Science

  • Issue 43 / July - September 2003



    The Amazing Olive

    Dr. Musa Saracoglu

    People pay attention to other people or things according to the degree of their importance. Thus, if the Lord of the Universe explicitly mentions something in His revelation to humanity, it surely is something upon which we should reflect.

    The Qur'an refers to olives directly in surahs al-An'am, al-Nahl, al-Nur, 'Abasa, and al-Tin, and indirectly in Surah al-Mu'minun. In Surat al-Tin, God takes an oath by the fig and the olive. When the Qur'anic verses and Prophetic sayings about olives are studied closely, we see that the olive, as well as its tree and oil, are all given importance.

    Olive trees

    Olive trees, which live from 300 to 400 years on average, require much attention. They are grown mainly in Turkey, Greece, Italy, Spain, and North Africa, and, after the sixteenth century, also in North and South America, China and Japan.

    While olives have been cultivated for some 6,000 years, they had been around for far longer than that: 39,000-year-old olive tree fossils have been found in archeological excavations on Santorini Island. Excavations also has revealed that the ancient city of Klazomenai, near Izmir, Turkey, used to be an important center for olives and olive oil. Today, there are more than 900 million olive trees in the world, 98% of which are in Mediterranean countries, where they occupy approximately 10 million hectares of land.

    Those with olive orchards benefit not only from the olives, but also from the tree's branches, leaves, and roots. Leaves are left to dry after pruning, and then used as fodder or made into various kinds of folk remedies. Branches and protruding roots removed by pruning are significant sources of firewood.

    The characteristics of olives

    Each olive tree yields abundant fruit once a year and then less the following year, due to climatic conditions and methods of cultivation.

    An olive weighs anywhere between 2-12 grams. The pit makes up 13-30%, the edible part makes up 66-85%, and the skin makes up the rest. Breakfast-type olives have a thinner skin and a smaller pit. One hundred grams of the edible part of a green olive gives us 144 calories of energy. It also contains 13.5 grams of oil, 2.8 grams of carbohydrate, 1.5 grams of protein, 90 mgs of calcium, 2 mgs of iron, and 300 units of vitamin A. In contrast, 100 grams of the edible part of a black olive gives us 207 calories of energy. It also contains 21 grams of oil, 1.1 gram of carbohydrate, 1.8 gram of protein, 77 mgs of calcium, 1.6 mgs of iron, and 60 units of vitamin A. Both kinds of olive also contain lesser amounts of other vitamins and minerals.

    In addition to being an important source of oil, olives also contain significant amounts of vitamin A, iron, and calcium. These nutritious qualities, which have been studied by scientists, are known to most people.

    In the last few years, important studies have been made on a group of substances found within the olive's proteins. Until recently, this group of substances received only a little attention. Bisignano et al., of the University of Messina, Italy, studied secoiridoids, which are found in an olive's poliphenols, and their effects on microorganisms. They discovered that secoiridoids prevent and hinder the growth of some bacteria-causing diseases in our respiratory and digestive systems. In light of these observations on olives and olive oil, some substances have been offered as possible sources for developing new antibiotics.

    Olive oil

    Around 1.6-2.6 million tons of olive oil, the olive's most important product, are produced each year. Around 75-80% of this amount is consumed by the producer countries, while the rest is sold abroad.

    Olive oil is extracted by squeezing olives and separating the so-called "black juice" by physical means. No chemical methods are used. There are three main types of olive oil. Natural olive oil, which is the best quality and can be consumed raw, is usually used in salads and sauces. Refined oil, which is made tastier by physical refining and has reduced acidity, is usually added in cooking. Riviera oil, which is produced by adding 10-20% of natural oil to refined oil, is used mainly for frying or added in cooking.

    Olive oil, which is 99.8% triglyceride (an oil), is composed of 14% saturated fat acids, 72% singular unsaturated fat acids, and 12% polyunsaturated fat acids. Furthermore, there are 300 mg of phenol and 150 mg of tocopherol in 1 kg of olive oil. When compared to other cooking oils, it has been shown to contain very high proportions of oleic acid, which is a singular unsaturated fat acid.

    The beneficial effects of olive oil

    Remarkably, there are fewer cases of cardiovascular diseases and cancer in Mediterranean countries where high amounts of olive oil are consumed. Cholesterol, famous for its role in causing cardiovascular diseases, is carried by two groups of lipoproteins found in our blood: LDL and HDL. The liver breaks down the HDL-carried cholesterol more effectively, which reduces the risk of cardiovascular disease. On the other hand, LDL-carried cholesterol is the major cause of cardiovascular disease. Therefore, lower LDL levels and higher HDL levels in our blood mean better resistance to cardiovascular disease.

