All about polyphenols and antioxidants in olive oil

Olive oil experts often talk about polyphenols and antioxidants in relation to the potential health benefits of extra virgin olive oil. It is so important to understand the difference between a polyphenol and an antioxidant, and the role they play in our health.

Summary

Antioxidants are molecules that protect our bodies from damage caused by free radicals. Polyphenols are a type of antioxidant found in abundance in extra virgin olive oil.
Oxidation and the importance of antioxidants
Many of the fruits and vegetables we consume contain a large number of compounds that are critical to health. One such type of compound is known as antioxidants. Why are antioxidants so important for our health? To understand this better, you first need to understand and appreciate how our bodies produce energy from the process of oxidation.

Oxidation is a natural process that our cells use to create energy from the oxygen we inhale. When energy is produced in our cells, some oxygen molecules (known as free radicals or reactive oxygen species) are produced as a by-product of these processes. These free radicals can damage your cells and DNA when present in high concentrations.

Continuous damage from free radicals, often called oxidative stress, can lead to various conditions, including:

Various forms of cancer
Cardiovascular disease
Diabetes
Osteoporosis
Alzheimer's disease
Dementia
Age-related wrinkles

Unfortunately, the production of these harmful chemicals is sometimes increased by the environment we live in. Several lifestyle, stress and environmental factors that have been shown to increase the production of free radicals include (but are not limited to):

Cigarette smoke
Alcohol consumption
High blood sugar levels
Air pollution
High intake of polyunsaturated fat
Excessive exposure to ultraviolet radiation
Various bacterial or viral infections
Antioxidant deficiency

So how do antioxidants fit into the grand scheme of our bodies and our health?

Antioxidants are chemicals known as "molecular scavengers" that help neutralise free radicals and thus prevent oxidative stress from occurring. There are hundreds of known antioxidants, some of which we eat in our daily diets:

Vitamin A
Vitamin C
Vitamin E
Selenium
Manganese
Carotenoids
And POLYPHENOLS!

What is a polyphenol, and how is it related to antioxidants?
Polyphenols are a type of antioxidant produced by plants, typically as a defence against ultraviolet radiation or foreign pathogens that may threaten the plant's overall health. Polyphenols also provide our senses with the bitterness, smell, colour and flavour we perceive when we eat specific food types, especially fruits and vegetables. (2)
Polyphenols are of great interest to researchers and nutritionists both for their antioxidant functions and for the prevention of various diseases. The field of polyphenol research, and specifically the mechanism of their antioxidant functions, is still a very fruitful area of scientific research. One type of polyphenol of interest for this particular discussion is olive polyphenols.

Polyphenols in olive oils

Olive oil, an oil known to be rich in monounsaturated fats and polyphenols, is a key component of many diets (including the Mediterranean diet). In extra virgin olive oils, most antioxidants and polyphenols are present, and depending on the amount of polyphenols, it can affect the flavour of the olive oil. Due to its higher concentration of polyphenols, extra virgin olive oil is more flavourful than ordinary olive oil. (3) The polyphenol content in olives can be affected by a range of factors that include:

Climate where grown (related to altitude, rainfall and irrigation levels)
The ripening stage of the fruit
Fruit yield per tree
Extraction conditions for polyphenols
Time spent in storage and storage conditions

While there are many types of olive polyphenols, much of the research to this point has focused on three types:

Hydroxytyrosol, a phenolic compound found in olive oil, has been identified as one of the most powerful antioxidants found in olive oil and may help reduce the risk of developing type 2 diabetes. (1)
Oleuropein, another antioxidant polyphenol found in olive oil, has also been shown to be quite effective at eliminating various bacteria and viruses that infect humans. (1)
It is suggested that Oleocanthal has anti-inflammatory and antioxidant effects similar to the actions of ibuprofen, and may therefore help reduce the severity of several chronic inflammatory diseases. (4)
Earlier studies have also demonstrated that these polyphenols from extra virgin olive oils (and not sunflower oil) protect against coronary heart disease by preventing oxidation of the cholesterol-carrying molecule known as low-density lipoprotein. (5)

What happens to polyphenols when we cook?

When cooking with extra virgin olive oil, various culinary methods can reduce the amount of polyphenols in vegetables (including potatoes, aubergines, tomatoes and pumpkin). Most of this loss is due more to the temperature to which the extra virgin olive oil is cooked than to the time spent cooking. (6) Fortunately, not all polyphenols and their antioxidant functions are lost. Studies have shown that these polyphenols typically migrate from the olive oil into vegetables that are cooked efficiently; it is recommended that olive oil be added to all vegetables as part of your meal preparation in order to achieve a diet rich in polyphenols. (8) It is also important to note that, although some mistakenly believe you should not cook with extra virgin olive oil, it has been shown to be one of the most stable cooking oils. (7)

Conclusion

The benefits of consuming natural plant polyphenols have been known for a long time. Studies suggest that these polyphenols can reduce morbidity and slow the progression of several types of cancer, neurodegenerative diseases as well as cardiovascular diseases. Oleuropein, hydroxytyrosol and other polyphenol compounds are abundant in olive oil. And although some olive polyphenols may be lost in cooking, not all are - and what remains is 100% more than what you find in other cooking oils. Therefore, an increase in the consumption of olive oil and other plant products that contain an abundance of polyphenols is a wise choice for those who want to improve their overall health.

References
1. Gorzynik-Debicka, M. et. al .., Potential Health Benefits of Olive Oil and Plant Polyphenols. International Journal of Molecular Sciences. 19; (547), 2018.
2. Pandey, K.B. and Rizvi, S. I. Plant Polyphenols as Dietary Antioxidants in Human Health and Disease. Oxidative Medicine and Cellular Longevity. 2; (5), 2009.
3. Rigacci, S. and Stefani, M. Nutraceutical Properties of Olive Oil Polyphenols. A Roadmap from Cultivated Cells through Animal Models to Humans. International Journal of Molecular Sciences. 17; (6), 2016. This sentence appears to have crept in by mistake: This is because ordinary olive oil is a blend of refined olive oil and virgin olive oil. While virgin olive oils are rich in polyphenols and antioxidants, refined olive oil is not. The polyphenol content of ordinary olive oil comes entirely from the virgin olive oil in the product.
4. Parkinson, L. and Keast, R. Oleocanthal, a Phenolic Derived from Virgin Olive Oil: A Review of the Beneficial Effects on Inflammatory Disease. International Journal of Molecular Sciences. 15; (7), 2014.
5. Aguilera, C.M., et al., Sunflower oil does not protect against LDL oxidation as virgin olive oil does in patients with peripheral vascular disease. Clinical Nutrition. 23; (4), 2004.
6. Lozano-Castellon, J. et. al., Domestic Sautéing with EVOO: Change in the Phenolic Profile. Antioxidants. 9; (1), 2020.
7. Guillaume, D. and Ravetti, L. Evaluation of Chemical and Physical Changes in Different Commercial Oils during Heating. Acta Scientific Nutritional Health. 2; (6), 2018.
8. Ramirez-Anaya, J.P., et. al., Changes in the Antioxidant Properties of Extra Virgin Olive Oil after Cooking Typical Mediterranean Vegetables. Antioxidants. 8, (8). 2019.

All about polyphenols and antioxidants in olive oil