Extra virgin olive oil (EVOO) is our oil of choice at WHFoods. We don't profile any other cooking oils on our website, and we don't include any other cooking oils in our recipes or our meal plans. In addition, we never cook with EVOO, but routinely add it to dressings, sauces, dips, pesto, and many already-cooked foods.
The reason that we place special emphasis on EVOO and take special care in its use is quite simple: we find the health benefits of this oil to be remarkable, and very closely tied to its phenol and polyphenol content. For us, EVOO is truly one of a kind. And we see no way to maximally preserve its phenols and polyphenols without avoiding cooking heats.
If EVOO is not a part of your current meal plan, we strongly encourage you to try it out! Start out with something simple, like our Mediterranean Dressing, our 5-Minute Boiled Large Shrimp, or our 3-Minute Bok Choy. We think that you will be delighted by the taste, and we know that EVOO will be providing you with a great array of phytonutrients.
If EVOO is already part of your current meal plan, we encourage you to take a look at your current level of intake. If you are already averaging one tablespoon of EVOO per day, that is great! We have seen numerous studies that show health benefits at this level. However, we have also seen health studies showing even greater benefits will higher levels of daily EVOO. Whatever your current intake level, we encourage you to consider gradual increases that will eventually bring you up to the EVOO average in our World's Healthiest Foods Meal Plan: namely, two tablespoons per day. And of course, our World's Healthiest Foods Meal Plan will make it easy for you to find delicious places in your meal plan for EVOO without resorting to its use as a cooking oil. While you could exceed this two tablespoon level and receive some potentially increased health benefits, we've found that this two tablespoon amount fits very comfortably into an 1800-1900 calorie meal plan that is rich in a wide variety of the World's Healthiest Foods.
Among the extensive list of phytonutrients provided to us by extra virgin olive oil (EVOO), no categories of nutrients are more important than its phenols and polyphenols. The list below shows some of the key phenols and polyphenols present in EVOO, organized by their chemical categories:
Most of these phenols and polyphenols have been studied individually for their anti-inflammatory properties and have been shown to provide us with anti-inflammatory benefits, especially related to reduced inflammation in our cardiovascular system. The impressive health benefits of these phenols and polyphenols is what led to our decision at WHFoods to avoid cooking with EVOO in our recipes and in our meal plans. Many of these anti-inflammatory phenols and polyphenols have been the subject of individual heating studies and have found to be damaged in substantial amounts with the heating of EVOO.
As described in the paragraphs above, phenols and polyphenols serve as the core substances that give EVOO its unique anti-inflammatory properties. Researchers have determined that small amounts of EVOO, as low as one tablespoon per day, can lower inflammatory signaling in our body, including levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha). Interestingly, in Mediterranean-type diets that include daily intake of EVOO, not only is there less production of signaling molecules like TNF-alpha, but there is also less activity by the cell receptors for these pro-inflammatory molecules. Levels of C-reactive protein (CRP) have also been shown to decrease with daily intake of EVOO.
While we are risking a little bit of "science overdose" here, we want to underscore just how well-documented the anti-inflammatory properties of EVOO actually are. In addition to the studies above, scientists have shown that individuals who regularly consume EVOO have reduced activity of their pro-inflammatory cyclo-oxygenase 1 (COX-1) and cyclo-oxygenase 2 (COX-2) enzymes, as well as reduced levels of related molecules including thromboxane B2 and leukotriene B4. Two molecules that are known to increase during inflammatory disease processes—vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1)—have also been shown to decrease in amount following intake of EVOO. These receptors may or may not be familiar to you, but they are the targets of many anti-inflammatory medications.
In this anti-inflammatory context, it is also worth noting that oxidative stress—a process that often parallels the process of chronic inflammation—is reduced by regular consumption of EVOO. One common blood marker used to monitor oxidative stress is the formation of substances called F2-isoprostanes, and studies have shown 10-15% lower levels of this blood marker following EVOO intake.
