Effects of fish oil alone and combined with long chain (n-6) fatty acids on some coronary risk factors in male subjects

The Link between Homocysteine and Omega-3 Polyunsaturated Fatty Acid: Critical Appraisal and Future Directions

Omega-3 polyunsaturated fatty acids and B vitamins are linked to metabolic and degenerative disorders, such as cardiovascular disease and cognitive decline. In the last two decades, the interplay between B vitamins and omega-3 polyunsaturated fatty acids gained increasing attention. Expression control on enzymes involved in the pathway of homocysteine by polyunsaturated fatty acids has been proposed. The methylation process seems crucial for the metabolism of polyunsaturated fatty acids and their distribution within the body. This review summarizes the available data in humans about the link between homocysteine and omega-3 polyunsaturated fatty acids, with a special focus on the meta-analyses of randomized clinical trials. Even if the paucity of available information about the topic does not allow for definitive conclusions, a synergic action between polyunsaturated fatty acids and B vitamins may play a key role in regulating several metabolic pathways. This element could explain a stronger action on homocysteine levels when omega-3 polyunsaturated fatty acids and B vitamins are supplemented simultaneously. To date, a robust rationale of intervention to prevent metabolic diseases is lacking and could be beneficial for individual health and healthcare policy.

EFEITO DO PRODUTO HOMEOPÁTICO HomeoAqua Mega 3® NO DESEMPENHO E NO PERFIL LIPÍDICO DA CABEÇA DE TILÁPIA DO NILO (Oreochromis niloticus)

Resumo Duas dietas foram avaliadas, uma controle (T1), com adição de 40 mL de solução hidroalcoólica a cada kg de ração e outra (T2), com adição de 40 mL do produto Homeopático a cada kg de ração em tilápias do Nilo. Foram distribuídos 200 peixes em 10 aquários, totalizando 20 animais em cada aquário, onde permaneceram por 63 dias. Foi realizado o monitoramento dos parâmetros físicos e químicos da água, desempenho dos animais, determinação da composição centesimal e a composição de ácidos graxos em cabeças de tilápia do Nilo. Não houve diferença estatística significativa entre os tratamentos em relação aos parâmetros da água, desempenho, determinação de umidade, cinzas, proteína bruta, lipídios totais. As tilápias do Nilo que receberam o produto homeopático incorporado na ração apresentaram a razão AGPI/AGS superior ao do tratamento controle, apresentado diferença significativa. As cabeças das tilápias analisadas constituem uma excelente fonte de lipídios totais.

Omega 6 fatty acids for the primary prevention of cardiovascular disease

BACKGROUND

Omega 6 plays a vital role in many physiological functions but there is controversy concerning its effect on cardiovascular disease (CVD) risk. There is conflicting evidence whether increasing or decreasing omega 6 intake results in beneficial effects.

OBJECTIVES

The two primary objectives of this Cochrane review were to determine the effectiveness of:1. Increasing omega 6 (Linoleic acid (LA), Gamma-linolenic acid (GLA), Dihomo-gamma-linolenic acid (DGLA), Arachidonic acid (AA), or any combination) intake in place of saturated or monounsaturated fats or carbohydrates for the primary prevention of CVD.2. Decreasing omega 6 (LA, GLA, DGLA, AA, or any combination) intake in place of carbohydrates or protein (or both) for the primary prevention of CVD.

SEARCH METHODS

We searched the following electronic databases up to 23 September 2014: the Cochrane Central Register of Controlled Trials (CENTRAL) on the Cochrane Library (Issue 8 of 12, 2014); MEDLINE (Ovid) (1946 to September week 2, 2014); EMBASE Classic and EMBASE (Ovid) (1947 to September 2014); Web of Science Core Collection (Thomson Reuters) (1990 to September 2014); Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment Database, and Health Economics Evaluations Database on the Cochrane Library (Issue 3 of 4, 2014). We searched trial registers and reference lists of reviews for further studies. We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions stating an intention to increase or decrease omega 6 fatty acids, lasting at least six months, and including healthy adults or adults at high risk of CVD. The comparison group was given no advice, no supplementation, a placebo, a control diet, or continued with their usual diet. The outcomes of interest were CVD clinical events (all-cause mortality, cardiovascular mortality, non-fatal end points) and CVD risk factors (changes in blood pressure, changes in blood lipids, occurrence of type 2 diabetes). We excluded trials involving exercise or multifactorial interventions to avoid confounding.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, extracted the data, and assessed the risk of bias in the included trials.

