鱼油和ω-3多不饱和脂肪酸在冠心病防治中的作用

鱼油和ω-3多不饱和脂肪酸在冠心病防治中的价值,历经临床流行病研究、队列研究、基础研究和临床多中心随机对照研究,积累了大量的证据,并形成了一定的共识,但由于近年来几个大型双肓临床多中心随机对照试验结果不一致,目前的结论仍需要今后高质量的研究工作证实.     

Oxidation of fish oil supplements in Australia

Fish oils oxidise readily, forming primary and secondary oxidation products, which may be harmful for humans. Some recent studies reported that fish oil supplements in Australasia are oxidised above acceptable international limits, however other studies reported low levels of oxidation. This study employed peroxide and p-anisidine values determination to measure primary and secondary oxidation of fish oils in the Australian market. Of 26 supplements tested, 38% exceeded the limit for primary oxidation, 25% exceeded the limit for secondary oxidation and 33% exceeded the limit for total oxidation, according to international recommendations. Four specially marketed supplements were found to deliver significantly lower amounts of fish oil per capsule (165 vs. 577?mg, p?=?.007), yet cost significantly more on a per gram basis ($2.97 vs $0.39, p?<?.001). However, there were no differences in any oxidative markers between regular supplements and the specially marketed products.     

The health benefits of omega-3 polyunsaturated fatty acids: a review of the evidence

The UK dietary guidelines for cardiovascular disease acknowledge the importance of long-chain omega-3 polyunsaturated fatty acids (PUFA) - a component of fish oils - in reducing heart disease risk. At the time, it was recommended that the average n-3 PUFA intake should be increased from 0.1 to 0.2 g day(-1). However, since the publication of these guidelines, a plethora of evidence relating to the beneficial effects of n-3 PUFAs, in areas other than heart disease, has emerged. The majority of intervention studies, which found associations between various conditions and the intake of fish oils or their derivatives, used n-3 intakes well above the 0.2 g day(-1) recommended by Committee on Medical Aspects of Food Policy (COMA). Furthermore, in 2004, the Food Standards Agency changed its advice on oil-rich fish creating a discrepancy between the levels of n-3 PUFA implied by the new advice and the 1994 COMA guideline. This review will examine published evidence from observational and intervention studies relating to the health effects of n-3 PUFAs, and discuss whether the current UK recommendation for long-chain n-3 PUFA needs to be revisited.     

The effect of fish oil supplementation on serum phospholipid fatty acids profile during pregnancy: A double blind randomized controlled trial

Omega-3 fatty acids (FAs) are essential unsaturated long-chain FAs necessary for proper health and growth. The objective of the authors in this study was to evaluate the effect of fish oil supplementation in pregnancy on maternal serum FA profiles. Participants (n = 150 pregnant women aged 18–35 years in Tabriz, Iran) were randomly assigned to receive either 1,000 mg fish oil supplements daily containing 120 mg docosahexanoic acid (DHA) and 180 mg eicosapentaenoic acid (EPA), or placebo from week 21 of pregnancy to delivery. The primary outcome measures were mean serum DHA and EPA proportion of total FAs at weeks 35–37 of pregnancy. Analyses were based on intention-to-treat. No significant differences were observed between the groups in consumption of fish and serum FAs levels at baseline. Fish oil supplementation significantly increased the mean DHA proportion of total FAs in the intervention compared to the placebo group at weeks 35–37 [adjusted Mean Difference (aMD) = 0.15; 95% CI 0.08–0.23]. The mean EPA proportion of total FAs also increased in the intervention group, but the difference between the groups was not significant (aMD = 0.04; 95% CI ?0.01 to 0.08). The dietary recommendation for consumption of 1,000 mg/day fish oil supplements during pregnancy seems beneficial for better serum FA composition.     

Evaluation of the composition of omega-3 fatty acids in dietary oil supplements

Aim: The aim of the present study was to determine the fatty acid composition of 19 dietary oil supplements that are commercially available in Australia, comparing findings with manufacturers' reported omega-3 fatty acid content. Methods: Fifteen fish oil supplements and four non-fish oil supplements were obtained from Australian retail stores. Fatty acids were derivatised, and fatty acid methyl esters were quantitated using classical GC-flame ionisation detection methods. Composition of eicosapentaenoic acid and docosahexaenoic acid reported by supplement manufacturers was compared with experimental values using the Bland-Altman plot. Results: The combined eicosapentaenoic acid and docosahexaenoic acid content in the fish oil and non-fish oil supplements was 17.63–71.45% and 0.00–0.05% respectively. A high level of congruency was observed for the composition of eicosapentaenoic acid and docosahexaenoic acid reported by manufacturers and determined experimentally (mean difference, eicosapentaenoic acid, 13.2 mg; docosahexaenoic acid, 12.8 mg). Conclusion: Current practice in pre-market assessment of complementary medicines in Australia is satisfactory for supplements examined in the present study. Intake of these fish oil supplements can be used to provide high levels of long-chain omega-3 fatty acids that would be otherwise difficult to achieve through normal dietary intake alone.     

