How to Find the Healthiest Real Olive Oil – Caveat Emptor

olive oil

Leonardo had spent all afternoon picking ripe olives from the hillside overlooking San Lorenzo Bellizzi along the northern border of Calabria. He now found himself helping his father loading the freshly picked fruit below his stone mill grinding wheel, crushing the olives into a thick, pulpy paste. While Leonardo noticed some frigid air this morning, things had warmed up significantly, even though he was high in the mountains. He may not have realized it, but he was “cold pressing” his olives as the temperature was under 27° Celsius, or 87° Fahrenheit. He was also producing an olive oil that was “first pressed,” as the olives were crushed and pressed only one time to make his delicious oil. These phrases were not present for Leonardo, as this method of making olive oil was a time-honored tradition, the only way he knew to make olive oil.

He then took the pulp and lathered it onto several mats, placing one on top of the other, creating a sandwich-like configuration. He placed a heavy stone atop the stock which, pushing down on the stack under its weight, squeezed the thick cloudy golden liquid olive oil into a vat below. The aromatic oil would eventually drain into a bottle. Leonardo and his family were left with a dense, golden, delicious olive oil.

While this scene may have played out over 125 years ago, few would argue the health benefits of olive oil nowadays. This nectar of the gods has been produced from olives around the Mediterranean basin since Neolithic times. Besides its previous use as soap, a fuel for oil lamps (known as lampante – remember this term), or a method for my uncle to avoid alopecia (apparently, all you need is a drop a day massaged into your scalp for life to keep a mop-like head of hair), olive oil has been a staple of the Mediterranean diet for thousands of years, and is certainly a staple in a low-carbohydrate or Mediterranean Ketogenic Lifestyle.

olive oil

San Lorenzo Bellizzi is one of many picturesque Italian villages clinging to the mountains, surrounded by olive trees

Athena, the Greek goddess from whom Athens is named, beat Poseidon in a competition by creating the olive tree and leaving it to produce the staple of the Mediterranean diet. The olive is beyond a health wonder, it is at times mythical and even god-like. At night, when I bathe in a vat of freshly made olive oil, I can always feel a mystical sensation throughout my body. I am kidding of course, though I would not be surprised if some biohackers over in Silicon Valley actually do this (and no, I am not judging).

From Athena’s victory, to the scenic beauty olive trees provide as they are dotted throughout the Italian countryside, to olive oil’s pleasant and complex taste allowing it to provide a delicious accompaniment to a plate of vegetables, there are likely other reasons that it has withstood the test of time.

The olive tree apparently spread from Iran to the Mediterranean some 6,000 years ago. If you ever have the opportunity to visit an area where olives are grown, I would strongly recommend it. These beautiful plants and the fruit they produce are a natural wonder. I may be biased, as my family is from an area surrounded by thousands of acres of olive groves, with the trees scattered throughout my great-grandfathers’ home town.

In other words, olive oil has appropriately been famous for thousands of years. Greek athletes even used to rub it over their rippling muscles and apparently naked bodies prior to sporting events, though nobody seems to know the truth (rumor has it one tripped over a loincloth, so decided to opt for an Old-School streaking through the squad run instead).

Olive Oil – Chemistry 101

Some knowledge of the chemistry of olive oil is necessary to understand its relationship to a healthy diet. Olive oil is nearly 100% fat. Around 70-80% of the fat in olive oil is the monounsaturated fat known as oleic acid, which is an anti-inflammatory fat that has taken the lion’s share of fame for olive oil’s health benefits (shhhh, don’t tell any of the anti-meat zealots, but bacon is nearly 50% oleic acid). Monounsaturated fats have been thought to lower the risk of heart disease based on research over the past several decades,1 and some feel as though they are a major part of the heath benefits of the Mediterranean Diet. The remaining composition of olive oil is generally about 14% polyunsaturated fat and 14% saturated fat (many nutrition “experts” are unaware of this this latter fact). For a review on the chemical structures of fats, refer back to my very old article on oils and fats from 2012 (and yes, the chemistry has not changed). Oleic acid, which is an omega-9 fatty acid, is less susceptible to oxidation than the polyunsaturated fats in most vegetable oils, providing olive oil enhanced protection from free radical damage. The percentage of oleic acid in olive oil varies by olive type and growing conditions. For instance, olives grown in cooler climates may produce higher amounts of oleic acid.

olive oil

A monounsaturated fat has only one double bond with two exposed areas fro free radicals to attack.