Importantly, the anti-inflammatory benefits of EVOO do not depend on large levels of intake. In most studies, these benefits become statistically significant with as little as one tablespoon of EVOO per day. The anti-inflammatory benefits of EVOO also appear to increase with daily intake above this level. We've seen studies that looked at benefits associated with EVOO intake all the way up to 4–5 tablespoons per day—the equivalent of 2–2.5 ounces and 476–595 calories. In our 7-Day Menu, we decided on an average daily EVOO amount of 2 tablespoons per day—enough to provide strong anti-inflammatory benefits, while still leaving daily calories at a very manageable level.
One place we don't want excessive ongoing inflammation is within our blood vessels. Our blood supply is just too important for maintaining the health of all our body systems, and it cannot effective support our body systems when compromised with ongoing inflammation. Given this relationship, it's not surprising to see cardiovascular benefits of EVOO rising to the top of the health benefits provided by this remarkable oil.
From a variety of different research perspectives—some of them described in the paragraphs above—we know that daily intake of EVOO in amounts as low as one tablespoon per day reduces inflammatory processes within our blood vessels. By reducing these processes, EVOO also reduces our risk of inflammation-related cardiovascular diseases like atherosclerosis.
Yet anti-inflammatory benefits are not the only cardiovascular benefits provided by EVOO. Two other broad types of heart-related benefits are well documented for this oil. The first type is lessened risk of forming unwanted blood clots. While blood clotting is a natural and healthy process required for the healing of wounds and prevention of excessive bleeding, clotting in the arteries can ultimately result in a heart attack or stroke. One risk factor for unwanted clotting in our arteries is excessive clumping together of our platelet blood cells. This clumping process is also called "aggregation." Regular incorporation of EVOO into a meal plan has been shown to lessen the risk of this excessive aggregation, and the reason that researchers refer to EVOO as an "anti-aggregatory" oil.
The other broad area of cardiovascular benefits involves improved levels of circulating fats in our bloodstream, as well as protection of those fats from oxygen-related damage. Decreased levels of total cholesterol and LDL cholesterol following consumption of EVOO are findings in the majority of studies that have analyzed this relationship. Yet equally important, the cholesterol molecules that remain in our blood also appear to be better protected from oxygen-related damage (oxidation). Since fats and cholesterol belong to a broader technical category called "lipids," damage to the fats and cholesterol in our blood stream is typically referred to as "lipid peroxidation." And it is precisely this lipid peroxidation process that gets reduced through incorporation of EVOO into a meal plan.
Some of the most active and exciting areas of EVOO research involve other body systems that are no less important than our cardiovascular system. Regulation of blood sugar—especially after eating—is one system that has a definite friend in EVOO. One recent study on individuals diagnosed with impaired fasting glucose (IFG) helps explain the ability of EVOO to improve blood sugar regulation. Like this name implies, IFG is a condition in which blood sugar levels are too high—even when no food is being eaten and digested. However, in this particular study, participants were given a little less than one tablespoon of EVOO along with a familiar lunch meal of pasta, salad, fruit, and a slice of ham. When the participants' insulin and blood sugar levels were measured at one hour and two hours after lunch, their blood sugar levels were found to be significantly lower due to this added EVOO. Researchers for this study went one step further, however. They looked at potential ways in which EVOO might have produced these desirable effects. What they found were higher levels of incretins—specifically glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) in the blood of participants after consuming EVOO. Since these incretins are molecules that stimulate more insulin production, raising their levels resulted in more insulin secretion and more removal of sugars from the blood. In short, these study participants achieved better insulin secretion and better regulation of blood sugar levels following their lunch meal through the addition of EVOO.
Decreased risk of bone fracture and better overall bone health is another area of increasing interest in EVOO research. One recent study compared the number of bone fractures in a group of 870 study participants over a period of seven years to see if intake of EVOO was associated with the number of reported bone fractures. When the study results were analyzed, the researchers divided this large group into three categories. In terms of their EVOO intake, the lowest third of the study participants averaged 38 grams of EVOO per day—approximately 3 tablespoons. The middle third averaged nearly 4 tablespoons (48 grams), and the top third averaged about 4.5 tablespoons (57 grams). Participants in the highest category of EVOO intake reported 51% fewer fractures than participants in the lowest category of EVOO intake. While all of these EVOO intake levels are fairly high, they nevertheless show a link between reduced risk of bone fracture and incorporation of EVOO into an ordinary meal plan. It's also worth noting that numerous animal studies have shown increased bone formation in rats and mice that were given EVOO in their feeding plan. This increased bone formation has also been specifically tied to the presence of two phenols—tyrosol and hydroxytyrosol—in EVOO.
