Effects of different quantities of fat on serum and liver lipids, phospholipid class distribution and fatty acid composition in alcohol-treated rats

The present study investigated the quantitative effect of dietary fats and ingestion of alcohol on serum and liver lipids, fatty acid bound to phospholipids and their class distribution of male Wistar rats. The rats in C (control) and A (alcohol) groups were fed a standard laboratory diet, HFC (high fat-control) and HFA (high fat-alcohol) groups were fed a high fat diet (standard diet supplemented with 20 g%w/w, sunflower oil: lard mixture 1: 1) for 6 wk. Alcohol-treated rats consumed alcohol at the rate of 9 g/kgbw/d (15-20% energy). Liver phospholipid (PL) content was decreased, and phospholipid/cholesterol liver molar ratio increased in the alcohol treated rats. The proportion of serum sphingophospholipid (Sph) was significantly lower and proportion of phosphatidylcholin (PC) significantly higher in serum PL in alcohol-treated rats. Phospholipid class distribution was unaffected by alcohol feeding in liver. Significantly lower levels of 16:1n-7 and higher levels of 20:5n-3 and 22:4n-6 in the serum PL were observed in the alcohol-treated rats. The groups on the HF diet increased levels of 20:4n-6, 22:4n-6 and total n-6, polyunsaturated fatty acid (PUFA) and decreased levels of 18:1n-9 and total monounsaturated fatty acids (MUFA)in both liver and serum PL, but n-3 fatty acid increased in serum PL and decreased in liver PL compared to groups on the standard diet. Alcohol fat interaction was evident in MUFA and PUFA/SFA in serum PL and n-6, MUFA, PUFA and polyunsaturated/saturated fatty acid ratios (PUFA/SFA) in liver PL. This study showed that the high fat intake in alcohol-treated rats increased levels of 20:4n-6, 22:4n-6 and 20:4/18:2 ratio, and decreased level of 18:1n-9 in liver and serum phospholipids.     

Changes in the fatty acid profiles of plasma lipid fractions induced by dietary nucleotides in infants born at term

This study was designed to determine the polyunsaturated fatty acid (PUFA) composition of plasma lipid fractions in newborn infants fed human milk (HM), milk formula (MF) or nucleotide-supplemented milk formula (NMF) during the first month of life. Linoleic acid was increased in infants fed formulas in all plasma lipid fractions with respect to those fed HM. Plasma phospholipids in MF-fed infants had lower percentages of PUFA of both omega 6 and omega 3 series, namely arachidonic and docosahexaenoic acids, than those fed HM or NMF; the unsaturation index was decreased in infants fed MF as compared to those fed HM or NMF. Arachidonic acid showed a similar behaviour in plasma cholesteryl esters as in phospholipids. No changes for long chain PUFA among the groups studied were observed for plasma triglycerides and free fatty acids. These results support previous findings that dietary nucleotides are involved in the regulation of desaturation and elongation of linoleic and linolenic acid to their longer superior homologous fatty acids. We suggest that dietary nucleotides may reverse the partial inhibition of delta 5-desaturase caused by an excess of linoleic acid in the diet during early postnatal life.     

Replacement of butter on bread by rapeseed oil and rapeseed oil-containing margarine: effects on plasma fatty acid composition and serum cholesterol.

The effects of zero-erucic acid rapeseed oil and rapeseed oil-containing margarine on plasma fatty acid composition and serum cholesterol were studied in butter users (n 43). Compliance to the substitution was followed by fatty acid analysis of total plasma and plasma phospholipids. The amount of substitute fats represented, on average, 21% of total fat and 8% of total energy intake. Changes in the relative fatty acid composition of plasma phospholipids indicated further fatty acid metabolism, and were closely related to the serum cholesterol level. The reduction in saturated fatty acids led to a significant increase in the proportion of n-3 and n-6 polyunsaturated fatty acids (PUFA) with the rapeseed oil diet, whereas the margarine caused a significant rise in n-6 PUFA only. The increase in the proportions of the two PUFA families occurred in accordance with their competitive order, most completely with the rapeseed oil diet. When butter was replaced by rapeseed oil, low-density-lipoprotein-cholesterol decreased by an average of 9.1% without a reduction in high-density-lipoprotein-cholesterol. During margarine substitution the reduction was 5.2%, on average. Of the plasma phospholipids, alpha-linolenic acid and the linoleic:stearic acid ratio, but not oleic acid, were the components most significantly correlated with serum cholesterol levels or the decrease in these levels. The results show that rapeseed oil can act primarily as a source of essential fatty acids, rather than that of monoenes, in the diet of butter users.     

