Polyphenols are organic chemicals present in many plants and fruits such as olives. Although olive oil is known for its healthier fat structure, it has been shown that the benefits of extra virgin olive oil are in fact mostly derived from the presence of polyphenols that act as antioxidants.

However, not all olive oils are created equal! If you are looking for a tasty olive with high phenolic content, here are the key things you should know.

The polyphenols in olive oil

Twenty five different polyphenols can be found in extra virgin olive oil. The most important ones are oleuropein, hydroxytyrosol and oleocanthal.

Polyphenols are most abundant in extra virgin olive oil (EVOO), but with very important variations (see below), while some polyphenols are present in virgin olive oil (1).

What are the benefits of the polyphenols in olive oil?

Polyphenols have been linked in numerous academic studies to various health benefits. One well-documented benefit is to lower the risk of heart disease by reducing blood pressure and low-density lipid (or “bad”) cholesterol '(2).

The consumption of high phenolic food also lowers blood sugar levels, which decreases the risk of type 2 diabetes (3). Among the reasons is probably that polyphenols stimulate insulin secretion, which helps move sugar from the bloodstream and deposit it in the cells. This keeps blood sugar levels stable.

Studies also suggest that polyphenols may help prevent and block the development of cancer, particularly prostate and breast cancer (4), and dementia. Researchers have found that oleocanthal regulates abnormalities in a receptor responsible for the development of Alzheimer’s disease (5).

How do I know if an olive oil has high polyphenols?

A good olive oil should have relatively high polyphenols! These compounds represent 2% or less of a fresh EVOO but are a major determinant of taste. They contribute decisively to the olive oil aromas, bitterness and pungency. An olive oil that does not smell of fresh fruit and does not give that peppery sensation is unlikely to have high polyphenols. See our quick guide for more information on how to taste olive oil.

It is considered that an EVOO has high phenolic content when it has more than 250 mg of phenolic compounds per kg, but some oils have as much as 1500 mg/kg. Most supermarket EVOOs are likely to have closer to 100 mg/kg.

So why do some EVOOs have more polyphenols than others? There are many determinants, which include:
- The olive variety: Coratina, Picual, Frantoio or Moraiolo naturally have higher polyphenols
- Climate: olives produce polyphenols to protect themselves against adverse weather conditions, so the phenolic content will vary in any particular year, all other things being equal
- Agricultural practices: organic olives tend to develop higher polyphenols as a natural protection against parasites
- The timing of the harvest: olives harvested early have more polyphenols
- Extraction process: controlling temperature and oxygen exposure during the malaxation phase is key to preserve polyphenols
- Storage: light, heat and exposure to oxygen are the enemies of polyphenols
- Age: polyphenols will decrease over time until the oil becomes rancid after 18-24 months

In other words, to choose a high-polyphenol EVOO, always make sure it is an early harvest (or “green fruitiness”) oil from a variety with high phenolic content, and that it is sold in a dark bottle. And, to the extent possible, taste it!

In our Boutique, you will find the range of expected polyphenol content for each oil based on the latest available analysis.

Notes:

(1) Virgin olive oil is an unrefined oil with slight defects of aroma and lower chemical standards compared to extra virgin

(2)  See “Polyphenol Health Effects on Cardiovascular and Neurodegenerative Disorders: A Review and Meta-Analysis” (2019) in International Journal of Molecular Sciences and ”Polyphenols and Oxidative Stress in Atherosclerosis-Related Ischemic Heart Disease and Stroke” (2017) in Journal of Oxidative Medicine and Cellular Longevity 

(3) See “Polyphenols and Glycemic Control” (2016) in Nutrients

(4) See “Anticancer Efficacy of Polyphenols and Their Combinations” (2016) in Nutrients

(5) See “Oleocanthal Nutraceuticals for Alzheimer’s Disease Amyloid Pathology: Novel Oral Formulations, Therapeutic, and Molecular Insights in 5xFAD Transgenic Mice Model” (2021) in Nutrients