Research studies are providing better and better documentation for the anti-cancer benefits of EVOO. Early studies in this area were largely limited to research using rats and mice or research on cell cultures in the lab. But more recent studies have looked at people incorporating EVOO into their everyday meal plan, and have found encouraging results. In survey studies, as few as 1–2 tablespoons of EVOO per day have been associated with decreased risk of breast, respiratory tract, and digestive tract cancers. In the case of the digestive tract, reduced risk seems more likely in the upper tract (stomach and small intestine) than in the lower digestive tract (large intestine, including the colon). Scientists have looked at several different mechanisms that might allow EVOO to provide these anti-cancer effects. One group of studies have focused on the secoiridoids, oleuropein and decarboxylmethyl oleuropein, and determined that these EVOO phytonutrients help shift some of our metabolic pathways in the direction of better stress resistance. In addition, the overall phenolic content of EVOO has been associated with a decreased ability of cancer cells to regenerate. At least some of this effect involves the ability of two phenols in EVOO—tyrosol and hydroxytyrosol—to block activity of an enzyme called matrix metalloproteinase 2 (MM-2). The multiplication of cancer cells depends on an adequate supply of oxygen, and in order to obtain this supply of oxygen, cancer cell growth is often accompanied by the formation of new blood vessels (through a process called angiogenesis). Because the activity of MM-2 is needed to trigger this process of new blood vessel formation, substances that block MM-2 activity can also lessen the likelihood of new blood vessel formation. The tyrosol and hydroxytyrosol in EVOO may decrease the likelihood of cancer cell regeneration by interfering with angiogenesis and lowering the supply of oxygen that would otherwise be available for new blood vessel formation.
In animal studies, supplementation with EVOO has been shown to slow growth of a bacterium called Helicobacter pylori in the stomach. This slowed growth can be potentially important for lowering risk of stomach ulcer since overgrowth of this bacterium and too much clinging of this bacterium to the stomach wall can cause ulcer and other digestive problems.
Olive oil is made from the crushing and then subsequent pressing of olives. The fact that olives are rich in oil is reflected in the botanical name of the olive tree—Olea europea—since the word "oleum" means oil in Latin. Olive oil is available in a variety of grades, which reflect the degree to which it has been processed. Extra virgin olive oil is derived from the first pressing of the olives and has the most delicate flavor and strongest overall health benefits. See How to Select and Store for more information on these different grades of olive oil.
Olives are native to Africa, the Arabian Peninsula (including Saudi Arabia and Yemen), and of course to the general Mediterranean area, including Greece, Italy, France, Portugal, Spain, Israel, Jordan, and Turkey. Over time, olive trees also became naturalized to Australia, New Zealand, and the United States. Yet today, olives are even more widely cultivated and olive oil is enjoyed in cuisines worldwide.
Extra virgin olive oils can naturally range in color from slightly pale yellow to golden to lighter shades and (sorry, we could not resist) olive green. There are many different types of chlorophyll-related molecules that contribute to these green shades, and many different carotenoids that contribute to the yellow and gold shades. There is no guaranteed relationship between the quality of EVOO and its color shade—in other words, there are high-quality versions of EVOO in all color shades, and low-quality versions of EVOO in all color shades. Taste and aroma make far better ways of evaluating EVOO quality than color. While not a hard and fast rule, yellow and golden versions of EVOO tend to be milder in taste, and green versions tend to be hardier in flavor. If the EVOO you are looking at is dark green in color, it's often because olive leaves have been added to the olive crush prior to the pressing of the oil.
As plants native to Africa, the Middle East, and the Mediterranean, olive trees and the olives they produce have one of the longest food histories among all known foods. The pressing of olive oil from olives dates back at least 3,000 years to food practices in this part of the world. (It's also worth noting that olive oil was not exclusively used as a food, but also as a medicine, a lamp fuel, and in other ways). European colonizers of North and Central America were responsible for bringing olive trees to what is now Mexico and the United States.
