What Are Polyphenols and Why Should You Care?

Extra virgin olive oil (EVOO) is celebrated for being the healthiest cooking oil.

Many would point to EVOO as a prominent source of monounsaturated fats, the consumption of which are associated with weight loss and lowering the risk of cardiovascular disease, among various other benefits.

However, Nasir Malik, a plant physiologist at the United States Department of Agriculture’s research service, said olive oil’s health benefits are almost entirely derived from a class of organic chemicals known as phenolic compounds – or polyphenols.

“The health benefits of olive oil are 99 percent related to the presence of the phenolic compounds, not the oil itself,” he told the Washington Post in 2012.

What are polyphenols?

Polyphenol is an umbrella term for a large family of naturally occurring plant compounds comprising multiple phenol units, which act as antioxidants.

There are 8,000 different types of polyphenols and more than 100 different types of foods with at least one milligram of polyphenols per 100 grams or milliliters of food or beverage. These vary widely from fruits and vegetables to whole grains and seeds.

According to Phenol-Explorer, a database, 25 polyphenols are found in extra virgin olive oil. Of these 25, the most significant are tyrosols – including oleuropein, hydroxytyrosol and oleocanthal.

Polyphenols are found most abundantly in extra virgin olive oil, and some polyphenols are present in virgin olive oil.

Refined olive oil only has trace amounts of the polyphenols, which are removed during the refining process and are added back in when the refined oil is blended with small quantities of virgin or extra virgin olive oil before it is bottled and sold.

Polyphenols lower heart disease risk

Polyphenols have been linked in hundreds of studies to various health benefits.

Chief among these health benefits is lowering the risk of heart disease, mainly due to their antioxidant properties. Antioxidants help reduce chronic inflammation, the primary risk factor for heart disease.

Two recent studies – one published in International Journal of Molecular Sciences and the other in the Journal of Oxidative Medicine and Cellular Longevity – linked polyphenol-enriched diets to lower blood pressure and LDL (low-density lipid) cholesterol, colloquially known as ‘bad cholesterol,’ and increased levels of HDL (high-density lipid) cholesterol, or ‘good’ cholesterol.

The consumption of polyphenols has also been associated with lowering the risk of blood clots by preventing excess platelet aggregation.

Polyphenols decrease diabetes risk

Along with providing benefits for heart health, polyphenols have also been shown to lower blood sugar levels, which decreases the risk of type 2 diabetes.

A 2017 study published in the British Journal of Medicine found that participants eating large amounts of polyphenol-rich foods had a 57-percent lower chance of developing type 2 diabetes over a two to four-year period than people who consumed very low amounts of polyphenols.

Among the reasons for this may be that polyphenols help stimulate insulin secretion, which helps move sugar from the bloodstream and deposit it in the cells. This keeps blood sugar levels stable.

Polyphenol-rich diets are also linked to lower fasting blood sugar levels and higher glucose tolerance, both of which are essential factors for reducing the risk of contracting type 2 diabetes.

Polyphenols may help cancer and dementia patients

Though researchers are the first to admit that many more studies need to be done on the subject, polyphenols have also been linked to a lower risk of prostate and breast cancer.

Some studies conducted on the subject suggest that polyphenols block the growth and development of these types of cancer cells.

As a result, a separate study suggested oleocanthal-based treatments may be effective as part of targeted therapy for some types of breast cancer patients.

The researchers behind this study also found that oleocanthal regulates abnormalities in a receptor responsible for the development of Alzheimer’s disease.

In Alzheimer’s patients, the receptor becomes over-stimulated and promotes inflammation. Therefore, researchers hypothesize that consuming oleocanthal may regulate the receptor and decrease inflammation.

Polyphenols restore gut bacteria

Along with helping prevent certain chronic diseases, some scientific studies also show that high-polyphenol extra virgin olive oil promotes the growth of beneficial gut bacteria, which helps with digestion.

One study demonstrated that adherents to the Mediterranean diet, which includes polyphenols from several of its components besides olive oil, had a more diverse gut bacteria, which is associated with better weight management.

Polyphenols also add plenty of flavor to EVOO

Along with endowing extra virgin olive oil with its many health benefits, polyphenols also contribute to the flavor profiles of the oil.

The presence of polyphenols contributes to astringency, bitterness and pungency. Depending on the types of olives and when they are harvested will impact which of these attributes can be sensed in an EVOO.

Astringency is the puckering sensation, which is created by tannins, a type of polyphenol. Astringency is associated with early harvested and robust extra virgin olive oils. Astringency will mostly be noticed when tasting the oil on its own and is less apparent when cooking with an EVOO.

On the other hand, bitterness – due to oleuropein – is one of the less sought-after flavors in most foods but is an excellent indicator that an EVOO has been made with fresh olives. As with certain types of beer, chocolate and coffee, bitterness is an acquired taste, the appreciation of which comes over time.

Meanwhile, pungency is the stinging sensation in the throat, which is mostly associated with oleocanthal. Occasionally the sensation, which is similar to that of chili peppers, is strong enough to force a cough.

Tips for selecting high-polyphenol EVOO

While few brands list the polyphenol contents of their EVOOs directly on the label, there are a few tricks to finding high-polyphenol EVOO at any store or market.

The first is to check the label to see if the olives were harvested early. Polyphenols accumulate in the olives earlier than the oil and steadily decrease as the fruit matures. Therefore, an early harvest EVOO has more of them.

Next, consumers should keep their eyes peeled for Coratina, Cornicabra, Maurino, Picual and Mission monocultivars or Tuscan blends. These olive varieties have the highest levels of polyphenols.

Additionally, olives harvested in temperate climates instead of arid ones also have higher levels of polyphenols. This is likely due to the rate of maturation of the olives in these specific climates.

Finally, if none of this information is readily available, select robust EVOOs over mild or delicate ones. The oils are robust because (as previously discussed) due to the presence of the polyphenols.