Besides the chemical structure of the fatty makeup of olive oil, an important, but often forgotten component of olive oil is the massive amount of phenolic chemicals that it contains. Much like in bold, red wines, phenols have a large effect on the taste and fragrance of olive oil. These chemicals, produced by the olive tree, work to aid in survival of the plant, and are synthesized in response to environmental encounters. These include:

  1. Defense against bacterial threats (i.e. phenols have antibiotic and antifungal properties).
  2. Defense against potential predators (i.e. phenols, like those in wasabi, can give off a pungent scent or taste to keep animals from eating them)
  3. Sun defense (i.e. like tanned skin, pigmented polyphenols can provide color to offset ultraviolet damage from the sun)

The phenolic chemicals include flavonoids and lignans, but the major phenols are oleuropein, hydroxytyrosol and tyrosol.2 Much like sulfur and many of the chemicals in other herbs, spices, vegetables, dark chocolate, and fruits, many of these phenolic chemicals that are literally squeezed from the olive fruit into olive oil contain a plethora of health benefits. These chemicals may be foul tasting or fatal to bacteria and insects, but when we consume them, they instead signal important messages to our cells. For instance, these chemicals “stress” our cells, which forces them to sound a cellular alarm known as nrf-2, which engages the immune system troops, activates our detoxification system to detoxify the body of harmful chemicals, and engages our cellular machinery to increase antioxidant production to rid the body of free radicals. In other words, they are likely not antioxidants, as previously thought, but rather signaling molecules that instruct our cells to produce their own antioxidants, which is likely more beneficial than consuming antioxidants alone.3,4

The names of the exact polyphenols are less important, but keep in mind that these chemicals work similarly to other plant defense chemicals to increase our cellular production of antioxidants and to disarm and reduce free radicals within our body. For instance, individuals randomized to a daily high phenol extra virgin olive oil experience 30% less oxidative damage to their DNA.5 These chemicals also provide antioxidant protection for the oil to help ward off oxidative damage when exposed to oxygen and free radicals, helping to keep it structurally sound as it sits in the bottle awaiting to be eaten. Many of these volatile chemicals impart their different flavors in the olive oil we eat, and high heat can destroy these compounds. Using a variety of olives at their appropriate maturity also provides the oil with a plethora of phenolic chemicals.


So how do we know we are getting the real thing?

olive oil

Tucked in the heel of Italy, olive trees with phenol-rich fruit span as far as the eye can see in Puglia

The following factors can ensure we are consuming the purest and healthiest olive oil available:

Extra Virgin Olive Oil (EVOO):

For a great primer on the amazing and controversial history of olive oil and the many attempts to adulterate it, check out Tom Mueller’s fascinating book Extra Virginity: The Sublime and Scandalous World of Olive Oil. Always buy oil that is labeled extra virgin olive oil. Real olive oil has always been produced by crushing olives and extracting the oil without the use of damaging chemicals like solvents or by adding excessive heat to bleed out any extra oil (damaging the oil in the process). Real olive oil is deliciously bitter and peppery, with some astringency and the aroma of fruit. EVOO is produced in ways that respect these naturally delicious and healthy aspects of olive oil by avoiding the usage of harsh chemicals or the additional of other lesser quality oils to adulterate its legitimacy. A tasteless oil is not quality olive oil, even though many consumers are actually accustomed to this flavorless profile because they have – unbeknownst to them – been using fake olive oil for so long.

While the label extra virgin olive oil does not guarantee that it is not fake, it is a good starting point.