Today, nearly 50 countries produce olive oil commercially, even though the largest producers are located in the Mediterranean. And on a global basis, over 3 million tons of olive oil are currently consumed each year.
Within the U.S., olive oil imports are fairly evenly split between two countries—Spain (45% of olive oil consumed) and Italy (43% of consumption), with imports from Greece, Tunisia, Portugal, Turkey, and Chile playing a smaller role. (Only 5% of olive oil consumed within the U.S. is also produced within the U.S., although this percentage has been increasing.)
In countries like Spain, Italy, and Greece, per capital consumption of olive averages between 10–16 kilograms per year—approximately 1-2 tablespoons per day. In the U.S. average per capita consumption is a little less than 1 kilogram per year (less than 1/4 tablespoon per day). However, since 1990 total olive oil consumption in the U.S. has steadily increased, and it is expected to continue increasing over the upcoming years. Interestingly, it is estimated that 40% of U.S. consumers who purchase olive oil purchase it in the form of EVOO.
Since olive oil can become rancid from exposure to light and heat, there are some important purchasing criteria you should follow to ensure buying a better quality product. Look for olive oils that are sold in dark tinted bottles since the packaging will help protect the oil from oxidation caused by exposure to light. In addition, make sure the oil is displayed in a cool area, away from any direct or indirect contact with heat.
When you shop for olive oil, you will notice a host of different grades are available, including extra-virgin, virgin, refined and pure:
It is important to note, however, that acidity is by no means the only difference between EVOO and other grades of olive oil. In fact, a sizeable amount of controversy has arisen within the olive oil industry over key characteristics of EVOO and the extent to which these characteristics are present in commercial products. Since over 90% of all EVOO consumed in the United States is imported, many evaluators of EVOO have looked to the International Olive Council (IOC) headquartered in Madrid, Spain for quality criteria in evaluating EVOO. However, unlike Italy, Spain, Greece, Portugal, and other European Union countries that were founding members of the IOC, the United States has never become an official IOC member country or adopted IOC standards for EVOO as its own mandatory standards.
In the United States, voluntary standards for olive oil have traditionally been set by the U.S. Department of Agriculture (USDA), which in 2010 did update its own standards to more closely resemble IOC standards in terms of EVOO chemistry. However, even though most IOC chemical standards like percent free acidity were adopted by the USDA, some differences remain between IOC and USDA chemical criteria. (In addition, since 2010, the IOC has gone on to update and revise some of its chemical standards, and these changes are not reflected in the existing USDA criteria.) But a perhaps even bigger part of the controversy over EVOO standards has not involved chemical criteria like percent free acidity but rather sensory criteria (also called "organoleptic" criteria) like taste and aroma. If you consider olive oil as falling into the category of a fresh fruit juice (in the sense that an olives actually belong to a special group of fruits called "drupes" and can be pressed to obtain their oil or "juice"), aroma and taste might be considered as defining characteristics of this food. Assurance of excellent taste and aroma is a more difficult regulatory standard than assurance of a chemical standard like percent free acidity, and to some extent may require closer monitoring of local conditions and plant varieties. In this context, several organizations in the U.S. offer their own quality seal for EVOO, including the California Olive Oil Council (COOC) and the North American Olive Oil Association (NAOOA). Quality seals from these organizations can help provide assurance about EVOO quality.
Similar organizations exist in Europe and can be helpful for assuring EVOO quality. In most cases, your best bet is to look for specific initials on the olive oil container that represent official review and sanctioning by these organizations. Among your options here are the designations "A.O.C." or "D.O.P." or "D.P.O." or "D.O." "A.O.C." stands for the French term "Appellation D'origine Controlée." "D.O.P." stands for the Italian "Denominazione d'Origine Protetta" (note that D.O.P. is also written as "D.P.O." in some other European countries). In Spain, a similar designation is "D.O." which stands for "Denominacion de Origen." Any of these initials can help provide assurance of quality with respect to extra virgin olive oils.
