Dietary monounsaturated fatty acids

The most common dietary fatty acids are the saturated long-chain fatty acids palmitate (C16) and stearate (C18), the monounsaturated fatty acid oleate (C18 l), and the polyunsaturated essential fatty acid, linoleate (C18 2) (To review fatty acid nomenclature, consult Chapter 5). Animal fat contains principally saturated and monounsaturated long-chain fatty acids, whereas vegetable oils contain linoleate and some longer-chain and polyunsaturated fatty acids. They also contain smaller amounts of branched-chain and odd-chain-length fatty acids. Medium-chain-length fatty acids are present principally in dairy fat (e.g., milk and butter), maternal milk, and vegetable oils. 

Dietary fatty acids will influence the cardiac phospholipid composition of the rat but to a lesser extent than the cardiac neutral lipids (Carroll, 1965). Dietary fatty acids may be incorporated as saturated and monounsaturated fatty acids, or they may be incorporated and converted to more polyunsaturated fatty acids (PUFA), i.e., linoleic acid to 20 4 n-6, 22 4 n-6, and 22 5 n-6 and linolenic acid to 20 5 r/-3, 22 5 n-3, and 22 6 n-3 (see Chapter 16). Dietary saturated and monounsaturated fatty acids are incorporated to a small extent into cardiac phospholipids (Carroll, 1965). On the other hand, dietary 18 2 n-6 and 18 3 n-3 cause a significant increase in the pentaenoic and hexaenoic acids which is greater in the heart than in any other organ of the rat (Rieckehoff et aL, 1949 Widmer and Holman, 1950). With this background it may be useful to discuss changes in the composition of the different cardiac phospholipids with diet. 

Printing Office, 2010. EFSA. Scientific opinion on Dietary Reference Values for fats, including saturated fatty acids, polyimsaturated fatty acids, monounsaturated fatty acids, trans fatty acids, and cholesterol. EFSA Journal. 2010,8(3) l46l. 

Medical evidence correlates a diet high in saturated fats with hardening of the arteries (atherosclerosis) and possible heart attack. Table 22.2 lists the percentage of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids in some common dietary fats and oils. This table compares human depot (storage) fat with butter and margarines, then with several vegetable oils. 

See also Antioxidants Diet and Antioxidant Defense Observationai Studies Intervention Studies. Coronary Heart Disease Lipid Theory. Dietary Fiber Role in Nutritional Management of Disease. Fatty Acids Monounsaturated Omega-3 Polyunsaturated Omega-6 Polyunsaturated Saturated. Fish. Folic Acid. Potassium. Sodium Physiology Salt Intake and Health. Vegetarian Diets. 

Whether or not increased intake of n-6 fatty acids can exacerbate inflammation via increased production of proinflammatory eicosanoids remains uncertain. Results of in vitro studies and intervention studies in humans are generally consistent with this theoretical potential of n-6 fatty acids to enhance inflammation, at least in comparison to n-3 fatty acids and probably n-9 monounsaturated fatty acids. The importance of absolute and relative intakes of n-6 fatty acids to inflammatory processes also remains unclear. The effects of changes in n-6 fatty acid intake on inflammatory processes may depend on the background dietary fatty acid intake, as well as proportional and absolute intake of n-3 fatty acids. 

The diets were a measured, laboratory-controlled diet based on ordinary foods. Fats provided 30% of the dietary calories. Saturated to monounsaturated to polyunsaturated fatty acid ratios are listed below each test fat. 

The fatty acids are a family of long-chain carboxylic acids that may be saturated, monounsaturated, or polyunsaturated. Several fatty acids are essential components of the human diet. Dietary intake of fats has important implications for health and well-being. 

The effects of dietary lipids on human health are complex. However, in general dietary terms, monounsaturated fatty acids are considered to be more healthful than saturated fatty acids. A lot of people, concerned about their health, have decreased their dietary intake of butter in favor of olive oil or vegetable oils. 

The fat from an animal or plant is a mixture of different fat molecules having various degrees of unsaturation. Fat molecules containing only one carbon-carbon double bond per fatty acid chain are monounsaturated. Those containing more than one double bond per fatty acid chain wee polyunsaturated. Table 13.1 on page 442 shows the percentage of saturated, monounsaturated, and polyunsaturated fats in a number of widely used dietary fats. 

