Once we start to sample a variety of extra-virgin olive oils from different parts of the world, tasting them in sequence, we begin to comprehend the enormous range of flavors to be distinguished among them. These flavors are the products of volatile compounds that are released when the fruit cells are broken, either when the fruit is damaged or when it is deliberately crushed in the milling process to extract the oil. The nature of these compounds depends on many factors, but especially on the cultivar itself, as well as on the place where it was grown and the climate in which it was produced: An austere Cornicabra oil from high in the Toledo mountains south of Madrid has very different flavors, a different sensory style, from what’s in a rich Nabulsi oil from the rocky terrain of Palestine at the other end of the Mediterranean, and both are quite distinctive when measured against, say, a spicy Koroneiki oil from the volcanic soils of the island of Crete. But despite the differences, it’s the volatile compounds in all these oils that help to produce the flavors. Those same compounds will also determine whether an oil is good or bad. Sink your nose into a glass of fresh, green, premium olive oil straight from the mill and you should smell lovely aromas of freshly cut grass, of green or ripe fruit, and possibly other fragrances, such as almonds or tomatoes or artichokes or green tomato leaves or citrus or crushed thyme—all aromas that are produced by volatile compounds in the oil.
Now leave that glass of oil out next to the stove in your kitchen for a week or so, and then sink your nose into it again. The aromas will be very different, possibly quite subdued, and the color will have changed from a bright or gentle green, perhaps with golden highlights, to a hue we might describe politely as the color of pee. All this is caused by the dispersal of those earlier compounds—it’s not for nothing that they’re called volatile—and the emergence of others that come about through oxidation. If you’re lucky, the oil will smell of nothing at all, or of old straw or hay; if you’re unlucky, it may actually have begun to stink of rancidity, the main clue to oxidation. What does rancidity smell like? Open a bin of whole wheat flour that has been kept closed for several months, or a bag of walnuts or peanuts forgotten in the back of the pantry shelf—that’s the smell of rancidity. Like the flour and the nuts, the olive oil, too, should be discarded. Not only is rancidity not good for you, but taken in quantity over time, it can also be downright dangerous.
And what makes one oil taste so very different from another is directly related to the positive effects olive oil has on human health and metabolism.
Years ago, when I first started to get more than casually interested in olive oil, this was not so well understood. In 1993, Oldways Preservation and Exchange Trust, a nonprofit I helped establish and with which I worked closely at the time, joined with the Harvard School of Public Health to organize the first Mediterranean Diet Conference in Cambridge, Massachusetts. Back then, we thought, along with just about everyone else who’d looked into it, that the role of olive oil in sustaining the remarkably good health of people who followed a traditional Mediterranean diet was the result of two facts: 1) olive oil was the principal fat in the diet, sometimes accounting for as much as 40 percent or more of daily calories; and 2) olive oil is primarily made up of oleic acid, a monounsaturated fat. Nutritional scientists were largely in agreement that monounsaturated fats (or MUFAs, as they’re sometimes called in the literature) work in human metabolism to regulate serum cholesterol, reducing dangerous low-density lipoproteins (LDLs), called “bad” cholesterol, and maintaining or even boosting high-density lipoproteins (HDLs), the so-called “good” cholesterol.[1] Olive oil contains anywhere from 55 percent to 83 percent monounsaturated oleic acid, depending on the cultivar, the maturity of the fruit at harvest, and the terroir of the orchard or field, that is, the nature of the soil, the altitude, the climate (cool climates produce oils with more oleic acid), and the weather throughout the growing season.
Another reason for the importance of MUFAs is their stability against oxidation—unlike the polyunsaturated fatty acids (PUFAs, naturally) that are in vegetable oils (corn, soy, sunflower, canola, and so on), MUFAs combat the production of free radicals that are linked to carcinogenesis.
