Fish Fatty Acids Research Articles

Dietary exposure to polychlorinated biphenyls and risk of myocardial infarction in men — A population-based prospective cohort study

BackgroundMajor food contaminants such as polychlorinated biphenyls (PCBs) are proposed to play a role in the etiology of cardiovascular disease (CVD), but to date the impact of PCBs on cardiovascular health need to be explored. Methods and resultsWe assessed the association between validated food frequency questionnaire-based estimates of dietary PCB exposure and risk of myocardial infarction, ascertained through register-linkage, among 36,759 men from the population-based Swedish Cohort of Men, free of cardiovascular disease, diabetes and cancer at baseline (1997). Relative risks were adjusted for known cardiovascular risk factors, long-chain omega-3 fatty acids (eicosapentaenoic and docosahexaenoic acids) and methyl mercury exposure. During 12years of follow-up (433,243 person-years), we ascertained 3005 incident cases of myocardial infarction (654 fatal). Compared with the lowest quintile of dietary PCB exposure (median 113ng/day), men in the highest quintile (median 436ng/day) had multivariable-adjusted relative risks of 1.74 (95% confidence interval [CI], 1.30–2.33; p-trend<0.001) for total and 1.97 (95% CI 1.42–2.75; p-trend<0.001) for non-fatal myocardial infarction. In mutually adjusted models, dietary PCB exposure was associated with an increased risk of myocardial infarction, while the intake of long-chain omega-3 fish fatty acids was associated with a decreased risk. We also observed an effect modification by adiposity on the association between of dietary PCB exposure and myocardial infarction, with higher risk among lean men (p value for interaction =0.03). ConclusionsExposure to PCBs via diet was associated with increased risk of myocardial infarction in men.

Novel non-methylated furan fatty acids in fish from a zero discharge aquaculture system

BackgroundFuran fatty acids (F-acids) are valuable minor fatty acids which are appraised for their protective role against lipid oxidation of polyunsaturated fatty acids (PUFAs). The most relevant dietary source for F-acids is fish with the predominant occurrence of up to five dimethyl- or monomethyl-substituted homologues. During the screening of fish from a zero discharge aquaculture (ZDA) system we noted the potential presence of unusual F-acids. MethodsWe developed a method by gas chromatography with mass spectrometry operated in the selected ion monitoring mode for elucidation of the structures of the uncommon F-acids. ResultsCarp from the ZDA system contained seven non-methylated F-acids with dominance of 8-(5-hexylfuran-2-yl)-octanoic acid (8F6). Non-methylated F-acids have never been detected before in fish. Subsequent analysis of other fish species and a batch of the fish feed confirmed the presence of non-methylated F-acids. ConclusionsF-acids in fish are derived from the feed. Our investigation indicates that more emphasis should be put on the F-acid concentrations in fish from aquaculture, which appears to depend on the quality of the fish feed.

An evaluation of the complete replacement of both fishmeal and fish oil in diets for juvenile Asian seabass, Lates calcarifer

An experiment was conducted to examine the potential for the complete replacement of fishmeal (FM) and fish oil (FO) in diets for barramundi, Lates calcarifer. A series of diets were formulated to the same digestible protein and energy specifications, but which were designed with FM inclusion levels at 300, 200, 100 or 0g/kg and FO at 100%, 30%, 15% or 0% of the added oil in the diets (4×4 factorial design). Ricebran oil was the alternative oil used in the growth study, while soybean meal and poultry meal were the main alternative protein sources used. For the growth study, fish of an initial weight of 154.4±1.1g were randomly allocated across 48 tanks (three replicates per treatment). After eight weeks, the average weight gain across all treatments was 187.7±2.3g/fish and feed conversion across all treatments averaged 1.04±0.01 feed/gain. A significant effect of FM on both feed intake and weight gain was observed, and this was observed as early as within the first few weeks, but no similar such effect was observed with FO. No effects were observed on protein deposition efficiency, though both lipid and energy deposition efficiencies were affected by FM level. The reduction in FO had a notable effect on the fatty acid composition of the diets and subsequently the fish fatty acid composition. Expression of key LC-PUFA metabolism genes in the liver of the fish was influenced by both FM and FO levels, but was only significant at the extremes of the treatment ranges. The results from this study demonstrate that there is clear potential to replace almost all the FM content of barramundi diets without loss of fish performance, up to and including diets with as little as 100g/kg fishmeal. Replacement of fish oil was more successful with the ability to completely replace all FO demonstrated at all but the lowest inclusion levels of FM. These results clearly demonstrate that the near complete replacement of both FM and FO in barramundi diets is a technical reality.