Dietary trans fatty acids alter diaphragm phospholipid fatty acid composition, triacylglycerol content and glucose transport in rats

The present study evaluates the effect of dietary trans fatty acids on diaphragm phospholipid fatty acid composition, intramyocellular triacylglycerol content and insulin-stimulated glucose uptake in comparison with dietary saturated fatty acids. Male weanling WNIN rats were divided into three groups and fed for 3 months on one of the following diets containing 10 % oil differing in fatty acid composition: control diet, saturated fatty acid diet and trans fatty acid diet. Dietary trans fatty acids increased the intramyocellular triacylglycerols and decreased the ratio of 20 : 4n-6 to 18 : 2n-6 and long-chain PUFA levels (20 %) in diaphragm phospholipids, indicating inhibition of PUFA biosynthesis. However, saturated fatty acids decreased both 18 : 2n-6 and 20 : 4n-6 without change in the ratio. Trans fatty acid-induced alterations in diaphragm phospholipid fatty acid composition and intramyocellular triacylglycerol content were associated with decreased insulin-stimulated glucose transport in the diaphragm. These observations suggest that dietary trans fatty acids decrease diaphragm insulin sensitivity, possibly due to increased intramyocellular triacylglycerol accumulation and decreased long-chain PUFA in phospholipids.     

Differences between polyunsaturated fatty acid status of non-institutionalised elderly women and younger controls: a bioconversion defect can be suspected.

OBJECTIVE: To evaluate the polyunsaturated fatty acid (PUFA) status in non-institutionalised elderly women and to detect a possible essential fatty acid bioconversion defect. DESIGN AND SUBJECTS: The fatty acid composition of total plasma lipids, plasma triglycerides (TG), cholesterol esters (CE), phospholipids (PL), and erythrocytes was determined by capillary column gas-liquid chromatography in a sample of 200 non-institutionalised healthy elderly women over 75 years of age. The data were compared with those of a control group of 50 young female volunteers aged 20-48 y. RESULTS: In elderly women, the n-6 series precursor, linoleic acid (18:2 n-6), was lower in TG and CE (P = 0.029 and 0.014, respectively). In CE, this fatty acid was highly correlated with vegetable and vegetal fat intakes (P < 0.0001), suggesting a lower dietary supply than in controls. Higher percentages of 16:1 n-7 were found in all the plasma lipid fractions in elderly women, especially in CE (P < 0.0001). The ratios 20:4 n-6/20:3 n-6 and 22:6 n-3/20:5 n-3 were significantly lower in PL from elderly women (P < 0.005 and P < 0.002, respectively), raising the question of the efficiency of the terminal steps of 20:4 n-6 and 22:6 n-3 biosynthesis. Dietary investigations in elderly women indicated that a high dietary protein intake via meat probably contributed to the supply of 20:4 n-6 and thus maintained the status of this fatty acid, despite the suspected altered biosynthesis. CONCLUSION: The PUFA status in the elderly women group could be more fragile and dependent on exogenous supply of long-chain PUFAs than previously suspected.     

