September 27, 2011
fatty acids and human health
have been 1643 times read 2009-10-4 11:12Personal Category: UncategorizedSystem Category: Research NotesKeywords: monounsaturated fatty acids, polyunsaturated fatty acids, trans fatty acids, conjugated linoleic acid, fatty acids in health 1 classification is a long hydrocarbon fatty acids chain and a carboxyl-terminal of the organic compounds in general. About 40 kinds of fatty acids in nature, but can be absorbed by the body but only an even number of carbon atoms of fatty acids, fatty acids contained in the human body is usually 14-24 carbon atoms, only the retina exception, with up to 36 carbon atoms, fatty acids . Fatty acids under saturated and unsaturated hydrocarbon chain can be divided into three categories, namely: saturated fatty acids (saturated fatty acids, SFA), unsaturated hydrocarbon is no key; monounsaturated fatty acids (Monounsaturated fatty acids, MUFA), the unsaturated hydrocarbon chain with a key; polyunsaturated fat (Polyunsaturated fatty acids, PUFA), the hydrocarbon chain has two or more unsaturated bonds. Animal fat, mainly saturated fatty acids. Solid at room temperature, while oils are mainly unsaturated fatty acids, usually liquid at room temperature. Fatty acids according to the different carbon chain lengths can also be divided into short-chain fatty acids (short chain fatty acids, SCFA), the carbon chain of less than 6 carbon atoms, also known as volatile fatty acids (volatile fatty acids, VFA) ; medium-chain fatty acids (Midchain fatty acids, MCFA), refers to the carbon chain of 6-12 carbon atoms of fatty acids, the main ingredient is bitter (C8) and capric acid (C10); long-chain fatty acids (Longchain fatty acids, LCFA) , the number of carbon atoms on the carbon chain greater than 12. There are essential fatty acids and fatty acids of non-essential points, essential fatty acids (essential fatty acid, EFA) is the body itself can not indispensable to the synthesis of fatty acids must be supplied through food. Unsaturated fatty acids generally contain one or two or more double bonds, double bonds are always separated between a methyl, the main body of the double bond configuration of these two types, namely, cis-fatty acids and trans fatty acids (Table 1) , cis-fatty acid (Cis-form fatty acids, cis-) to the natural plant and animal fatty acid form. Trans fatty acids (Trans fatty acids, Trans-) trans double bond formation is usually caused because β-oxidation and cis-double bond rearrange oil processing (hydrogenation process that aims to reduce the degree of unsaturation), some of the gastrointestinal microorganisms within the trans double bonds can also be synthesized fatty acids. Trans fatty acids also include monounsaturated trans fatty acids and polyunsaturated trans fatty acids. The structure of the different fatty acids, functions are not the same, some special features of their nutrition research is an important area of ??research and development. Currently considered the most nutritional value of fatty acids there are two types: ① n-3 series polyunsaturated fatty acids, the number from the methyl end of the first unsaturated bond in the third and fourth carbon atoms of various unsaturated fatty acids; ② n-6 series polyunsaturated fatty acids, the number from the methyl end of the first carbon double bond between the sixth and seventh.
