Docosahexaenoic acid and arachidonic acid prevent essential fatty acid deficiency and hepatic steatosis

Objectives: Essential fatty acids are important for growth, development, and physiologic function. α‐Linolenic acid and linoleic acid are the precursors of docosahexaenoic and arachidonic acid, respectively, and have traditionally been considered the essential fatty acids. However, the authors hypothesized that docosahexaenoic acid and arachidonic acid can function as the essential fatty acids. Methods: Using a murine model of essential fatty acid deficiency and consequent hepatic steatosis, the authors provided mice with varying amounts of docosahexaenoic and arachidonic acids to determine whether exclusive supplementation of docosahexaenoic and arachidonic acids could prevent essential fatty acid deficiency and inhibit or attenuate hepatic steatosis. Results: Mice supplemented with docosahexaenoic and arachidonic acids at 2.1% or 4.2% of their calories for 19 days had normal liver histology and no biochemical evidence of essential fatty acid deficiency, which persisted when observed after 9 weeks. Conclusion: Supplementation of sufficient amounts of docosahexaenoic and arachidonic acids alone without α‐linolenic and linoleic acids meets essential fatty acid requirements and prevents hepatic steatosis in a murine model.     

n-3多不饱和脂肪酸在肿瘤防治中的意义

n-3脂肪酸属必需脂肪酸,包括α-亚麻酸、二十碳五烯酸(EPA)和二十二碳六烯酸(DHA).大量研究证实,n-3脂肪酸能抑制多种肿瘤细胞生长,预防肿瘤的发生.作者就 n-3脂肪酸防治肿瘤的作用、机制及应用作一综述.     

Polyunsaturated fatty acids,inflammation and immunity

Consumption of n-6 polyunsaturated fatty acids greatly exceeds that of n-3 polyunsaturated fatty acids. The n-6 polyunsaturated fatty acid arachidonic gives rise to the eicosanoid family of inflammatory mediators (prostaglandins, leukotrienes and related metabolites) and through these regulates the activities of inflammatory cells, the production of cytokines and the various balances within the immune system. Fish oil and oily fish are good sources of long chain n-3 polyunsaturated fatty acids. Consumption of these fatty acids decreases the amount of arachidonic acid in cell membranes and so available for eicosanoid production. Thus, n-3 polyunsaturated fatty acids act as arachidonic acid antagonists. Components of both natural and acquired immunity, including the production of key inflammatory cytokines, can be affected by n-3 polyunsaturated fatty acids. Although some of the effects of n-3 fatty acids may be brought about by modulation of the amount and types of eicosanoids made, it is possible that these fatty acids might elicit some of their effects by eicosanoid-independent mechanisms. Such n-3 fatty acid-induced effects may be of use as a therapy for acute and chronic inflammation, and for disorders which involve an inappropriately activated immune response.     

Assessment of individual fatty acid intake

Dietary assessment of individual fatty acid intake is difficult due to a number of limitations. Information regarding the type, quantity and brand-name of fat used in cooking and at the table is required. In addition, margarine manufacturers may change the component oils used for reasons of cost, which changes the fatty acid composition of their products from season-to-season. Independent markers of fatty acid intake are required, therefore, to compensate for these limitations. Adipose tissue concentrations have been used as a measure of habitual intake of fatty acid groups and individual fatty acids in numerous studies. Saturated (SFA) and monounsaturated fatty acids (MUFA) are generally poorly correlated with adipose tissue concentrations, which can be explained partly by endogenous synthesis. In general, adipose tissue concentrations of exogenously-produced fatty acids (n-3 and n-6 polyunsaturated fatty acids (PUFA)) are well correlated with estimates of habitual intake. Correlations between dietary trans unsaturated fatty acids (TUFA) and adipose tissue concentrations vary between countries, which may be due to differences in dietary sources. Correlations may be affected by differences in bioavailability or selective retention of fatty acids in certain tissue lipids.     

