Fat as a physiological regulator: the news gets better (original) (raw)
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Fish, fish oils, n-3 polyunsaturated fatty acids and cardiovascular health
Epidemiological studies Modern industrialised societies are characterised by a high intake of saturated, omega-6 PUFA and trans fatty acids, and a low intake of n-3 PUFA. The ratio of n-6:n-3 in the Palaeolithic period has been estimated as 0.79, which is similar to that in Crete before 1960. 54,55 In contrast, in the USA and Northern Europe, the ratio is currently about 15:1. 55,56 Both the absolute amount of n-3 PUFA (especially marine n-3 PUFA) and the n-6:n-3 ratio seem to be important for health. 57 More than a dozen studies in populations with a moderate to high prevalence of CHD have confirmed the findings from early studies of Chinese and Greenland Eskimos: a high intake of fish is associated with low CHD mortality. 58,59 An inverse relationship between fish consumption and CHD was documented in China nearly four decades ago. The Chinese Academy of Medical Sciences in Beijing noted that the lowest incidence of CHD was in fishermen from the Choushan archipelago. 60 Nomads consuming predominantly animal fat in Xinjiang province had an eight times higher incidence of CHD than the average population. 61 The beneficial association between fish intake and low rates of CHD in China was confirmed in the prospective study from Shanghai, 62 which involved 18,224 subjects over 12 years. At about the same time as the Chinese studies, Bang and Dyerberg s studies of Greenland Eskimos also suggested that seafood, rich in marine n-3 PUFA, prevents CHD and stroke. 63-65 Their seminal studies, coupled with the emerging understanding of prostaglandin metabolism, opened up a new research area.
Arteriosclerosis, Thrombosis, and Vascular Biology, 2003
We reviewed available evidence for cardiovascular effects of n-3 polyunsaturated fatty acid (PUFA) consumption, focusing on long chain (seafood) n-3 PUFA, including their principal dietary sources, effects on physiological risk factors, potential molecular pathways and bioactive metabolites, effects on specific clinical endpoints, and existing dietary guidelines. Major dietary sources include fatty fish and other seafood. n-3 PUFA consumption lowers plasma triglycerides, resting heart rate, and blood pressure and might also improve myocardial filling and efficiency, lower inflammation, and improve vascular function. Experimental studies demonstrate direct antiarrhythmic effects, which have been challenging to document in humans. n-3 PUFA affect a myriad of molecular pathways, including alteration of physical and chemical properties of cellular membranes, direct interaction with and modulation of membrane channels and proteins, regulation of gene expression via nuclear receptors and transcription factors, changes in eicosanoid profiles, and conversion of n-3 PUFA to bioactive metabolites. In prospective observational studies and adequately powered randomized clinical trials, benefits of n-3 PUFA seem most consistent for coronary heart disease mortality and sudden cardiac death. Potential effects on other cardiovascular outcomes are less-well-established, including conflicting evidence from observational studies and/or randomized trials for effects on nonfatal myocardial infarction, ischemic stroke, atrial fibrillation, recurrent ventricular arrhythmias, and heart failure. Research gaps include the relative importance of different physiological and molecular mechanisms, precise dose-responses of physiological and clinical effects, whether fish oil provides all the benefits of fish consumption, and clinical effects of plant-derived n-3 PUFA. Overall, current data provide strong concordant evidence that n-3 PUFA are bioactive compounds that reduce risk of cardiac death. National and international guidelines have converged on consistent recommendations for the general population to consume at least 250 mg/day of long-chain n-3 PUFA or at least 2 servings/week of oily fish. (J Am Coll
n-3 Polyunsaturated Fatty Acids, Fish, and Nonfatal Acute Myocardial Infarction
Circulation, 2001
The relation between n-3 polyunsaturated fatty acids (PUFAs), fish intake, and risk of coronary heart disease is controversial. An Italian case-control study including 507 patients with nonfatal acute myocardial infarction (AMI) and 478 hospital controls found a multivariate odds ratio (OR) of 0.67 (95% CI, 0.47 to 0.95) for the highest n-3 PUFA intake and 0.68 (95% CI, 0.47 to 0.98) for an intake of >1 portion of fish per week compared with >/=2 portions per week. Small amounts of n-3 PUFAs may be inversely related to AMI risk in this low-risk population.
British Journal of Nutrition, 2012
There is convincing evidence that consumption of fish and fish oil rich in long-chain (LC) n-3 PUFA (n-3 LCPUFA), EPA (20 : 5n-3) and DHA (22 : 6n-3) reduce the risk of CHD. The aim of the present study was to investigate whether n-3 LCPUFA-enriched food products provide similar beneficial effects as fish oil with regard to incorporation into plasma lipids and effects on cardiovascular risk markers. A parallel 7-week intervention trial was performed where 159 healthy men and women were randomised to consume either 34 g fish pâté (n 44), 500 ml fruit juice (n 38) or three capsules of concentrated fish oil (n 40), all contributing to a daily intake of approximately 1 g EPA and DHA. A fourth group did not receive any supplementation or food product and served as controls (n 37). Plasma fatty acid composition, serum lipids, and markers of inflammation and oxidative stress were measured. Compared with the control group, plasma n-3 LCPUFA and EPA:arachidonic acid ratio increased equally in all intervention groups. However, no significant changes in blood lipids and markers of inflammation and oxidative stress were observed. In conclusion, enriched fish pâté and fruit juice represent suitable delivery systems for n-3 LCPUFA. However, although the dose given is known to reduce the risk of CVD, no significant changes were observed on cardiovascular risk markers in this healthy population.
American Journal of Clinical Nutrition, 2010
Background: Consumption of fish and n-3 (omega-3) long-chain polyunsaturated fatty acids (LCPUFAs) has been associated with reduced risk of coronary artery disease (CAD) mortality. Objective: The aim was to examine the relation between dietary intake of n-3 LCPUFAs or fish and risk of future coronary events or mortality in patients with well-characterized CAD. Design: This was a substudy of 2412 participants in the Western Norway B Vitamin Intervention Trial with a median follow-up time of 57 mo. Patients aged .18 y diagnosed with CAD (81% men) completed a food-frequency questionnaire at baseline, from which daily intakes of eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids as well as fish were estimated on the basis of diet and intakes of supplements including fish and cod liver oils. The main endpoint was a composite of coronary events, including coronary death, nonfatal acute myocardial infarction, and unstable angina pectoris. Results: The mean (6SD) intakes of n-3 LCPUFAs in quartiles 1-4 were 0.58 6 0.29, 0.83 6 0.30, 1.36 6 0.44, and 2.64 6 1.18 g/d, respectively. We found no dose-response relation between quartiles of n-3 LCPUFAs (based on intake as percentage of total energy) or fish and coronary events or separate endpoints. A post hoc additive proportional hazards model showed a slightly increased risk of coronary events at an intake of n-3 LCPUFAs , '0.30 g/d. Conclusion: Among Norwegian patients with CAD consuming relatively high amounts of n-3 LCPUFAs and fish, there were no significant trends toward a reduced risk of coronary events or mortality with increasing intakes. This trial was registered at clinicaltrials.gov as NCT00354081.