MAIN RESULTS

We included four RCTs (five papers) that randomised 660 participants. No ongoing trials were identified. All included trials had at least one domain with an unclear risk of bias. There were no RCTs of omega 6 intake reporting CVD clinical events. Three trials investigated the effect of increased omega 6 intake on lipid levels (total cholesterol, low density lipoprotein (LDL-cholesterol), and high density lipoprotein (HDL-cholesterol)), two trials reported triglycerides, and two trials reported blood pressure (diastolic and systolic blood pressure). Two trials, one with two relevant intervention arms, investigated the effect of decreased omega 6 intake on blood pressure parameters and lipid levels (total cholesterol, LDL-cholesterol, and HDL-cholesterol) and one trial reported triglycerides. Our analyses found no statistically significant effects of either increased or decreased omega 6 intake on CVD risk factors.Two studies were supported by funding from the UK Food Standards Agency and Medical Research Council. One study was supported by Lipid Nutrition, a commercial company in the Netherlands and the Dutch Ministry of Economic Affairs. The final study was supported by grants from the Finnish Food Research Foundation, Finnish Heart Research Foundation, Aarne and Aili Turnen Foundation, and the Research Council for Health, Academy of Finland.

AUTHORS' CONCLUSIONS

We found no studies examining the effects of either increased or decreased omega 6 on our primary outcome CVD clinical endpoints and insufficient evidence to show an effect of increased or decreased omega 6 intake on CVD risk factors such as blood lipids and blood pressure. Very few trials were identified with a relatively small number of participants randomised. There is a need for larger well conducted RCTs assessing cardiovascular events as well as cardiovascular risk factors.

Composição proximal e perfil de ácidos graxos do lambari-do-rabo-vermelho (Astyanax fasciatus) de diferentes classes de peso

O trabalho foi realizado com o objetivo de avaliar a composição proximal e perfil de ácidos graxos de lambaris-do-rabo-vermelho de acordo com a classe de peso corporal: Classe I (3,24 - 4,46g); Classe II (9,08 - 11,62g); Classe III (15,8 - 18,89g) e Classe IV (32,25 - 54,64g). Não foi observado efeito do peso corporal sobre o conteúdo de cinzas corporal dos peixes. Os peixes de Classe I apresentaram maiores teores de umidade e menores teores de lipídios corporal em relação aos peixes das classes II, III e IV. O maior nível de lipídios foi observado em peixes da Classe IV e não sendo observadas diferenças entre peixes das Classes II, III e IV. O ácido palmitico (16:0) e oléico (18:1 n-9) foram os ácidos graxos saturados e monoinsaturados mais abundantes, respectivamente, independentemente da classe de peso dos peixes. A quantidade total de ácidos graxos saturados foi maior nos peixes da Classe I, que também apresentaram níveis mais elevados dos ácidos palmítico, linoléico e docohexaenóico. Os peixes de Classe II, III e IV apresentaram maior relação de ácidos graxos n-3/n-6 em comparação com os peixes da Classe I, porém os peixes de todas as classes de peso demonstraram valor nutricional satisfatório para consumo humano em termos de proteína bruta, lipídios e relações de ácidos graxos n-3/n-6 e AGP/AGS.

