Circulating and dietary omega-3 and omega-6 polyunsaturated fatty acids and incidence of CVD in the Multi-Ethnic Study of Atherosclerosis

Omega-3 world map: 2024 update

In 2016, the first worldwide n3 PUFA status map was published using the Omega-3 Index (O3I) as standard biomarker. The O3I is defined as the percentage of EPA + DHA in red blood cell (RBC) membrane FAs. The purpose of the present study was to update the 2016 map with new data. In order to be included, studies had to report O3I and/or blood EPA + DHA levels in metrics convertible into an estimated O3I, in samples drawn after 1999. To convert the non-RBC-based EPA + DHA metrics into RBC we used newly developed equations. Baseline data from clinical trials and observational studies were acceptable. A literature search identified 328 studies meeting inclusion criteria encompassing 342,864 subjects from 48 countries/regions. Weighted mean country O3I levels were categorized into very low ≤4%, low >4-6%, moderate >6-8%, and desirable >8%. We found that the O3I in most countries was low to very low. Notable differences between the current and 2016 map were 1) USA, Canada, Italy, Turkey, UK, Ireland and Greece (moving from the very low to low category); 2) France, Spain and New Zealand (low to moderate); and 3) Finland and Iceland (moderate to desirable). Countries such as Iran, Egypt, and India exhibited particularly poor O3I levels.

Circulating Omega-3 Polyunsaturated Fatty Acids Levels in Coronary Heart Disease: Pooled Analysis of 36 Observational Studies

Long-chain n-3 polyunsaturated fatty acid (PUFA) supplementation has shown potential benefits in the prevention of coronary heart disease (CHD); however, the impact of omega-3 fatty acid levels on CHD risk remains a subject of debate. Here, we aimed to investigate the association between n-3 PUFA levels and the risk of CHD, with particular reference to the subtypes of n-3 PUFA.

METHODS

Prospective studies and retrospective case-control studies analyzing n-3 PUFA levels in CHD, published up to 30 July 2022, were selected. A random effects meta-analysis was used for pooled assessment, with relative risks (RRs) expressed as 95% confidence intervals (CIs) and standardized mean differences expressed as weight mean differences (WMDs). Subgroup and meta-regression analyses were conducted to assess the impact of n-3 PUFA exposure interval on the CHD subtype variables of the study.

RESULTS

We included 20 prospective studies (cohort and nested case-control) and 16 retrospective case-control studies, in which n-3 PUFAs were measured. Higher levels of n-3 PUFAs (ALA, EPA, DPA, DHA, EPA + DHA, total n-3 PUFAs) were associated with a reduced risk of CHD, with RRs (95% CI) of 0.89 (0.81, 0.98), 0.83 (0.72, 0.96); 0.80 (0.67,0.95), 0.75 (0.64, 0.87), 0.83 (0.73, 0.95), and 0.80 (0.70, 0.93), respectively, p < 0.05. CHD patients had significantly lower n-3 PUFA levels compared to healthy controls (p < 0.05). In the subgroup analysis, a significant inverse trend was found for both fatal CHD and non-fatal CHD with n-3 PUFA (EPA + DHA) levels. Also, the link between n-3 PUFA levels in erythrocytes with total CHD was generally stronger than other lipid pools.

CONCLUSIONS

n-3 PUFAs are significantly related to CHD risk, and these findings support the beneficial effects of n-3 PUFAs on CHD.

Associations between dietary fatty acids intake and abdominal aortic calcification: a national population-based study

BACKGROUND

Abdominal aortic calcification (AAC) is a crucial indicator of cardiovascular health. This study aims investigates the associations between dietary fatty acid intake and AAC.

METHODS

In this study, a cross-sectional assessment was performed on a group of 2,897 individuals aged 40 and above, utilizing data from the NHANES. The focus was on examining dietary consumption of various fatty acids, including Saturated (SFA), Monounsaturated (MUFA), Polyunsaturated (PUFA), as well as Omega-3 and Omega-6. The evaluation of AAC was done by applying the Kauppila AAC score to results obtained from dual-energy X-ray absorptiometry scans. For statistical analysis, weighted multivariate linear and logistic regression were employed, with adjustments for variables like gender, age, ethnicity, and overall health condition.

RESULTS

Participants with higher intake of SFA and PUFA showed a positive association with AAC score, while higher levels of dietary Omega-3 and Omega-6 fatty acids was connected with a negative correlation. Subgroup analyses indicated consistent associations across different sexes and age groups. The study found that an increase in SFA and PUFA intake correlated with an increase in AAC score, whereas Omega-3 and Omega-6 intake correlated with a decrease.

