Twice weekly intake of farmed Atlantic salmon (Salmo salar) positively influences lipoprotein concentration and particle size in overweight men and women

Fish consumption and its lipid modifying effects - A review of intervention studies

Fish is an important source of nutrients, particularly the long chain n-3 polyunsaturated fatty acids (n-3 PUFAs). The incorporation of fish into the diet has been shown to have several health benefits, including lowering the risk of cardiovascular disease (CVD). Elevated plasma lipids are one of the main modifiable risk factors contributing to CVD and may be partly mediated by n-3 PUFAs. Although n-3 PUFAs in the form of supplementation have been shown to exert lipid modifying effects, the effects of fish consumption on the lipid profile have not been well summarised to date. Therefore, the aim of the present review is to discuss the current evidence from intervention studies investigating the effect of fish consumption on the lipid profile in both apparently healthy and non-healthy populations. Existing evidence appears to support the role of fish in promoting a shift towards a less inflammatory lipid profile through raising n-3 PUFAs and potentially lowering n-6 PUFA and triglyceride concentrations in both healthy and non-healthy populations. Fish consumption has a negligible effect on cholesterol concentrations; however, fish consumption may promote a small increase in high density lipoprotein (HDL) cholesterol amongst people with lower HDL at baseline. Limited studies have shown fish consumption to result in shifts in phospholipid and sphingolipid species and structure, albeit it is not yet clear whether these alterations have any meaningful impact on CVD risk. Future well-designed studies that utilise NMR and/or lipidomics analysis are warranted to explore the effects of these shifts in lipid content and structure in the context of disease development. Public health guidance should emphasise the cardioprotective benefits of fish and encourage consumption particularly in the Global North where fish consumption remains low.

Association of oily fish and nonoily fish intakes with all-cause mortality and cause-specific mortality: a large population-based prospective study

BACKGROUND

There are inconsistent results of cohort studies analyzing the association between fish intake and mortality.

OBJECTIVE

This study was performed to explore the association of oily fish consumption and nonoily fish consumption with all-cause mortality and cause-specific mortality.

METHODS

A total of 431,062 participants from the UK Biobank who were without cancer or cardiovascular disease (CVD) at baseline between 2006 and 2010 were included in this study, and they were followed up through 2021. We constructed Cox proportional hazard models to calculate the hazard ratio (HR) and 95% confidence interval (CI) to assess the correlation of oily fish and nonoily fish intakes with mortality. Then, we performed subgroup analyses, and sensitivity analyses were developed and performed to examine the robustness of this study.

RESULTS

Among the participants, 383,248 (88.9%) and 410,499 (95.2%) consumed oily fish and nonoily fish, respectively. Compared with the participants who did not consume oily fish, the adjusted HRs for the association of oily fish consumption (1 serving/week) with all-cause mortality and CVD mortality were 0.93 (0.87 to 0.98; p < 0.05) and 0.85 (0.74 to 0.98; p < 0.05), respectively. The multivariable-adjusted HRs of all-cause mortality for those who reported consuming < 1 serving/week of oily fish were 0.92 (0.86 to 0.98; p < 0.05).

CONCLUSION

Compared with participants who reported never consuming oily fish, the consumption of oily fish with 1 serving/week was more beneficial for all-cause and CVD mortality.

Fish intake and risk of cardiovascular events: an analysis of the VITAL cohort

BACKGROUND

Dietary habits with fish consumption have been associated with a lower risk of cardiovascular (CV) disease, based on heterogenous observational studies. Current recommendations suggest eating at least 1-2 fish servings per week for CV prevention.

METHODS

We conducted a retrospective evaluation of a cohort study that enrolled a large primary prevention population to determine the potential benefit of fish intake ≥1.5 serving per week, through a multivariate Cox regression model. The outcomes of interest included all-cause mortality, cardiovascular mortality, MACE (composite endpoint of myocardial infarction, stroke, and death from cardiovascular causes), expanded MACE (MACE plus coronary revascularization), total myocardial infarction (MI), total coronary heart disease (CHD) and total stoke. The estimates were reported using hazard ratio (HR) with 99% confidence intervals (99% CI).

RESULTS

A total of 25,435 patients were evaluated (11,921 individuals ≥1.5 fish servings/week; 13,514 < 1.5 fish servings per week). Intake ≥1.5 servings/week was not independently associated with CV outcomes reduction, such as CV mortality, MI risk MACE, expanded MACE outcomes, CHD or stroke (HR 0.78, 99% CI 0.57-1.07).

CONCLUSION

Fish intake ≥1.5 servings/week was not associated with CV outcomes improvement in this analysis, but potential benefit cannot be ruled out.