Table 1.1 common fatty acids
Table1.1 The familiar fatty acids butyrate code name (butyric acid) C4: 0 hexanoic acid (caproic acid) C6: 0 acid ( caprylic acid) C8: 0 decanoic acid (capric acid) C10: 0 Lauric acid (lauric acid) C12: 0 myristic acid (myristic acid) C14: 0 palmitic acid (palmitic acid) C16: 0 palmitic acid (palmitoleic acid) C16: 1, n-7cis stearic acid (stearic acid) C18: 0 acid (oleic acid) C18: 1, n-9cis anti-oleic acid (elaidic acid) C18: 1, n-9trans linoleic acid (linoleic acid ) C18: 2, n-6, 9, all cis a-linolenic acid (a-linolenic acid) C18: 3, n-3, 6,9, all cis r-linolenic acid (r-linolenic acid) C18: 3 , n-6, 9,12 all cis arachidic acid (arachidic acid) C20: 0 arachidonic acid (arachidonic acid) C20: 4, n-6, 9,12,15 all cis eicosapentaenoic acid (timnodonic acid, EPA) C20: 5, n-3, 6,9,12,15 all cis sinapic acid (erucic acid) C22: 1, n-9 cis docosahexaenoic acid (docosahexenoic acid) C22: 6, n-3, 6,9,12,15,18 all cis twenty-four carbon single acid (nerve acid) (nervonic acid) C24: 1, n-9 cis 2 have a major impact on human health of fatty acids
2.1 monounsaturated fatty acids (MUFA) Monounsaturated fatty acids (MUFA) in the carbon chain containing only one unsaturated double bond, MUFA can lower plasma total cholesterol (TC) and low density lipoprotein (LDL) levels, but triglyceride (TG) level is not elevated, high-density lipoprotein (HDL) levels have increased. MUFA in reducing the risk of coronary heart disease has great significance. It is mainly on blood coagulation, blood pressure, lipids and other aspects of regulation which affect the incidence of coronary heart disease.
2.1.1 MUFA on blood coagulation
The first is the impact on endothelial cell function, endothelial cells through the release of vasodilator and vasoconstrictor substances to regulate vascular tone , endothelial cells secrete a variety of metabolites and blood coagulation, blood protein, fiber dissolution, adhesion and so on. MUFA can affect different substances on the arterial wall in atherosclerosis play a role in the process. Experiments confirmed that the lipid in the oleic acid can be selectively adsorbed in the arterial intima of mononuclear cells, reducing the types of endothelial leukocyte adhesion molecule expression. Oleic acid also reduced the mRNA of these cells, interfere with an important transcription factor-κB activity, the factor can control the activity of endothelial cells. MUFA prevention of atherosclerosis may be due to its improved endothelial leukocyte adhesion molecule gene expression. In a determination of LDL-induced inhibition of copper ion experiments, MUFA-rich food group, the maximum inhibitory effect. The intake of MUFA phase, LDL induced monocyte adhesion to endothelial cells is higher than the control group. Tsimikas et al [1] experiments show that, MUFA may be inhibition of LDL to the early inflammatory substances into, so to achieve minimal modification of LDL. Another experiment showed that: MUFA reduces the plasma von Willebrand factor, tissue factor pathway inhibitor increased (TFPI) and tissue-type plasminogen activator levels, and these substances are derived from endothelial cells. Hypercholesterolemia in patients with endothelial cell dysfunction or lack of occurrence of atherosclerosis is a major reason. Diet is the basis for treatment of hypercholesterolemia, dietary therapy to restore normal endothelium-dependent expansion. Studies have shown that high intake of MUFA in the diet during the expansion of endothelium-dependent significant increase in blood levels of P-selectin decreased, indicating that high-MUFA diet can lower LDL levels by endothelial cells, vascular endothelium-dependent for expansion, reduce the P- selectin. Smooth muscle cell proliferation in atherosclerotic injury has an important role, experiments show that the intake of MUFA period [2], LDL oxidation modification significantly enhanced the amount of thymidine incorporation into DNA was significantly reduced, so that the rich MUFA diet can reduce the smooth muscle cells.
Second, the effects on coagulation, thrombosis is one of the clinical symptoms of coronary heart disease, and platelet aggregation, blood coagulation and blood protein dissolved in the combined effect of fiber formation of blood clots. MUFA reduces collagen-induced platelet aggregation and coagulation process impact. There are data to show that MUFA reduce thrombus formation factor FV Ⅱ level [3], but there are also no effect on the FV Ⅱ factor reported [4]. There experiments suggest that MUFA reduce tissue factor in mononuclear cells [5].