Type of fish consumed and thyroid autoimmunity in pregnancy and postpartum.

Fish consumption or supplementation with omega-3 fatty acids was reported to cure and/or prevent autoimmune and nonautoimmune disorders. Serum positivity for thyroid autoantibodies is a predictive marker of postpartum thyroiditis and postpartum depression. We hypothesized that stable consumption of the omega-3-rich oily fish was associated with a more favorable profile of serum thyroid antibodies throughout pregnancy and early postpartum compared with stable consumption of swordfish, a predator that concentrates pollutants. We prospectively measured serum thyroglobulin antibodies and thyroperoxidase antibodies in pregnancy (first, second trimesters) and postpartum (day 4), in 236 thyroid disease-free, nonsmoker Caucasian women with stable dietary habits. We did not measure thyroid autoantibodies prior to pregnancy. Women were divided into groups A (n = 48; swordfish), B (n = 52; oily fish), C (n = 68; swordfish + other fish, not necessarily oily fish), and D (n = 68; fish other than swordfish and oily fish). Major endpoints were positivity rates and serum concentrations of the two autoantibodies. We resorted to previous studies for the estimated content of fatty acids and microelements in the consumed fish. Positivity rates and serum concentrations of both antibodies were the greatest in group A and the lowest in group B (P < 0.001 and P < 0.05 to < 0.001, respectively). Relationship between monthly fish consumption and serum concentrations of either antibody was direct in group A but inverse in group B. The estimated content of omega-3 fatty acids in fish consumed by group B was the greatest (P < 0.001 vs. any other group). These data reinforce recommendations that pregnant women should avoid consuming swordfish and indicate consumption of oily fish as a favorable alternative. Because thyroid autoantibodies are markers of autoimmune-related postpartum problems, our data suggest a dietary prophylaxis of such problems.

Maternal fish consumption, fatty acid levels and angiogenic factors: The Generation R Study

IntroductionAngiogenic factors, such as placental growth factor (PlGF) and soluble Flt-1 (sFlt-1), are key regulators of placental vascular development. Evidence from in vitro studies indicates that fatty acids can affect angiogenesis. We investigated the associations of maternal fish consumption and fatty acids levels with angiogenic factors during pregnancy, and in cord blood in a large population-based prospective cohort. MethodsFirst trimester fish consumption was assessed among 3134 pregnant women using a food-frequency questionnaire. Plasma fatty acid levels were measured in second trimester. Plasma PlGF and sFlt-1 were measured in first and second trimester and in cord blood. Associations of fish consumption or fatty acid levels with angiogenic factors were assessed by multivariable linear regression analyses. ResultsThere were no consistent associations of total fish or lean fish consumption with levels of PlGF, sFlt-1, or sFlt-1/PlGF ratio. Neither fatty fish nor shellfish were associated with angiogenic factors. Plasma omega-3 polyunsaturated fatty acids, which are the main type of fatty acids in fish, were inconsistently associated with angiogenic factors in second trimester and cord blood. Yet, higher levels of arachidonic acid, an omega-6 polyunsaturated fatty acid, were associated with lower levels of PlGF and sFlt-1. DiscussionWe found no consistent associations of fish consumption or fatty acids levels with angiogenic factors in a population with low fish consumption. Studies including populations with higher fish consumption are required to fully grasp the potential effects of maternal fish consumption on placental angiogenesis.

