The European Food Safety Authority (EFSA) last month approved the claim that “consumption of olive oil polyphenols contributes to the protection of blood lipids from oxidative damage.”

Here we speak to the leader of the research team whose investigation of EVOO’s health benefits was pivotal to the approval.

Dr. María-Isabel Covas is head of the Cardiovascular Risk and Nutrition Research Group at the IMIM-Research Institute, Hospital del Mar in Barcelona, Spain. She is also head investigator of the CIBER of Obesity and Nutrition (CIBEROBN) a Network of Research Groups of Excellence in Spain. Last week she won an inaugural Catalan olive oil DOPs prize in recognition of her outstanding research.

Dr. Covas explains why lipid oxidation matters and that the key to benefiting from EVOO is not to take it as a medicine. “You must enjoy it.”

Please tell us about the research that led to the EFSA approval.

Our research started about twelve years ago and focuses on the health benefits of olive oil, in particular the effects of its polyphenols on the heart. Until 2004, it had been known that olive oil was good for you but there was a controversy over the in vivo antioxidant power (in humans) of the polyphenols.

We started several studies with Catalan olive oil and our hypotheses were successful but we needed full proof, because in this area of science, for a health professional to be able to say, “take this, it is good for you,” you need evidence from randomized and controlled studies with humans. You also need to be very accurate when you determine the average daily dose necessary to get sufficient quantities of polyphenols, because the effect will be not a pharmacological one but physiological.

We therefore held an initial trial with Catalan olive oil involving about 30 healthy individuals here in Catalonia. We also did another study here with 38 people with stable coronary heart disease. Then, in order to have definitive clinical proof, we organized a European study, the EUROLIVE Study, encompassing 200 healthy individuals from five European Countries. They consumed 25ml/day of three types of olive oil that were similar but different in polyphenol content.

What were the results of these studies?

We were able to prove that there was an increase in levels of high density lipoprotein (HDL), the good cholesterol, and that this was directly proportional to the olive oil polyphenol content. There was also a proven decrease in lipid oxidation, one of the main risk factors for cardiovascular disease, and this risk was shown to be inversely related to the polyphenol content of the olive oil.

All this work paid off on April 8 when EFSA concluded that a cause and effect relationship had been established between the consumption of olive oil polyphenols and protection of low density lipoprotein (LDL- the “bad” cholesterol) particles from oxidative damage, and that this was a beneficial physiological effect. This was mainly based on our study and we were really happy about it.

How much EVOO must we consume each day to benefit from this antioxidant effect?

EFSA says that 5mg of hydroxytyrosol and its derivatives (e.g. oleuropein complex and tyrosol) in olive oil should be consumed daily.

That means taking 25ml/day of a virgin olive oil that contains 300mg/kg of polyphenols, or 30ml/day of a virgin olive oil containing 200mg/kg of polyphenols. (Virgin olive oils have an average concentration of around 250mg/kg of phenolic compounds.)

These amounts, if provided by moderate amounts of olive oil, can easily be consumed in the context of a balanced diet. However, the concentrations in some olive oils may be too low to provide a sufficient amount of polyphenols while still maintaining a balanced diet.

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