MUFA dissolved in the blood also affect the fiber protein. In the process of thrombosis, blood protein solution has an important role in fiber, fiber dissolved by tissue-type plasminogen activator and inhibitor to achieve a balance between regulation. Experimental results show that intake of MUFA-rich diet led to reduced plasma concentrations of inhibitors, suggesting that increased activity of serum soluble fiber protein. There are experiments that are rich in MUFA Mediterranean diet can prevent thrombosis [6].
2.1.2 MUFA on blood pressure [7-8]
MUFA have lower blood pressure, both systolic and diastolic blood pressure decreased 3% to 9%. MUFA can lower the risk of coronary heart disease by 27%, for the prevention of hypertension provides a nutritional approach. Cardiovascular disease mortality in Mediterranean countries than in the U.S. is low, the diet rich in MUFA may be relevant [9]. Its mechanism is not yet clear, the MUFA diet may affect endothelial cell function, including regulation of endothelial-dependent vasomotor function.
2.1.3 MUFA on blood lipids
LDL oxidative modification of atherosclerosis is the initial reason, when the LDL particle concentration is high in MUFA, the LDL oxidation sensitivity is reduced [10]. Baroni on hypercholesterolemia and other studies show that [11]: MUFA content and is not susceptible to oxidative modification of LDL. Some people think that olive oil may be associated with anti-LDL oxidation of polyphenolic compounds containing the [12-13]. The study confirmed some of the peanut oil [14]: rich in MUFA peanut oil may reduce plasma concentrations of LDL, increased HDL concentrations, which can reduce the incidence of coronary heart disease risk of 18.4% to 21.7%.
2.2 polyunsaturated fatty acids (PUFA)
polyunsaturated fatty acids have a wide range of important biological functions, PU FA including n-3, n-6 and n -9 series fatty acids. But there is a biologically important n-3 and n-6 ??PU FA. One of the linoleic acid (LA) and a-linolenic acid (a-LNA) essential fatty acids in human (EFA), which are n-6 and n-3 polyunsaturated fatty acids (PU FA) precursors. n-6 and n-3 PU FA in the arachidonic acid (AA) and twenty eicosapentaenoic acid (EPA) is the class of twenty carbon acid compounds (eico sano ids) of the precursor, and Docosahexaenoic Acid (DHA) is an important brain and retinal lipid composition, function of the brain and retina development needs n-3PUFA.
PU FA s and type of lipid structure, metabolism and the formation of sperm and so on. Polyunsaturated fatty acid composition of cell membrane is an essential ingredient, it is involved in phospholipid synthesis in the body, and in the form of phospholipids in mitochondria and cell membranes, the phospholipid composition of membrane function is an important factor in the decision. With mononuclear cells, prokaryotes and experimental studies have shown that the yeast model, the biological origin and integrity of cell membranes need to PU FA. PU FA can promote cell membrane fluidity and assembly [15]. Formation of mammalian cell membranes need to provide the dietary n-3 and n-6 ??PU FA. During cell division requires some PU FA support the replication and assembly of mitochondrial membrane, resulting in mitochondria if the PUFA supply assembly fails, the resulting daughter cells lack mitochondrial DNA, and thus the accumulation of small mutations have a long time can not form functional mitochondria.
PUFA regulation of gene expression, PU FA regulation of gene expression can directly control the activities of the nucleus to regulate transcription of certain genes [16]. PU FA inhibition of hepatic lipogenesis by inhibiting hepatic lipogenesis and glycolytic enzymes (such as fatty synthase) gene to achieve. In contrast, saturated or monounsaturated fatty acids does not have this effect.
PUFA can prevent cardiovascular disease, it is the role for the prevention of cardiovascular disease is multifaceted. N-3 PU FA anti-arrhythmic, the major effect of anti-ventricular fibrillation, the mechanism is free of PU FA can form conductive myocardial cells more stable, PUFA and specificity of the direct electrophysiological effects of blocking the fast voltage-dependent sodium ion channels. Free fatty acids directly with the sodium channel protein, thereby causing the channel to extend the inactive state. PUFA affect the formation of atherosclerosis and inflammation, because the PU FA have regulating endothelial cell activation and cytokine function. In the absence of dietary PUFA, may improve the body white blood cells and vascular endothelial cell interactions sensitivity of the pathological process.