Role of food matrix in modulating dairy fat induced changes in lipoprotein particle size distribution in a human intervention

BACKGROUND

Intake of dairy fat within the matrix of cheese lowered circulating LDL cholesterol concentration to a greater extent than the same components consumed separately as butter, protein, and calcium. However, circulating LDL cholesterol is not indicative of concentration or size of LDL particles (LDL-P), which are recognized as more sensitive risk markers of CVD.

OBJECTIVES

This was an exploratory analysis to investigate the role of the food matrix on lipoprotein particle size distribution, after a dairy fat intervention, in overweight adults aged ≥50 y.

METHODS

Lipoprotein particle size distribution was measured in fasting EDTA blood samples taken at week 0 (baseline) and at week 6, using NMR. In total, 127 participants (BMI ≥ 25 kg/m², aged ≥50 y) received ∼42 g dairy fat in 1 of 4 treatments: group A, 120 g full-fat cheddar cheese (FFCC); group B, reduced-fat cheese plus butter (RFC+B); group C, butter, calcium caseinate powder, and calcium supplement (CaCO₃) (BCC); or group D, 120 g FFCC (as per group A) but after a 6-wk washout period during which they excluded cheese before intervention.

RESULTS

Total VLDL and chylomicron particles (VLDL/CM-P) decreased after intervention. There was a strong correlation between reduced VLDL/CM-P and a reduction in small proatherogenic VLDL-P (r = 0.888, P < 0.001). Reductions in total LDL-P were associated with a reduction in small LDL-P and, to a lesser extent, with large LDL-P. There was a significant main effect of treatment for change in intermediate-density lipoprotein particles (IDL-P) after the intervention (P = 0.023) between groups B and D (-46.86 ± 30.38 and 40.69 ± 32.72 nmol/L, respectively). HDL particle (HDL-P) parameters (diameter, concentration, or size distribution) were not affected by diet.

CONCLUSIONS

Our findings indicate that reductions in LDL cholesterol observed with dairy fat consumption are driven by reductions in LDL-P concentration. A trend toward a less atherogenic profile was observed, but there was no clear effect of the individual food matrices. This trial was registered at ISRCTN as ISRCTN86731958.

Fish Consumption and Risk of Stroke in Chinese Adults: A Prospective Cohort Study in Shanghai, China

Present studies on the association of fish consumption with risk of stroke have shown controversial results, and this association within the Chinese population remains unknown. We aimed to investigate the association between fish consumption and incidence of total stroke, ischemic stroke and hemorrhagic stroke among adults in China. We analyzed the data of 57,701 adults aged 20–74 years, with no history of stroke, in a prospective cohort study in Shanghai. Fish consumption was calculated from a food frequency questionnaire at baseline and divided into four categories (less than 300, 300–450, 450–600 and more than 600 g/week). Participant information was linked to health information systems in which stroke event information was collected up until 31 December 2021. The hazard ratios (HR) and 95% confidence intervals (CI) of the associations of fish consumption with risk of total stroke, ischemic stroke and hemorrhagic stroke were estimated using cox proportional hazards regression models. Dose–response relationships were estimated using restricted cubic spline analyses. During a median follow-up of 4.56 years, 807 newly developed stroke events were ascertained, including 664 ischemic stroke events and 113 hemorrhagic stroke events. Fish consumption of 300–450 g/week was associated with a reduced risk of total stroke (HR: 0.78, 95% CI: 0.64–0.94) and ischemic stroke (0.70 (0.57–0.88)) compared with fish consumption of less than 300 g/week, after adjustment for comprehensive covariates including sociodemographic characteristics, lifestyle, dietary patterns and disease histories. No significant association was found between fish consumption and hemorrhagic stroke. The findings of our study support the consumption level of fish recommended in the dietary guidelines.

Comprehensive lipid and metabolite profiling in healthy adults with low and high consumption of fatty fish: a cross-sectional study

