Overall, polyphenols appear to offer many promising health benefits. However, more research is needed before additional doses of polyphenols can be recommended. For now, it is best to consume polyphenols in the form of natural plant foods. The Mediterranean diet is a diet that includes many foods rich in polyphenols.
Many of the health benefits associated with polyphenols may be related to their role as antioxidants. Antioxidants are known for their ability to combat cell damage. Polyphenols may also impact genes and gene expression. A person’s specific genes can also affect how their body responds to certain types of polyphenols. Polyphenols may even influence gut bacteria.
What are Polyphenols?
Polyphenol is an umbrella term for a large family of naturally occurring plant compounds containing multiple phenol units that act as antioxidants.
There are 8,000 different types of polyphenols. There are more than 100 different types of foods that contain at least one milligram of polyphenols per 100 grams of food or drink. These range widely from fruits and vegetables to whole grains and seeds.
Extra virgin olive oil contains 25 polyphenols. The most important of these 25 are tyrosols, including oleoropein, hydroxytyrosol, and oleocanthal.
Polyphenols are most commonly found in extra virgin olive oil, and some polyphenols are only found in extra virgin olive oil.
The amount of polyphenols in olive oil varieties
The beneficial effects of olive oil may be related to the polyphenol content of the oil. Extra virgin olive oil (EVOO) is not subject to refining and retains the highest levels of polyphenols.
- Extra Virgin olive oil: 150–400 mg per kilogram (kg)
- Common olive oil: 10–100 mg/kg
- Pomace olive oil: 10–30 mg/kg
- Refined olive oil: 0–5 mg/kg
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.
Polyphenol levels do not appear on labels, and many EVOOs sold commercially are not fresh. People can look for an oil that has a recent harvest date and is in a container protected from sunlight.
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. That’s 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.
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.
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.
Type 2 diabetes
Some researchers have reported that polyphenols may reduce the risk of type 2 diabetes. They can increase insulin sensitivity and slow the rate at which the body digests and absorbs sugar. According to one review, a type of flavonoid called flavan-3-ols may be particularly beneficial for lowering insulin resistance. The same review also found that flavonoids appear to be the type of polyphenol most commonly associated with a lower risk for type 2 diabetes. An analysis of studies on flavonoid intake and type 2 diabetes concluded that people who consumed the most flavonoids had a lower risk of developing type 2 diabetes than those who took the least. Increasing flavonoid intake also appeared as a way to significantly reduce disease risk. Extra virgin olive oil is a rich source of flavonoids.
An animal study examined the effect of green tea polyphenols on measures of inflammation after exercise. Rats that received tea polyphenols were able to stay active longer than rats that did not receive the polyphenols. They also had significantly lower levels of chemicals in their blood that signal inflammation and muscle damage. Lignans are a class of polyphenols found at their highest levels in extra-virgin olive oil, flaxseed, and whole-grain rye flour. One way to study lignan uptake is to look at lignan levels in the urine. In a study of adults in the United States, researchers found that higher levels of lignans in the urine were associated with lower levels of a measure of inflammation. This may be important, as long-term inflammation has been associated with certain diseases such as heart disease and cancer.
He studied the polyphenols in extra-virgin olive oil and its effect on risk factors for heart disease. They found that extra virgin olive oil significantly reduced LDL or “bad” cholesterol and raised HDL or “good” cholesterol.
Polyphenol intake may also play a role in the regulation of body weight. One study compared the intake of flavonoids, a class of polyphenols, with body mass index (BMI) and waist circumference. Researchers found that a higher intake of flavonoids was associated with lower BMI and waist circumference. These results are important because obesity is associated with a higher risk for many chronic diseases.