Total fat intake modifies plasma fatty acid composition in humans

Plasma fatty acid composition reflects dietary fatty acids. Whether the total fat content of the diet alters the fatty acid composition of plasma phospholipid, cholesteryl ester, triacylglycerol and free fatty acids is unknown. To evaluate the effects of low versus high fat diets on plasma fatty acids, a 12-wk, randomized, crossover, controlled feeding trial was conducted in healthy men and women with isoenergic low fat (20% energy) and high fat (45% energy) diets containing constant proportions of fatty acids. Ten subjects consumed one experimental diet for 28 d, their usual diet for 4 wk and the alternate experimental diet for 28 d. Endpoint measures of plasma fatty acids were determined at the end of each experimental period. The effects of the two diets were compared within subjects by analysis of variance. Plasma fatty acids (%) varied in response to total dietary fat with significantly greater total polyunsaturated fat, (n-6) and 18:2(n-6) levels in phospholipids and cholesteryl esters after high fat dietary consumption. The low fat diet was associated with significantly greater total (n-3) fatty acids, 20:5(n-3) and 22:6(n-3) levels in plasma phospholipid fatty acids and cholesteryl esters. Consumption of a low fat diet alters fatty acid patterns in a manner similar to that observed with feeding of (n-3) long-chain fatty acids. This change is likely related to decreased competition for the enzymes of elongation and desaturation, with reduced total intake of 18:2(n-6) favoring elongation and desaturation of available (n-3) fatty acids.     

Dietary n-3 polyunsaturated fatty acids: rate and extent of modification of fatty acyl composition of lipid classes of mouse lung and kidney

The rate and extent of modification of fatty acid composition of mice lung and kidney by dietary menhaden oil (MO) was investigated. White mice were fed 2 wt% safflower oil and either 10 wt% MO or 10 wt% hydrogenated coconut oil (HCO) for 23 d. The stability of dietary MO-induced fatty acid modifications was assessed by replacing the MO diet of a group of mice after 23 d with the HCO diet for an additional 10 d. Mice were sacrificed on d 0, 1, 3, 5, 7, 14, 23 and 33. The n-3 polyunsaturated fatty acid (PUFA), 20:5n-3 and 22:6n-3 were rapidly incorporated into lung and kidney phosphoglyceride (PL) classes during the first 7 d of MO ingestion relative to the controls. After 1 wk of MO consumption, the rate of incorporation either plateaued at an elevated level or continued to increase at a much more gradual rate. A marked increase in the content of 22:5n-3 in lung and kidney was observed. A concomitant and rapid decrease was observed in the n-6 PUFA, 20:4n-6, 22:5n-6 and 18:2n-6. The minimum content of 20:4n-6 was reached between 1 and 2 wk, whereas the minimum levels of 18:2n-6 and 22:5n-6 occurred within 72 h. The n-6/n-3 PUFA ratio in lung and kidney and PL classes increased in mice fed HCO and decreased in mice fed dietary MO. When dietary MO was removed, the n-3 PUFA levels decreased with a concomitant increase in n-6 PUFA after 10 d of HCO consumption.(ABSTRACT TRUNCATED AT 250 WORDS)     

Associations of plasma n-3 polyunsaturated fatty acids with blood pressure and cardiovascular risk factors among Chinese

The relationship between plasma fatty acid (FA) levels and hypertension in Chinese is not fully understood. The aim of this study was to examine relationships between plasma phospholipid (PL) FAs and hypertension in Chinese subjects. One thousand one hundred and fifty-four subjects in Hangzhou, China, were recruited in this cross-sectional study. Two hundred and fourteen (160 males, 54 females) subjects with hypertension and 940 (664 males, 276 females) healthy subjects were identified. The prevalence of hypertension in females (19.6%) was significantly higher than that in males (16.4%). Compared with healthy subjects, hypertensive subjects showed significantly lower plasma PL 22:5n-3 (p?=?0.017), 22:6n-3 (p?=?0.008), PL polyunsaturated fatty acids (PUFAs; p?相似文献   

