Effect of n-3 polyunsaturated fatty acids on ischemic heart disease and cardiometabolic risk factors: a two-sample Mendelian randomization study

Assessment of causal relationships between omega-3 and omega-6 polyunsaturated fatty acids in autoimmune rheumatic diseases: a brief research report from a Mendelian randomization study

Background

Currently, the association between the consumption of polyunsaturated fatty acids (PUFAs) and the susceptibility to autoimmune rheumatic diseases (ARDs) remains conflict and lacks substantial evidence in various clinical studies. To address this issue, we employed Mendelian randomization (MR) to establish causal links between six types of PUFAs and their connection to the risk of ARDs.

Methods

We retrieved summary-level data on six types of PUFAs, and five different types of ARDs from publicly accessible GWAS statistics. Causal relationships were determined using a two-sample MR analysis, with the IVW approach serving as the primary analysis method. To ensure the reliability of our research findings, we used four complementary approaches and conducted multivariable MR analysis (MVMR). Additionally, we investigated reverse causality through a reverse MR analysis.

Results

Our results indicate that a heightened genetic predisposition for elevated levels of EPA (ORIVW: 0.924, 95% CI: 0.666-1.283, P IVW = 0.025) was linked to a decreased susceptibility to psoriatic arthritis (PsA). Importantly, the genetically predicted higher levels of EPA remain significantly associated with an reduced risk of PsA, even after adjusting for multiple testing using the FDR method (P IVW-FDR-corrected = 0.033) and multivariable MR analysis (P MV-IVW < 0.05), indicating that EPA may be considered as the risk-protecting PUFAs for PsA. Additionally, high levels of LA showed a positive causal relationship with a higher risk of PsA (ORIVW: 1.248, 95% CI: 1.013-1.538, P IVW = 0.037). It is interesting to note, however, that the effects of these associations were weakened in our MVMR analyses, which incorporated adjustment for lipid profiles (P MV-IVW > 0.05) and multiple testing using the FDR method (P IVW-FDR-corrected = 0.062). Moreover, effects of total omega-3 PUFAs, DHA, EPA, and LA on PsA, were massively driven by SNP effects in the FADS gene region. Furthermore, no causal association was identified between the concentrations of other circulating PUFAs and the risk of other ARDs. Further analysis revealed no significant horizontal pleiotropy and heterogeneity or reverse causality.

Conclusion

Our comprehensive MR analysis indicated that EPA is a key omega-3 PUFA that may protect against PsA but not other ARDs. The FADS2 gene appears to play a central role in mediating the effects of omega-3 PUFAs on PsA risk. These findings suggest that EPA supplementation may be a promising strategy for preventing PsA onset. Further well-powered epidemiological studies and clinical trials are warranted to explore the potential mechanisms underlying the protective effects of EPA in PsA.

Association of dietary fats with ischemic heart disease (IHD): a case-control study

BACKGROUND

This study aimed to investigate the association between different types of dietary fats with ischemic heart disease (IHD).

METHODS

This case-control study was conducted on 443 cases and 453 controls aged 40-80 years in Tehran, Iran. The semi-quantitative 237-item food frequency questionnaire (FFQ) was used to assess the amount of food intake. Nutritionist IV was applied to test the amount of consumption of dietary fats.

RESULTS

The case group had a lower intake of docosahexaenoic acid (DHA) (11.36 ± 12.58 vs. 14.19 ± 19.57, P = 0.01) than the control group. A negative association was found between IHD and DHA (OR 0.98, CI 95% 0.97-0.99, P = 0.01). No significant association was observed between IHD with the intake of cholesterol, trans fatty acids (TFA), saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), eicosatetraenoic acid (EPA), and α-Linolenic acid (ALA).

CONCLUSION

It was found that DHA may reduce the risk of IHD, whereas there was no significant association between other types of dietary fats with the odds of IHD. If the results of this study are confirmed in future research, a higher intake of DHA in diet can be recommended as a strategy to prevent IHD events.

The relationship of fatty acids to ischaemic heart disease and lifespan in men and women using Mendelian randomization

BACKGROUND

Observationally, polyunsaturated fatty acids (PUFAs) have health benefits compared with saturated fatty acids (SFAs); randomized controlled trials suggest fewer benefits. We used uni- and multi-variable Mendelian randomization to assess the association of major fatty acids and their sub-species with ischaemic heart disease (IHD) overall and sex-specifically and with lifespan sex-specifically, given differing lifespan by sex.

METHODS

We obtained strong (P <5x10-8), independent (r2<0.001) genetic predictors of fatty acids from genome-wide association studies (GWAS) in a random subset of 114 999 UK Biobank participants. We applied these genetic predictors to the Cardiogram IHD GWAS (cases = 60 801, controls = 123 504) and to the Finngen consortium GWAS (cases = 31 640, controls = 187 152) for replication and to the UK Biobank for sex-specific IHD and for lifespan based on parental attained age (fathers = 415 311, mothers = 412 937). We used sensitivity analysis and assessed sex differences where applicable.

RESULTS

PUFAs were associated with IHD [odds ratio 1.23, 95% confidence interval (CI) 1.05 to 1.44] and lifespan in men (-0.76 years, 95% CI -1.34 to -0.17) but not women (0.20, 95% CI -0.32 to 0.70). Findings were similar for omega-6 fatty acids and linoleic acid. Independent associations of SFAs, mono-unsaturated fatty acids or omega-3 fatty acids with IHD overall or lifespan in men and women were limited.