n-3 fatty acids and coronary heart disease Epidemiology from Eskimos to Western populations

The original cross-cultural comparisons between Greenland Eskimos and Danes and between Japan and Western countries suggested that a high fish intake was associated with low mortality rates from coronary heart disease. More comprehensive cross-cultural studies, eg the Seven Countries Study showed that the saturated fat content of the diet is more important than the amount of fish in explaining differences in coronary heart disease mortality between countries. Cohort studies carried out in cultures with a low level of fish consumption showed that persons who eat fish once or twice a week had lower mortality rates from coronary heart disease than persons who did not eat fish. The results of the epidemiological studies carried out so far suggest that a diet low in saturated fat in combination with a low level of fish consumption may be of importance for coronary heart disease prevention.     

Effects of a 1-year dietary intervention with n-3 polyunsaturated fatty acid-enriched olive oil on non-alcoholic fatty liver disease patients: a preliminary study

Abstract

Background and aims Non-alcoholic fatty liver disease (NAFLD) is a worldwide diffuse condition due to alimentary, environment and genetic factors. The aim of our preliminary study was to evaluate the effectiveness of long-term consumption of food enriched with n-3 polyunsaturated fatty acids (PUFA) in patients with NAFLD.

Methods Eleven patients were enrolled; six (four males, two females) were planned for oral administration of 6.5 ml olive oil enriched with n-3 PUFA for 12 months, while five (four males, one female) were used as controls.

Results Consumption of olive oil enriched with n-3 PUFA demonstrated a significant improvement of liver echo-texture and of the Doppler Perfusion Index after 12 months (after: 0.19 ± 0.02 vs. pre: 0.15 ± 0.03; P < 0.05), whereas no significant changes were seen at the end of follow-up in controls. Moreover, patients who consumed the olive oil enriched with n-3 PUFA showed a significant amelioration of liver enzymes, and of triglycerides (post: 132.8 ± 63.7 vs. pre: 164.5 ± 85.5 mg/dl; P = 0.04) in a general linear model adjusted for age and gender. Interestingly, patients reported to have a significant increase of adiponectin levels (post: 1,487.9 ± 96.7 vs. pre: 1,143 ± 24.8 μg/ml; P = 0.04).

Conclusion The results of this preliminary study showed that long-term consumption of olive oil enriched with n-3 PUFA in patients with NAFLD is able to decrease circulating liver enzymes and triglycerides, with a significant improvement of adiponectin levels.     

Use of microencapsulated fish oil as a means of increasing n-3 polyunsaturated fatty acid intake

Background: The successful incorporation of fish oil into foods may provide a means of increasing intakes of n-3 polyunsaturated fatty acids (n-3 PUFA). The aim of the present study was to evaluate the bioavailability of n-3 PUFA in microencapsulatd fish oil compared with a fish oil capsule. Methods: Twenty-eight healthy volunteers were recruited to take part in this randomized controlled trial. Volunteers were supplemented with 0.9 g n-3 PUFA daily for 4 weeks, delivered either as microencapsulated fish oil in a milkshake or as a fish oil capsule. Plasma fatty acid composition and plasma total cholesterol levels were measured at baseline and after supplementation. In addition, volunteers completed a questionnaire on fish consumption, use of supplements and exercise. Results: Responses to the questionnaire indicated that the males who took part in this study took more physical exercise, consumed less fish and were less likely than the females to take supplements. Plasma n-3 PUFA concentrations were raised significantly and by a similar level by both fish oil supplements. Furthermore, no significant difference was observed in plasma n-3 PUFA concentrations following supplementation with either form of fish oil. Plasma total cholesterol levels were not significantly altered by n-3 PUFA supplementation in either group. The results of this study indicated that there was no difference in the bioavailability of n-3 PUFA given as microencapsulated fish oil compared with n-3 PUFA delivered as a fish oil capsule. Fortification of foodstuffs with microencapsulated fish oil therefore offers the potential to increase intakes of n-3 PUFA in line with current recommendations.     