Early Harvest Olive Oil:

Olives that are picked early in the harvest are greener and higher in polyphenols. While they may have less oil, this oil is imparted with a more bitter and astringent taste from more polyphenols. Because of the higher polyphenols and antioxidants, early harvest oils often have a longer shelf life and are blended with late harvest oils to improve their shelf life.

One such chemical in olive oil, known as oleocanthal, causes a burning sensation in the back of the throat. If you have yet to experience this sensation, try drinking a good amount of some high-quality olive oil and you will know what I am referring to. This sensation is so typical of olive oil, that researcher Gary Beauchamp of the Monell Chemical Senses Center got déjà vu when he first experienced it. The burn reminded him of a similar sensation that he experienced while chewing ibuprofen during a sensory research experiment. While tasting some olive oil at a gastronomy conference in Sicily, he experienced the same burn, and the sensation had motivated him to later isolate the chemical responsible. Oleocanthal is the same chemical in the anti-inflammatory drug ibuprofen, and Beauchamp would publish his findings in Nature. This same chemical, unsurprisingly, appears to be responsible for the anti-inflammatory actions of olive oil.6

Olive Oil Marketing:

We live in a time of marketing, and olive oil has been one of the foods hardest struck with marketing schemes to help promote sales. For instance, lite olive oil (described in more detail below) is labeled as such to make it sound like a diet product, when in reality it guarantees that the oil is refined, which removes nearly all the health benefits and leaves us with a damaged and potentially harmful oil. Check out my previous post on this back in 2012 or a more extensive discussion in Misguided Medicine that describes these issues at length. This oil is referred to as lampante, because it is only fit for burning in a lamp and never for consuming.

Fancy bottles are meaningless when it comes to quality, and many contain meaningless labeling. These terms include natural, all-natural, pure, from Italy (could have only been bottled there), and even cold pressed. While heating the paste or using chemicals during milling and extraction of the oil can damage or remove many of the beneficial and flavorful chemicals in olive oil, all genuine extra virgin olive oils are cold pressed. However, not all cold pressed olive oils are extra virgin, and this is where the trickery can begin. Thus, labeling this on bottles is generally meaningless and can even be deceitfully confusing to the consumer.

Refined and Lite Olive Oil:

Avoid any oil that is refined. The process of refining is used to remove impurities and defects from rancid or poor sources of oil to make it taste more palatable. This obviously removes all the healthful aspects of olive oil, while masking the fact that it is a spoiled, rancid, and oxidized oil. Olive oil which is old, rancid, made from diseased olives, or has some other defect can be made palatable by refining. This is done by filtering, heating, applying charcoal, or chemical treatment to adjust acidity. Refined oils are low in tyrosol and other phenols. These oils are often deodorized to remove foul smelling impurities.

This oil is often labeled “lite” olive oil. Lite has nothing to do with the number of calories or density of the olive oil, but rather that it is lite on flavor and the components that make olive oil, olive oil. And like anything labeled lite or diet, avoid it like the plague. Sometimes, the phrase “pure” is used as well for similar inferior quality oil.

Finally, these oils are often blended in with higher quality oils in most commonly available supermarket oils. Even worse, oftentimes harmful vegetable oils are blended in with olive oil, leaving an adulterated oil that is nothing like healthy extra virgin olive oil.

Olive Oil Date Harvested:

Olive oil, like all oils, becomes oxidized over time as free radicals attack their carbon backbone and leave them rancid. In other words, at that point you are no longer consuming an anti-inflammatory, healthy, and omega-3 and polyphenol-rich liquid, but rather a rancid, free-radical laden oil.

Therefore, you want the freshest and most recent olive oil. If no date harvested is listed, do not buy or consume this oil – a date harvested is absolutely required. This does not include the typical best by or bottled on, as these dates add no value. An oil could have been harvested years ago, sat in a vat, and was bottled recently.

Along those lines, use your olive oil as quickly as possible and avoid buying massive bottles that will sit on your shelf for months, as the oil will quickly oxidize. While olive oil can oxidize if it sits in a sealed bottle for too long, the same issue will occur much more rapidly once it is opened. Many recommend using the olive oil in several months, but I personally like to finish it off in a couple weeks (yes, I use a lot of olive oil).