Fish consumption is associated with reduced risk of CVD, which may be partly mediated by alterations in plasma lipids, such as HDL-cholesterol. However, comprehensive analyses of associations between fatty fish consumption and lipoprotein subclass profile are limited and show inconsistent results. Therefore, the aim of the present exploratory study was to investigate the association between fatty fish consumption and lipoprotein subclass particle concentrations and composition, with an emphasis on HDL. We performed a comprehensive plasma metabolite profiling in 517 healthy adults, using a targeted high-throughput NMR spectroscopy platform. The participants were divided into tertiles based on consumption of fatty fish, reported through a validated FFQ. We compared the concentration of metabolites between the participants in the lowest and highest tertiles of fatty fish consumption. We show that high consumers of fatty fish (>223 g/week, median intake 294 g/week) had higher particle concentrations and content of total lipids, free cholesterol and phospholipids in large and extra-large HDL particles and higher content of total cholesterol, cholesteryl esters and TAG in large HDL particles than low consumers (<107 g/week, median intake 58 g/week). Using fatty fish consumption as a continuous variable, we found that fatty fish consumption was associated with lower levels of the inflammation marker glycoprotein acetyls. In conclusion, high consumers of fatty fish seem to have a more favourable HDL-cholesterol-related lipoprotein profile and anti-inflammatory phenotype than low consumers of fatty fish. Thus, these data support the current Norwegian dietary recommendations for fish consumption regarding CVD risk.

Associations of Fish Consumption With Risk of Cardiovascular Disease and Mortality Among Individuals With or Without Vascular Disease From 58 Countries

IMPORTANCE

Cohort studies report inconsistent associations between fish consumption, a major source of long-chain ω-3 fatty acids, and risk of cardiovascular disease (CVD) and mortality. Whether the associations vary between those with and those without vascular disease is unknown.

OBJECTIVE

To examine whether the associations of fish consumption with risk of CVD or of mortality differ between individuals with and individuals without vascular disease.

DESIGN, SETTING, AND PARTICIPANTS

This pooled analysis of individual participant data involved 191 558 individuals from 4 cohort studies-147 645 individuals (139 827 without CVD and 7818 with CVD) from 21 countries in the Prospective Urban Rural Epidemiology (PURE) study and 43 413 patients with vascular disease in 3 prospective studies from 40 countries. Adjusted hazard ratios (HRs) were calculated by multilevel Cox regression separately within each study and then pooled using random-effects meta-analysis. This analysis was conducted from January to June 2020.

EXPOSURES

Fish consumption was recorded using validated food frequency questionnaires. In 1 of the cohorts with vascular disease, a separate qualitative food frequency questionnaire was used to assess intake of individual types of fish.

MAIN OUTCOMES AND MEASURES

Mortality and major CVD events (including myocardial infarction, stroke, congestive heart failure, or sudden death).

RESULTS

Overall, 191 558 participants with a mean (SD) age of 54.1 (8.0) years (91 666 [47.9%] male) were included in the present analysis. During 9.1 years of follow-up in PURE, compared with little or no fish intake (≤50 g/mo), an intake of 350 g/wk or more was not associated with risk of major CVD (HR, 0.95; 95% CI, 0.86-1.04) or total mortality (HR, 0.96; 0.88-1.05). By contrast, in the 3 cohorts of patients with vascular disease, the HR for risk of major CVD (HR, 0.84; 95% CI, 0.73-0.96) and total mortality (HR, 0.82; 95% CI, 0.74-0.91) was lowest with intakes of at least 175 g/wk (or approximately 2 servings/wk) compared with 50 g/mo or lower, with no further apparent decrease in HR with consumption of 350 g/wk or higher. Fish with higher amounts of ω-3 fatty acids were strongly associated with a lower risk of CVD (HR, 0.94; 95% CI, 0.92-0.97 per 5-g increment of intake), whereas other fish were neutral (collected in 1 cohort of patients with vascular disease). The association between fish intake and each outcome varied by CVD status, with a lower risk found among patients with vascular disease but not in general populations (for major CVD, I2 = 82.6 [P = .02]; for death, I2 = 90.8 [P = .001]).

CONCLUSIONS AND RELEVANCE

Findings of this pooled analysis of 4 cohort studies indicated that a minimal fish intake of 175 g (approximately 2 servings) weekly is associated with lower risk of major CVD and mortality among patients with prior CVD but not in general populations. The consumption of fish (especially oily fish) should be evaluated in randomized trials of clinical outcomes among people with vascular disease.

Polyunsaturated fatty acids synthesized by freshwater fish: A new insight to the roles of elovl2 and elovl5 in vivo