Modification of plant lipids for human health: development of functional land-based omega-3 fatty acids

We have remodeled canola seeds to accumulate the omega-3 fatty acid, stearidonic acid (SDA). In doing so, we have demonstrated the feasibility of developing a land-based source of functional omega-3 fatty acids on a large scale. Land-based omega-3 fatty acids represent a sustainable source of omega-3 fatty acids that can be produced on large acreages and delivered to consumers in a wide variety of functional foods. And unlike alpha-linolenic acid, SDA can provide eicosapentaenoic acid equivalence at moderate intakes. Widely applied, SDA-enriched foods could become a valuable tool for delivering recommended levels of omega-3 fatty acids to large portions of the population. By obviating the need for dietary changes, SDA-enriched foods may facilitate increased compliance with recommendations for daily omega-3 intakes.     

Fatty acid composition of frequently consumed foods in Turkey with special emphasis on trans fatty acids

Fatty acid compositions of frequently consumed foods in Turkey were analyzed by capillary gas chromatography with particular emphasis on trans fatty acids. The survey was carried out on 134 samples that were categorized as meat products, chocolates, bakery products and others. The meat products except chicken-based foods have trans fatty acids, arising as a result of ruminant activity, with an average content of 1.45 g/100 g fatty acids. The conjugated linoleic acid content of meat and chicken doner kebabs were found higher than other meat products. Chocolate samples contained trans fatty acids less than 0.17 g/100 g fatty acids, with the exceptional national product of chocolate bars and hazelnut cocoa cream (2.03 and 3.68 g/100 g fatty acids, respectively). Bakery products have the highest trans fatty acid contents and ranged from 0.99 to 17.77 g/100 g fatty acids. The average trans fatty acid contents of infant formula and ice-cream, which are milk-based products, were 0.79 and 1.50 g/100 g fatty acids, respectively. Among the analyzed foods, it was found that coffee whitener and powdered whipped topping had the highest saturated fatty acid contents, with an average content of 98.71 g/100 g fatty acids.     

一种红细胞膜脂肪酸甲酯化的改良方法

[目的]建立一种红细胞膜脂肪酸甲酯化的改良方法。[方法]收集健康体检人员的血液,分别采用传统方法和改良方法对其红细胞膜脂肪酸进行甲酯化处理,用气相色谱-质谱联用仪(GC-MS)进行分析。[结果]两种方法都检测出相同种类的15种脂肪酸。改良方法检测的饱和脂肪酸和多不饱和脂肪酸的绝对含量明显高于传统方法,对单不饱和脂肪酸绝对含量的测定,2者差异无统计学意义。两种方法测得的脂肪酸相对含量差异无统计学意义;重现性试验,各脂肪酸的CV均小于20%。改良方法所测得脂肪酸回收率为87.8%～110.7%。[结论]改良方法红细胞膜脂肪酸抽提较传统方法简单,保证了长链脂肪酸的鉴定,实验精密度和准确度较高,适用于临床上大样本量血液脂肪酸的检测。     

Serum fatty acid reference ranges: percentiles from a New Zealand national nutrition survey

Serum fatty acids are increasingly used in cross-sectional surveys and cohort studies as biomarkers of dietary fat intake; however, it is currently difficult to judge whether an individual has low or high fatty acid status, or whether the distribution of fatty acids of a group of people is low or high due to a lack of appropriate reference values. In the absence of interpretive criteria, the distribution of serum fatty acids from a suitable reference population can be used as an alternative. We describe the distribution of the fatty acid composition of the three most commonly reported lipid classes in serum; cholesterol ester, phospholipid and triacylgycerol. Results for each serum lipid class are presented as means (SD) and percentiles (5, 10, 25, 50, 75, 90, and 95) of serum fatty acids in non-fasting blood samples collected from a population based cross-sectional survey of New Zealand adults (n = 2793). These serum fatty acid reference ranges are applicable and relevant to Australia, United Kingdom, and United States as well as other countries where fat intakes are similar to New Zealand.     

