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Complementary and Alternative Medicine: Fair and Balanced

Fat composition in dietary oils compared

Olive oil is higher in monounsaturated fats than other dietary oils, making it more healthy than some. But as a fat, its use should be limited.

By John Russo Jr./Vicus.com

VICUS.COM (18 Oct. 2000) -- The Lyon Diet Heart Study showed that the so-called Mediterranean diet was associated with a lower risk of a second heart attack in people who had a previous myocardial infarction. Other cardiovascular conditions (unstable angina, stroke, heart failure, pulmonary or peripheral embolism) and even hospitalizations for cardiovascular disease were also reduced (de Lorgeril, et al., 1999).

A key component in the Mediterranean diet is olive oil, along with a high consumption of plant-based foods and a low consumption of red meat. According to a recent study (Trichopoulou, et al., 2000), olive oil is more beneficial against cancer than other forms of added lipids.

This study also estimates that up to 25% of the incidence of colorectal cancer (also see Stoneham, et al., 2000), approximately 15% of the incidence of breast cancer, and approximately 10% of the incidence of prostate, pancreas and endometrial cancer could be prevented if the populations of highly developed Western countries could shift to the traditional healthy Mediterranean diet.

The health benefits and characteristics of olive oil are the topic of this article.

The distinct taste and types of olive oil

One of the main reasons to cook with olive oil is to benefit from the flavor it adds. Cooking with olive oil is like cooking with wine. Never use a wine or olive oil that does not taste good to you. An inferior one will leave an aftertaste.

You'll understand the difference if you do a taste test and compare the "pure" to the "extra-virgin" olive oil.

There are many olive oils available. They all share the high level of monounsaturated fats, but differ in other ways. Table 1 provides a summary of the most common types of olive oil.

Olive oil vs. other cooking oils

Fats should contribute no more than 30% of the calories in a diet. The majority of calories from fat should come from monounsaturated fats, as they have been shown to lower LDL ("bad") cholesterol (Kris-Etherton, et al., 1999; Williams, et al., 1999; Aro, et al., 1998).

Polyunsaturated fats should be used in moderation. Saturated fats should be avoided. They come from animal meats, dairy products and tropical oils such as coconut and palm oil. As noted throughout the literature, consumption of saturated fats has been shown to raise LDL cholesterol.

Table 2 shows how olive oil compares with other cooking oils in the percentage of fat from monounsaturated, polyunsaturated and saturated fat.

Benefits and characteristics of extra virgin olive oil

Extra virgin olive oil is a unique dietary lipid, according to Visioli and Galli (2000), in the sense that it is not extracted from seeds by means of solvents. Rather, it is obtained from the whole fruit (drupe), by using the cold-press technique, which does not alter the chemical nature of the drupe or that of the resulting oil. 

According to a study published in The Lancet in October 2000 (Owen, et al.), high consumption of extra-virgin olive oils, which are particularly rich in phenolic antioxidants (as well as squalene and oleic acid), should afford considerable protection against cancer (colon, breast, skin), coronary heart disease and aging by inhibiting oxidative stress. It is the unique profile of the phenolic fraction, along with high intakes of squalene and the monounsaturated fatty acid, oleic acid, which are believed to confer the extra-virgin oil's health-promoting properties. 

Extra virgin olive oil is graded by acidity. Lower acidity is associated with a higher quality product because acidity affects the taste and the aroma of the oil. Extra virgin olive oils are permitted to have a maximum acidity of 1%, but the top-quality oils tend to have less than 0.5% acidity. Virgin oil, by comparison, can have up to 3% acidity.

Olive oil or pure olive oil, in contrast to extra virgin oil, is chemically treated, heated and filtered to reduce its acidity. Ugo Erasmus, in his book Fats That Heal, Fats That Kill: The Complete Guide to Fats, Oils, Cholesterol and Human Health, notes that this manufacturing process alters an oil's characteristics. In fact, heating during processing or in cooking destroys the beneficial compounds in most oils, including olive oil. 

The color of extra virgin olive oil ranges from a pale yellow to bright green. Usually, the deeper the color, the more intense the flavor. It should taste sweet, with a little "edge" to it.

As an additional note, bottling olive oil in plastic can be detrimental to its quality. The oil can capture the chemicals from the plastic and air can seep in, causing rancidity. The ideal packaging for olive oil should be dark glass, which prevents exposure to light, a basic cause of quality deterioration. Olive oil should not be stored in the refrigerator.  

John Russo Jr., PharmD, is senior vice president of medical communications at Vicus.com. He is a pharmacist and medical writer with more than 20 years of experience in medical education.

 

Reference:

Aro A, Pietinen P, et al. Effects of reduced-fat diets with different fatty acid compositions on serum lipoprotein lipids and apolipoproteins. Public Health Nutr.  1998 Jun;1(2):109-16.

de Lorgeril M, Salen P, et al. Mediterranean diet, traditional risk factors, and the rate of cardiovascular complications after myocardial infarction: final report of the Lyon Diet Heart Study. Circulation. 1999 Feb; 99(6):779-85.

Erasmus U. Fats That Heal, Fats That Kill: The Complete Guide to Fats, Oils, Cholesterol and Human Health. Burnaby, British Columbia, Canada: Alive Books; 1993.

Kris-Etherton PM, Pearson TA, et al. High-monounsaturated fatty acid diets lower both plasma cholesterol and triacylglycerol concentrations. Am J Clin Nutr. 1999 Dec; 70(6):1009-15.

Owen RW, Giacosa A, et al. Olive-oil consumption and health: the possible role of antioxidants. Lancet Oncol. 2000 Oct; (1):107112.

Stoneham M, Goldacre M, et al. Olive oil, diet and colorectal cancer: an ecological study and a hypothesis. J Epidemiol Community Health. 2000 Oct; 54(10):756-760.

Trichopoulou A, Lagiou P, et al. Cancer and Mediterranean dietary traditions. Cancer Epidemiol Biomarkers Prev. 2000 Sep; 9(9):869-73.

Visioli F, Galli C. Olive oil: more than just oleic acid. Am J Clin Nutr. 2000 Sep; 72(3):853.

Williams CM, Francis-Knapper JA, et al. Cholesterol reduction using manufactured foods high in monounsaturated fatty acids: a randomized crossover study. Br J Nutr. 1999 Jun; 81(6):439-46.