Large and cheap bottles of olive oil that are too good to be true are likely too good to be true and are commonly filled with fake or rancid oil. The process of olive oil is generally not cheap or easy (recall Leonardo’s technique in the beginning of this article). If it is being sold by the gallon for dollars, you are likely paying for cheaper, low quality, and even harmful vegetable oil.

Olive Oil Shelf Life/Container:

Stick with dark glass containers of olive oil. Dark glass filters out harmful UV rays that can promote oxidation and destruction of the oil. Glass imparts less chemicals into the oil than plastic, can be recycled, and is much less annoying than annoying plastic. Metal containers provide protection of the oil, but are often coated with chemicals, so I generally avoid.

Olive oils with large amounts of phenols are most resistant to damage by oxidation, providing even more impetus to buy good quality,7 phenol-rich olive oil (keep in mind that refined oils have the phenols removed).

Storing at colder temperatures appears to improve shelf life (for example 50° F may be better than 60° F).8 The best way to test shelf life remains controversial. Sources vary, with some stating unopened and well-sealed olive oil containers, if stored in a cool, dark place, can stay for 3-4 years, while most recommend 1-2 years tops. Other studies have shown that by 12 months phenol content can begin to decrease.9 It seems most reasonable to top it off at six months if you need to store it. The concern, of course, is that we have no clue how long the olive oil was stored prior to purchasing it, again emphasizing the importance of a harvest date. Along these lines, I would strongly recommend using your olive oil immediately and avoid stocking up on it.

Once opened, quickly using the oil is the prudent strategy. Opening the bottle introduces air to the oil and increases oxygen contact, especially as the level of oil decreases with usage, increasing oxidation.10 Oxygen in air attacks the molecular structure of the fat in olive oil creating peroxide. For those of you aging olive oil (you know who you are), congratulations as you likely just turned your once delicious olive oil into lampante. By all means, if you do happen to obtain a special, small-batch EVOO, and feel like you should moderate its use, don’t. You’ll lose the value, taste, and health benefits associated with it. Instead, find different recipes to use it in, or dab a dot in your scalp! Keep the aging for your fancy wines.

Olive Oil Taste – Savor the Burn:

Real olive oil contains many chemicals that provide it with an array of flavors and aromas, beyond the chemical that causes that typical burn in the back of your throat. Fruity flavors and perfume aromas are common, intermixed with nutty and bitter flavors. Real olive oil is not thick or greasy, while fake olive oil has a greasy texture on the palate, which is actually a reason why I used to dislike olive oil, not realizing I was tasting the fake stuff. Real olive oil has a crisp taste that does not leave a greasy or unpleasant residue on the palate. Avoid olive oil that is bland, a characteristic of a refined oil, or has a metallic or musty flavor, or tastes like burnt bacon or stale nuts, which may indicate oxidation.

Olive Oil Certifications:

International Olive Oil Council (IOOC):

Formed at the International Agreement on Olive Oil in Geneva in 1955, the IOOC tests and classifies olive oils. This includes:

  1. Extra virgin olive oil (free acidity, expressed as oleic acid, is at most 0.8 grams per 100 grams)
  2. Virgin olive oil (free acidity, expressed as oleic acid, is at most 2 grams per 100 grams),
  3. Ordinary virgin olive oil (free acidity, expressed as oleic acid, is at most 3.3 grams per 100 grams).

Anything over 3.3 grams free acidity per 100 grams is categorized as lampante and is not fit for human consumption. Olive oil obtained from refining virgin olive oil to reduce its free acidity is characterized as refined olive oil and should be avoided. A blend of refined olive oil and virgin olive oil is characterized as olive oil (yes, this is confusing, so just go for extra virgin olive oil always). Olive pomace oil is made from olive pomace treated with harmful chemicals and solvents. Every time this happens, the spirit of Leonardo cries.

