labeled by the European Food Safety Authority as contributing “to the protection of blood lipids from oxidative stress.”
Several studies have associated a more diverse gut microbiota with the adherence to a Mediterranean diet or the consumption of EVOO high in phenols. These positive effects on the gut microbiota have been linked to colorectal cancer prevention , decreased blood lipids , increased intestinal immune function , enhanced insulin sensitivity , and protection against gastritis-causing Helicobacter pylori .
ABOUT THE AUTHOR: Dr. Limor Goren is the founder of kyoord. She is a cancer researcher with a PhD in Molecular Biology. Her research centers on one of the most important anti-inflammatory molecules found in medicinal olive oil called Oleocanthal. Kyoord is dedicated to educating consumers and making healthy, high-phenolic olive oils available in the US. At Kyoord, we are proud of what our olive oil contains; we always provide customers with a certificate of analysis to fully disclose the amounts of each constituent.
Note: Some of this information has previously appeared on Kyoord’s Learning Blog.
As an exclusive offer for Dr. Kara Fitzgerald readers, kyoord is offering 10% off your first olive oil order by using the code DrKF10 here.
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