What this means in effect is that all olive oil, both extra-virgin and the regular stuff (just plain olive oil, that which has been refined or rectified as described in Chapter 6), is regarded favorably as a good source of the kind of healthy fats that help fend off cardiovascular disease. Those who heard him will never forget Dr. Walter Willett, the esteemed chair of the Department of Nutrition at the Harvard School of Public Health, when he said with regard to the U.S. Department of Agriculture’s food pyramid, “As far as I’m concerned, you can just take the whole pyramid and pour olive oil over it.” That was a profoundly revolutionary statement about a food that is primarily a fat, at a time when the good-nutrition mantra chanted by every academic dietician and nutritionist was: low fat, low fat, low fat.
But as it turned out, MUFAs are only part of the story, an important part, it’s true, but there is much, much more going on with extra-virgin olive oil than even authorities like Dr. Willett imagined back then. Note that I wrote extra-virgin. Although plain olive oil—which is, just like extra-virgin, a monounsaturated fat or MUFA—is good for us, the very process of refining it, stripping the oil of compounds that produce flavors and colors, also strips it of some major health benefits. The two go hand in hand—the aromas, flavors, and colors that give extra-virgin olive oil such a unique place in the kitchen and on the table are testimony to the presence of the vital compounds that make the oil indispensable in a healthy diet. So olive oil is good for us, but extra-virgin olive oil is better. And the better the oil, the more complex its flavor, the deeper its color, the better it is for our health. In a way, this is analogous to consuming whole grains naturally rich in vitamins, minerals, active compounds, and fiber versus consuming highly processed grains stripped of these vital nutrients.
Almost every week, it seems, nutritional scientists find new evidence of the beneficial impact of extra-virgin olive oil. Cardiovascular disease, diabetes (especially type 2, so-called adult onset diabetes), many types of cancer, including breast and prostate cancers, even Alzheimer’s disease are among the catastrophic illnesses for which extra-virgin olive oil is believed to have therapeutic or preventative (or sometimes both) effects. And new conditions get added to this list just about every month or so as scientists and nutritionists continue their research. At this point it’s believed that extra-virgin olive oil, especially at its freshest, seems to have a profound anti-inflammatory outcome because of an element in its composition that accounts for the catch in the back of the throat that’s typical of fine fresh oils.
The positive effects of extra-virgin olive oil come about largely because of the presence of powerful antioxidants that are naturally present in the oil, especially as polyphenols with suggestive names like oleuropein, oleocanthal, hydroxytyrosol, tyrosol, and many others, some of which have yet to be identified. The presence of these extremely valuable antioxidants is indicated by those same volatile compounds that you smell and taste in fine extra-virgin olive oil. That is, while “there is no direct relationship between the amount of antioxidants and the aromas perceptible in an oil,” says Mario Bertuccioli, professor at the University of Florence and one of Europe’s leading figures in sensory science, “we can say that the aromatic freshness of an oil is a good indication of a quantity of antioxidants.” It would be difficult to overemphasize the importance these antioxidants play in a healthy diet.
No doubt the most impressive polyphenol in olive oil is hydroxytyrosol (which, interestingly, is also present in white wine), sometimes called a “superstar” because of its ability to absorb free radicals and protect cells against oxidative stress.[2] If you look up hydroxytyrosol online, you will find a number of sites that guarantee equivalent effects from hydroxytyrosol supplements. Be skeptical: That’s not a great idea. Despite the fact that it has been heralded as the most potent antioxidant found in nature, no one so far has been able to tease out the synergistic effects of any of these elements that make olive oil so good for us. Might it be that the magic bullet, the potion that will restore health and ensure a long life, is not hydroxytyrosol alone but hydroxytyrosol and fat, or hydroxytyrosol and cooked vegetables, or hydroxytyrosol and garlic, or hydroxytyrosol and all of the above, including other antioxidants present in olive oil?