Dietary flavonoids increase plasma very long-chain (n-3) fatty acids in rats

Flavonoids probably contribute to the health benefits associated with the consumption of fruit and vegetables. However, the mechanisms by which they exert their effects are not fully elucidated. PUFA of the (n-3) series also have health benefits. Epidemiological and clinical studies have suggested that wine flavonoids may interact with the metabolism of (n-3) PUFA and increase their blood and cell levels. The present studies in rats were designed to assess whether flavonoids actually increase plasma levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the main very long-chain (n-3) PUFA. Rats were fed a corn-derived anthocyanin (ACN)-rich (ACN-rich) or ACN-free diet with constant intakes of plant and marine (n-3) PUFA for 8 wk (Expt. 1). Plasma fatty acids were measured by GC. The ACN-rich diet contained ~0.24 ± 0.01 mg of ACN/g pellets. There were no significant differences between groups in the main saturated, monounsaturated, and (n-6) fatty acids. In contrast, plasma EPA and DHA were greater in the ACN-rich diet group than in the ACN-free diet group (P < 0.05). We obtained similar results in 2 subsequent experiments in which rats were administered palm oil (80 μL/d) and consumed the ACN-rich or ACN-free diet (Expt. 2) or were supplemented with fish oil (60 mg/d, providing 35 mg DHA and 12 mg EPA) and consumed the ACN-rich or ACN-free diet (Expt. 3). In both experiments, plasma EPA and DHA were significantly greater in the ACN-rich diet group. These studies demonstrate that the consumption of flavonoids increases plasma very long-chain (n-3) PUFA levels. These data confirm previous clinical and epidemiological studies and provide new insights into the health benefits of flavonoids.     

Plasma phospholipid polyunsaturated fatty acids and homocysteine in Chinese type 2 diabetes patients

The main aim of the present study was to investigate the plasma phospholipids (PL) fatty acids status and its association with plasma Hcy in patients with type 2 diabetes mellitus (T2DM). One hundred and four T2DM (aged 57.3±13.4 y) and 150 healthy subjects (aged 48.4±8.7 y) were recruited. Plasma Hcy and PL fatty acids were determined by standard methods. Plasma Hcy concentration in T2DM was significantly higher than that in healthy subjects (p<0.001). The prevalence of hyperhomocysteinemia was significantly higher in T2DM (36.54%) than that in healthy subjects (17.32%) (p=0.012). Plasma PL 20:4n-6 (r=0.303, p=0.012), 22:5n-3 (r=0.312, p=0.01), total PUFA (r=0.303, p=0.012), n-6 PUFA (r=0.261, p=0.032) were significantly positively associated with plasma Hcy concentration in T2DM. While, plasma PL n-3:n-6 PUFA (r=-0.400, p=0.046) was negatively associated with plasma Hcy in T2DM. In healthy subjects, plasma PL 22:6n-3 (r=-0.201, p=0.042) was negatively associated with plasma Hcy. In addition, plasma PL 22:6n-3 (r=0.193, p=0.044) and 22:5n-6 (r=0.234, p=0.038) were significantly negatively associated with plasma vitamin B-12 in healthy subjects. Our results suggested that increased plasma Hcy levels in T2DM associated with low n-3:n-6 ratio intake. We suggest that T2DM increase their long chain n-3 PUFA intake from fish or fish oil while decrease n-6 PUFA intake.     

Dietary (n-3) fatty acids affect rat heart, liver and aorta protective enzyme activities and lipid peroxidation