PUFA in the growth and development also play an important role, n-6 PU FA to promote the growth and development, in addition to AA can increase the growth-related early response genes cf os and E g r-1 expression to induce cell growth, there are AA-derived PG2 series regulation of hypothalamic function, although the n-3PU FA growth-promoting effect will be negligible, but the brain and retina, and renal function in healthy skin is important. Studies of Rhesus confirmed restriction in pregnancy n-3 PUFA intake, can affect offspring vision, learning ability damage, abnormal ERG (ERG) and polydipsia. Study in mice found that age of △ 4 desaturase system damage may cause retinal DHA levels decline.
large number of experiments show that the polyunsaturated fatty acids also has good anti-cancer effects, its anti-cancer mechanism has four main aspects: ① ω-3 fatty acids interfere with ω-6 polyunsaturated fatty acids formation, and reduce the concentration of arachidonic acid to reduce PGE2 generated for the amount of interleukin, thereby reducing the occurrence of cancer was sure to promote the role of PGE2 generation; ② cell membrane synthesis of cholesterol requirements large, and ω-3 fatty acids can lower cholesterol levels, which can inhibit the growth of cancer cells; ③ immune cells in DHA and EPA had a more beneficial physiological effects of substances involved in the regulation of gene expression, increased body immunity, reduced tumor necrosis factor; ④ EPA and DHA significantly increased membrane fluidity, cell metabolism and repair will help prevent the abnormal proliferation of tumor cells [17-18].
Zhu other study found that postmenopausal breast cancer patients, the intake of EPA and DHA in the diet and the proportion of DHA in breast adipose tissue total phospholipid ratio was significantly lower than patients with benign breast disease, the proposed intake into the ω-3 fatty acids can be prevented (especially postmenopausal women) the incidence of breast cancer [19].
In addition, polyunsaturated fatty acids can prevent skin aging, anti-aging, anti-allergic reactions and promote hair growth and so on.
In recent years, ω-3 polyunsaturated fatty acids EPA and DHA has become the focus of attention, which related to its important physiological functions, DHA and EPA in the body mainly in the deep-sea cold-water fish, fish with season, of different origin, fish oil DHA and EPA content of 4% to 40%, and the current global total annual production of 1000t DHA EPA [20-22]. In the seaweed also has accumulated a lot of DHA and EPA [23]. Bacteria in seawater DHA and EPA are also there, Kyoto University, Japan produced 400μg of bacterial culture [24]. In addition, there are many fungi DHA, EPA, has been reported in Mortierella [25], long spore Mortierella [26], the ultimate Pythium [27] and other fungi found in EPA, the broken capsule chytrid fungus found in DHA [28]. The main physiological function of anti-clotting, anti-cardiovascular disease; lipid-lowering, anti-arteriosclerosis; brain by chi; protect eyesight; anti-cancer, anti-inflammatory effects [28].
as EPA, DHA has an important physiological functions, has been in health care, food industry, feed industry, and many other widely used.
2.4 conjugated linoleic acid (conjugated linoleic acid, CLA)
conjugated linoleic acid (CLA) can be seen as essential fatty acids linoleic acid derived from the total conjugate acid of the double geometrical isomers of a variety of locations and the general term for a group of linoleic acid and isomers conformation, a common feature of these isomers for the two double bonds directly through a carbon – carbon single key connection [29].