The prize for the polyphenol with the best back story surely goes to oleocanthal, which was “discovered” back in 1999 when Gary Beauchamp, a biologist and director of the prestigious Monell Chemical Senses Center in Philadelphia, was given a taste of oil fresh from the mill while visiting friends in Sicily during the olive harvest. The burn or sting he experienced in the back of his throat would be familiar to anyone who has ever tasted very fresh oil, an overwhelmingly pungent sensation that often leads to a coughing attack—and also leads some wags to refer to olive oils as one-cough, two-cough, or three-cough oils. The Monell scientist, however, recognized that back-of-the-throat pungency as a characteristic of ibuprofen, a non-steroid anti-inflammatory drug (NSAID) widely available in over-the-counter remedies for aches and pains, especially those associated with inflammation—arthritis, rheumatoid arthritis, menstrual pain, and injuries. (Advil is probably the best known brand-name NSAID to American consumers.) Dr. Beauchamp’s crew at Monell spent three years studying the effects of olive oil, concluding, not surprisingly, that the more coughs the oil produced, the more of the valuable polyphenol oleocanthal it contained.[3] Anti-inflammatory drugs like ibuprofen are also associated with lowering the risk of certain cancers, heart disease, stroke, and dementia, and oleocanthal, it appears, has a similar effect.[4] Although structurally unrelated, both oleocanthal and ibuprofen are potent anti-inflammatory compounds, and both produce the same effects, inhibiting enzymatic reactions in the body that promote inflammation.
At about 10 percent of the total phenolic compounds, ibuprofen-like oleocanthal is one of many positive elements in extra-virgin olive oil, which, it appears, might just be nature’s most perfect food after mother’s milk, providing beneficial fats and good antioxidant vitamins and polyphenols to protect us, and in fact providing just about everything we need in life except for protein. (But if you want protein, take a plate of beans cooked slowly with garlic, a slice of onion, and a few leafy greens, and pour a healthy dollop of olive oil over, as generations of Mediterranean cooks have done down through the ages, and you have something close to a perfect meal. And one that’s good for you, too, as modern generations of scientists are proving almost every day.)
But there’s more. Alessandro Leone, an agronomist from the University of Foggia, in Puglia, explains it: “Pungency in the back of the throat,” he tells me, “is not negative. On the contrary, it is absolutely positive because it’s a symbol of the enormous quantity of polyphenols that the oil contains.” And beyond their implications for human health, Dr. Leone tells me, polyphenols carry another benefit: “They’re also indications of an oil with a long life, one that will maintain its organoleptic qualities for a very long time.” Of course, the oil must be protected from exposure to light, heat, and the atmosphere, but even so, an oil rich in polyphenols, with, let’s say, around 400 ppm (parts per million), like one from the massive ancient Ogliarola and Coratina trees that Leone’s family maintains in a magnificent grove below the whitewashed town of Ostuni in Puglia, will endure with most of its structure intact far longer than a sweeter Taggiasca oil from Liguria, for instance, or a Biancolilla from Sicily. Oils from olives such as Biancolilla, Taggiasca, and other varieties that are naturally low in polyphenols, as low as 80 ppm, are often delicious when fresh, but within six months or so, even if carefully maintained, they will lose their flavor impact, their polyphenolic structure, and their positive effect on health.
Green, bitter, pungent: That’s the word on extra-virgin olive oil from Maria Isabel Covas, head of the Cardiovascular Risk and Nutrition Research Group associated with the Ospedal del Mar in Barcelona and a renowned Spanish researcher into the effects of olive oil on health risks and oxidative stress. “Use any oil you like,” Dr. Covas says with her typically unstoppable enthusiasm, “as long as it’s green and bitter.”
Look up bitterness in a thesaurus and you will not be surprised to find that the primary synonyms for the word are all negative: acrimony, anger, having a sharp, strong, unpleasant taste. Look up pungent and it’s almost as bad: strong smelling, caustic, overpowering. Why then should we be seeking bitterness and pungency in olive oil?
