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The ASA-IM Middle East Soy Oil ProgramASA-IM continues to provide technical assistance to edible oil refining plants in the region, in order to assure that soybean oil from these plants is of the highest possible quality. This helps to assure a positive consumer response and, of course, ultimately adds to the viability and profitability of the concerned regional companies. From the ASA-IM perspective, high quality soybean oil going into the markets of the Middle East helps to promote U.S. soybean and CDSO (crude degummed soybean oil) sales here, as elsewhere in the world. Links to Soy Oil-related technical publications
http://www.aocs.or
The Role of Soybean Oil in Human Nutrition*Introduction For a long time, it has been recognized that dietary fats and oils have a significant effect on our health. Arising from this concern, a great deal of research has been done to investigate the quantitative and qualitative aspect of dietary fats and oils related to human nutrition and health. The key results indicate that the amount and type of dietary fats and oils are an important risk factor for certain chronic diseases including heart diseases, some forms of cancer and diabetes and thus, different dietary fats and oils posses different effects on these disease tendencies depending on their constituent fatty acids. As a result of these findings, consumers today don't consider only factors such as preference, taste and economic factors; they also consider nutritional attributes as equally important factors. Among the premium edible oils and fats, soybean oil has specific nutritional properties due to its unique fatty acid composition in addition to being a rich source of both essential fatty acids and vitamin E. All of them are considered to be an important key to prevent many diseases and perform a variety of vital physiological functions. The following discussion is made as an attempt to put the nutritional advantages of soybean oil into factual perspective in light of the current findings. Soybean oil in diet Soybean oil is the major oil produced and traded in the world. The major attributes of soybean oil are the versatility of its uses in a wide variety of food products and industrial applications, availability, and low prices in addition to its high nutritional quality. Soybean oil can process and modified to provide performance and functionality based on market needs and changing requirements of the various food industries. All of these advantages have contribute to the increase in the area of applications of soybean oil and secured its leading position among edible oils and fats in terms of production, consumption, and competitiveness. Soybean oil consumption has been growing steadily in recent years. The published data have shown that soybean oil consumption has grow from 16 million metric tons in the year 1990 to about 38.4 million metric tons in the year 2007. The major areas of demand growth have been U.S, China, and India, but significant growth also has occurred in Middle East and North Africa and elsewhere. Oils and fats Oils and fats occur naturally in a wide range of sources. They can be of plant, land animals, or marine animals origin. They are hydrophobic substances insoluble in water, but soluble in most non-polar organic solvents. The term fat usually refers to those products that are solid at room temperature, while oils are liquid at the same temperature. Dietary fats and oils are categorized as visible and invisible. Visible fats and oils are defined as those which have been isolated from their original sources and consumed directly as it is or as an ingredient of the food complex, such as oils, margarines, shortenings, chocolates and butter. Invisible fats are those which have not been isolated from their original sources and are consumed as part of the tissue in the diet, e.g. meat, fish, poultry and dairy products, fruits, seeds, etc. Triglycerides are the major component of oils and fats. They are esters formed from glycerol and fatty acids.
When all the fatty acid molecules are of the same kind, the resulted ester is described as a simple triglyceride, if more than one kind is present it is a mixed triglyceride. Simple triglycerides occur naturally in fats and oils only in limited amounts, while mixed triglycerides are the more common forms. All fats and oils contain small amounts of nonglyceride components which are termed minor components. They may range from 5 % to less than 0.2 %. The various classes of minor constituents can be divided into two groups. The first group consists of fatty acid derivatives such as mono and diglycerides, phosphatides, waxes and esters of sterols. The second group includes classes of compounds non related chemically to fatty acids such as hydrocarbons, aliphatic alcohols, free sterols, tocopherols, chlorophylls, carotenoids, and polar phenolic compounds. Some classes of minor constituents such as phosphatides and phenols are removed during the course of ordinary refining, while the other classes are subjected only to some quantitative and qualitative changes. Oils and fats are one of the major components of our food. They play an important role in our health since they supply some nutritional functions which must be taken into account when considering a well-balanced diet. The specific nutritional function of oils and fats can be summarized as:
Fatty acids Fatty acids are composed of a carboxylic group and a hydrocarbon chain.