Biomarkers of dairy fat

Dear Editor: There were 2 interesting articles in a recent issue of the Journal in which odd-chain fatty acids (15:0 and 17:0) were used as circulating biomarkers of dairy fat (1, 2). In one of the studies (1), serum pentadecanoic acid (15:0) was shown to be inversely associated with incident type 2 diabetes, and in the other study (2) the association of pentadecanoic acid and heptadecanoic acid (17:0) with the risk of incident stroke was studied and no significant association was found. These odd-chain fatty acids are considered to be validated biomarkers for dairy fat and they correlated with dairy consumption in many studies (1–4). However, the association between the intake of dairy fat and the relative serum content of heptadecanoic acid has not been clear in all studies (5, 6). In a large cohort study [EPIC (European Prospective Investigation into Cancer and Nutrition)], there was a strong positive ecologic correlation (r = 0.8, P ≤ 0.01) between the total intake of fish and plasma concentration of heptadecanoic acid, whereas there was no correlation between heptadecanoic acid or pentadecanoic acid and dairy products (6). Accordingly, we have seen in our studies (MA Lankinen et al., 2015) a positive correlation between pentadecanoic and heptadecanoinc acids with DHA in plasma phospholipids. The fatty acid heptadecanoic acid is present in the fat of fish (0.31–2.0% depending on fish species) (7, 8). Salmon contains ∼40 mg heptadecanoic acid and 20 mg pentadecanoic acid per 100 g (9). Therefore, we are a bit concerned if these odd-chain fatty acids are considered to be a valid biomarker for dairy fat intake in populations who consume considerable amounts of fish. In populations with a high consumption of dairy fat and a low consumption of fish, odd-chain fatty acids are probably valid biomarkers for dairy fat intake. In populations who consume fish, the presence of odd-chain fatty acids in fish should be taken into account to avoid misleading conclusions.

Abstract P009: Dietary Exposure to Polychlorinated Biphenyls and Incidence of Myocardial Infarction in Men - A Population-Based Prospective Cohort Study

Introduction: Fish consumption may promote cardiovascular health. The role of major food contaminants present in fish, such as polychlorinated biphenyls (PCBs) is, however, largely unexplored. Experimental studies indicate that PCBs cause endothelial cell dysfunction, hyperlipidemia and hypertension and cross-sectional associations have been observed between PCB-biomarkers and several intermediate risk factors for cardiovascular disease. PCBs accumulate and magnify in the food chain and fatty fish is a dominating source of exposure in populations with a relatively high fish intake. We assessed the hypothesis that dietary PCB exposure is associated with increased risk of myocardial infarction (MI) and that the exposure may mask a protective association with marine omega-3 fish fatty acids intake. Methods: Validated food frequency questionnaire-based estimates of dietary PCB exposure was obtained at baseline (1997) in 36,759 men from the population-based Cohort of Swedish Men, free of cancer, cardiovascular disease and diabetes. The estimated dietary PCB exposure was based on the food concentrations of PCB congener 153 at the time of baseline. PCB-153 is the most abundant congener in food and an excellent indicator for total PCB in food and in blood. The long-term dietary PCB exposure assessments showed acceptable validity against six PCB congeners in serum (correlation coefficients 0.30 to 0.58). Cases of MI were ascertained via register-linkage through 2010. Relative risks (RR) and 95% confidence intervals (CI) were adjusted for known cardiovascular risk factors. : Results During 12 years of follow-up (433,243 person-years), we ascertained 3,005 incident cases of MI. The major dietary sources of PCB exposure was fish, dairy products and meat. Compared with the lowest quintile of dietary PCB exposure (median 113 ng/day), men in the highest quintile (median 436 ng/day) had multivariable-adjusted RR of 1.22 (95% CI, 1.05-1.41) for MI, without adjusting for the intake of marine omega-3 fish fatty acids. In a separate model, we observed no association between the intake of marine omega-3 fish fatty acids and MI (RR, 1.07; 95% CI, 0.93-1.24). In mutually-adjusted models, dietary PCB exposure was associated with RR 1.72 (95% CI 1.28-2.30), and the intake of marine omega-3 fish fatty acids with RR, 0.67 (95% CI, 0.50-0.90), comparing highest quintiles with lowest. Conclusions: Exposure to an integrated measure of total PCBs from food was associated with increased risk of MI in men. The results may provide important information regarding the risk-benefit analysis of fish consumption. To increase the net benefits of fish consumption, PCB contamination should be reduced to a minimum: Future studies are needed to clarify the concentrations of PCBs that may offset the beneficial effects of fish consumption.