In a 16-wk study, weanling Wistar rats (32 males and 32 females) were fed a modified AIN-76 diet containing 20% fat with various (n-3) fatty acids. All dietary fats provided the same amount of saturates, monounsaturates, and total essential fatty acids [(n-6) + (n-3)]. The control diet contained lard/corn oil (L/CO). The other diets contained (n-3) fatty acids from linseed oil (LSO), from linseed oil + menhaden oil (LSO + MO) or from menhaden oil (MO). The (n-3) diets reduced total and HDL-cholesterol, particularly in rats fed the MO diet. Platelet thromboxane levels were equally depressed by the LSO and MO diets. Dietary (n-3) fatty acids significantly elevated docosahexaenoic acid in livers and hearts of male and female rats, with females reaching higher levels. This increase was accompanied by reduced arachidonic acid, except for hearts of females in which the major decrease was in linoleic acid. Overall, enzyme activities in the MO-fed group were decreased to the following levels (relative to the activity in the control group): heart Mn superoxide dismutase (SOD), 28%; liver CuZnSOD, 82%; aorta CuZnSOD, 32%. Greater reductions in these enzyme activities were seen in the female rats fed the MO diet compared with male rats. Lipid peroxidation, assessed by urinary, heart and liver thiobarbituric acid reactants, was increased by dietary (n-3) fatty acids (MO greater than LSO + MO greater than LSO greater than L/CO) and was higher in females than in males. These results indicate that enhanced lipid peroxidation occurs with the increased oxidative stress of elevated tissue (n-3) fatty acids accompanied by reduced SOD activity.     

不同n-3/n-6多不饱和脂肪酸构成比膳食对大鼠一磷酸腺苷活化蛋白激酶表达的影响

目的研究不同n-3/n-6配比脂肪酸对大鼠磷酸腺苷酸活化蛋白激酶(AMP-activated protein kinase,AMPK)蛋白及活性表达的影响。方法58只SD大鼠适应性喂养7d后,尾静脉取血。根据血清总胆固醇水平随机分为:空白(基础饲料);高脂(高脂饲料);高脂1:1(高脂饲料+n-3/n-6=1:1配方油);高脂1:5(高脂饲料+n3/n6=1:5配方油);低脂1:1(脱脂基础饲料+n-3/n-6=1:1配方油);低脂1:5(脱脂基础饲料+n3/n6=1:5配方油)6组,喂养45d,观察大鼠摄食与体重增长。于实验前1d,15d,30d,45d分别各取血测血清总胆固醇水平,于D45处死动物。Western blotting分别分析肝和下丘脑组织中AMPK-α总蛋白及其活性表达。结果添加PUFA的4个比例组血清TC、体重与高脂组相比,显著降低,且低脂2个比例组和高脂1:1组均与高脂1:5组相比有显著差异。添加PUFA的4个比例组均与高脂组相比,大鼠下丘脑AMPK-α总蛋白表达水平明显降低,肝AMPK-α蛋白表达水平均比高脂组明显升高。结论PUFA改善血脂可能是通过增加肝AMPK表达,抑制下丘脑AMPK表达,增加肝脂肪酸氧化和抑制食欲,影响血脂代谢。     

Polyunsaturated fatty acid concentrations in young men and women consuming their habitual diets

Young women of reproductive age appear to have a greater capacity than men to convert the essential fatty acid alpha-linolenic acid to DHA. The purpose of this study was to test the hypothesis that gender-related differences in n-3 PUFA metabolism are reflected in the concentrations of n-3 PUFA in plasma lipids. The subjects were healthy men (n 13) and women (n 23) aged 18-35 years consuming their habitual diet. Dietary habits were assessed by food-frequency questionnaire. Venous blood samples were collected following an overnight fast. For the women, blood collection took place on the tenth day of their menstrual cycle. The fatty acid concentrations of plasma phosphatidylcholine, triacylglycerol, NEFA and cholesteryl esters were determined by gas chromatography. There were no significant differences between men and women in their consumption of protein, carbohydrate, total fat, alcohol, individual fatty acids and selected micronutrients. DHA concentration alone was significantly higher in plasma phosphatidylcholine (31 %, P = 0.02), triacylglycerol (71 %, P = 0.02) and NEFA (33 %, P = 0.01), but not cholesteryl esters, in women compared with men. There were no significant differences between men and women in the concentrations of any other fatty acids measured. Overall, the present data support the suggestion that greater DHA synthesis in women than men results in a higher DHA concentration in plasma lipids.     