Fatty acids are very important component of all oils and fats. They represent 90 % of the oil and fat molecule. It is therefore obvious that the physical, chemical and biological properties of oils and fats are greatly depending on the types of fatty acids present in the triglyceride molecules. Fatty acids can be classified into three basic types:
Most oils and fats contain a mixture of different types of fatty acids whereas animal and vegetable fats are especially high in saturated fatty acids; they also contain some monounsaturated and polyunsaturated fatty acids. And while vegetable oils are high in unsaturated fatty acids, they always contain some saturated fatty acids. The fatty acids in natural oils and fats have (with few exceptions) a straight-hydrocarbon chain where the carbon atoms are linked together by single linkage in the saturated acids while one or more double linkages (bonds) occur in the unsaturated acids. The hydrogen atom around the double bond can be either on opposite sides (Trans) or on the same side (Cic). Most of naturally occurring oils and fats are made up of fatty acids with even carbon numbers and chain lengths between 12-22 carbon atoms in cic-configuration if unsaturation is present. However, the most common fatty acids in edible fats and oils consumed by man are those containing 16 or 18 carbon atoms. Those include the saturated palmetic (C16: 0) and stearic (C18:0), monounsaturated oleic acid (C18:1) and polyunsaturated acids linoleic (C18:2) and linolenic (C18: 3). Essential fatty acids Certain unsaturated fatty acids are essential nutrients and their exclusion results in a serious deficiency of many vital functions of our bio- system. They are termed essential fatty acids, because the body cannot synthesize them from the other fatty acids or nutrients and the requirements must be provided by the diet. Tow fatty acids are recognized as the essential fatty acids (EFAs). One is linoleic acid (C18:2 n-6) of the omega-6 class and the other is alpha-linolenic acid (C18:3 n-3) of omega-3 class. Both are polyunsaturated fatty acids that differ in the location of double bonds and the degree of un-saturation, thus, they provide different nutritional properties. Linoleic acid is widely distributed in the majority of edible oils and fats, while only few plant sources are known to contain appreciable amount of linolenic acid and soybean oil is one. In view of nutrition, the more important fatty acids are the higher 20-carbon homologies of the EFAs. These are; arachidonic acid (C20:4 n-6), dihomo-gamma linolenic acid (C20:3 n-6), eicosapentaenoic acid (C20:5 n3). These fatty acids are important in membrane structure and as immediate precursors to prostanoids that regulate most of the body processes and functions. Arachedonic acid is widely distributed in fats and oils of animal (land and sea) origin, dihomo-gamma linolenic acid is found in mammal's milk and both of them can be synthesized in the body from linoleic acid. Eicosapentaenoic acid is found in cold-water fish and many sea foods and in the body it can be synthesized from linolenic acids. These fatty acids are not a dietary essential unless a deficiency of their precursors exists. As all of the double bonds of the essential fatty acids are in the cic configuration and at specific position (C9, C12 and C15) along the carbon chain, the other geometrical or positional isomers do not act as essential fatty acids. The specific functions of essential fatty acidsThe essential fatty acids play an important role in every life process in the human body. Among their many functions are:
Health risks associated with essential fatty acids deficiency Essential fatty acids deficiency may lead to diversity of health problems since the tendencies of many diseases are increased. Many evidences show that essential fatty acids deficiency may lead to:
However, the therapeutic and clinical trials have shown that the adequate and proper intake of essential fatty acids help protect against these diseases. Circulatory diseases The most important circulatory diseases are:
Impact of dietary fats and oils on the cardiovascular diseases Despite significant medical advances, the heart and vascular diseases are the leading cause of illness and death in the advanced countries. Populations of developing countries have less severe cardiovascular disease and thus less mortality than the developed countries. The relevant studies link the geographic differences in cardiovascular diseases with high proportions of cholesterol and saturated fats in the diet and with various aspects of lifestyle. Intrigued by these observations, a great deal of research has been done to investigate the quantitative and qualitative aspects of dietary fats and oils related to their role in the prevention or progression of certain chronic diseases including heart disease. The key results indicate that the amount and type of dietary fats and oils are the main risk factor for heart diseases and different dietary fats and oils posses different effects on cardiovascular disease tendencies depending on their constituent fatty acids. These cardiovascular disease tendencies are closely controlled by numerous parameters which their role influenced beneficially or inversely by alteration of the ratios of certain compounds in our bio-system. Among these compounds which play a determining role on the cardiovascular disease tendencies are those controlled by the amount and type of dietary fatty acids. These are:
Impact of plasma lipids on cardiovascular disease The main components of plasma lipids are cholesterol and triglycerides. They have several nutritional roles in the human organism. Cholesterol is required to form cell membranes, steroids hormones, vitamin D, and bile salt. Cholesterol is not an essential diet because the human body can make all the required amount of it. Plasma lipids may have a harmful effect on the circulatory system. It has been established that plasma lipids (cholesterol and triglycerides) are implicated in occlusive cardiovascular disease particularly when they present in high levels in the blood. They slowly build up in the walls of arteries causing plaque and obstruction of the blood vessels in direct proportion to their concentration in the blood whereas cholesterol has the largest contribution in this event. Being insoluble in blood, most cholesterol and triglycerides are circulated in the blood to and from the cells in soluble complexes which are a fat - protein combination molecules called lipoproteins. Lipoproteins are classified by the type and ratio of the constituent protein and fats which determines their size and density. The higher the proteins portion in these molecules, the higher their density. There are several kinds of lipoproteins but the most important lipoproteins are the low-density lipoproteins (LDL) and the high-density lipoproteins (HDL). Low density lipoproteins (LDLs) are responsible for transporting cholesterol from the liver to various tissues and body cells. Low density lipoproteins (LDL) carry most cholesterol and are identified as the most important cause of atherosclerosis which is the major cause of coronary heart diseases. When too much LDL (above 160 mg/dl) is circulating in bloodstream, cholesterol and lipids carried by the LDL (bad cholesterol) start to accumulate along the interior walls of arteries causing a build-up or forming plaque that clog the arteries and this could cause heart disease leading to heart attack or stroke. High levels of LDL-c reflect an increased risk of heart disease, while lower levels reflect a lower risk. High density lipoproteins (HDLs) are large, dense protein-fat molecule that circulates in the blood, picking up the released cholesterol and lipids from tissues to the liver for recycling or disposal. HDL (the good cholesterol) help in preventing build up of cholesterol in the walls of arteries. Thus, high levels of HDL cholesterol reflect a lower risk of cardiovascular disease and the low levels of HDL (below 50 mg/dl) cholesterol indicates a greater risk. Effect of individual fatty acids on plasma lipid levels In addition to genetically determined aspects of plasma lipid metabolism, it has been found that the amount and composition of dietary fats play a crucial role in the control of plasma lipid levels. Many studies in both animals and humans have demonstrated that the intake of saturated fats particularly those with relatively high content of lauric, myristic and palmetic acids elevate LDL and total cholesterol (TC) level, while the polyunsaturated fatty acids (linoleic and linolenic) and the monounsaturated fatty acids (oleic) on the other hand lower serum cholesterol level. The several human clinical studies have shown that there is a sharp reduction in plasma lipid levels when the diet provides 5-10 % of the total calories as polyunsaturated fatty acids. Moreover, switching from diets rich in polyunsaturated fats to diets rich in saturated fats causes a marked increase in plasma lipid levels and the opposite effect is obtained when switched back to one rich in polyunsaturated fats. The explanation is that, the liver produces cholesterol from saturated fats, in addition the saturated fatty acids block receptors in the liver that remove LDL cholesterol from bloodstream, causing LDL levels to rise, while polyunsaturated acids lower the LDL synthesis and increase its breakdown. Eicosanoids Eicosanoids are a short-lived hormon-like lipid that differs from hormones in that they synthesized very rapidly by many organs in the body as and when requires. Eicosanoids is the broader term that includes prostanoids, peroxides and leukotrienes. Prostanoids is a term that includes both prostaglandins and thromboxanes. The immediate sources of eicosanoids in the human body are dihomo-gamma linolenic acid, arachidonic acid, and eicosapentaenoic acid. These fatty acids are usually lacking in the normal diet, but they can be synthesized in the body from their precursor's linoleic and alpha-linolenic acids and therefore, the essential fatty acids are indirect precursors for eicosanoids. As the eicosanoids are formed from three different sources that yield different classes of eicosanoids with different activities, they can be divided into three series with respect to their precursors. Dihomo-gamma linolenic acid yields the series-1 eicosanoids including prostaglandins PGE1, thromboxanes TXA1 and the other related compounds. Arachidonic acid is the precursor to series-2 eicosanoids that includes prostaglandins PGE2, prostacyclin PGI2, thromboxanes TXA2 and leukotrienes LTB4. Eicosapentaenoic acid yields the series-3 eicosanoids including prostaglandins PGE3, prostaglandins PGI3, thromboxanes TXA3 and leukotrienes LTB5. Physiological effects of eicosanoids Eicosanoids play an important role in a wide variety of physiological processes. Prostanoids rather than leukotrienes or the other eicosanoids are the most important derivatives of the omega-6 and omega-3 fatty acids due to their protective effects against many diseases and their involvement in many fundamental physiological functions. There are many prostanoids that have a contrary functions, but, under optimal conditions, all three forms of prostanoids must be present in optimal ratio to counterbalance each other effects to maintain a healthy blood vessel walls, a healthy clotting system, to halt atherosclerosis and the other cardiovascular disease as well as the proper functioning of cells and general metabolism and the healthy conditions of the body as a whole. Many scientists believe that the major reason for high incidence of chronic disease particularly atherosclerosis and thrombosis is the profound imbalance between the various classes of prostanoids. The main physiological effects of the various eicosanoids are shown in the following tables.