Another term that you may see on a bottle of olive oil is "cold pressed." This term means that very minimal heating (and by IOC standards, under 81F/27C) was used when mechanically processing the olives to obtain their oil. We like the idea of cold pressed extra virgin olive oil, because we believe that minimal use of heating, combined with the phytonutrient-rich first pressing of the oil, provides the strongest possible nutrient composition from an extracted oil.
Proper storage techniques for olive oil are very important, not only to preserve the delicate taste of the oil, but also to ensure that it does not spoil and become rancid, which will have a negative effect on its nutritional profile.
Even though olive oil's monounsaturated fats are more stable and heat-resistant than the polyunsaturated fats that predominate in other oils (especially the easily damaged omega-3 fatty acids found in flax seed oil, which should always be refrigerated and never heated), olive oil should be stored properly and used within 1-2 months to ensure its healthy phytonutrients remain intact and available. Research studies have shown compromise in the nutritional quality of olive oil after two months' period of time, even when the oil was properly stored.
At WHFoods, we encourage the purchase of certified organically grown foods, and extra virgin olive oil is no exception. Repeated research studies on organic foods as a group show that your likelihood of exposure to contaminants such as pesticides and heavy metals can be greatly reduced through the purchased of certified organic foods, including extra virgin olive oil.
Proper storage techniques for olive oil are very important, not only to preserve the delicate taste of the oil, but also to ensure that it does not spoil and become rancid, which will have a negative effect on its nutritional profile.
Even though olive oil's monounsaturated fats are more stable and heat-resistant than the polyunsaturated fats that predominate in other oils, olive oil should always be stored properly. In this case, proper storage means tightly sealed to minimize exposure to oxygen in the air and in a dark place (if packaged in glass) to minimize exposure to light. Both oxygen and light can interact with the phenols, polyphenols, and other phytonutrients in olive oil and prevent them from providing us with health benefits. In addition, even when properly stored, we recommend consumption of EVOO within 3 months of purchase. In studies that we have seen on oleocanthol and other phenolic substances in EVOO, there is relatively little loss of its phenolic contents during the first three months of storage, but a greater percentage loss from 3–6 months.
Because proper storage of olive oil includes protection from light, there has been ongoing debate about the ideal type of storage container for EVOO. Tinted glass bottles are one of the best storage options for preventing unwanted contamination of the olive oil with packaging materials (as might occur, for example, with the use of dark plastic bottles in which very small amounts of plastic might migrate from the bottle into the oil). However, depending upon the degree and type of glass tinting, exposure to all light might not be prevented with the use of tinted glass. Metal containers for olive oil storage are also an option, although it is unclear about the potential for olive oil to be affected by the metal elements in the container. The transfer of olive oil to a sealed ceramic container is also an option. If you decide to purchase olive oil in a tinted glass bottle, we still recommend that you store it in a lightproof area, like a cabinet with solid doors or closed pantry. If you decide to purchase in either plastic or metal containers, you may want to take the additional step of moving the oil into a ceramic container that can be sealed. If you aren't sure how quickly you will be using your olive oil, you may want to buy it in small-size amounts to avoid the problems that can arise with longer-term storage.
Purchase only as much as you will use in one to three months and store away from light and heat. Protect your olive oil's flavor and antioxidants by transferring 7 to 10 days' worth of oil to a smaller bottle to lessen the oxidation that occurs when the oil is exposed to air. Leave this small bottle at room temperature for easy use, but refrigerate the rest. When chilled, olive oil will solidify slightly and turn cloudy, but once restored to room temperature, it will regain its normal appearance, and its quality will be better maintained. Although it may be convenient, definitely don't store your olive oil near the stove (for example, in a cabinet above the stove) since phytonutrients in the oil may become damaged through exposure to the heat.
You'll find that many of our recipes feature extra virgin olive oil. For example, we like to add it to vegetables after they have been lightly cooked, either on its own, or as part of our Mediterranean Dressing.
If you'd like even more recipes and ways to prepare extra virgin olive oil the Nutrient-Rich Way, you may want to explore The World's Healthiest Foods book.
Olive Oil, cold pressed extra virgin
GI: very low
|vitamin E||1.94 mg (ATE)||13||2.0||good|
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Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%