Decrease of polyunsaturated fatty acids and elevation of the oleic/stearic acid ratio in plasma and red blood cell lipids of malnourished cancer patients

The fatty acids profiles of plasma and red blood cell lipids have been evaluated in 12 malnourished cancer patients in comparison with samples from eight healthy controls. In such patients, significantly lower levels of linoleic acid (LA) as percentage of total fatty acids were observed in plasma phospholipids (PL) and cholesterol esters (CE), and in red blood cells PL. The levels of arachidonic acid (AA) and the unsaturation index of the two lipid classes were also reduced in plasma CE but not in PL. In spite of the marked reduction of LA and, more generally, of total polyunsaturated fatty acids (PUFA), no elevation of eicosatrienoic acid (20:3 n-9) was observed, such acid being considered a typical index of essential fatty deficiency. Moreover, no modification of the parameters indicating impairment of the fatty acid desaturation activity was shown. In addition, the levels of palmitic and oleic acids were significantly higher in both plasma PL and CE and in red blood cells PL. The reported elevation of the oleic to stearic acid ratio in lipids of red blood cells from malnourished cancer patients, already observed by other authors, was confirmed in our study. This ratio was even more markedly elevated in plasma lipids of the patients. A very good correlation was found between the reduction of linoleic acid levels, especially in plasma CE, and weight loss, suggesting enhanced utilization of this fatty acid in association with extensive depletion of lipid stores, in this pathological state.     

Bread enriched with microencapsulated tuna oil increases plasma docosahexaenoic acid and total omega-3 fatty acids in humans

The aim of this study was to determine the acute and chronic effects of low doses of long chain (LC) n-3 polyunsaturated fatty acids (PUFA) (<100 mg per day) on plasma LC n-3 PUFA levels using a novel delivery form; bread containing microencapsulated tuna oil (MTO). Six omnivores (three men and three women) participated in the acute study, which involved ingesting a prototype MTO bread containing approximately 80 mg of LC n-3 PUFA/four slices. Plasma triacylglycerol fatty acid compositions were measured after an overnight fast and postprandially at 2 and 4 h. In the chronic study, 10 vegetarian subjects (nine men and one woman) consumed MTO bread at six to eight slices/day (comprising 60 mg of LC n-3 PUFA) as the only dietary source of these PUFA for three weeks. Fasting plasma total and phospholipid fatty acid compositions were measured at baseline and endpoint. In the acute study, the proportions of 22:6 n-3 and total n-3 PUFA in plasma triacylglycerol were significantly increased (P < 0.05). In the chronic study, the proportions of 20:5 n-3, 22:5 n-3, 22:6 n-3, total n-3 PUFA in plasma, and 22:6 n-3 and total n-3 PUFA in plasma phospholipid fractions were significantly increased (P < 0.05) at the endpoint compared with the baseline. This study showed that a low dose of LC n-3 PUFA, consumed as MTO-enriched bread, was bioavailable, as measured by an increase in LC n-3 PUFA levels in the plasma of human subjects.     

Maternal dietary n-6 polyunsaturated fatty acid deprivation does not exacerbate post-weaning reductions in arachidonic acid and its mediators in the mouse hippocampus

Objectives: The present study examines how lowering maternal dietary n-6 polyunsaturated fatty acids (PUFA) (starting from pregnancy) compared to offspring (starting from post-weaning) affect the levels of n-6 and n-3 fatty acids in phospholipids (PL) and lipid mediators in the hippocampus of mice.

Methods: Pregnant mice were randomly assigned to consume either a deprived or an adequate n-6 PUFA diet during pregnancy and lactation (maternal exposure). On postnatal day (PND) 21, half of the male pups were weaned onto the same diet as their dams, and the other half were switched to the other diet for 9 weeks (offspring exposure). At PND 84, upon head-focused high-energy microwave irradiation, hippocampi were collected for PL fatty acid and lipid mediator analyses.

Results: Arachidonic acid (ARA) concentrations were significantly decreased in both total PL and PL fractions, while eicosapentaenoic acid (EPA) concentrations were increased only in PL fractions upon n-6 PUFA deprivation of offspring, regardless of maternal exposure. Several ARA-derived eicosanoids were reduced, while some of the EPA-derived eicosanoids were elevated by n-6 PUFA deprivation in offspring. There was no effect of diet on docosahexaenoic acid (DHA) or DHA-derived docosanoids concentrations under either maternal or offspring exposure.