Long chain omega-3 fatty acids intake,fish consumption and mental disorders in the SUN cohort study

Background Very long chain omega-3 fatty acids (w-3 PUFA) intake and fish consumption have been suggested as protective factors against neuropsychiatric disorders but there is scarcity of large cohort studies assessing this association. Aim of the study To assess the association between w-3-PUFA intake and fish consumption and mental disorders. Methods A prospective cohort study was performed in 7,903 participants. W-3 PUFA intake and fish consumption were ascertained through a validated semi-quantitative food frequency questionnaire. The outcomes after 2 years of follow-up were: (1) Incident mental disorder (depression, anxiety, or stress), (2) incident depression, and (3) incident anxiety. Logistic regression models and generalized additive models were fit to assess the relationship between w-3 PUFA intake or fish consumption and the incidence of these outcomes. Odds ratios (OR) and their 95% confidence intervals (CI) were calculated. Results 173 cases of depression, 335 cases of anxiety, and 4 cases of stress were observed during 2-year follow-up. ORs (95% CI) of mental disorder for successive quintiles of energy-adjusted w-3 PUFA intake were 1 (reference), 0.72 (0.52–0.99), 0.79 (0.58–1.08), 0.65 (0.47–0.90), and 1.04 (0.78–1.40). Subjects with a moderate consumption of fish (third and fourth quintiles of consumption: median of each quintile 83.3 and 112 g/day, respectively) had a relative risk reduction higher than 30%. Conclusions A potential benefit of w-3 PUFA intake on total mental disorders is suggested, although no linear trend was apparent.     

Effects of fatty and lean fish intake on blood pressure in subjects with coronary heart disease using multiple medications

BACKGROUND: Intake of fish and long-chain n-3 fatty acids has been of wide interest due to their beneficial effects on cardiovascular risk factors and lower coronary heart disease (CHD) risk. AIM OF THE STUDY: The aim of this pilot study was to examine the effects of fatty fish and lean (white) fish on fatty acid composition of serum lipids and cardiovascular risk factors in subjects with CHD using multiple drugs for this condition. METHODS: The study was an 8-week controlled, parallel intervention. Inclusion criteria were myocardial infarction or unstable ischemic attack, age under 70 years, use of betablockers and presence of sinus rhythm. The subjects were randomized to one of the following groups: 4 meals/week fatty fish (n = 11), 4 meals/week lean fish (n = 12) and control diet including lean meat (n = 10). RESULTS: The mean (+/-SD) of reported fish meals per week was 4.3 +/- 0.4, 4.7 +/- 1.1 and 0.6 +/- 0.4 in the groups, respectively. The proportions of eicosapentaenoic and docosahexaenoic acids in serum lipids increased in the fatty fish group only (P < 0.05). Systolic and diastolic blood pressure levels decreased in the lean fish group (0 vs. 8 week: 3.5 +/- 3.2 and 4.6 +/- 3.6%, respectively, P < 0.05). Serum total triglyceride concentration did not significantly change. HDL cholesterol concentration change differed among groups but without significant post hoc differences. Apolipoprotein A-1 concentration decreased in the control group (0 vs. 8 week, P < 0.05). Coagulation factors, 25-hydroxy vitamin D, and heart rate variability (24 h Holter) did not change among the groups. CONCLUSIONS: Our results suggest that intake of lean fish at least four times per week could reduce blood pressure levels in CHD patients.     

An approach for quantitatively balancing methylmercury risk and omega-3 benefit in fish consumption advisories

Background: Nearly all fish consumption advisories for methylmercury (MeHg) are based only on risk. There is a need to also address benefits, especially those from polyunsaturated fatty acids (PUFAs), in neurodevelopmental function and cardiovascular health. However, because MeHg and PUFA generally act on these same end points, disentangling risk and benefit is challenging.Objectives: We propose an approach for balancing risk and benefit that is based on the use of statistically dissociated measures of risk and benefit.Discussion: Because of mutual coexposure of MeHg and PUFAs in population-based studies and their opposite effect on many of the same end points, MeHg risk and PUFA benefit are tightly linked statistically, which results in mutual (negative) confounding. Thus, neither MeHg risk nor PUFA benefit can be accurately quantified without taking the other into account. A statistical approach that generates unconfounded risk and benefit coefficients for each end point can permit their subsequent recombination to describe the overall risk–benefit profile of each species of fish or fish diet. However, it appears that some end points may be adversely affected by MeHg without experiencing counterbalancing benefit from PUFAs. Such end points may drive consumption advisories and may preclude balancing of risk and benefit on the basis of other end points.Conclusions: Our thinking about fish consumption advisories now recognizes the need to balance risk and benefit. However, although statistical analysis of the appropriate data can eliminate mutual confounding, care is required to address the most sensitive end points that may be sensitive to risk and not benefit.     