At present, fish provide an important supply of long-chain polyunsaturated fatty acids (LC-PUFAs) for human consumption. Previous studies have shown that fatty acyl elongase 2 (elovl2) and elovl5 play important roles in fish LC-PUFA synthesis. Generally, freshwater fish have a stronger ability to synthesize LC-PUFAs than marine fish. However, the roles of elovl2, elovl5 and elovl2 + elovl5 in LC-PUFA synthesis of freshwater fish in vivo are not very clear. In this study, the elovl2 knockout zebrafish (elovl2^-/-), elovl5 knockout zebrafish (elovl5^-/-) and the double gene knockout zebrafish (DKO) were generated by CRISPR/Cas9 technology for the first time. Compared with wild type zebrafish (WT), elovl5-deletion zebrafish showed a significant increase in C22 PUFA content, which might be due to the up-regulation expressions of elovl4b and elovl2. elovl5 expressed at very low levels in livers of elovl2^-/- relative to WT, indicating that elovl5 may be an "assistant attacker" of elovl2 in LC-PUFA synthesis of zebrafish. Moreover, there were no significant differences in levels of C18-C22 PUFAs between DKO and WT, indicating that besides elovl2 + elovl5 path, LC-PUFA synthesis in zebrafish could be performed by other paths. In addition, the hepatic lipidomic analysis results revealed that the contents of C22:6n-3 in phosphatidyl ethanolamine (PE-DHA) and PE-C22 PUFAs were more easily affected by the absence of elovl2 and elovl5. Our results suggest that the elovl2+elovl5 path is not the only path for LC-PUFA synthesis in zebrafish, and provide novel insights into the roles of elovl2 and elovl5 in LC-PUFA synthesis of freshwater fish.

CRISPR/Cas9-mediated ablation of elovl2 in Atlantic salmon (Salmo salar L.) inhibits elongation of polyunsaturated fatty acids and induces Srebp-1 and target genes

Atlantic salmon can synthesize polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (20:5n-3), arachidonic acid (20:4n-6) and docosahexaenoic acid (22:6n-3) via activities of very long chain fatty acyl elongases (Elovls) and fatty acyl desaturases (Fads), albeit to a limited degree. Understanding molecular mechanisms of PUFA biosynthesis and regulation is a pre-requisite for sustainable use of vegetable oils in aquafeeds as current sources of fish oils are unable to meet increasing demands for omega-3 PUFAs. By generating CRISPR-mediated elovl2 partial knockout (KO), we have shown that elovl2 is crucial for multi-tissue synthesis of 22:6n-3 in vivo and that endogenously synthesized PUFAs are important for transcriptional regulation of lipogenic genes in Atlantic salmon. The elovl2-KOs showed reduced levels of 22:6n-3 and accumulation of 20:5n-3 and docosapentaenoic acid (22:5n-3) in the liver, brain and white muscle, suggesting inhibition of elongation. Additionally, elovl2-KO salmon showed accumulation of 20:4n-6 in brain and white muscle. The impaired synthesis of 22:6n-3 induced hepatic expression of sterol regulatory element binding protein-1 (srebp-1), fatty acid synthase-b, Δ6fad-a, Δ5fad and elovl5. Our study demonstrates key roles of elovl2 at two penultimate steps of PUFA synthesis in vivo and suggests Srebp-1 as a main regulator of endogenous PUFA synthesis in Atlantic salmon.

Intake of Fatty Fish Alters the Size and the Concentration of Lipid Components of HDL Particles and Camelina Sativa Oil Decreases IDL Particle Concentration in Subjects with Impaired Glucose Metabolism

SCOPE

Intake of long-chain n-3 PUFAs affects the lipoprotein subclass profile, whereas the effect of shorter chain n-3 PUFAs remains unclear. We investigated the effect of fish and camelina sativa oil (CSO) intakes on lipoprotein subclasses.

METHODS AND RESULTS

Altogether, 79 volunteers with impaired glucose metabolism were randomly assigned to CSO, fatty fish (FF), lean fish (LF), or control group for 12 weeks. Nuclear magnetic resonance spectroscopy was used to determine lipoprotein subclasses and their lipid components. The average HDL particle size increased in the FF group (overall p = 0.032) as compared with the control group. Serum concentrations of cholesterol in HDL and HDL₂ (overall p = 0.024 and p = 0.021, respectively) and total lipids and phospholipids in large HDL particles (overall p = 0.012 and p = 0.019, respectively) increased in the FF group, differing significantly from the LF group. The concentration of intermediate-density lipoprotein (IDL) particles decreased in the CSO group (overall p = 0.033) as compared with the LF group.

CONCLUSION

Our study suggests that FF intake causes a shift toward larger HDL particles and increases the concentration of lipid components in HDL, which may be associated with the antiatherogenic properties of HDL. Furthermore, CSO intake decreases IDL particle concentration. These changes may favorably affect cardiovascular risk.