Dietary exposure to polychlorinated biphenyls and risk of myocardial infarction — A population-based prospective cohort study

BackgroundFish consumption may promote cardiovascular health. The role of major food contaminants, such as polychlorinated biphenyls (PCBs) common in fatty fish, is unclear. We assessed the association between dietary PCB exposure and risk of myocardial infarction taking into account the intake of long-chain omega-3 fish fatty acids. MethodsIn the prospective population-based Swedish Mammography Cohort, 33,446 middle-aged and elderly women, free from cardiovascular disease, cancer and diabetes at baseline (1997) were followed-up for 12years. Validated estimates of dietary PCB exposure and intake of fish fatty acids (eicosapentaenoic acid and docosahexaenoic acid; EPA-DHA) were obtained via a food frequency questionnaire at baseline. ResultsDuring follow-up 1386 incident cases of myocardial infarction were ascertained through register-linkage. Women in the highest quartile of dietary PCB exposure (median 286ng/day) had a multivariable-adjusted RR of myocardial infarction of 1.21 (95% confidence interval [CI], 1.01–1.45) compared to the lowest quartile (median 101ng/day) before, and 1.58 (95% CI, 1.10–2.25) after adjusting for EPA-DHA. Stratification by low and high EPA-DHA intake, resulted in RRs 2.20 (95% CI, 1.18–4.12) and 1.73 (95% CI, 0.81–3.69), respectively comparing highest PCB tertile with lowest. The intake of dietary EPA-DHA was inversely associated with risk of myocardial infarction after but not before adjusting for dietary PCB. ConclusionExposure to PCBs was associated with increased risk of myocardial infarction, while some beneficial effect was associated with increasing EPA and DHA intake. To increase the net benefits of fish consumption, PCB contamination should be reduced to a minimum.

A Perspective of the Research on Food Factors in Human Health: A Return to the Mechanistic Approach.

Food is a mixture of several nutrients and non-nutrients. The functions of food in human health can be categorized as its primary function in nutrition, its secondary function in palatability and its tertiary function in bioregulation. Nutrients contribute mainly to the primary function, while many non-nutrients in foods and foodstuffs are strongly associated with the secondary and/or tertiary functions. Individual food ingredients and ingredients as a whole are the so-called food factors. Much interest has arisen in the tertiary function of food factors related to the prevention of lifestyle-related diseases and promoting health in an aging society. This is why many studies evaluating the tertiary functions of food factors are now in progress all over the world. This symposium aims to present cutting-edge knowledge from celebrated Asian professors on the molecular mechanisms for the tertiary functions of food factors, in particular, polyphenols in soybeans and green tea, and n-6 polyunsaturated fatty acids in fish. In this context, this article will briefly review recent trends in research on the tertiary function of food factors.

Nutritional Responses of Round Goby (Neogobius melanostomus) caught from Rhine River (Germany) as a Wild Species to Different Fish Oils

This study was aimed to determine the effects of food supplementation with different levels of two types of fish oil (anchovy and menhaden oils), on growth and the composition of fatty acids and essential amino acids in muscle of a wild and alien species. In this study round goby (Neogobius melanostomus) caught from Rhine River (0.95–1.0 g fresh mass) were fed for 47 days diets containing 5% anchovy oil (AO), 5% menhaden oil (MO) or 2.5% AO+2.5% MO. Fish were cultured in indoor 40 L aquaria (12 aquaria in total). The feeding rate was adjusted to 10% of the fish fresh mass per day and water temperature was constantly maintained at 19°C. After 47 days, no differences were observed in weight gain, specific growth rate (SGR), feed conversion ratio (FCR) and condition factor (P>0.05). The lowest FCR was found in AO diet. Muscle fatty acid composition was influenced by dietary fish oils, and fish fed the AO diet have shown slightly higher contents of eicosapentaenoic and docosahexaenoic acid in their muscle. Muscle amino acid composition was not affected by the diet, an except for leucine. The results indicated that addition of fish oil is important in maintaining the content of n-3 fatty acids in fish in aquaculture.

