Essential fatty adds

The RDA for the essential fatty acids is 1 to 2% of total energy intake. Generally, between 5 and 10% of our energy intake consists of EFAs. Because of our ample intake of fat, a deficiency in EFAs is quite rare. The biochemical steps in the modification of nonessential fatty acids, such as oleic add, and essential fatty adds (linoleic add and linolenic acid) are generally the same. These steps include elongation and desaturation. Modification of fatty adds by their repeated desatu- 

In addition to chain elongation, fatty acids are modified by the introduction of double bonds (desaturation). Enz5maes, called desaturases, catalyze the synthesis of unsaturated fatty acids. They can use saturated or partially unsaturated fatty acids as substrates. A -Desaturase, for example, catalyzes the introduction of a double bond between carbons 9 and 10 of a fatty acid (covmting from the carboxylic acid end). Three examples of reactions of A-desaturases are shown in Figiue 9.95. 

Mammalian desaturases can introduce double bonds into fatty acids only between carbon-10 and the carboxyl carbon. In contrast, plants can produce linoleic acid, which has double bonds between carbons 9 and 10, and between carbons 12 cmd 13. Plants also synthesize linolenic acid, which has double bonds between carbons 9 and 10, carbons 12 and 13, and carbons 15 and 16. 

Linolenic acid is abbreviated as 18 3A 2 i or 18 3co3. The number before the colon indicates the total number of carbon atoms in the fatty acid. The number after the colon indicates the number of double bonds. According to the delta terminology, the superscripts indicate the carbon numbers at which a double bond occurs (counting from the —COOH end). According to the omega terminology, the num- 

CHjCHjCHjCHjCHjCH = CHjCHjCH = CHCHjCHjCHjCHjCHjCH CHjCOOH (linoleic acid 18 2A 18 2 u6l -Des8turase 

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Essential fatty adds in foetal and neonatal development... 

A normal diet may not provide sufficient essential fatty adds to satisfy proliferation in trauma or infection, so that they are mobilised from adipose tissue. Muscle protein is broken down in trauma even on a normal diet (Chapter 18). 

Figure 20.3 Essential fatty acids in the diet, production of physiological essential acids and their roles in the cell cycle. Essential fatty adds in the diet are mainly linoleic and a-linolenic but they are converted by desaturation and elongation reactions to the essential acids that are used in phospholipid formation and synthesis of eicosanoids. (For details of the elongation and desaturation reactions and eicosanoid formation, see Chapter 11.).

Essential Fatty Adds, Physiology and Clinical Significance of... 

Vincent JE, and Zijlstra FJ. (1978). Formation by phospholipase A2 of prostaglandins and endoperoxides in platelets of normal and essential fatty add-defident rats. Adv. Prostaglandin Thromboxane Res. 3,143-146. 

Step 1. An excess of dietary energy somehow provokes the production of prostaglandin ]2 within the pre dipocyte (Forman et ai, 1995). The biosynthetic pathway of PGJj from arachidonic acid is outlined in Figure 7.11. Prostaglandins are detailed in the Essential Fatty Add section. 

A, Vitamin and ITiynoid Hormone at the Genome, and in the Essential Fatty Add section. 

Farrell, F M., Gutcher, G. R, Palla, and DeMets, D. (1988). Essential fatty add deficiency in premature infants Am. J. Clin. Nutr. 48, 220-229. 

Vtamin E, Antioxid ts, and Atiteiosclerosis Essential Fatty Adds... 

Richardson, T. J., and Sgoutas, D. (1975). Essential fatty add defidency in foru adult patients during total parenteral nutrition. Am.. Clin. Nutr. 28,258-263. 

A. Pancreatic lipase catalyzes the breakdown of dietary triacylglycerols into free fatty acids and 2-monoacylglycerols, an essential step in the digestion of dietary lipids. Since prostaglandins are produced from linoleate, an essential fatty add, a deficiency of pancreatic lipase would eventually cause a prostaglandin defidency. 

Das VN, Vaddadi KS (2004) Essential fatty adds in Huntington s disease. Nutrition 20 942-947... 

Schneider P, Hampel H, Buetger K (2009) Biological marker candidates of Alzheimer s disease in blood, plasma, and serum. CNS Neurosci Ther 15 358-374 Simopoulos AP (2002) The importance of the ratio of omega-6/omega-3 essential fatty adds. Biomed Pharmacother 56 365-379... 

Essential Fatty Adds Then and Now Howard Sprecher... 

Simopoulos, A.P. (2001) Evolutionary Aspects of Diet and Essential Fatty Adds, World Rev. Nutr. Diet 88,18 27. 

Bezard, J., Blond, J.P., Bernard, A., and Clouet, P. (1994) The Metabolism and Availability of Essential Fatty Adds in Animal and Human Tissues, Reprod. Nutr. Dev. 34,539-568. 

Source of calories and essential fatty adds for parenteral nutrition... 

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