Dr. Covas described for me an important study that she conducted along with colleagues in four Spanish cities—Barcelona, Valencia, Navarre, and Seville. It is to date one of the few large controlled studies, using human subjects, of the effects of olive oils with different phenolic structures on cholesterol levels.[5] The greater the polyphenolic content of the oil, the study found, the greater the increase in HDL cholesterol (“good” cholesterol) in blood samples taken after eating. And it’s precisely the bitter flavors and pungent impact in fine extra-virgin olive oil, Dr. Covas assured me, that indicate the presence of polyphenols in the oil—polyphenols that are strongly protective against chronic illnesses related to oxidative stress. Other researchers have suggested that olive oil has a positive effect on many other debilitating conditions and problems—osteoporosis, for example, and depression, and even, quite tentatively, on the outcomes of infertility treatments.[6]
How does it all work? Atherosclerosis, cardiovascular disease, many types of cancer, metabolic syndrome, diabetes, and quite likely neurodegenerative conditions such as Alzheimer’s are triggered by an inflammatory reaction that is derived from oxidative stress. And polyphenols in olive oil, in turn, trigger a genetic response that combats inflammation. These antioxidant components—called “minor components” because in fact they form a very small but critical part of the overall composition of olive oil—seem to repress the genes that lead to inflammation. Genetic expression is simply the latest in ongoing research by very distinguished scientific institutions throughout the world to identify where, what, and how olive oil can produce such positive effects.
Genetic expression was featured in a project carried out at the University of Cordoba’s Maimonides Institute for Biomedical Investigation, led by Dr. Francisco Pérez-Jiménez, chief of internal medicine at the Reina Sofia Hospital in that city. The study, which involved 20 subjects, all with metabolic syndrome, concluded that olive oil with a high phenolic content influenced the regulation of almost 100 genes, among them those linked to obesity, high blood fat levels, diabetes, and heart disease. Admittedly, this was a very small sampling—only 20 subjects—and admittedly it was carried out at an institution located in the very heart of Spanish olive oil production. Still, Dr. Pérez-Jiménez is highly regarded by his peers as an impeccable scientist and his conclusions, while positive, are cautiously so. “Several of the repressed genes are known to be involved in pro-inflammatory processes,” he said in a press statement, “suggesting that the diet can switch the activity of immune system cells to a less deleterious inflammatory profile, as seen in metabolic syndrome.”
Polyphenols are not the only hard-working guardians of good health in extra-virgin olive oil. There are also hundreds, possibly thousands, of other active compounds, “and we don’t know what most of them are,” explains Antonia Trichopoulou, head of the World Health Organization Collaborating Center for Nutrition at the medical school of the University of Athens (Greece) and a longtime advocate for the traditional Mediterranean diet. Some of these other factors, she pointed out to me, include tocopherols (think vitamin E), carotenoids (think beta carotene and lutein), and squalene (with strong tumor-inhibiting properties), all powerful antioxidants that work in our bodies to fend off (scavenge is the word scientists use) free radicals caused by pollution, tobacco smoke, the exigencies of daily life, and the normal process of aging, as well as those caused by the excess of omega-6 fatty acids that’s so typical of modern diets.[7]
We know, too, that all of these compounds react with each other to produce distinctive aromas and flavors. But Dr. Trichopoulou stresses, “It’s not about a set of individual components, or even individual foods. It’s really about how all these factors interact with each other. Maybe olive oil facilitates the absorption or even the metabolism of other food elements. Maybe wine does that too. But we should not try to medicalize the Mediterranean diet.” In short, we shouldn’t try to reduce olive oil, as some have tried to do, to a series of extractable components that can then be put into a pill to swallow on a regular basis.
So important are polyphenols to sustaining good health that Dr. Covas in Barcelona believes they should be listed on bottle labels, just like the free oleic acid content and the harvest and bottling date. But there’s a problem with that. As we saw at the beginning of this chapter, between olive oil fresh from the press and possibly year-old olive oil left to sit on the counter of a heated kitchen next to the stove for a week, the polyphenolic content can change drastically. A polyphenol-rich olive oil may be full of a delicious complex of flavors, bright in color and seductive in aroma, when it leaves its producer’s care, but there is absolutely no guarantee that all those positive characteristics will be sustained and maintained over the long journey from the producer to the consumer. In the very ordinary course of events, a shipment of oil may well be exposed to excessive heat, if not necessarily to light. You only have to imagine a container of oil sitting on a sunny dock in New York City for a day or two in August waiting to be picked up by an importer to understand that the perishable product will be assaulted and rendered deeply defective by the experience.