CONCLUSION

This study underscores the importance of dietary fatty acid composition in the prevalence of AAC and its potential implications for dietary guidelines and cardiovascular disease prevention strategies.

Omega-3 Polyunsaturated Fatty Acids are not associated with Peripheral Artery Disease in a Meta-Analysis from the Multi-Ethnic Study of Atherosclerosis and Atherosclerosis Risk in Communities Study Cohorts

BACKGROUND

Research suggests omega-3 polyunsaturated fatty acids (PUFAs) exert favorable effects on several biological processes involved in the development and progression of atherosclerotic cardiovascular disease (ASCVD). However, studies examining the relationship between omega-3 PUFAs and peripheral artery disease (PAD) are scarce.

OBJECTIVES

We evaluated the associations between omega-3 PUFAs and incident PAD in a meta-analysis of the Multi-Ethnic Study of Atherosclerosis (MESA) and Atherosclerosis Risk in Communities (ARIC) study cohorts.

METHODS

Omega-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were measured at baseline for all MESA (n = 6495) and Minnesota ARIC participants (n = 3612). Incident clinical PAD events (MESA n = 106; ARIC n = 149) identified primarily through ICD discharge codes were assessed through follow-up of each cohort. Associations between omega-3 PUFAs (EPA, DHA, and EPA+DHA) and incident PAD were modeled in MESA and ARIC as quartiles and continuously using Cox proportional hazards regression, respectively. A fixed-effects meta-analysis was conducted to evaluate associations in the 2 cohorts combined.

RESULTS

In the fully adjusted model, in 10,107 participants, no significant associations were observed between EPA, DHA, or EPA+DHA, and incident PAD modeled as quartiles or continuously for either MESA or ARIC cohorts separately or in the meta-analysis after a follow-up of approximately 15 y.

CONCLUSION

This study is consistent with previous literature indicating that the beneficial effects of omega-3 PUFAs on the markers of ASCVD may not translate to a clinically meaningful decrease in PAD risk.

Fish and Omega-3 Fatty Acids: Sex and Racial Differences in Cardiovascular Outcomes and Cognitive Function

Both cardiovascular disease (CVD) and cognitive decline are common features of aging. One in 5 deaths is cardiac for both men and women in the United States, and an estimated 50 million are currently living with dementia worldwide. In this review, we summarize sex and racial differences in the role of fish and its very long chain omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in preventing CVD events and cognitive decline. In prospective studies, women with higher nonfried and fatty fish intake and women and Black individuals with higher plasma levels of EPA and DHA had a lower risk of CVD. In randomized controlled trials of EPA and DHA supplementation in primary CVD prevention, Black subjects benefited in a secondary outcome. In secondary CVD prevention, both men and women benefited, and Asians benefited as a prespecified subgroup. Fish and omega-3 polyunsaturated fatty acids are associated with prevention of cognitive decline in prospective studies. In randomized controlled trials of EPA and DHA supplementation, women have cognitive benefit. DHA seems more beneficial than EPA, and supplementation is more beneficial when started before cognitive decline. Although studies in women and racial groups are limited, life-long intake of nonfried and fatty fish lowers the risk of CVD and cognitive decline, and randomized controlled trials also show the benefit of EPA and DHA supplementation. These findings should be factored into recommendations for future research and clinical recommendations as dietary modalities could be cost-effective for disease prevention.

Association between dietary omega-3 intake and coronary heart disease among American adults: The NHANES, 1999-2018

BACKGROUND

Omega-3 has been extensively studied for its cardiovascular disease (CVD) benefits. However, the results of this evidence are inconsistent. Therefore, in this study, dietary omega-3 intake was investigated further in relation to coronary heart disease (CHD) risk among U.S. adults.

METHODS

We used data from the National Health and Nutrition Examination Survey (NHANES) database for people ages 20 years and older between 1999 and 2018 to conduct a cross-sectional survey. The Medical Condition Questionnaire (MCQ) was used to determine CHD status. We measured dietary omega-3 intake using two 24-hour dietary recall interviews. Multivariate logistic regression and subgroup analysis were used to explore the correlation between dietary omega-3 intake and CHD. The dose-response relationship between the two was analyzed with a restricted cubic spline (RCS).