Great Lakes Basin Fish Consumption, Vitamin D, Selenium, Fatty Acids, Contaminant Distributions and Associations in 154 Wisconsin Anglers

Essential nutrients such as Vitamin D, selenium and omega-3 fatty acids are keys to maintaining good health. Fish is an important potential source of these nutrients; however, fish, especially fres...

Low Doses of Eicosapentaenoic Acid and Docosahexaenoic Acid From Fish Oil Dose-Dependently Decrease Serum Triglyceride Concentrations in the Presence of Plant Sterols in Hypercholesterolemic Men and Women

Plant sterols (PSs) lower LDL cholesterol (LDL-C) concentrations, whereas the n–3 (ω-3) fish fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) lower triglyceride (TG) concentrations. Incorporating both PSs and EPA+DHA from fish oil (FO) in a single food format was expected to beneficially affect 2 blood lipid risk factors. The aim of this study was to investigate the dose-response relation between low doses (<2 g/d) of EPA+DHA from FO, incorporated in a low-fat PS-enriched spread, and TG concentrations. In addition, effects on LDL-C were investigated. The study was designed as a randomized, double-blind, placebo-controlled parallel study. After a 4-wk run-in period, subjects were randomly assigned to consume either a control (C) spread (no PSs, no FO) or 1 of 4 intervention spreads containing a fixed amount of PSs (2.5 g/d) and varying amounts of FO (0.0, 0.9, 1.3, and 1.8 g/d of EPA+DHA) for 4 wk. Before and after the intervention, fasting blood samples were drawn for measuring serum lipids and EPA and DHA in erythrocyte membranes. In total, 85 hypercholesterolemic men and 247 women with a mean age of 57.9 y (range: 25–74 y) were included. Eighteen subjects dropped out during the study. At baseline, mean TG and LDL-C concentrations were 1.09 and 4.00 mmol/L, respectively. After the intervention, a significant dose-response relation for the TG-lowering effect of EPA+DHA [βln(TG) = −0.07 mmol/L per gram of EPA+DHA; P < 0.01] was found. Compared with the C group, TG concentrations were 9.3–16.2% lower in the different FO groups (P < 0.05 for all groups). LDL-C concentrations were 11.5–14.7% lower in the different PS groups than in the C group (P < 0.01 for all groups). EPA and DHA in erythrocyte membranes were dose-dependently higher after FO intake than after the C spread, indicating good compliance. Consumption of a low-fat spread enriched with PSs and different low doses of n–3 fatty acids from FO decreased TG concentrations in a dose-dependent manner and decreased LDL-C concentrations. This trial was registered at >clinicaltrials.gov as NCT01313988.

Erratum to: U.S. adults are not meeting recommended levels for fish and omega-3 fatty acid intake: results of an analysis using observational data from NHANES 2003–2008

Erratum to: U.S. adults are not meeting recommended levels for fish and omega-3 fatty acid intake: results of an analysis using observational data from NHANES 2003–2008

Dietary exposure to polychlorinated biphenyls is associated with increased risk of stroke in women

