The Polyphenol Story
What is a Polyphenol?
Polyphenols are found in all plants to varying degrees. They are nutrients that plants produce to defend themselves against ultraviolet radiation, stress, insects and diseases. They act as natural antioxidants and anti-inflammatories. You could say a bit like a natural Ibuprofen.
Different plants have vastly different concentrations of polyphenols – some are unique to certain plants, others are present in all plants. The highest naturally occurring levels of polyphenols are found in dark berries like blueberries or blackcurrants, red onions, olives, chestnuts, wholegrains and drinks like green tea, coffee and cocoa.
They are mostly concentrated in the outer layers of the plant in the bark or leaf tissue and in the skin or peel of fruits and vegetables.
What’s good about them?
Polyphenols are highly beneficial to us as humans They act as powerful antioxidants and anti-inflammatories. Research links them to a lower risk of chronic conditions, including heart disease, type 2 diabetes, certain cancers, and cognitive decline.
What are the Main Benefits?
· Heart Health: They help regulate blood pressure, improve blood circulation, and prevent the build up of plaque in arteries.
· Brain Function: Polyphenols can boost memory, protect against neurodegenerative diseases, and help prevent mental fatigue.
· Gut Health: They act as prebiotics, feeding the beneficial bacteria in your digestive tract and strengthening your gut barrier.
· Metabolic Health: They aid in blood sugar regulation and are linked to a reduced risk of insulin resistance and type 2 diabetes.
What About Polyphenols in Olive Oil?
In Extra Virgin Olive Oil (EVOO), they are responsible for its bitter, peppery taste and are the scientifically backed force behind its heart-healthy properties. All olive oils have a certain level of polyphenols with the most found in Extra Virgin Olive Oil. The main ones are Oleocanthal (this is the one that acts like a natural anti-inflammatory similar to Ibuprofen), Oleuropein, Hydroxytyrosol, and Tyrosol.
Generally speaking, the more fruity, bitter and peppery an oil, the more polyphenols it is likely to contain. If you want a specific number to benchmark against, to qualify for any official health claim and olive must be shown to contain at least 250mg of polyphenols per kilogram of oil. Some varieties of olive naturally have higher levels of polyphenols: Koroneiki (common in Greece), Picual (Spain), Coratina (Italy) being some of them.
Likewise, early harvest Extra Virgin Olive Oils have higher concentrations and truly exceptional examples can be as high as 1,000 – 2,000mg/kg of oil. However, the higher the concentration, the more rapidly they decline so an Early Harvest Oil may have as much as 2000mg immediately after pressing but after 2 months or so this is likely to have reduced by as much as 40% and after 6 months or so this will have likely fallen further to less than the 250mg benchmark.
Which is the Most Important Polyphenol in Olive Oil?
Oleuropein is, in our view, the most important polyphenol of them all. It is found in olive leaves and olive oil. It has a number of potential health benefits, including:
- Antioxidant activity: Oleuropein is a powerful antioxidant, which means it can help protect cells from damage caused by free radicals. Free radicals are unstable molecules that can damage cells and contribute to the development of chronic diseases such as heart disease, cancer, and Alzheimer's disease.
- Anti-inflammatory activity: Oleuropein has anti-inflammatory properties, which can help reduce inflammation throughout the body. Inflammation is a major factor in many chronic diseases, such as arthritis, asthma, and heart disease.
- Blood pressure-lowering effects: Oleuropein has been shown to lower blood pressure in both animals and humans. This is likely due to its antioxidant and anti-inflammatory properties.
- Antibacterial and antiviral activity: Oleuropein has antibacterial and antiviral activity, which can help fight infections.
- Anticancer activity: Oleuropein has been shown to have anticancer activity in both animals and humans. It may help to kill cancer cells or prevent them from growing.
- Neuroprotective activity: Oleuropein has neuroprotective activity, which means it can help protect the brain from damage. This may be beneficial for people with conditions such as Alzheimer's disease and Parkinson's disease.
More research is needed to confirm the health benefits of oleuropein. However, the available evidence suggests that it may be a beneficial compound for human health.
Here are some ways to get more oleuropein in your diet:
- Use Extra Virgin Olive Oil: Whether or not it is sold expensively as High in Polyphenols, all decent Extra Virgin Olive Oil is a good source of oleuropein, and it is also a healthy fat that can be used in cooking. Just make sure it’s in dark glass, tins or pouches to protect it from the light and air. So much the better if it’s early harvest and you consume it shortly after the harvest!
- Eat olives. Olives are a good source of oleuropein, and they can be eaten on their own or added to salads, sandwiches, and other dishes.
We used many sources to compile this brief – the two most interesting and useful are referenced below – we don’t just make this stuff up!
Sources:
National Library of Medicine: Systemic Health Effects of Oleuropein and Hydroxytyrosol Supplementation: A Systematic Review of Randomized Controlled Trials
Frumuzachi O, Gavrilaș LI, Vodnar DC, Rohn S, Mocan A. Systemic Health Effects of Oleuropein and Hydroxytyrosol Supplementation: A Systematic Review of Randomized Controlled Trials. Antioxidants (Basel). 2024 Aug 27;13(9):1040. doi: 10.3390/antiox13091040. PMID: 39334699; PMCID: PMC11428715.
Cambridge University Press: Can rapeseed oil replace olive oil as part of a Mediterranean-style diet?
Hoffman R, Gerber M. Can rapeseed oil replace olive oil as part of a Mediterranean-style diet? British Journal of Nutrition. 2014;112(11):1882-1895. doi:10.1017/S0007114514002888
Which concludes: based on current evidence, RO cannot be recommended as equivalent in terms of health benefits compared with EVOO.