The California Olive Oil Council (COOC):

The COOC is the United States’ version of the IOOC. They test domestic olive oils, providing grading and certification. COOC certification of extra virgin olive oil takes into account sensory testing, along with chemical testing for impurities. The testing is extremely strict and is considered some of the firmest in the world. Check out their list of certified oils in 2017.

Protected Designation of Origin (PDO):

The European Union’s PDO designation deals with the production and manufacture of the olive oil. It certifies “the name of an area, a specific place or, in exceptional cases, the name of a country, used as a designation for an agricultural product or a foodstuff, which comes from such an area, place or country, whose quality or properties are significantly or exclusively determined by the geographical environment, including natural and human factors, whose production, processing and preparation takes place within the determined geographical area.” Protected geographical indication is similar.

Italy’s Indicazione Geografica Protetta (IGP – Indication of Geographic Protection):

Wine, cheese, olive oil, and other foods with an IGP label links the quality of the item to the region of production and processing. This is less strict than DOP, as it follows foods from their geographic production, but focuses on only one step of production.

Denominazione d’Origine Protetta (DOP – Protected Designation of Origin):

Foods labeled with DOP guarantee that they are grown, produced, processed, and packaged via regulated steps in a specific geographical area according to the local tradition. The Spanish Designation of Original (DO) is similar.

Olive Oil – The Ultimate Caveat Emptor:

Like all aspects of our life and health, we must take a proactive stance and follow an Intentional Lifestyle. Caveat Emptor may be an old term, but it has never been more appropriate than recently, when companies espouse the health benefits of everything from low-fat cookies, to oxidized vegetable oil. The spread of olive oil, and the potential to profit off our naivete, makes becoming a knowledgeable consumer vital. As with all healthy foods and activities, there are no easy ways out, and even that healthy olive oil you are using may not be so healthy (and may not even be olive oil). An educated consumer is a smart consumer, applying an approach of “Buyer Beware”, and this is clearly a necessity with olive oil. Follow the rules I discussed above to find the healthiest, most delicious olive oil that is 100% real olive oil.





Olive Oil References:

  1. Kris-Etherton, P. M. Monounsaturated Fatty Acids and Risk of Cardiovascular Disease. Circulation 100, 1253–1258 (1999).
  2. Tuck, K. L. & Hayball, P. J. Major phenolic compounds in olive oil: metabolism and health effects. J. Nutr. Biochem. 13, 636–644 (2002).
  3. Ristow, M. & Schmeisser, S. Extending life span by increasing oxidative stress. Free Radic. Biol. Med. 51, 327–336 (2011).
  4. McCaslin, T. Free radicals are not your enemy | An interview with Dr. Michael Ristow (part i). Geroscience (2018). Available at: http://geroscience.com/free-radicals-are-not-your-enemy-an-interview-with-dr-michael-ristow-part-i/. (Accessed: 8th February 2018)
  5. Salvini, S. et al. Daily consumption of a high-phenol extra-virgin olive oil reduces oxidative DNA damage in postmenopausal women. Br. J. Nutr. 95, 742–51 (2006).
  6. Beauchamp, G. K. et al. Ibuprofen-like activity in extra-virgin olive oil. Nature 437, 45–46 (2005).
  7. Velasco, J. & Dobarganes, C. Oxidative stability of virgin olive oil. Eur. J. Lipid Sci. Technol. 104, 661–676 (2002).
  8. Li, X. & Wang, S. C. Shelf Life of Extra Virgin Olive Oil and Its Prediction Models. J. Food Qual. 2018, 1–15 (2018).
  9. Morelló, J.-R., Motilva, M.-J., Tovar, M.-J. & Romero, M.-P. Changes in commercial virgin olive oil (cv Arbequina) during storage, with special emphasis on the phenolic fraction. Food Chem. 85, 357–364 (2004).
  10. Kanavouras, A., Cert, A. & Hernandez, R. J. Oxidation of Olive Oil under Still Air. (2005). doi:10.1177/1082013205055001

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