Discussion: These results indicate that the maternal exposure to dietary n-6 PUFA may not be as important as the offspring exposure in regulating hippocampal ARA and some lipid mediators. Results from this study will be helpful in the design of experiments aimed at testing the significance of altering brain ARA levels over different stages of life.     

Protective effect of dietary n-3 polyunsaturated fatty acids on myocardial resistance to ischemia-reperfusion injury in rats

Dietary n-3 polyunsaturated fatty acids (PUFA) reduce coronary heart disease (CHD) complications, such as chronic arrhythmia and sudden cardiac death. Improved myocardial resistance to ischemia-reperfusion injury results in smaller myocardial infarction, which is a major factor in the occurrence of CHD complications. We hypothesized that a specific dietary fatty acid profile (low in saturated and n-6 PUFA but high in plant and marine n-3 PUFA) may improve myocardial resistance to ischemia-reperfusion injury and reduce infarct size. To test this assumption, we used a well-defined rat model of myocardial infarction. Based on our results, in comparison to a diet that is high in either saturated or n-6 PUFA but poor in plant and marine n-3 PUFA, a diet that is low in saturated fats and n-6 PUFA but rich in plant and marine n-3 PUFA results in smaller myocardial infarct size (P < .01). The effects of the 3 diets were also examined by analyzing the fatty acid composition of plasma, erythrocyte cell membranes, and the phospholipids of myocardial mitochondria. The results show a great accumulation of n-3 PUFA and a parallel decrease in arachidonic acid, the main n-6 PUFA, in plasma, cell membranes, and cardiac mitochondria (P < .0001). We conclude that improved myocardial resistance to ischemia-reperfusion may be one of the critical factors explaining the protective effects of dietary n-3 PUFA against CHD complications in humans. In addition to increasing n-3 PUFA intake, an optimal dietary pattern aimed at reducing cardiovascular mortality should include a reduction of the intake of both saturated and n-6 PUFA.     

Menhaden oil, but not safflower or soybean oil, aids in restoring the polyunsaturated fatty acid profile in the novel [increment]-6-desaturase null mouse

ABSTRACT: BACKGROUND: Polyunsaturated fatty acids (PUFA) have diverse biological effects, from promoting inflammation to preventing cancer and heart disease. Growing evidence suggests that individual PUFA may have independent effects in health and disease. The individual roles of the two essential PUFA, linoleic acid (LA) and alpha-linolenic acid (ALA), have been difficult to discern from the actions of their highly unsaturated fatty acid (HUFA) downstream metabolites. This issue has recently been addressed through the development of the [increment]-6 desaturase knock out (D6KO) mouse, which lacks the rate limiting [increment]-6 desaturase enzyme and therefore cannot metabolize LA or ALA. However, a potential confounder in this model is the production of novel [increment]-5 desaturase (D5D) derived fatty acids when D6KO mice are fed diets containing LA and ALA, but void of arachidonic acid. OBJECTIVE: The aim of the present study was to characterize how the D6KO model differentially responds to diets containing the essential n-6 and n-3 PUFA, and whether the direct provision of downstream HUFA can rescue the phenotype and prevent the production of D5D fatty acids. Methodology Liver and serum phospholipid (PL) fatty acid composition was examined in D6KO and wild type mice fed i) 10% safflower oil diet (SF, LA rich) ii) 10% soy diet (SO, LA+ALA) or iii) 3% menhaden oil +7% SF diet (MD, HUFA rich) for 28 days (n = 3-7/group). RESULTS: Novel D5D fatty acids were found in liver PL of D6KO fed SF or SO-fed mice, but differed in the type of D5D fatty acid depending on diet. Conversely, MD-fed D6KO mice had a liver PL fatty acid profile similar to wild-type mice. CONCLUSIONS: Through careful consideration of the dietary fatty acid composition, and especially the HUFA content in order to prevent the synthesis of D5D fatty acids, the D6KO model has the potential to elucidate the independent biological and health effects of the parent n-6 and n-3 fatty acids, LA and ALA.     

