Olive oil is the oil obtained from the fruit that comes from the olive tree (Olea Europaea). These plants are usually found in the Mediterranean region such as the Middle East, Italy, Spain, Greece, and other countries in the vicinity and become the major component of Mediterranean diet. Many studies have uncovered the benefits of olive oil and one of them is that people who consume olive oil have a chance to live longer than those who do not. One of the study published in Lancet (Gjonca & Bobak, 1997) revealed that even though Albania is the poorest country in Europe, the adult people there has the lowest mortality compared to other countries in Europe. This paradox of high adult life expectancy in very-low-income country can be most plausibly explained by diet—kind of Mediterranian diet that can improve health and prolong life. This particular diet has low consumption of total energy, meat, and milk products but high consumption of fruit, vegetables, and carbohydrates. Analysis of the geographical distribution of mortality within Albania (1978) showed that mortality was lowest in the south-west where most of the olive oil, fruits, and vegetables are produced and consumed.
In terms of fat composition, the main type of fat found in all kinds of olive oil is monounsaturated fatty acids (MUFAs) that considered a healthy dietary fat. The composition of olive oil varies by cultivar, region, altitude, time of harvest, and extraction process (Beltran et. al, 2004). Olive oil is composed mainly of the mixed triglyceride esters of oleic acid and palmitic acid and of other fatty acids, along with traces of squalene (up to 0.7%) and sterols (about 0.2% phytosterol and tocosterols).
Fatty acid | Percentage |
Oleic acid | 55-83% |
Linoleic acid | 3.5-21% |
Palmitic acid | 7.5-20% |
Stearic acid | 0.5-5% |
ALA (α-Linolenic acid) | 0-1.5% |
Oleic acid (a monounsaturated, omega-9 fat) is a good source of vitamin E and also provides valuable amounts of the antioxidant beta-caroteneas well as squalene, a much less common antioxidant that also plays a special role in skin health. According to USDA, the nutritional value of 1 tablespoon (13.5g) olive oil is as follows:
- Calories: 119 kcal
- Fat: 13.50 g (21% of the Daily Value, DV)
- Saturated fat: 2 g (9% of DV)
- Vitamin E: 1.9 mg (10% of DV)
- Vitamin K: 8.1 µg (10% of DV)
When you purchase olive oil, you will notice a host of different grades are available, including extra-virgin, virgin, refined and pure. Here are the definition of all those grades:
Grades of Olive Oil |
Definition |
Extra virgin olive oil | the unrefined oil derived from the first pressing of the olives and has the most delicate flavor, contains no more than 0.8% free acidity |
Virgin olive oil | Derived from the first pressing of the olives but has a higher acidity level than extra virgin olive oil (as well as lower phytonutrient levels and a less delicate taste). Chemically, the difference between extra virgin olive oil and virgin olive oil involves the amount of free oleic acid, which is a marker for overall acidity. According to the standards adopted by the International Olive Oil Council, “virgin” can contain up to 2% free acidity (expressed as oleic acid) |
Pure olive oil | The oil is a blend of refined and unrefined virgin olive oils. |
Refined olive oil | Obtained from unrefined virgin olive oils, and it’s only allowed to contain up to 0.3% of free acidity. However, while lower in free acidity than extra virgin or virgin olive oils, refined olive oil loses some of its unique nutrient content through the refining process. |
Extra virgin olive oil is a particularly valuable of antioxidant and anti-inflammatory phytonutrients, including polyphenols, such as tyrosols (oleuropein, tyrosol, hydroxytyrosol), flavones (apigenin, luteolin), secoiridoids (oleocanthal), anthocyanidins (cyanidins, peonidins), hydroxycinnamic acids (caffeic, cinnamic, ferulic, and coumaric acids), flavonols (quercetin, kaempferol), lignans (pinoresinol), and hydroxybenzoic acids (vanillic and syringic acids). One of the polyphenols, known as oleuropein can help lower bad cholesterol and blood pressure, prevent cancer, protect against oxidative damage, and help guard against cognitive decline. Oleuropein provides the distinctive tangy, pungent, almost bitter flavor found in high quality extra virgin olive oils.It’s also responsible for most of olive oil’s antioxidant, anti-inflammatory, and disease-fighting characteristics (Omar, 2010, Wahle et. al, 2004 and Waterman & Lockwood, 2007). In fact, when oleuropein was given to animals with tumors, the tumors completely regressed and disappeared in 9 to 12 days (Hamdi & Castellon, 2005).