Co-supplementation of healthy women with fish oil and evening primrose oil increases plasma docosahexaenoic acid, gamma-linolenic acid and dihomo-gamma-linolenic acid levels without reducing arachidonic acid concentrations

Fish oil supplementation during pregnancy not only improves maternal and neonatal DHA status, but often reduces gamma-linolenic acid (GLA), dihomo-GLA (DGLA), and arachidonic acid (ARA) levels also, which may compromise foetal and infant development. The present study investigated the effects of a fish oil/evening primrose oil (FSO/EPO) blend (456 mg DHA/d and 353 mg GLA/d) compared to a placebo (mixture of habitual dietary fatty acids) on the plasma fatty acid (FA) composition in two groups of twenty non-pregnant women using a randomised, double-blind, placebo-controlled parallel design. FA were quantified in plasma total lipids, phospholipids, cholesterol esters, and TAG at weeks 0, 4, 6 and 8. After 8 weeks of intervention, percentage changes from baseline values of plasma total lipid FA were significantly different between FSO/EPO and placebo for GLA (+49.9 % v. +2.1 %, means), DGLA (+13.8 % v. +0.7 %) and DHA (+59.6 % v. +5.5 %), while there was no significant difference for ARA ( - 2.2 % v. - 5.9 %). FA changes were largely comparable between plasma lipid fractions. In both groups three subjects reported mild adverse effects. As compared with placebo, FSO/EPO supplementation did not result in any physiologically relevant changes of safety parameters (blood cell count, liver enzymes). In women of childbearing age the tested FSO/EPO blend was well tolerated and appears safe. It increases plasma GLA, DGLA, and DHA levels without impairing ARA status. These data provide a basis for testing this FSO/EPO blend in pregnant women for its effects on maternal and neonatal FA status and infant development.

Evidence for a protective (synergistic?) effect of B-vitamins and omega-3 fatty acids on cardiovascular diseases

The results of dietary intervention trials favor the hypothesis that higher intakes of B-vitamins (folate, vitamin B(6) and B(12)), and subsequently lower total homocysteine (tHcy) concentrations, are causally associated with a decreased risk of vascular disease in patients with cardiovascular diseases (CVD). The same is true for a higher intake of omega-3 fish fatty acids. Yet, the lack of hard end points and/or appropriate study designs precludes a definitive conclusion about causality. In the future, intervention trials with hard end points and randomized double-blind placebo-controlled designs should be able to elucidate the causality problem. There are several pathways by which B-vitamins and omega-3 fatty acids may exert their protective effect on CVD, a common pathway is a beneficial effect on the endothelial function and hemostasis. With respect to synergy between B-vitamins and omega-3 fatty acids, there is no evidence that fish oils have a tHcy-lowering effect beyond the effect of the B-vitamins. Nevertheless, animal studies clearly illustrate that vitamin B(6)- as well as folate-metabolism are linked with those of long-chain omega-3 fatty acids. Furthermore, a human study indicated synergistic effects of folic acid (synthetic form of folate) and vitamin B(6) together with omega-3 fatty acids on the atherogenic index and the fibrinogen concentration. Although these results are promising, they were produced in very small selective study populations. Thus, confirmation in large well-designed intervention trials is warranted.

A review of the safety of DHA45-oil

Polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA), are natural constituents of the human diet; however, dietary intakes of these fatty acids are below recommended values. The main dietary source of DHA is fatty fish, with lesser amounts provided by shellfish, marine mammals, and organ meats. The addition to traditional food products of refined oils produced by marine microalgae represents potential sources of supplemental dietary DHA. DHA45-oil is manufactured through a multi-step fermentation and refining process using a non-toxigenic and non-pathogenic marine protist. Comprising approximately 45% DHA, and lesser concentrations of palmitic acid and docosapentaenoic acid, DHA45-oil is intended for use in foods as a dietary source of DHA. The safety of DHA45-oil was evaluated in various genotoxicity and acute, subchronic, and reproductive toxicity studies. DHA45-oil produced negative results in genotoxicity assays and demonstrated a low acute oral toxicity in mice and rats. Dietary administration of DHA45-oil to rats in subchronic and one-generation reproductive studies produced results consistent with those observed in oral studies using high concentrations of omega-3 PUFAs from fish or other microalgal-derived oils. The results of these studies, as well as those of various published metabolic, toxicological, and clinical studies with DHA-containing oils, support the safety of DHA45-oil as a potential dietary source of DHA.