The potentially beneficial effects of fish consumption on stroke may be modified by major food contaminants in fish. Polychlorinated biphenyls (PCBs) in particular are proposed to play a role in the aetiology of stroke. The aim of this study was to assess the association between dietary PCB exposure and stroke risk with the intake of long-chain omega-3 fish fatty acids and fish consumption. The prospective population-based Swedish Mammography Cohort was examined. It was comprised of 34,591 women free of cardiovascular diseases and cancer at baseline in 1997 and followed up for 12 years. Validated estimates of dietary PCB exposure were obtained via a food frequency questionnaire at baseline. Incident cases of stroke were ascertained through register linkage. During 12 years of follow-up (397,309 person-years), there were 2015 incident cases of total stroke (1532 ischaemic strokes, 216 intracerebral haemorrhages, 94 subarachnoid haemorrhages and 173 unspecified strokes). Multivariable-adjusted relative risks (RR), controlled for known stroke risk factors and fish consumption, were 1.67 [95% confidence interval (CI), 1.29-2.17] for total stroke, 1.61 (95% CI, 1.19-2.17) for ischaemic stroke and 2.80 (95% CI, 1.42-5.55) for haemorrhagic stroke for women in the highest quartile of dietary PCB exposure (median 288 ng day(-1) ) compared with women in the lowest quartile (median 101 ng day(-1) ). Dietary exposure to PCBs was associated with an increased stroke risk in women, especially haemorrhagic stroke. The results provide important information regarding the risk-benefit analysis of fish consumption, particularly for cerebrovascular disease prevention.

Update on cardiometabolic health effects of ω-3 fatty acids

The fish fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may promote cardiometabolic health. This review summarizes the results of recent meta-analyses of prospective studies on cardiovascular diseases, diabetes type 2 and markers of atherosclerosis and thrombosis. The results of recently published meta-analyses of prospective cohort studies showed that eating fish once a week was associated with a 16% lower risk of fatal coronary heart disease (CHD) and a 14% lower risk of stroke incidence, but was not related to heart failure. Fish consumption may be associated with a higher risk of diabetes in Western countries and a lower risk in Asian countries. Recent meta-analyses of randomized controlled trials showed that EPA-DHA supplementation reduced the risk of fatal CHD and sudden death by 10% of which the latter was not significant. Extra EPA-DHA did not reduce the risk of heart failure, stroke and cardiac arrhythmias. ω-3 fatty acid (FA) supplementation did reduce markers of ventricular fibrillation, inflammation and endothelial dysfunction and platelet aggregation. There is strong evidence for a protective effect of ω-3 FA on fatal CHD and for some markers of atherosclerosis and thrombosis. Consistent results were not obtained for other vascular diseases and diabetes. ω-3 FA reduced markers of ventricular fibrillation but did not reduce the risk of atrial fibrillation.

Fatty acid profile in muscles of carp (Cyprinus carpio L.) raised in a semi-intensive production system fed with grains, pelleted and extruded feed

The effects of grains, pelleted and extruded feed on the fatty acid content in carp meat has not been examined yet. In this work, we present evidence that the high carbohydrate content in all three types of feed causes oleic acid to predominate in all meat samples. A higher PUFA content in the meat of fish fed with granulated feed was detected. The extruded feed diet led to 69% greater n-3, and 53% lower n-6 fatty acid contents. Their ratio is thus 2.64-fold higher than in meat of carp fed with pelleted feed. A higher content of n-3 fatty acids in fish fed with extruded feed was the consequence of higher DHA (1.6 times) and EPA (3.3 times) contents. The detected differences could be the consequence of the thermal treatment of extruded feed that makes the proteins, carbohydrates and lipids more accessible to fish than in a pelleted feed.

Antioxidant capacity of meagre (Argyrossomus regius) fed different lipid content and source, with and without selenium

Antioxidant capacity of meagre (Argyrossomus regius) fed different lipid content and source, with and without selenium

Effect of Alpha Linolenic Acid Supplementation on Serum Prostate Specific Antigen (PSA): Results from the Alpha Omega Trial