From all grades of olive oil, extra virgin olive oil is the most recommended for salad dressing and variety of cooked foods. However, this type of olive oil is not recommended for cooking. Different manufacturers list different smoke points for their olive oils, and some of them have a very close temperature to smoke point as their maximum limit for safe heating of the oil. Even though these temperatures can prevent the creation of some harmful substances through heating of the oil, they are not correct limits for preserving the unique nutrients (especially polyphenols) found in high-quality, extra virgin olive oil. Oxidation of nourishing substances found in extra virgin olive oil and acrylamide formation, can occur at cooking temperatures around 1480C. The one that usually used for cooking is olive pomace oil (refined pomace olive oil often blended with some virgin oil) because it has a high smoke point. It also has the same fat composition as regular olive oil, giving it the same health benefits.
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. Morello et. al. (2004) found that levels of chlorophyll, carotenoids and antioxidant phenols dropped dramatically after virgin olive oil had been in storage 12 months-even under the best controlled conditions. Chlorophyll content dropped by as much as 30%; beta-carotene by 40%, and vitamin E (alpha-tocopherol) by 100%. Phenols, which are not only the main antioxidants in virgin olive oil, but are also responsible for its distinctive rich flavor, also dropped precipitously after 12 months storage. Light destroys many of the antioxidants in olive oil. Oils stored in clear bottles under supermarket lighting lost at least 30% of their tocopherols (vitamin E) and carotenoids. After just two months’ exposure to light, the olive oil could no longer be classified as extra virgin because the peroxide (free radical) levels had too much increased.
Here are some tips to purchase and store olive oil:
- Choose olive oils that are sold in dark tinted bottles since the packaging will help protect the oil from oxidation caused by exposure to light. Don’t forget to put olive oil in a lightproof area, like a cabinet with solid doors or closed pantry.
- Ensure the oil is displayed in a cool area, away from any direct or indirect contact with heat. Do not store your olive oil near the stove as the heat will damage it.
- Olive oil should be stored properly and used within 1-2 months to ensure its healthy phytonutrients remain intact and available. Even though the olive oil was properly stored, research studies have shown compromise in its nutritional quality after two months’ period of time. It’s better to purchase small size amount of olive oil if you aren’t sure how quicky you’ll finish the olive oil.
- 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, its normal appearance will be regained, and its quality will be better maintained.
In the other hand, even healthier fats like olive oil are high in calories, so use it moderately. Olive oil should be used as substitute for other fatty foods such as butter and margarine, not in addition to them. If your diet replaces saturated and trans fats with unsaturated fats such as MUFAs and polyunsaturated fats (PUFAs), you may gain certain health benefits. Simply adding olive oil to unhealthy foods don’t make them become healthier.
REFERENCES:
- Beltran, G., Del Rio, C. Sanchez, S., and Martinez, L. Influence of Harvet Date and Crop Yield on the Fatty Acid Composition of Virgin Olive Oils from CV. Picual. J. Agric. Food Chem. 2004, 52, 3434−3440
- Gjonca, A. and Bobak, M. Albanian paradox, another example of protective effect of Mediterranean lifestyle? The Lancet Vol. 350, No. 9094, p1815–1817, 20 December 1997.
- Morello JR, Motilva MJ, Tovar MJ, Romero MP. Changes in commercial virgin olive oil (cv Arbequina) during storage, with special emphasis on the phenolic fraction. J Agric Food Chem, 2004 May; 85(3):357-364. 2004
- NDL/FNIC Food Composition Data Base Homepage. http://ndb.nal.usda.gov//
- Omar SH. Oleuropein in olive and its pharmacological effects. Sci Pharm. 2010;78(2):133-54.
- Frankel EN. Nutritional and biological properties of extra virgin olive oil. J Agric Food Chem. 2011 Feb 9;59(3):785-92. Epub 2011 Jan 6. 2011.
- Hamdi HK, Castellon R. Oleuropein, a non-toxic olive iridoid, is an anti-tumor agent and cytoskeleton disruptor. Biochem Biophys Res Commun.2005 Sep 2;334(3):769-78.
- Wahle KW, Caruso D, Ochoa JJ, Quiles JL. Olive oil and modulation of cell signaling in disease prevention. Lipids.2004 Dec;39(12):1223-31.
- Waterman E, Lockwood B. Active components and clinical applications of olive oil. Altern Med Rev. 2007 Dec;12(4):331-42.