3‐carboxy‐4‐methyl‐5‐propyl‐2‐furanpropanoic acid (CMPF): A metabolite identified after consumption of fish oil and fish

3‐carboxy‐4‐methyl‐5‐propyl‐2‐furanpropanoic acid (CMPF) is a known metabolite of furan fatty acids and was first referred to as a urofuran fatty acid, as it was found in urine of humans and other species after consumption of furan fatty acids or foods containing furan fatty acids. More recently, CMPF has been identified as a highly prominent metabolite following the consumption of fish oil, fish oil fractions and diets rich in fish, and can be regarded as biomarker of oil‐rich fish or fish oil intakes. As furan fatty acids are known to occur in fish and fish oil (at a low level), it is possible that the CMPF in plasma arises from these furan fatty acids. On a structural basis, this is a likely explanation rather than the CMPF being an actual metabolite of long‐chain marine omega‐3 fatty acids. Recent studies in high fat‐fed mice given purified CMPF suggest that CMPF might contribute to the improved metabolic effects observed following consumption of long‐chain marine omega‐3 fatty acids but much is still to be known about the relationships between CMPF and health.     

The Role of Microbial Amino Acid Metabolism in Host Metabolism

Disruptions in gut microbiota composition and function are increasingly implicated in the pathogenesis of obesity, insulin resistance, and type 2 diabetes mellitus. The functional output of the gut microbiota, including short-chain fatty acids and amino acids, are thought to be important modulators underlying the development of these disorders. Gut bacteria can alter the bioavailability of amino acids by utilization of several amino acids originating from both alimentary and endogenous proteins. In turn, gut bacteria also provide amino acids to the host. This could have significant implications in the context of insulin resistance and type 2 diabetes mellitus, conditions associated with elevated systemic concentrations of certain amino acids, in particular the aromatic and branched-chain amino acids. Moreover, several amino acids released by gut bacteria can serve as precursors for the synthesis of short-chain fatty acids, which also play a role in the development of obesity. In this review, we aim to compile the available evidence on the contribution of microbial amino acids to host amino acid homeostasis, and to assess the role of the gut microbiota as a determinant of amino acid and short-chain fatty acid perturbations in human obesity and type 2 diabetes mellitus.     

What are the health effects of fat?

In order to answer the question which health benefits are to be expected from dietary fat, we have to differentiate between different kinds of fat with varying fatty acid composition. Saturated fatty acids are commonly judged to have a negative health impact as they lead to increased serum cholesterol levels and a higher risk of coronary heart disease. Therefore, all recommendations stress the importance to limit the intake of saturated fatty acids. Monounsaturated fatty acids, on the other hand, have a positive impact on the serum lipid profile, lead to decreased LDL-oxidation and favorably influence the metabolism of diabetics. However, it is essential that monounsaturated fatty acids be mainly supplied by plant oils like rape seed or olive oil and not by foods that are simultaneously rich in saturated fatty acids. Concerning polyunsaturated fatty acids, it is important to increase the supply of n-3 fatty acids (ratio of n-6:n-3: about 5:1) as there is substantial evidence for their protective effects. If the fatty acid composition of the diet is optimized, even a total dietary fat content of 35% of total energy intake can be adequate as long as there is enough physical activity and the diet is rich in plant-derived foods like vegetables, fruits, cereals, potatoes, beans and legumes.     

Fatty acid composition of frequently consumed foods in Turkey with special emphasis on trans fatty acids

Fatty acid compositions of frequently consumed foods in Turkey were analyzed by capillary gas chromatography with particular emphasis on trans fatty acids. The survey was carried out on 134 samples that were categorized as meat products, chocolates, bakery products and others. The meat products except chicken-based foods have trans fatty acids, arising as a result of ruminant activity, with an average content of 1.45 g/100 g fatty acids. The conjugated linoleic acid content of meat and chicken doner kebabs were found higher than other meat products. Chocolate samples contained trans fatty acids less than 0.17 g/100 g fatty acids, with the exceptional national product of chocolate bars and hazelnut cocoa cream (2.03 and 3.68 g/100 g fatty acids, respectively). Bakery products have the highest trans fatty acid contents and ranged from 0.99 to 17.77 g/100 g fatty acids. The average trans fatty acid contents of infant formula and ice-cream, which are milk-based products, were 0.79 and 1.50 g/100 g fatty acids, respectively. Among the analyzed foods, it was found that coffee whitener and powdered whipped topping had the highest saturated fatty acid contents, with an average content of 98.71 g/100 g fatty acids.     