Omega-3 fatty acids and cardiovascular disease: The epidemiological evidence

Epidemiological studies in the last 40 years suggest that omega-3 fatty acids derived from fish and fish oil decrease the risk of coronary heart disease, hypertension and stroke, and their complications. The beneficial effects of omega-3 fatty acids include effects on lipids, blood pressure, cardiac and vascular function, eicosanoids, coagulation, and immunological responses. However, not all population studies have shown that omega-3 fatty acids are associated with reduced rates of coronary mortality. Such studies suffer either from small numbers of subjects or the population already had a high intake of fish. When comparing the highest intake of fish to that of the lowest fish intake, the beneficial effects of omega-3 fatty acids have been shown. In population-based case-control studies, the patients consuming modest amounts of fish, the equivalent of one fatty fish meal per week, had a significant lower risk of primary cardiac arrest compared with those who did not eat fish at all. In case-control studies, the intake of eicosapentaenoic acid and docosahexaenoic acid as reflected in adipose tissue content is inversely associated with risk of myocardial infarction.     

The effects of fish or fish oil on the omega‐3 index

Aim: To compare the impact of recommended intakes of fish and fish oil supplements on the omega‐3 index and selected risk factors in patients with coronary heart disease. Methods: A 12‐week crossover intervention comparing the impact of 1 g/day of long‐chain omega‐3 polyunsaturated fatty acids from fresh salmon or fish oil capsules on the omega‐3 index and cardiovascular risk factors. Eleven patients with coronary heart disease, recruited from St. Vincent's Hospital, Melbourne, participated in the study. Results: A decrease in blood pressure (>5 mmHg; P < 0.05) was observed after the fish but not the fish oil. The change in waist to hip ratio also favoured the fish intervention. Resting heart rate fell by a similar amount on both interventions, and the omega‐3 index increased significantly on both; from 6% to 7–8% (P < 0.01). Blood lipids did not improve on either arm. Conclusions: In Australians with coronary heart disease, 1 g/day of long‐chain omega‐3 polyunsaturated fatty acid from fish or supplements over 12 weeks was effective in increasing the omega‐3 index. Fish intake may have additional cardiovascular benefits beyond the omega‐3 effect as evidenced by the substantial blood pressure reduction following the fish arm warranting examination in a larger study.     

A perinatal strategy to prevent coronary heart disease

I investigated whether metabolism of essential fatty acids and the concentrations of their long-chain metabolites (long-chain polyunsaturated fatty acids [LCPUFAs]) are altered in fetal or perinatal growth retardation, maternal hypercholesterolemia, low-grade systemic inflammation, insulin resistance, and atherosclerosis, conditions that predispose to the development of coronary heart disease (CHD).I critically reviewed the literature pertaining to the metabolism of essential fatty acids in CHD and conditions that predispose to it.LCPUFAs enhance endothelial nitric oxide synthesis, suppress the production of the proinflammatory cytokines tumor necrosis factor and interleukin-6, attenuate insulin resistance, and have antiatherosclerotic properties. Low-birthweight infants have decreased concentrations of LCPUFAs, especially arachidonic acid. Neonatal arachidonic acid status is related to intrauterine growth, and LCPUFAs improve fetal and postnatal growth. LCPUFAs are useful in the management of hyperlipidemia, inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase activity, and may mediate the beneficial actions of statins. Plasma concentrations of various LCPUFAs are low in diabetes mellitus, hypertension, and CHD and in populations at high risk of CHD. Breast milk is rich in LCPUFAs, and this may explain why and how adequate (6 mo to 1 y) breast feeding protects against the development of obesity, hypertension, insulin resistance, and CHD.LCPUFAs are essential for the growth and development of the fetus and infant. LCPUFAs can prevent various conditions that predispose to the development of CHD. The low incidence of CHD seen in adequately breast-fed infants can be linked to the LCPUFA content of breast milk. Based on this evidence, I suggest that provision of LCPUFAs during critical periods of growth, especially from the second trimester of pregnancy to age 5 y, prevents CHD in adult life.     