Olive oil, corn oil, and n-3 fatty acids differently affect lipids, lipoproteins, platelets, and superoxide formation in type II hypercholesterolemia.

To evaluate which dietary fat may provide the best response in terms of plasma lipids and lipoproteins and also of platelet aggregability and superoxide formation by white blood cells, 12 type II patients were randomly allocated to three different diets, which provided polyunsaturated fatty acids (corn oil), monounsaturated fatty acids (olive oil), and a supplementation of ethyl esters of n-3 fatty acids to a prudent diet. Olive oil and, more significantly, n-3 ethyl esters lowered total cholesterol best (-2.2% and -5.8%, respectively); the latter diet, as expected, also significantly lowered triglyceridemia (-21.4%). The corn-oil diet exerted a small, statistically significant reduction of high-density-lipoprotein cholesterol (HDL) (-4.3%), and it also lowered plasma total apo B concentrations (-3.8%). n-3 ethyl esters significantly raised both total (+3.1%) and particularly HDL2 cholesterol (+24%). Platelet reactivity was insignificantly reduced by the three regimens, but all three significantly reduced thrombin-stimulated formation of thromboxane B2. Finally, only the n-3 fatty acid supplementation significantly reduced O2- generation by adherent monocytes. Dietary unsaturated fatty acids are generally effective on the plasma lipid and lipoproteins in type II patients, but significant differences may be found between the three tested regimens.     

Lack of effect of dietary n-6:n-3 PUFA ratio on plasma lipids and markers of insulin responses in Indian Asians living in the UK

Summary Background Indian Asians living in Western Countries have an over 50 % increased risk of coronary heart disease (CHD) relative to their Caucasians counterparts. The atherogenic lipoprotein phenotype (ALP), which is more prevalent in this ethnic group, may in part explain the increased risk. A low dietary long chain n-3 fatty acid (LC n-3 PUFA) intake and a high dietary n-6 PUFA intake and n-6:n-3 PUFA ratio in Indian Asians have been proposed as contributors to the increased ALP incidence and CHD risk in this subgroup. Aim To examine the impact of dietary n-6:n-3 PUFA ratio on membrane fatty acid composition, blood lipid levels and markers of insulin sensitivity in Indian Asians living in the UK. Methods Twentynine males were assigned to either a moderate or high n-6:n-3 PUFA (9 or 16) diet for 6 weeks. Fasting blood samples were collected at baseline and 6 weeks for analysis of triglycerides, total-, LDL- and HDL-cholesterol, non-esterified fatty acids, glucose, insulin, markers of insulin sensitivity and C-reactive protein. Results Group mean saturated fatty acid, MUFA, n-6 PUFA and n-3 PUFA on the moderate and high n-6:n-3 PUFA diets were 26 g/d, 43 g/d, 15 g/d, 2 g/d and 25 g/d, 25 g/d, 28 g/d, 2 g/d respectively. A significantly lower total membrane n-3 PUFA and a trend towards lower EPA and DHA levels were observed following the high n-6:n-3 PUFA diet. However no significant effect of treatment on plasma lipids was evident. There was a trend towards a loss of insulin sensitivity on the high n-6:n- 3 PUFA diet, with the increase in fasting insulin (P = 0.04) and HOMA IR [(insulin x glucose)/ 22.5] (P = 0.02) reaching significance. Conclusion The results of the current study suggest that, within the context of a western diet, it is unlikely that dietary n-6:n-3 PUFA ratio has any major impact on the levels of LC n-3 PUFA in membrane phospholipids or have any major clinically relevant impact on insulin sensitivity and its associated dyslipidaemia. Source of support: This project was funded by the Food Standards Agency (FSA), UK.