الفهرس 
Chapter 1: Essential Fatty AcidsOnly 14 pages are availabe for public view
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Abstract
Omega-3 and omega-6 are polyunsaturated essential fatty acids which can’t be constructed by the body and must be obtained throughdiet. Sources of omega-3 (linolenic acid, eicosapentaenoic acid and docosahexaenoic acid) include fish and flax (eg. Fish oil) and sources of omega-6 (Linoleic acid) account for majority of polyunsaturated fats inthe food (eg. Corn oil).
Metabolism of omega-3 and omega-6 requires the same desaturation enzymes resulting in competition between the two families.Consumed omega-3 fatty acids partially replace omega-6 in the membranes of all cells. Eicosanoids from both families have opposing effects. Arachidonic acid and eicosapentaenoic acid are the parent compounds for the production of eicosanoids.
The anti-inflammatory properties of omega-3 are due to competition with AA as a substrate for cyclo-oxygenase and 5-lipooxygenasefor eicosanoids production. In addition to their effects on prostaglandins, thromboxanes and leukotrienes, omega-3 fatty acids alter gene expression (eg., suppress the production of IL-1ß by suppressing theIL-1ß mRNA)
Omega-6 eicosanoids are generally pro-inflammatory and omega-3 eicosanoids are much less so. Linoleic acid increases pro-inflammatory cytokine secretion, whereas fish oil reduces pro-inflammatory cytokine secretion. Incorporation of omega-3 fatty acids modifies inflammatoryand immune reactions, making omega-3 fatty acids potential therapeuticagents for inflammatory and autoimmune diseases.
Polyunsaturated fatty acids are vitally important structural elementsof cellmembranes and essential for formation of new tissues.
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Fetus andinfants are unable to convert enough α-lionlenic acid and are dependenton maternal supply. The human milk provides all dietary essential fattyacids.
Docosahexaenoic acid is a predominant structural fatty acid in theretina and brain and is critical for optimal brain health and function at alleges. Omega-3 is important for brain and emotional health, neurological function, better developmental milestones and intelligence quotient.
Eicosapentaenoic acid and docosahexaenoic acid have powerful model evading and stabilizing qualities and help to overcome many psychiatric disorders as schizophrenia, childhood autism.
Omega-3 fatty acids have cardioprotective effect, important for digestive tract health, bone and joint health, eye health, and play an important role in immune system maturation.
Omega-3 supplementations can improve many symptoms of cysticfibrosis, promotes respiratory health and function and decreases the prevalence of asthma. Also, it is helpful in treatment of acute respiratorydistress syndrome, ocular diseases, irritable bowel disease, IgA nephropathy, nephrotic syndrome, chronic renal failure and type 1 diabetes mellitus. Topical omega-3 application can benefit many dermaldiseases as psoriasis, eczema and atopic dermatitis. Epidemiological studies have shown a reduced incidence of cancer in populationsconsuming high levels of dietary fish.
Humans evolved on a diet in which the omega-6/omege-3 ratio wasabout 1.Over the past 150 years this balance has been changed. Current estimates in Western cultures suggest a ratio of 10–20:1 instead of 1–4:1.
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Many cause as agribusiness and modern agriculture have led to decreases in omega-3 fatty acids and increases in omega-6 fatty acids
Omega-6 fatty acids are important in the diet but should be consumed in equal or lesser proportions as omega-3.as their Imbalance in the diet leads to a pro-inflammatory response.also a high omega-6:omega-3 fatty acid ratio increases theexpression of genes that lead to inflammation which isat the base of CHD, Obesity, Diabetes, Cancer and other chronic diseases
Excessive intake of omega-6 fatty acids produces an imbalance ofomega-6 to omega-3 fatty acids which changes the physiological state topro-thrombotic, pro-constrictive, and pro-inflammatory one. The balance ofomega-6/omega-3 fatty acids is an important determinant in decreasing the risk for coronary heart disease. Increased dietary intake of linoleic acid leads to oxidation of LDL, platelet aggregation, and interferes with the incorporation of eicosapentaenoic acid and docosahexaenoic acid in cell membrane phospholipids increased risk of atherosclerosis andcoronary artery disease.
Inflammation is at the base of many chronic diseases which are multigenic and multifactorial. Dietary intake of omega-3 may prevent thedevelopment of such diseases. Studies show that background diet, whenbalanced in omega-6/omega-3, decrease the drug dose and improve thepatient condition. Many chronic diseases (DM, rheumatoid arthritis…etc)are associated with increased production of TXA2, LTB4, IL-1b, IL-6,TNF, and C-reactive protein. These factors increase by increases inomega-6 intake and decrease by increases in omega-3 intake
Thecompetition that exists between omega- 6 and omega-3fatty acids applies to their balance being critical for braindevelopment and structural integrity. DHA is essential for vision, brain neurons, and cell
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signaling. While DHA isclearly concentrated in the signaling systems of the brain.
EPA is more likely to be involved in vascular blood flow andeicosanoid production where it can down-regulate the AA metabolites to maintain homeostasis. The most common Egyptian oils rich with omega fatty acids are cotton seed, sunflower, corn, olive, canola, soybean,linseed, and palm oil.
Finally: we conclude that omega-3 and omega-6 fatty acids areimportant to human health and the optimal ratio of omega-6/omega-3 is from 1-4/1. There is a need to return to a more physiologic omega-6/omega-3 ratio of about 1-4/1 by decreasing the intake of omega-6 fromvegetable oils and increasing the intake of omega-3 by using oils rich inomega-3 fatty acids and increase the intake of oily fish (eg., mullet, tunaand sardine) to 2-3 times/week or take supplements. Breast feeding ismandatory to all infants, or DHA and AA enriched formula when breastfeeding is not available. Omega-3 fatty acids can be used in treatment ofmany diseases.