BackgroundAlpha linolenic acid (ALA) is the major omega-3 fatty acid in the diet. Evidence on health effects of ALA is not conclusive, but some observational studies found an increased risk of prostate cancer with higher intake of ALA. We examined the effect of ALA supplementation on serum concentrations of prostate-specific antigen (PSA), a biomarker for prostate cancer.MethodsThe Alpha Omega Trial (ClinicalTrials.gov Identifier: NCT00127452) was a double-blind, placebo-controlled trial of ALA and the fish fatty acids eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) on the recurrence of cardiovascular disease, using a 2×2 factorial design. Blood was collected at the start and the end of the intervention period. The present analysis included 1622 patients with a history of a myocardial infarction, aged 60–80 years with an initial PSA concentration <4 ng/mL. They received either 2 g per day of ALA or placebo in margarine spreads for 40 months. T-tests and logistic regression were used to assess the effects of ALA supplementation on changes in serum PSA (both continuously and as a dichotomous outcome, cut-off point: >4 ng/mL).FindingsMean serum PSA increased by 0.42 ng/mL on placebo (n = 815) and by 0.52 ng/mL on ALA (n = 807), a difference of 0.10 (95% confidence interval: −0.02 to 0.22) ng/mL (P = 0·12). The odds ratio for PSA rising above 4 ng/mL on ALA versus placebo was 1.15 (95% CI: 0.84–1.58).InterpretationAn additional amount of 2 g of ALA per day increased PSA by 0.10 ng/mL, but the confidence interval ranged from −0.02 to 0.22 ng/mL and included no effect. Therefore, more studies are needed to establish whether or not ALA intake has a clinically significant effect on PSA or prostate cancer.Trial registration informationClinicalTrials.gov; Identifier: NCT00127452. URL: http://www.clinicaltrials.gov/ct2/show/NCT00127452.

Organic plant ingredients in the diet of Rainbow trout (Oncorhynchus mykiss): Impact on fish muscle composition and oxidative stability

Rainbow trout were fed diets containing either fish meal and fish oil (FM‐FO) (control) or diets in which 40% of the fishmeal was substituted with a mixture of ingredients grown organically including plant protein concentrate (PP) in combination with either fish oil (FO) as lipid source, or one of the following organic plant oils; rapeseed (RO), linseed/flaxseed (LO), grape seed (GO), or sunflower (SO). The impact of these substitutions was investigated by measuring fish muscle fatty acid profile as well as oxidative and color stability of the fillet during 14 days ice storage. The inclusion of plant protein concentrate did not affect the fatty acid profile significantly but resulted in a slightly improved oxidative stability of the fish fillets as compared to the control diet. The fatty acid profile of the oil used was in general well reflected in the fish muscle fatty acid profile. Fish fed PP‐RO were the most oxidatively stable during ice storage but the omega‐3 fatty acid content was reduced by 40% compared to fish fed the FM‐FO control diet. Replacing FO by LO was not suitable as it induced oxidation and the fillet contained 40–50% less of long chain omega‐3 fatty acids.Practical applications: Replacing marine ingredient by organic plant ones in the diet of rainbow trout is feasible but it impacts the fish fatty acid profile of the fish muscle and its oxidative stability. Plant protein improved the oxidative stability of the fillet during ice storage. Moreover, replacement of fish oil with more saturated plant oils in the diet of trout lead to an increased oxidative stability of the fillet, but at the same time reduced the level of omega‐3 fatty acids in the fish muscle. Linseed oil resulted in a more favorable omega‐3 content (ALA) than the other plant oils but resulted in highly unstable fish muscle with respect to oxidation. Substitution of fish ingredients in the fish diet significantly influenced the nutritional value of the fish fillet, as it resulted in significant less EPA and DHA in the muscle.

Proposal on the usage of conversion factors for fatty acids in fish and shellfish

Different approaches for converting fatty acid (FA) data in fish and shellfish expressed as weight percent of total FA or of total lipid content (TL) to per 100g edible portion fresh weight (EP) are used. FAO/INFOODS studied on a dataset of 668 fish and shellfish firstly the impact on their FA and TL content per 100g EP using two fatty acid conversion factors, namely the factors published by Weihrauch et al. (XFAW) and Greenfield and Southgate (XFAGS), and secondly the usefulness of Sheppard factors (ShF), which convert fatty acid methyl esters to fatty acids. The data show that XFAW should be used as they are applicable to fish and shellfish and the resulting FA values are a continuous function of the TL content while applying a minimum TL value of 0.55g/100g EP even for lower TL values. This study showed that the use of ShF is not necessary for fish and shellfish as they do not influence fatty acid values significantly.