CONCLUSIONS

PUFAs, via specific subspecies, may contribute to disparities in lifespan by sex. Sex-specific dietary advice might be a start towards personalized public health and addressing inequities.

The Prognostic Value and Treatment Strategies of Nutritional Status in Heart Failure Patients

Heart failure is a complex clinical syndrome caused by a variety of reasons leading to abnormal changes in the structure and/or function of the heart, with ventricular systolic and/or diastolic dysfunction, which is a serious manifestation or late stage of various heart diseases. The overall prognosis of patients is poor, and risk assessment of patients with HF is currently a hot topic of research due to the large heterogeneity of etiology, phenotype, and genetic background of HF patients. Besides, the nutritional level and status of HF patients are affected by various aspects. Patients with malnutrition, high saturated fatty acids and cholesterol, low minerals, and other conditions tend to have a poor prognosis. So targeted improvement of the nutritional status of HF patients is important to improve the prognosis and the quality of survival of patients. We use heart failure, nutrition, and diet therapy as the keyword method to summarize the prognostic value of indicators of nutritional status in HF patients, the effects of nutritional status on HF patients with different etiology, and potential treatment strategies for HF patients with different etiology. This review is valuable for understanding the prognostic value of nutritional levels in patients with HF and guiding clinical therapeutic approaches.

The Role of α-Linolenic Acid and Its Oxylipins in Human Cardiovascular Diseases

α-linolenic acid (ALA) is an essential C-18 n-3 polyunsaturated fatty acid (PUFA), which can be elongated to longer n-3 PUFAs, such as eicosapentaenoic acid (EPA). These long-chain n-3 PUFAs have anti-inflammatory and pro-resolution effects either directly or through their oxylipin metabolites. However, there is evidence that the conversion of ALA to the long-chain PUFAs is limited. On the other hand, there is evidence in humans that supplementation of ALA in the diet is associated with an improved lipid profile, a reduction in the inflammatory biomarker C-reactive protein (CRP) and a reduction in cardiovascular diseases (CVDs) and all-cause mortality. Studies investigating the cellular mechanism for these beneficial effects showed that ALA is metabolized to oxylipins through the Lipoxygenase (LOX), the Cyclooxygenase (COX) and the Cytochrome P450 (CYP450) pathways, leading to hydroperoxy-, epoxy-, mono- and dihydroxylated oxylipins. In several mouse and cell models, it has been shown that ALA and some of its oxylipins, including 9- and 13-hydroxy-octadecatrienoic acids (9-HOTrE and 13-HOTrE), have immunomodulating effects. Taken together, the current literature suggests a beneficial role for diets rich in ALA in human CVDs, however, it is not always clear whether the described effects are attributable to ALA, its oxylipins or other substances present in the supplemented diets.

Effects of fatty acid-ethanol amine (FA-EA) derivatives on lipid accumulation and inflammation

This study aimed to investigate the effect of fatty acid-ethanol amine (FA-EA) derivatives (L1-L10) on the mitigation of intracellular lipid accumulation and downregulation of pro-inflammatory cytokines in vitro. First, the series of FA-EA derivatives were synthesized and characterized. Then, their cytotoxic, intracellular lipid accumulation and inhibition of pro-inflammatory cytokines were evaluated. The oil red O staining experiment showed that the tested compounds L4, L6, L8, L9, and L10 could reduce intracellular lipid accumulation induced by palmitic acid (PA). Moreover, ω-3/ω-6 PUFA-EA derivatives showed inhibitory effect on the production of pro-inflammatory cytokines in lipopolysaccharide (LPS) -stimulated RAW 264.7 cells. ω-3/ω-6 PUFA-EA derivatives at a concentrations of 10 μM could significantly decrease mRNA levels of IL-6, IL-1β, and TNF-α, inhibit NO production, and alleviate the protein expression of IL-1β in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. These data suggest that ω-3 PUFA-EA derivatives can be beneficial for further pharmaceutical development to treat chronic low-grade inflammation diseases such as obesity.

N-3 polyunsaturated fatty acids for cardiovascular risk

PURPOSE OF REVIEW

Use of omega-3 fatty acid (OM3FA) supplements to reduce risk of cardiovascular events has been investigated, largely without evidence of meaningful benefit, over the last 4 decades.

RECENT FINDINGS

The first contemporary clinical trial to show benefit of OM3FA use was the REDUCE-IT trial (2018), showing a remarkable 25% relative risk reduction in the intervention group that received icosapent ethyl 4 g daily compared to a mineral oil placebo group. The STRENGTH trial (2020), which was similar in design to the REDUCE-IT trial but compared 4 g daily dose of combined OM3FA with a corn oil placebo, was terminated early due to futility.

SUMMARY

This article provides a review of the data surrounding these trials and discusses the differing results of the two trials. There are key differences in the design of the two trials, the most notable is the use of mineral oil in the REDUCE-IT trial, which was potentially a nonneutral comparator. Additionally, both trials showed an increase in the incidence of atrial fibrillation. With the unclear benefit of OM3FA supplementation and possibility of harm, the current data suggest that the risk of routine use of OM3FA outweighs the possibility of reduction in risk of cardiovascular events.