Jerusalem artichoke tubers contain little or no starch, virtually no fat, and have a relatively low calorific value. Of the small amount of fat present, trace amounts of monounsaturated and polyunsaturated fatty acids have been reported, but no saturated fatty acids (Whitney and Rolfes, 1999). The polyunsaturated fatty acids linoleic (18 2 cis, cis n-6) and a-linoleic acid (18 3 n-3) have been recorded as present at 24 mg and 36 mg-100 g 1 of raw tuber, respectively (Fineli, 2004). The tubers are a good source of dietary fiber, because of the presence of inulin. 

Ertas et al. (2005) investigated the potential effects of dietary supplementation by coriander seed (considered as a lipolytic and antioxidant compound) on carcass lipid composition of quails. Their aim was to reduce saturated fatty acid consumption and to increase essential fatty acids (particularly n3 unsaturated acids) in alimentation. Dietary supplementation by coriander seed affected the lipid composition of carcass greatly by decreasing saturated fatty acid (SFA) contents (palmitic and stearic acids) and by increasing monounsaturated and polyunsaturated fatty acid (MUFA and... 

Dietary MUFA have been found to have several positive effects that include, in addition to lowering human LDL-cholesterol plasma levels, positive effects on lipoprotein oxidation, coagulation, and fibrinolysis (29). Low-fat, monounsaturate-rich diets reduce the susceptibility of low-density lipoproteins to peroxidation ex vivo (30). In hypercholesterolemic subjects, diets containing MUFA resulted in favorable alterations in the fatty acid composition and oxidative profile of LDL in hypercholesterolemic subjects that were characterized as an increase in lipid peroxide lag time and a decrease in lipid peroxide formation (30). In animal studies. 

The current interest in dietary fat, however, stems primarily from its implication in the origin of several chronic diseases. Interest has centered on both the amount and type of dietary fat in the development of cardiovascular disease, cancer, hypertension, and obesity. As a result, dietary recommendations in many countries call for a reduction in total fat intake, to 30% of energy, and in saturated fat intake, to less than 10% of energy. In addition, some nutrition recommendations specify recommended levels of n-6 and n-3 fatty acids in the diets. Hence, the source of fat in the diet has assumed considerable importance over the past few years. Interest in the nutritional properties of canola oil developed because of its fatty acid composition (Table 2). Canola oil is characterized by a low level of saturated fatty acids, a relatively high level of monounsaturated fatty acids, and an appreciable amount of the n-3 fatty acid ot-linolenic acid (18 3 n-3). 

There, also, is interest in dietary monounsaturated fatty acids because of their possible protective effect against oxidation of LDL cholesterol (101). There is appreciable evidence that the uptake of LDL cholesterol and the formation of fatty streaks in the intima of large blood vessels, which is considered an early lesion of atherosclerosis, is enhanced by the oxidation of the LDL cholesterol (102, 103). LDL cholesterol was found to be appreciably more stable to oxidation when subjects were fed diets rich in oleic acid than when fed linoleic acid enriched diets (104-106). 

Appreciable research on the effect of canola oil on plasma cholesterol and lipoproteins has been reported. The primary impetus for this research was the finding that dietary monounsaturated fatty acids were as effective as polyunsaturated fatty acids in lowering plasma total and LDL cholesterol (100, 109). These findings also provided a possible explanation for the observation that canola oil was as effective as soybean oil in lowering plasma cholesterol in normolipidemic men (110). Prevailing theory had held that saturated fatty acids raised plasma cholesterol, polyunsaturated fatty acids lowered plasma cholesterol, and monounsaturated fatty acids were neutral, they neither raised nor lowered plasma cholesterol (111, 112). 

Intestinal Handling of FFA In the cells of the small intestine, several enzymes can act on free but not on esterified fatty acids. In contrast to MAGs, FFA are diluted with fatty acids originating from the plasma free fatty acid pool (44). After activation they can be oxidized, elongated, chain desaturated, and converted into complex lipids (45, 46). The relative rates depend on the nature of the fatty acids and on the presence of other components in the intestinal cells (47). Conversion of saturated fatty acids in monounsaturated ones when they are absorbed as FFA, i.e., when they were present in the outer position of the dietary TAGs, could... 

LDL-cholesterol ("bad cholesterol") is reduced when saturated fats are replaced with FUFAs or w ith carbohydrates. Howev er, HDLsaturated fats arc replaced with FUFAs or with carbohydrates. These responses indicate that dietary monounsaturates may be of more value than FUFAs or carbohydrates. However, this statement should be vici cd with caution because it has not been established that an elevated HDLhumans prevents formation of atherosclerotic lesions and cardiovascular disease. High levels of saturated fatty acids in dietary fats are a risk factor for cardiovascular disease. The percentage of energy derived from fat is recommended to be reduced to 30%, but not much below this level. 

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