Effect of dietary fats on prostanoid balance In the cells of the body, the various types of fatty acids including saturates and monousaturates can be incorporated into the cell membranes. In the cell membrane they can partially replace each other depending on their relative dietary intake levels. Consequently, the omega-6 and omega-3 fatty acids as precursors for prostanoids will control and influence the prostanoid balance depending on their proportions in the cell membranes which is a function of their dietary intake. High ingestion of one fatty acid will cause a deficiency of the other or even the improper metabolism of itself. Thus, a balanced intake of omega-6 to omega-3 fatty acids is crucial for proper prostanoid balance. As the main sources of the omega acids in the normal diet are linoleic and linolenic oils, thus, too large consumption of linoleic oils (sunflower, corn oil) in relation to consumption of linolenic oils (soybean oil) may lead to an over production of prejudicial prostanoids and a scarcity of beneficial prostanoids. This may lead to a variety of health disturbances. The differences in chronic disease rates between the Eskimo and Western societies were explained due to the differences in dietary fat intakes. The high incidence of chronic diseases observed in the western countries were largely linked to the general population diets which are rich in saturated fats, linoleic and arachidonic acid while are deficient in linolenic and eicosapentaenoic acid. The research results of the Eskimo diet confirmed that high content of eicosapentaenoic and docosahexaenoic omega-3 fatty acids found in the cold-water fish and marine mammals that form the bulk of the Eskimo diet are responsible for the low incidence of many chronic diseases in Eskimos in spite of using a diet incredibly high in fat. Free radicals-oxidative stress and degenerative diseases The physiological damage (harm) that results from the chemical breakdown of cells or part of organism tissues via oxidation reactions is called oxidative stresses. The most common result of such oxidation reactions is the generation (within the tissues) of free radicals. Once free radicals are formed a chain reaction develops producing more free radicals. It has been concluded that free radicals are the major initiators of the blood vessel wall damage. Free radicals cause oxidative damage to plasma lipids. The oxidized low density lipoproteins (LDL) is more toxic to the vessel walls and stickier than its native form and thus increase the risk of plaque formation and a blood clot that leads to artery blockage. On the other hand the oxidative break-down products of cholesterol are strongly toxic to the endothelium (the inner layer of the blood vessels) and thereby can increase the atherosclerotic incidences. The oxidative damage to the constituent compound of the cell and the various oxidation products resulted by the oxidative activity of the free radicals leads to destructive and toxic damage to the cells. Also the oxidative damage to the membrane lipids and the membrane enzymes of the prostanoid pathways can shift the prostanoid balance toward proinflammatory and pro-atherosclerotic and the other harmful patterns. All of these processes may contribute to the development of various degenerative diseases including cardiovascular diseases, atherosclerosis, thrombosis, heart failure and cancer. Free radicals result naturally from normal metabolism in cells, but exposure to sunlight, x-rays and carcinogens promote their formation. In the body, the free radicals normally are eliminated by antioxidant factors including scavenging enzymes, vitamin C and E as well as the enzymes mineral cofactors such as selenium and zinc. However, when the oxidants such as polyunsaturated fatty acids are ingested at high doses, the produced amount of these defenders (within the body) is not sufficient to scavenge all of the free radicals which may be formed, thus, the high intake of these fatty acids should be undertaken in conjunction with a sufficient intake of antioxidants. The most common dietary sources of free radicals are frying food, precooked meat products, dried dairy and egg products, oils and fats including margarines and shortenings and any food with substantial content of rancid fats. The nutritional aspects of vitamin E Based on the above illustration, attention must be drawn to possible adverse effect arising from the oxidation of the membrane polyunsaturated fatty acids and the recycling plasma lipids. To unfold their health benefits, they must be protected from oxidation by using antioxidants both in the diet and in supplement. For this purpose, the most commonly used naturally occurring antioxidants are vitamin E. The relevant studies indicate that vitamin E can offered the following beneficial effects:
All of these properties help protect against cardiovascular diseases and cancer and enhance many of the fundamental body functions. The U.S. Food Nutrition Board, recommend the intake of 8-9 mg of alpha-tocopherol equivalent / day for adults. Specific nutritional functions of soybean oil It is become increasingly clear, that the quality of oils and fats lies in their essential fatty acid content and their proportions (n6/n3 or omega 6 / omega 3 ratio), saturates to polyunsaturates ratio (S/P), monounsaturates to polyunsaurates ratio (M/P) and the antioxidant to oxidant balance. The recommended (n6/n3) ratio is 4-7/1, the S/P is 0.7-1/1 and the M/P is 1-1.5/1 and 0.6 mg alpha-tocopherol / gram polyunsaturated fatty acids ingested. Soybean oil includes 53.2% linoleic acid, 7.8% linolenic acid, about 24% oleic acid and about 15% saturated fatty acids. As it can be observed, it is a rich source of essential fatty acids, both linoleic and linolenic acid and it is unique among edible oils in their optimal n6/n3 ratio which is slightly under 7/1. The U.S. National Institute of Health recommends a total daily intake of 4.44g/day of linoleic acid, and 2.22 g/day linolenic acid. However, in any case, a table-spoon (14 gr) serving of soybean oil would provide the requirements. Normally, the remaining tocopherol content in refined soybean oil is about 7 mgr/100 gr oil, but usually the oil is conditioned prior to packaging to contains about 10 mg/100 gr oil of vitamin E as antioxidant and such content is sufficient to protect the ingested polyunsaturated fatty acids from oxidation prior to their metabolism. On the other hand, a single serving of such product would supply about 17.5% of vitamin E daily requirement. All of these nutritional advantages of soybean oil composition are an important key to prevent cardiovascular diseases by lowering plasma lipids levels through reducing the low density lipoprotein (LDL) synthesis and increasing its break-down by the effect of existing polyunsaturated acids on the related bio-mechanisms. In addition, linolenic acid reduces the plaque and the clot formation by decreasing platelet aggregation promoting the synthesis of series- 3 prostaglandins. On the other hand, linoleic acid shifts the prostanoid pathway toward the beneficial prostanoids balance which helps prevent the abnormal health conditions. O'Keefe, James IL,Jr,M.D., et al., Vitamin E and Risk of Coronary Disease, New England Journal of Medicine, Nov. 4,1993;1424. Heart-Healthy Ingredient Found in Vegetable OilA new science advisory from the American Heart Association (AHA) concludes that omega-6 fatty acids may decrease risk for heart disease when part of a healthy eating plan. Omega-6s are essential polyunsaturated fatty acids naturally-occurring in soybean oil, nuts, and seeds. These findings dispel debate that omega-6s may cause inflammation leading to heart disease, the nation's number one killer. Circulation, an AHA journal, published the findings that diets rich in omega-6 fatty acids prove to be heart healthy. Dr. William Harris, Ph.D., and colleagues from the Sanford School of Medicine at the University of South Dakota, felt it was important to objectively evaluate reports that omega-6s promote inflammation and thus may increase heart disease risk. In a statement from AHA, Dr. Harris says, "That idea is based more on assumptions and extrapolations than on hard data." While an acid that causes early stages of inflammation may be formed from omega-6s, they also produce anti-inflammatory properties--particularly in the lining of blood vessels--that are much stronger. After reviewing results of more than two dozen controlled and observational studies, Dr. Harris determined that participants in the controlled trials consuming diets higher in omega-6s had less incidence of heart disease than those whose omega-6 intake was low. A meta-analysis of several trials indicated that replacing saturated fats with omega-6 lowered heart disease risk by 24 percent. Soybean oil is about 50 percent omega-6 fatty acids, one of the most concentrated sources, while olive oil and canola oil are both low in omega-6s. Soybean oil is commonly labeled vegetable oil in the grocery store--check the ingredients label to be sure. "The news that soybean oil may lower heart disease risk when replacing oils with higher levels of saturated fat is especially important," says Lisa Kelly, RD, MPH, of the United Soybean Board. The advisory recommends Americans aim for 5 percent to 10 percent of their daily calories from omega-6 fatty acids. The recommended daily intake of omega-6s ranges from 12 grams to 22 grams depending on age, gender, and physical activity. References
For further information on the ASA-IM Middle East Soy Oil Program, you may contact: |
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