Long-chain polyunsaturated fatty acids and chemically induced diabetes mellitus: effect of omega-6 fatty acids

OBJECTIVE: We previously showed that prior oral supplementation of oils rich in omega-3, eicosapentaenoic acid and docosahexaenoic acid, and omega-6, gamma-linolenic acid and arachidonic acid, can prevent the development of alloxan-induced diabetes mellitus in experimental animals. But the effect of individual fatty acids on chemically induced diabetes mellitus is not known. We report the results of our studies with omega-6 fatty acids. METHODS: Alloxan-induced in vitro cytotoxicity and apoptosis in an insulin-secreting rat insulinoma cell line, RIN, was prevented by prior exposure of these cells to linoleic acid, gamma-linolenic acid, and arachidonic acid (AA) but not to dihomo-gamma-linolenic acid. Cyclo-oxygenase and lipoxygenase inhibitors did not block this protective action of AA. Prior oral supplementation with gamma-linolenic acid and pre- and simultaneous treatments with AA prevented alloxan-induced diabetes mellitus. RESULTS: Even though pretreatment with linoleic acid and dihomo-gamma-linolenic acid and simultaneous treatment with linoleic acid, gamma-linolenic acid, and dihomo-gamma-linolenic acid did not prevent the development of diabetes mellitus, the severity of diabetes was much less. The saturated fatty acid stearic acid and the monounsaturated fatty acid oleic acid were ineffective in preventing alloxan-induced diabetes mellitus. gamma-Linolenic acid and AA not only attenuated chemically induced diabetes mellitus but also restored the antioxidant status to normal range in various tissues. Changes in the concentrations of various fatty acids of the phospholipid fraction of plasma that occurred as a result of alloxan-induced diabetes mellitus also reverted to normal in the AA-treated animals. CONCLUSIONS: These results suggest that polyunsaturated fatty acids can prevent chemically induced diabetes in experimental animals and attenuate the oxidant stress that occurs in diabetes mellitus.     

Comprehensive evaluation of fatty acids in foods. IV. Nuts, peanuts, and soups.

As part of USDA research to provide reliable and up-to-date tabulations of lipids and fatty acids in foods, representative values have been derived and tabulated for nuts and commercially canned condensed soups. Except for palm-type nuts, unsaturated fatty acids are the major acids in nuts; oleic acid is generally the predominant unsaturated fatty acid. The new fatty acid values indicate greater concentrations of saturated fatty acids than previously reported. The P:S ratios for nuts and peanuts are presented. The fatty acid contents of soups are varied and reflect the lipid composition of the source(s) of fat of the particular ingredients used in the manufacture of these products. These new values for fatty acids in nuts and soups should greatly help nutritionists and dietitians to better assess the total contribution of each particular fatty acid to the diet.     

Plasma total and free fatty acids composition in human non-alcoholic steatohepatitis