many foods contain CLA, but their concentrations are very low. Ruminant animal sources of food is the most important natural source of CLA, and the main biologically active c-9, t -11 isomer. Natural CLA mainly in the rumen animals such as cattle, sheep milk fat and meat products [12], per gram of milk fat content ranging from 2-25 mg. c-9, t-11 conjugated linoleic acid is linoleic acid soluble fiber in the anaerobic Vibrio isomerase-catalyzed conversion of linoleic acid formed. Mouse large intestine is also able to linoleic acid into c-9, t-11 isomer, but in the absence of the necessary bacteria that can not occur in vivo transformation. Ruminant intestinal anaerobic soluble fiber produced by Vibrio linoleic acid to make linoleic acid isomerase into CLA, and mainly in the c-9, t-11 isomer form [30-31] . A small amount of conjugated linoleic acid also exists in other animal tissues, blood, but very few plants in the CLA content, CLA content in the marine food rarely. Human dietary sources of CLA are mainly dairy products and ruminant meat [32-33]. It was found that the CLA content of fermented dairy products is much higher than raw milk, and cheese and other dairy products by processing the content of CLA, the impact of storage time [34]. Fatty acids in milk and milk products in the CLA content of 4-17mg / g between; lamb fatty acid CLA content of 12 mg / g, significantly higher levels than other meat; fish fatty acids in CLA content of 0.01% -0.09% between vegetable oil and margarine in was not detected CLA [35]. Found during the preparation of cheese, and additives to improve the processing temperature increases the concentration of whey protein products in the CLA content of beef barbecue will increase after the CLA content [36].
biologically active c-9, t-11 isomers in plant foods contain only small amounts. In general, vegetable oils, such as gram contains only 0.1 mg-0.7 mg CLA, and which c-9, t-11 isomer content of less than 50%. Thermal isomerization of food, industrial partial hydrogenation process can produce a mixture of conjugated linoleic acid, such as turkey isomerization occurs because heat can be generated CLA. However, with the resulting product with heterogeneous enzyme is different is that the formation of a series of position and geometric isomers of the mixture. One of CLA per gram of fat content of 2. 5 mg to 11 mg, between 75% and the CLA is a c-9, t-11 isomer. In the conventional food processing and storage in the oxidation of CLA is not greatly affected. In short, the content of CLA in nature is not very high.
The results showed that conjugated linoleic acid with the formation of anti-atherogenic, anti-diabetic, anti-allergy, immune regulation, to promote growth and reduce the amount of body fat and increase lean meat and impact of bone formation a variety of physiological functions. In the lipid-lowering effects of CLA in animal studies have shown that, CLA can reduce animal fat, prevent atherosclerosis, which play a major biologically active CLA isomers c-9, t-11 and t-10, c- 12 pairs of fat metabolism are closely related. CLA can be involved in fat breakdown and metabolism [37-39], induction of energy utilization, leading to weight loss and does not store fat. CLA can prevent fat and platelet-like lesions in the arterial wall deposition of porridge, which is the CLA main anti-atherosclerosis. In this respect the effect of CLA is linoleic acid five times. At the same time, CLA can reduce blood cholesterol levels [40].
2.5 trans fatty acids (Trans fatty acids, TFA)
in combination with double bonds of unsaturated fatty acids, the molecular structure may appear smooth, anti-two kinds of geometric isomers, TFA refers to at least one double bond of trans fatty acid configurations, namely: the trans configuration on the C = C 2 carbon atoms with hydrogen atoms are located on both sides of the double bond, conformation showing shape , and similar to saturated fatty acids. Now widely recognized that trans fatty acids (TFA) is a not ignore the potential hazards of unsaturated fatty acids, excessive intake of harmful to human health. Awareness of TFA Dutch and British scientists began a study: margarine useful in reducing high-density cholesterol (HDL) levels leaving the harmful low-density cholesterol (LDL) levels increased. This finding raises in the international security of universal attention. The current study found that the main hazards to human health exists in the impact of growth and development, leading to thrombosis, promote atherosclerosis, resulting in brain function decline and risk of type Ⅱ diabetes induced by women in several areas [41].
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