RESULTS

31,184 study subjects were included, of whom 1,604 (5.14%) were patients with CHD. By quintile (Q) of dietary omega-3 intake, after adjusting for all confounding factors, compared with Q1, when total dietary omega-3, alpha-linolenic acid (ALA), docosapentaenoic acid (DPA), eicosatetraenoic acid (ETA), eicosapentaenoic acid (EPA), and docosahexenoic acid (DHA) intake reached Q5, the odds ratio (95% confidence interval, CI) of CHD were 0.76 (0.60, 0.96), 0.73 (0.57, 0.94), 0.70 (0.54, 0.92), 0.66 (0.50, 0.85), 0.84 (0.69, 1.02), and 0.83 (0.64, 1.07), respectively, while EPA and DHA were not significantly associated with the disease (Trend p > 0.05). Intake of omega-3 and CHD were linearly related (P for nonlinear = 0.603). No significant interactions were found within subgroups except for the age group (P for interaction = 0.001). Sensitivity analysis and multivariate logistic regression results are generally in agreement.

CONCLUSIONS

Total dietary omega-3, ALA, DPA, and ETA intake were negatively associated with CHD risk. In contrast, EPA and DHA had no significant correlation with CHD.

Associations of Macronutrients Intake With MRI-determined Hepatic Fat Content, Hepatic Fibroinflammation, and NAFLD

CONTEXT

A healthy lifestyle is the cornerstone of management in nonalcoholic fatty liver disease (NAFLD). However, the associations between dietary macronutrient composition and different aspects of NAFLD pathology are unclear and dietary recommendations for NAFLD are lacking.

OBJECTIVE

This work aimed to evaluate the associations of dietary macronutrient composition with hepatic steatosis, hepatic fibroinflammation, and NAFLD.

METHODS

In this cross-sectional study, a total of 12 620 UK Biobank participants who completed both the dietary questionnaire and magnetic resonance imaging (MRI) examination were included in this study. Dietary consumption of macronutrient was self-reported and calculated. MRI-determined hepatic fat content, fibroinflammation, and NAFLD were estimated.

RESULTS

First, we found that saturated fatty acid (SFA) intake was associated with higher hepatic steatosis, fibroinflammation, and NAFLD prevalence. In contrast, higher fiber or protein intake was reversely correlated with hepatic steatosis and fibroinflammation. Interestingly, starch or sugar intake was significantly associated with hepatic fibroinflammation, whereas monounsaturated fatty acid (MUFA) intake was negatively correlated with hepatic fibroinflammation. Isocaloric analysis revealed that replacing SFA with sugar, fiber, or protein was significantly associated with a reduction in hepatic steatosis, while replacing starch, sugar, or SFA with protein or MUFA was significantly correlated with a decrease in hepatic fibroinflammation.

CONCLUSION

Overall, our results demonstrate that specific macronutrients are associated with different aspects of NAFLD, and specific dietary compositions should be recommended for distinct NAFLD-risk populations.

Genome-Wide Association Study and Identification of Candidate Genes for Intramuscular Fat Fatty Acid Composition in Ningxiang Pigs

Ningxiang pigs exhibit a diverse array of fatty acids, making them an intriguing model for exploring the genetic underpinnings of fatty acid metabolism. We conducted a genome-wide association study using a dataset comprising 50,697 single-nucleotide polymorphisms (SNPs) and samples from over 600 Ningxiang pigs. Our investigation yielded novel candidate genes linked to five saturated fatty acids (SFAs), four monounsaturated fatty acids (MUFAs), and five polyunsaturated fatty acids (PUFAs). Significant associations with SFAs, MUFAs, and PUFAs were found for 37, 21, and 16 SNPs, respectively. Notably, some SNPs have significant PVE, such as ALGA0047587, which can explain 89.85% variation in Arachidic acid (C20:0); H3GA0046208 and DRGA0016063 can explain a total of 76.76% variation in Elaidic Acid (C18:1n-9(t)), and the significant SNP ALGA0031262 of Arachidonic acid (C20:4n-6) can explain 31.76% of the variation. Several significant SNPs were positioned proximally to previously reported genes. In total, we identified 11 candidate genes (hnRNPU, CEPT1, ATP1B1, DPT, DKK1, PRKG1, EXT2, MEF2C, IL17RA, ITGA1 and ALOX5), six candidate genes (ALOX5AP, MEDAG, ISL1, RXRB, CRY1, and CDKAL1), and five candidate genes (NDUFA4L2, SLC16A7, OTUB1, EIF4E and ROBO2) associated with SFAs, MUFAs, and PUFAs, respectively. These findings hold great promise for advancing breeding strategies aimed at optimizing meat quality and enhancing lipid metabolism within the intramuscular fat (IMF) of Ningxiang pigs.