    The risk-lowering effect of olives on cancer is believed to be caused by the antioxidant effect of its phenols. Due to the antioxidant effect of these substances, they are thought to help restore DNA damage by neutralizing those substances that might damage it. Owen et al., of the German Oncology Research Center, reported that olive oil prevents the onset of coronary heart disease and some types of cancer (e.g., large intestine, breast, and skin cancers) through some of its phenols' antioxidant features.

    Alarkon de la Lastra et al., of the University of Seville in Spain, published an article evaluating the positive effects of olive oil. In this article, they reported that olive oil lowers the risk of cancer by decreasing LDL cholesterol and increasing HDL cholesterol in our blood; it lowers the risk of cancer in the large intestine and the breast, especially by its effect upon triglyceride metabolism; it reduces the formation of such auto-immune diseases as rheumatoid arthritis; it lowers the risk of calcification in the gall bladder by making it secrete regularly; and it also reduces the formation of ulcers and facilitates the recovery of existing ulcers with its effect on our stomach.

    Budiyanto et al., of the University of Kanazawa in Japan, studied the effects of applying olive oil externally to rats that had been exposed to cancer-causing ultraviolet rays. After dividing the rats into three groups, the first group received no olive oil, the second group received olive oil before being exposed, and the third group received olive oil after being exposed. Researchers observed far lower rates of cancer development in the third group than in the other two.

    Conclusion

    The Omnipotent One, who knows our heart, veins, and the mechanism of cancer, stored its cure in a tree found just beside us. Olive oil is believed to have other as yet undiscovered qualities as well. By the time these qualities are discovered, its consumption will have increased and, at the same time, it will pioneer the development of new medicines and treatment methods. In addition, olive oil is commonly used in medicine and the cosmetic industries, and it is already being used to treat various hair and skin diseases. Hopefully olive oil, which is a blessing from the Almighty, will be consumed in larger amounts in the near future.

    References:
    - Owen RW, Giacosa A, Hull WE, Haubner R, Wurtele G, Spiegelhalder B, Bartsch H.Olive-oil consumption and health: the possible role of antioxidants.
    - Lancet Oncol. 2000 Oct;1:107-12. Review.
    - Owen RW, Mier W, Giacosa A, Hull WE, Spiegelhalder B, Bartsch H.Phenolic compounds and squalene in olive oils: the concentration and antioxidant potential of total phenols, simple phenols, secoiridoids, lignansand squalene.
    - Food Chem Toxicol. 2000 Aug;38(8):647-59.
    - Owen RW, Mier W, Giacosa A, Hull WE, Spiegelhalder B, Bartsch H. Identification of lignans as major components in the phenolic fraction of olive oil.
    - Clin Chem. 2000 Jul;46(7):976-88.
    - Owen RW, Giacosa A, Hull WE, Haubner R, Spiegelhalder B, Bartsch H. The antioxidant/anticancer potential of phenolic compounds isolated from olive oil.
    - Eur J Cancer. 2000 Jun;36(10):1235-47.
    - Bisignano G, Lagana MG, Trombetta D, Arena S, Nostro A, Uccella N, Mazzanti G, Saija A. In vitro antibacterial activity of some aliphatic aldehydes from Olea europaea L.
    - FEMS Microbiol Lett. 2001 Apr 20;198(1):9-13. Erratum in: FEMS Microbiol Lett 2001 Jul 10;201(1):117.
    - Bisignano G, Tomaino A, Lo Cascio R, Crisafi G, Uccella N, Saija A. On the in-vitro antimicrobial activity of oleuropein and hydroxytyrosol.
    - J Pharm Pharmacol. 1999 Aug;51(8):971-4
    - Budiyanto A, Ahmed NU, Wu A, Bito T, Nikaido O, Osawa T, Ueda M, Ichihashi M.Protective effect of topically applied olive oil against photocarcinogenesis following UVB exposure of mice.
    - Taris Zeytin ve Z.Yagi Birligi/ Zeytin Hakkinda
    - www.taris.com.tr/zeytin/zhak.htm
    - Zeytinyagi
    - http://www.maximumbilgi.com/saglik/zeytinyagi.htm

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