Structural Elucidation of Irish Organic Farmed Salmon (Salmo salar) Polar Lipids with Antithrombotic Activities

While several marine polar lipids (PL) have exhibited cardioprotective properties through their effects on the platelet-activating factor (PAF) pathways, salmon PL have not been tested so far. In this study, the antithrombotic activities of salmon PL were assessed in human platelets and the structural characterisation of bioactive salmon PL was performed by GC-MS and LC-MS analyses. PL from fillets of Irish organic farmed salmon (Salmo salar) were extracted and separated into several lipid subclasses by thin-layer chromatography (TLC), while their fatty acid profile was fully characterised by GC-MS. Salmon total lipids (TL), total neutral lipids (TNL), total polar lipids (TPL), and each PL subclass obtained by TLC were further assessed for their in vitro effects towards PAF-induced and thrombin-induced platelet aggregation in human platelets. Salmon PL exhibited antithrombotic effects on human platelet aggregation, mostly through their strong inhibitory effects against the PAF pathway with IC50 values comparable to other marine PL, but with lower effects towards the thrombin pathway. PL fractions corresponding to phosphatidylcholine and phosphatidylethanolamine derivatives exhibited the most potent anti-PAF effects, while LC-MS analysis putatively elucidated their structure/function relationship. Several diacyl-PC/PE and alkyl-acyl-PC/PE species containing mostly docosahexaenoic acid at their sn-2 glycerol-backbone may be responsible for the bioactivity. The data presented suggests that salmon contains PL with strong antithrombotic bioactivities.

Fish consumption and cardiovascular disease related biomarkers: A review of clinical trials

The purpose of this review is to collect and compare fish intervention studies. Prospective studies have outlined the beneficial effect of frequent fish consumption on cardiovascular incidents that is attributed to n-3 fatty acids incorporated in fish, mainly eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids. This outcome triggered clinical trials to examine the effect of either fish intake or consumption of n-3 fatty acids via capsules on biomarkers related to cardiovascular disease (CVD). The absence of a recent review focusing on clinical trials regarding fish intake and not n-3 fatty acids supplements rendered necessary the composition of this article. In total, 28 studies on healthy volunteers were found to meet the inclusion criteria. With EPA and DHA intake varying between 0.03 to 5 g per day, biomarkers, such as triglycerides, high-density lipoprotein and platelet aggregation, tended to ameliorate when daily intake exceeded 1 g per day, while the most common inflammatory marker, C-reactive protein, was not affected. In all, fish consumption gives promising results; yet fish micronutrients, total diet fat, as well as other dietary habits may also affect biomarkers. Therefore, all these factors should be considered in future clinical trials in order for one to draw more reliable conclusions.

Repeat dose NRPT (nicotinamide riboside and pterostilbene) increases NAD+ levels in humans safely and sustainably: a randomized, double-blind, placebo-controlled study

NRPT is a combination of nicotinamide riboside (NR), a nicotinamide adenine dinucleotide (NAD⁺⁾ precursor vitamin found in milk, and pterostilbene (PT), a polyphenol found in blueberries. Here, we report this first-in-humans clinical trial designed to assess the safety and efficacy of a repeat dose of NRPT (commercially known as Basis). NRPT was evaluated in a randomized, double-blind, and placebo-controlled study in a population of 120 healthy adults between the ages of 60 and 80 years. The study consisted of three treatment arms: placebo, recommended dose of NRPT (NRPT 1X), and double dose of NRPT (NRPT 2X). All subjects took their blinded supplement daily for eight weeks. Analysis of NAD⁺ in whole blood demonstrated that NRPT significantly increases the concentration of NAD⁺ in a dose-dependent manner. NAD⁺ levels increased by approximately 40% in the NRPT 1X group and approximately 90% in the NRPT 2X group after 4 weeks as compared to placebo and baseline. Furthermore, this significant increase in NAD⁺ levels was sustained throughout the entire 8-week trial. NAD⁺ levels did not increase for the placebo group during the trial. No serious adverse events were reported in this study. This study shows that a repeat dose of NRPT is a safe and effective way to increase NAD⁺ levels sustainably.

It’s possible to boost declining levels of NAD⁺, a molecule required for fundamental chemical reactions in the human body, with a dietary supplement. A team led by Leonard Guarente of MIT and Elysium Health gave 120 healthy adult volunteers between the ages of 60 and 80 NRPT (known commercially as Basis) over the course of eight weeks. Volunteers taking the regular dose of NRPT had 40 percent more NAD⁺ compared to their baseline when tested at four weeks and at eight weeks. Others who took a double dose of NRPT had even higher levels of NAD⁺, while those who took the placebo saw no increase. Research shows that NAD⁺ levels decline in animals and humans with age. Boosting NAD⁺ in animals improves age-associated diseases, so researchers now want to understand whether humans, too, may benefit.