Investigating the catalytic efficiency of C22-Fatty acids with LOX human isozymes and the platelet response of the C22-oxylipin products

Polyunsaturated fatty acids (PUFAs) have been extensively studied for their health benefits because they can be oxidized by lipoxygenases to form bioactive oxylipins. In this study, we investigated the impact of double bond placement on the kinetic properties and product profiles of human platelet 12-lipoxygenase (h12-LOX), human reticulocyte 15-lipoxygenase-1 (h15-LOX-1), and human endothelial 15-lipoxygenase-2 (h15-LOX-2) by using 22-carbon (C22) fatty acid substrates with differing double bond content. With respect to kcat/KM values, the loss of Δ4 and Δ19 led to an 18-fold loss of kinetic activity for h12-LOX, no change in kinetic capability for h15-LOX-1, but a 24-fold loss for h15-LOX-2 for both C22-FAs. With respect to the product profiles, h12-LOX produced mainly 14-oxylipins. For h15-LOX-1, the 14-oxylipin production increased with the loss of either Δ4 and Δ19, however, the 17-oxylipin became the major species upon loss of both Δ4 and Δ19. h15-LOX-2 produced mostly the 17-oxylipin products throughout the fatty acid series. This study also investigated the effects of various 17-oxylipins on platelet activation. The results revealed that both 17(S)-hydroxy-4Z,7Z,10Z,13Z,15E,19Z-DHA (17-HDHA) and 17-hydroxy-4Z,7Z,10Z,13Z,15E-DPAn6 (17-HDPAn6) demonstrated anti-aggregation properties with thrombin or collagen stimulation. 17-hydroxy-7Z,10Z,13Z,15E,19Z-DPAn3 (17-HDPAn3) exhibited agonistic properties, and 17-hydroxy-7Z,10Z,13Z,15E-DTA (17-HDTA) showed biphasic effects, inhibiting collagen-induced aggregation at lower concentrationsbut promoting aggregation at higher concentrations. Both 17-hydroxy-13Z,15E,19Z-DTrA (17-HDTrA), and 17-hydroxy-13Z,15E-DDiA (17-HDDiA) induced platelet aggregation. In summary, the number and placement of the double bonds affect platelet activation, with the general trend being that more double bonds generally inhibit aggregation, while less double bonds promote aggregation. These findings provide insights into the potential role of specific fatty acids and their metabolizing LOX isozymes with respect to cardiovascular health.

Dietary intake, biomarkers and supplementation of fatty acids and risk of coronary events: a systematic review and dose-response meta-analysis of randomized controlled trials and prospective observational studies

We aimed to review the association of dietary fats and risk of coronary events in adults. We searched PubMed, Embase, CENTRAL, Scopus, and Web of Sciences to April 2022 for prospective cohorts and randomized trials investigating the association of dietary intake and biomarkers of fats and fatty acid interventions and the risk of coronary events. We performed random-effects meta-analyses to estimate relative risk (RR) for the top versus bottom tertiles of exposures. One-hundered sixty-five prospective cohorts and randomized trials were included. Dietary intake and biomarkers of total fat and saturated, monounsaturated, and polyunsaturated fatty acids were not associated with the risk of coronary events. Dietary intake of trans fatty acids, palmitic acid, stearic acid, and saturated fatty acids from meat and unprocessed meat was modestly associated with a higher risk and, in contrast, intake of alpha-linolenic acid, long-chain omega-3 fatty acids, and linoleic acid was modestly associated with a lower risk. Supplementation with long-chain omega-3 fatty acids and increasing the consumption of alpha-linolenic and linoleic acids in place of saturated fats reduced the risk of coronary events. Existing evidence, in its totality, provides a modest support in favor of current recommendations suggesting replacement of saturated fats with polyunsaturated fats.

A case-control study on the association between adherence to a Mediterranean-style diet and breast cancer

Background

Previous studies on the association between diet and breast cancer are mostly from Western populations, and data from Middle East countries are scarce, where the prevalence of breast cancer is high; therefore, it ranks first among other cancers. This population-based case-control study aimed to investigate the relationship between a Mediterranean-style diet and breast cancer among Iranian women.