Effects of Perioperative Supplementation with Omega-3 Fatty Acids on Leukotriene B4 and Leukotriene B5 Production by Stimulated Neutrophils in Patients with Colorectal Cancer: A Randomized,Placebo-Controlled Intervention Trial

Omega-3 fatty acids (n-3 FA) may have beneficial clinical and immune-modulating effects in surgical patients. In a randomized, double-blind, prospective, placebo-controlled trial, 148 patients referred for elective colorectal cancer surgery received an n-3 FA-enriched oral nutritional supplement (ONS) providing 2.0 g of eicosapentaenoic acid (EPA) and 1.0 g of docosahexaenoic acid (DHA) per day or a standard ONS for seven days before surgery. On the day of operation, there was a significant increase in the production of leukotriene B₅ (LTB₅) (p < 0.01) and 5-hydroxyeicosapentaenoic acid (5-HEPE) (p < 0.01), a significant decrease in the production of leukotriene B₄ (LTB₄) (p < 0.01) and a trend for a decrease in the production of 5-hydroxyeicosatetraenoic acid (5-HETE) (p < 0.1) from stimulated neutrophils in the active group compared with controls. There was no association between LTB₄ values and postoperative complications. In conclusion, oral n-3 FA exerts anti-inflammatory effects in surgical patients, without reducing the risk of postoperative complications.     

Secondary prevention in coronary heart disease

After myocardial infarction, beta-blockers, aspirin and (in selected patients) ACE inhibitors all reduce substantially the risk of further myocardial infarction or coronary death. With regard to life-style changes, giving up cigarette smoking reduces coronary risk by about 50%. Weight reduction and regular exercise are advised, although the effect of these measures on prognosis is uncertain. Recently, two major trials, the Scandinavian Simvastatin and West of Scotland Pravastatin studies, have radically changed ordinary medical practice. In these trials HMG CoA reductase inhibitor (statin) treatment reduced coronary events by 30–40%, reduced all-cause mortality, and proved safe and well-tolerated. The accepted policy now is to treat all patients with coronary heart disease, who have a cholesterol concentration 5.5 mmol/l or higher, with a statin. Where does this leave cholesterol-lowering dietary advice in secondary prevention? The benefits of statin treatment were attained by reducing serum cholesterol by an average of 25%. Diet change rarely attains such a fall in cholesterol and should therefore be used only as an adjunct to drug therapy. When recommending a lipid-lowering diet there is a danger that patients may be denied highly-effective drug treatment because of the «threshold» effect. A decision on the need for cholesterol reduction should be made before diet change is advised. Once the decision is made the target is a 25% cholesterol reduction, which will require drug therapy in addition to diet changes.     

冠心病基因检测与冠心病的关联性

目的观察冠心病基因检测与冠心病是否有关联性,以及关联程度如何。方法选取120例住院患者,其中60例为冠心病人,60例为非冠心病人。年龄40—65岁。冠心病为观察A组,非冠心病为对照B组,记录性别、年龄、冠心病家族史、高血压史、糖尿病史,并均抽血行冠心病基因检测。A组选1人和B组选1人按年龄相近、性别相同配对,共形成60对。开始进行1：1条件Logistic回归分析。结果冠心病家族史、高血压史、糖尿病史、以及冠心病基因检测与冠心病均有关联性。其中冠心病基因检测与冠心病的关联程度低于其他3个因素。结论冠心病基因检测与冠心病有关联性。     

非酒精性脂肪肝与冠心病和脑血管病关系的研究

目的非酒精性脂肪肝与冠心病和脑血管病关系的研究。方法基于非酒精性脂肪肝患者冠心病和脑血管病的发病风险增高这一假设，我们对我院6年间的住院病历进行了回顾性研究，对年龄和性别匹配的550例非酒精性脂肪肝患者和550例正常肝脏患者的临床资料加以对比分析。结果非酒精性脂肪肝患者的收缩压、舒张压以及体重指数均显著高于正常肝脏者，非酒精性脂肪肝患者的ALT水平较之于正常肝脏者明显增高。非酒精性脂肪肝患者中冠心病发病率为36．5％，脑血管病发病率为25．6％；正常肝脏中冠心病发病率为12．2％，脑血管病发病率为7．1％。结论非酒精性脂肪肝患者的冠心病发病率和脑血管病发病率均显著增高。