Saturated fatty adds dietary

Chamock, J.S. (1 1) Omega-3 and omega-6 PUFA s have different effects on the phospholipid fatty acid composition of rat myocardial muscle when added to a saturated fatty add dietary supplement. Nutr. Res. 11, 1013-1024. 

A typical American diet contains about 40% of its total energy content as fat. About half this energy is in the form of saturated fatty adds, one-fourth as monounsatu-rated fatty acids, and one-fourth as pol5nmsaturated fatty acids (PUFAs) (Ginsberg et al, 1990). The quantity and nature of dietary fats can influence the level of plasma cholesterol. A reduction in total fat from the t3q>ical 40% of energy intake to 30% can result in a decrease in plasma cholesterol. 

The present data suggests that the normal dietary intake of saturated fatty adds that conditioned our species genome likely fell between 10 to 15% of total energy, and that values lower than 10% or higher than 15% would have been the exception rather than the rule. Consequendy, population-wide recommendations to lower... 

Absorption of fatty adds in the small intestine follows a complex process that varies in efficiency depending on certain qualitative characteristics of dietary fat. Unsaturated fatty acids tend to be absorbed at a higha- effidraicy than saturated fatty adds. Fatty acids with slO carbons are directly absorbed into the portal drculation, while fatty acids with al2 carbons are absorbed into the lymphatic system packaged as chylomicrons. Fat digestion products incorporated into micelles occur largely through passive diffusion. Absorption of micellar components into intestinal mucosal cells depends on the penetration of the micelles across the unstirred water layer that separates the intestinal content from the brush border of the small intestine. ... 

Palmihc add (16 0) iS the primary saturated fatty acid in most diets. This compound constitutes about 25% of the fatty acids of beef or pork fat, but only 6-10% of Ihc fatly acids of sunflower, safflower, peanut, or soy oils (see Table 6.8). Dietary palmitic add increases LDL-cholesterol (Grundy and Denke, 1990), Myrislic acid (14 0) is present at high levels in butter fat and in the "tropical oils" palm oil and coconut oil. Although myristic add elevates LDL-cholesterol, it is generally a rather minor component of the diet. Stearic acid (18 0) is also a major component... 

Note Percentage of recommended dietary allowances (RDA) is based on a 2000 kcal diet SFA, saturated fatty acids MUFA, monounsaturaled fatty acids PUFA, polyunsaturated fatty adds. 

Various dietary fats (lipids) and fatty adds total fats, saturated fats, and cholesterol medium-chain triglycerides omega-3 and omega-6 fatty adds conjugated linoleic acid (CLA) and wheat germ oil and octacosanol... 

Figure 1 Fatty-acid structure and nomenclature. (A) Chemical formula and carbon atom numbering system for a 16-carbon saturated fatty acid (16 0). (B) Schematic representation of 16 0. (C) A monounsaturated fatty add, 18 1n-9, showing the double bond nine carbon atoms from the methyl end (carbon 18). (D) The essential n-6 fatty acid 18 2n-6, where the first double bond is found six carbon atoms from the methyl end. The two double bonds are separated by a methylene (-CH2-) group. (E) The essential n-3 fatty acid 18 3n-3, where the first double bond is found three carbon atoms from the methyl end. (F) Phytanic acid, a dietary / -methyl-branched-chain fatty acid (3,7,11,15-tetramethyl 16 0). The melhyl group on carbon 3 prevents this fatty acid from degradation by /3-oxidation. (G) Pristanic acid (2,6,10,14-tetramethyl 15 0) is the product of phytanic acid o-oxidation, in which a single carbon (carbon 1) is lost. The methyl group on carbon 2 does not preclude subsequent degradation by /3-oxidation.

For adults, based on the Acceptable Macronutrient Distribution Range, the lOM recommmds a range of 20 to 35% of total calorie intake to be ingested as fat. Low intake of fats may increase the risk of inadequate intakes of essential fatty acids such as linoleic add and a-linolenic acid, and vitamin E. In addition, low-dietary-fat intake may have a potmtial adverse affect on lipid profiles due to increased carbohydrate intake often assodated with low-fat diets. Therefore, the NCEP reconunends a lower limit of 25% for individuals with elevated plasma cholesterol concentrations, established cardiovascular disease, and more than one major risk factor. On the other hand, an upper level intake of total fat, i.e., approximately 35% of total calories, is assodated with increased calorie and saturated fat intake. In individuals with lipid or metabofic disorders, total fat intakes should not be extreme... 

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