BACKGROUND AND AIM: Non-alcoholic steatohepatitis (NASH), the association of steatosis with an inflammatory response, is a novel liver disease of unknown pathogenesis and prognosis. Triacylglycerols and their precursors, the fatty acids, are the likely candidates to accumulate in the hepatocyte. Disturbed fatty acid metabolism can be involved in the pathogenesis of NASH but there is no information concerning its plasma fatty acid profile. The aim of this study was to evaluate plasma total (esterified plus free) and free fatty acids concentrations to assess the association of NASH with plasma fatty acid accumulation. MATERIALS AND METHODS: Overnight fasting blood samples from 22 biopsy-proven NASH patients and of 6 matched age healthy controls were studied. RESULTS: NASH patients had significantly higher concentration of total and free fatty acids than controls (P<0.05), higher total saturated and monounsaturated levels in both studied lipid fractions (P<0.05), mainly due to the increase of hexadecanoic, hexadecenoic and octadecenoic acids. Absolute polyunsaturated fatty acids (PUFA) concentrations were similar in both groups. The C20:4/C18:2 and the C18:1/C18:0 ratios as well as the peroxidability index were not significantly different. CONCLUSION: In overweight/obese patients NASH is associated with deranged fatty acid metabolism which may be involved in its pathogenesis and/or progression.     

Oxygenated fatty acids isolated from wheat bran slurries

Oxygenated fatty acids are classified as secondary metabolites in wheat, produced by oxidation of free fatty acids (FFAs). Oxygenated fatty acids have significant impact on the organoleptic and sensory properties of food products and participate in regulation of defense and developmental processes in plants. The objective of this study was to identify oxygenated fatty acids from wheat flour slurries. Wheat bran/water slurries were incubated for 4?h and freeze dried. Total lipids were extracted in chloroform/methanol/water; and methylated and silylated FFAs were analyzed with gas chromatography/mass spectroscopy. Seven oxygenated fatty acids were identified, (A) 12,13-dihydroxy-9-octadecenoic acid, (B) 9-hydroxy-10,12-octadecadienoic acid, (C) 13-hydroxy-9cis,11trans-octadecadienoic acid, (D) 9,10,13-trihydroxy-11trans-octadecenoic acid, (E) 9,12,13-trihydroxy-10trans,15cis-octadecadienoic acid, (F) 10-oxo-13-hydroxy-11trans-octadecenoic acid and (G) 12-oxo-13-hydroxy-octadecanoic acid, in wheat bran slurries. Our results are important for whole wheat food applications since oxygenated fatty acids can result in bitter flavors in the final product.     

Modification of plasma and hepatic lipids of guinea pigs by feeding high oleic acid pork compared with regular pork.

Meat from such monogastric animals as swine can be modified to substitute monounsaturated fatty acids for saturated fatty acids. Because monounsaturated fatty acids have a beneficial effect on serum lipids as compared with saturated fatty acids, the objective of this study was to assess the effect of modified pork as compared with regular pork on serum and hepatic lipids. Guinea pigs were fed diets containing pork from control diet-fed hogs or from hogs fed a diet containing high oleic acid sunflower oil. The pork provided almost all of the fat in the diets at the level of 4 and 15 g/100 g diet, 10 or 34% energy. The high oleic pork muscle and fat contained 26 and 46% less palmitic and stearic acids (the primary saturated fatty acids), respectively, and 31 and 29% more oleic acid (the primary monounsaturated fatty acid) than the regular pork muscle and fat, respectively. Cholesterol concentration of diets ranged from 0.06 to 0.08% of the diet. Although total serum cholesterol, HDL cholesterol and triglyceride concentrations did not differ due to type of pork, results indicated that serum LDL cholesterol was lower (15%) and hepatic cholesterol was greater (15%) in the high oleic pork, 15% fat group as compared with the control pork 15% fat group. Also, serum LDL cholesterol concentration was higher in the groups fed 15% fat compared with those fed 4% fat. In this study pork modified to have more oleic acid and less saturated fatty acids had a positive effect on tissue lipids when fed to animals.     

ESSENTIAL FATTY ACIDS: STRUCTURAL REQUIREMENTS FOR BIOLOGICAL ACTIVITY

Polyenoic 17-C fatty acids with a double bond at the sixth or ninth carbon from the carboxyl end of the fatty acid chain, were nearly as effective as linoleate in curing external symptoms of essential fatty acid deficiency. These fatty acids were converted to a 19-C fatty acid with four double bonds, quite similar to arachidonate.