Slick Extra Virgin

In 2003 something really exciting happened to the world of extra virgin olive oil (EVOO) –but most people missed it. It was buried within a Dutch research paper which tentatively reported the sensory properties of the different types of polyphenols found in EVOO. For years we knew that the total amount of polyphenols in an EVOO strongly correlated with its combined level of bitterness and pepperyness – EVOO’s high in polyphenols were almost always really bitter and/or peppery and vice versa. But there are dozens of different types of polyphenols in EVOO, but with the exception of a couple of them, no one knew what each of the individual types contributed to the overall taste of EVOO.

It was really clever work. The researchers got a bitter and peppery EVOO and extracted the total pool of polyphenols from it. They then pumped this extract through a bed of sticky material specifically designed to grab phenolics. They then removed each of the different phenolics off the bed one by one by washing using stronger and stronger solvents. After the solvents were removed, the different phenolic fractions were tasted and described by a trained taste panel.

They were tasted one by one… the first bitter, the second bitter, then very bitter, a little astringent, ….. peppery as hell…., bitter, bitter… Hang on a minute, go back!… peppery as hell!  A lot of EVOO’s are peppery and throat catching but until that time no one knew what caused it. Here was the first clue.

The phenolic was tentatively identified as deacetoxy-ligstroside aglycone or p-HPEA-EDA, later to be given the more digestible name, “oleocanthal”. The name derives from the latin oleo=olive, “canth”=sting – referring to the peppery throat catching sensation that it causes, and “al” from the fact that the phenolic was in the aldehyde chemical group.

The find was really exciting. While the Mediterranean diet has long been lauded for its healthfulness, I always thought that there was something special about it that we didn’t know. Similar dietary patterns containing lots of monounsaturated fats and polyphenols didn’t seem to confer the same benefits. ‘That’ peppery sensation was unique to EVOO (and by definition to the Mediterranean diet). So I always felt that it was an important marker of the healthy Mediterranean diet (so much so that I tried to find it in myself while working for the University of Adelaide in 2000, but my scientific hunch as to what it might have been was a little astray).

The potential importance of oleocanthal became immediately apparent. Firstly, many EVOO’s were found to have lots and lots of it. Almost every other week some new phenolic is discovered in some food or other. However in most cases, only miniscule amounts of the stuff is found – a few parts per billion here or there. Oleocanthal was different. A survey of over 250 Italian EVOO’s showed that the average amount of oleocanthal in EVOO wes around 100 milligrams per litre (1/10^th of a gram per litre). Ok the oils were Italian, but there is no reason to believe that EVOO’s from other places are any different. EVOO’s from elsewhere were found to contain up to 300 mg/kg (1/3 of a gram per litre) of oleocanthal. This might not sound much, but take it from me, that’s an absolute mozza for a single phenolic in any food. It is the second most abundant phenolic in EVOO and contributes up to around 35% of their total polyphenol content.

One of the first things that scientists noticed was oleocanthal’s similarity to the anti-inflammatory painkiller Ibuprofen. Not surprisingly, Ibuprofen is also a pretty pungent number. In fact its rather unpleasant ‘taste’ tipped off the scientists to look into the similarities between the two.  Their studies on oleocanthal showed that, like Ibuprofen, it too was a powerful anti-inflammatory. So what does this mean? One of the preliminary steps to coronary heart disease is the inflammation of artery walls following blood macrophages attacking oxidised LDL’s. Anti-inflammatories block this all important step to coronary heart disease.

Later work showed that oleocanthal is also one of the most powerful antioxidants in EVOO, making others like the much lauded hydroxytyrosol look pretty lightweight in comparison. Antioxidants such as polyphenols hitchhike on the nasty LDL’s, which increases its resistance to oxidation, which in turn reduces the havoc the LDL can cause on our cardiovascular system. Recently, oleocanthal was also reported to be extremely effective in reducing the oxidative stresses on red blood cells. A fortnight go, it was reported that oleocanthal suppresses the formation of certain proteins which are thought to coat neuronal connections resulting in Alzheimers and other degenerative neural disorders. So health wise, oleocanthal is ticking all the right boxes. I seriously doubt that we have heard the end of it either.

Luckily, oleocanthal is also pretty resistant to degradation by heating, although there is some suggestion that it loses some of its protective abilities after being heated. Logically, this suggests that oleocanthal works in combination with other antioxidants s in protecting us. However this possibility has not been explored to date. It also resists degradation during storage. While all polyphenols decline in the oil over time, oleocanthal holds on better than most, particularly when stored in cool conditions.

Great news on lots of fronts:

It’s easy to get – eat EXTRA VIRGIN olive oil. NO OTHER food has it. (Note that refined olive oils such as “pure”, “light” and “olive oil” do not contain oleocanthal.  It, like other phenolics, is removed during the refining process).

Easy to get lots of it – Use peppery extra virgin olive oil. It’s super rich in the stuff.

So how can you tell which EVOO’s have lots of oleocanthal? Well you won’t find it on back labels any time soon. The method used to analyse the amount of oleocanthal is not in widespread use, primarily because the pure standard of oleocanthal which chemists need to positively identify it (and quantify how much there is) isn’t widely available. But if the EVOO you are using is nice and peppery then almost certainly you are getting a liberal dose of oleocanthal in your everyday diet.

Just a personal opinion, but I believe that oleocanthal will be known as one of the most important anti-oxidants and anti-inflamatories in the western diet. Watch this space. There is a lot more to the oleocanthal story which is yet to unfold.

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