Beyond that, however, there is a further problem in the very long chain from producer to consumer. That is that wholesalers and retailers alike don’t understand the product and don’t know how to treat it. Or perhaps they do know and simply find it easier to be sloppy in their administration. And I’m not just talking about North American retailers. All over the world, it seems, olive oil is treated as if it were a product like seed oil or corn oil or canola, or any one of a dozen different highly refined (and thus highly stable) products, instead of as the precious and somewhat delicate product that it is.
Too much fat in the diet has been cited as a primary cause behind so many modern diseases that it is quite amazing to find a single dietary fat that can provide major health benefits. But olive oil’s anti-inflammatory, antioxidant effects are more and more established as important partners in a healthful diet. It is increasingly recognized that heart disease, for instance, is not so much caused by a buildup of fat as it is by an inflammatory response in the arteries that leads to atherosclerosis (narrowing of the arteries). That inflammatory response can be triggered by environmental factors—diet, tobacco smoke, air pollution, water pollution, pesticides—and by the very process of human existence as we grow, mature, and age. And extra-virgin olive oil combats it.
Olive oil alone, in no matter what quantity, no matter how high in antioxidants, will have a hard time defending a body against a steady diet of Big Macs, fried potatoes, Coca-Cola, and so forth. But a diet that stresses fresh vegetables, beans and other legumes, seafood rather than red meat, and a very low to nil consumption of fast food and highly processed food—that diet, whether Mediterranean, Asian, or somewhere in between, coupled with plenty of olive oil, plenty of physical activity, and another element we might call the luck of the genes—can be effective in promoting a long and healthy life.
Olive oil is the common thread that runs through it.
1. This is not the place for a discussion of primate metabolism. Suffice to say that a lipoprotein is made up of a fat, a lipid (that’s the cholesterol), combined with a protein. A low-density lipoprotein has more cholesterol than protein, and that isn’t good. A high-density lipoprotein has more protein than cholesterol, and that is what we’re looking for when we look at healthy cholesterol levels. For a much more comprehensive discussion, see the Harvard School of Public Health’s website: http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-full-story.
2. A brief explanation: Oxidative stress results from the normal process of living. We need oxygen in order to survive but, as with many essential elements, too much of it can be a bad thing. The oxygen in the air we breathe helps convert food into energy. But this basic metabolic process, without which life cannot continue, also creates by-products called free radicals, which can destabilize the organism entirely. Free radicals thus come about through the very process of living, breathing, and aging, although they are also created by pollution in the air, water, and food we eat, and in toxic substances such as tobacco smoke. All these effects combined are what we call oxidative stress. And antioxidants help defend us against its effects.
3. Their results were published in the weekly journal Nature: 437 (September 1, 2005), Beauchamp, Gary K., et al., “Phytochemistry: Ibuprofen-Like Activity in Extra-Virgin Olive Oil.”
4. For a more scientific discussion of this than I can possibly provide, see: Monti, Maria Chiara, Luigi Margarucci, Alessandra Tosco, Raffaele Riccio, and Agostino Casapullo, “New Insights on the Interaction Mechanism between Tau Protein and Oleocanthal, an Extra-Virgin Olive-Oil Bioactive Component,” published in Journal of the Royal Society of Chemistry and cited as DOI: 10.1039/c1fo10064e (www.rsc.org/foodfunction); received April 29, 2011, accepted June 14, 2011. This study, by a group of research scientists at the Università degli Studi di Salerno, concluded: “The reduced risk of neurodegenerative pathologies as AD [Alzheimers disease] in Mediterranean area has been associated with high consumption of extra virgin olive oil, which also exerts beneficent effects on cancer and cardiovascular diseases. These healthy properties have been attributed mainly to minor phenolic compounds found in extra virgin olive oil, which also bear antioxidant, anti-inflammatory and anti-thrombic activities.”
6. I have no medical training and am not in a position to give professional medical advice. But for those willing to seek it, there is plenty of information available to link monounsaturated fats that are high in phenolic compounds with positive health outcomes. The one fat that fits that definition is extra-virgin olive oil.
7. Omega-6 fatty acids are not bad for us. They are essential, meaning our bodies cannot manufacture them. The problem is an imbalance: We get plenty of omega-6 through our heavily meat-laden diets and through vegetable oils, including olive oil, but not enough omega-3, found mostly in fish.