Dietary fat (virgin olive oil or sunflower oil) and physical training interactions on blood lipids in the rat

OBJECTIVE

We investigated whether the intake of virgin olive oil or sunflower oil and performance of physical exercise (at different states) affect plasma levels of triacylglycerols, total cholesterol, and fatty acid profile in rats.

METHODS

The study was carried out with six groups of male rats subjected for 8 wk to a diet based on virgin olive oil (three groups) or sunflower oil (three groups) as dietary fat. One group for each diet acted as sedentary control; the other two groups ran in a treadmill for 8 wk at 65% of the maximum oxygen consumption. One group for each diet was killed 24 h after the last bout of exercise and the other was killed immediately after the exercise performance. Triacylglycerols, total cholesterol, and fatty acid profile were analyzed in plasma. Analysis of variance was used to test differences among groups.

RESULTS

Animals fed on virgin olive oil had lower triacylglycerol and cholesterol values. Physical exercise reduced these parameters with both dietary treatments. Fatty acid profile showed higher monounsaturated fatty acid proportion in virgin olive fed oil animals and a higher omega-6 polyunsaturated fatty acid proportion in sunflower oil fed animals. Physical exercise reduced the levels of monounsaturated fatty acids with both diets and increased the proportions of omega-3 polyunsaturated fatty acids.

CONCLUSIONS

Results from the present study supported the idea that physical exercise and the intake of virgin olive oil are very good ways of reducing plasma triacylglycerols and cholesterol, which is desirable in many pathologic situations. Concerning findings on fatty acid profile, we had results similar to those of other investigators regarding the effect of different sources of dietary fat on plasma. The most interesting results came from the effect of physical exercise, with significant increases in the levels of omega-3 polyunsaturated fatty acids, which may contribute to the antithrombotic state and lower production of proinflammatory prostanoids attributed to physical exercise.

Effect of fish oil on LDL oxidation and plasma homocysteine concentrations in health

Oxidation of low-density lipoprotein (LDL) and hyperhomocysteinemia are believed to play a role in therogenesis. Whether n-3 polyunsaturated fatty acids increase LDL susceptibility to oxidation or influence homocysteine (Hcy) metabolism has long been a subject of controversy. In this study, we evaluated the effect of 8 weeks of dietary supplementation with 6 g/day of fish oil (FO; 3 g of n-3 fatty acids) on plasma lipoproteins, in vitro LDL peroxidation, antioxidant status, and plasma Hcy concentrations in 16 normolipidemic subjects. FO rapidly and significantly (P < .01) decreased plasma total and very low density lipoprotein triglyceride concentrations and had no effect on LDL or high-density-lipoprotein cholesterol. The mean lag time before onset of Cu(2+)-induced LDL oxidation, as well as plasma and LDL alpha-tocopherol and beta-carotene concentrations, was unchanged. However, changes in plasma aminothiol concentrations occurred during the study. Specifically, a progressive and significant increase in total Hcy plasma concentrations was observed (13.4% and 20% after 4 and 8 weeks, respectively; P < .01). Total glutathione concentrations were significantly higher after 8 weeks (P < .05). The tHcy increase was not associated with changes in plasma folate or vitamin B(12) concentrations. However, concentrations of plasma nitric oxide metabolites (NO(x) = NO(2) + NO(3)) were significantly higher than at baseline after 8 weeks of FO intake (74%; P < .01). Further, the changes in total Hcy and NO(x) plasma concentrations observed after 8 weeks of FO were found to be significantly correlated (r = .78, P < .001). With this study, we report for the first time the apparent interaction of n-3 fatty acids and nitric oxide on Hcy metabolism.