Methods

In the current study, 350 new cases of breast cancer and 700 age- and socioeconomic status-matched controls were enrolled. We evaluated the dietary intakes of participants by using a 106-item Willett-format semi-quantitative dish-based food frequency questionnaire (SQ-FFQ). We calculated the Mediterranean diet score according to the dietary intakes of participants. In addition, using pre-tested questionnaires, we collected information on potential confounding variables.

Results

In this study, we found a significant inverse association between the Mediterranean diet and breast cancer so that after controlling for potential confounders, individuals in the highest tertile of the Mediterranean diet score compared with those in the lowest tertile were 57% less likely to have breast cancer [odds ratio (OR): 0.43, 95% confidence interval (CI): 0.28-0.67]. Such an inverse association was also observed for postmenopausal women. Similarly, after controlling for potential confounding variables, high adherence to the Mediterranean dietary pattern was associated with lower odds of breast cancer (OR: 0.37, 95% CI: 0.23-0.60). However, this relationship was not significant among premenopausal women.

Conclusion

We found that adherence to Mediterranean dietary pattern was associated with reduced odds of breast cancer. Studies with prospective design are needed to further examine this association.

Omega-3 Fatty Acids Interact with DPP10 Region Genotype in Association with Childhood Atopy

Associations of omega-3 fatty acids (n-3) with allergic diseases are inconsistent, perhaps in part due to genetic variation. We sought to identify and validate genetic variants that modify associations of n-3 with childhood asthma or atopy in participants in the Vitamin D Antenatal Asthma Reduction Trial (VDAART) and the Copenhagen Prospective Studies on Asthma in Childhood 2010 (COPSAC). Dietary n-3 was derived from food frequency questionnaires and plasma n-3 was measured via untargeted mass spectrometry in early childhood and children aged 6 years old. Interactions of genotype with n-3 in association with asthma or atopy at age 6 years were sought for six candidate genes/gene regions and genome-wide. Two SNPs in the region of DPP10 (rs958457 and rs1516311) interacted with plasma n-3 at age 3 years in VDAART (p = 0.007 and 0.003, respectively) and with plasma n-3 at age 18 months in COPSAC (p = 0.01 and 0.02, respectively) in associationwith atopy. Another DPP10 region SNP, rs1367180, interacted with dietary n-3 at age 6 years in VDAART (p = 0.009) and with plasma n-3 at age 6 years in COPSAC (p = 0.004) in association with atopy. No replicated interactions were identified for asthma. The effect of n-3 on reducing childhood allergic disease may differ by individual factors, including genetic variation in the DPP10 region.

Circulating Omega-3 and Omega-6 Fatty Acids, Cognitive Decline, and Dementia in Older Adults

BACKGROUND

Comprising nearly 35% of brain lipids, polyunsaturated fatty acids (PUFA) are essential for optimal brain function. However, the role of PUFA on cognitive health outcomes later in life is largely unknown.

OBJECTIVE

We investigated prospective associations of plasma phospholipid omega-3 (ALA [18 : 3], EPA [20 : 5], DPA [22 : 5], DHA [22 : 6]) and omega-6 (LA [18 : 2], AA [20 : 4]) PUFA with cognitive decline, risk of cognitive impairment and dementia among adults aged≥65 years in the Cardiovascular Health Study.

METHODS

Circulating fatty acid concentrations were measured serially at baseline (1992/1993), 6 years, and 13 years later. Cognitive decline and impairment were assessed using the 100-point Modified Mini-Mental State Examination (3MSE) up to 7 times. Clinical dementia was identified using adjudicated neuropsychological tests, and ICD-9 codes.

RESULTS

Among 3,564 older adults free of stroke and dementia at baseline, cognitive function declined annually by approximately -0.5 3MSE points; 507 participants developed cognitive impairment and 499 dementia over up to 23 years of follow-up. In multivariable models, higher circulating arachidonic acid (AA) concentrations were associated with slower cognitive decline and lower dementia risk, with associations growing stronger with greater length of follow-up (hazard ratio [HR,95% CI] of dementia per interquintile range, 0.74 [0.56-0.97] at 5 years, and 0.53 [0.37-0.77] at 15 years). Circulating docosapentaenoic (DPA) concentrations were associated with slower cognitive decline and lower risk of cognitive impairment (extreme-quintile HR, 0.72 [95% CI: 0.55, 0.95]). Findings were generally null or inconsistent for other omega-3 or omega-6 PUFA.

CONCLUSION

Circulating AA and DPA, but not other PUFA, are associated with slower rate of cognitive decline and lower risk of dementia or cognitive impairment later in life.

Clinical significance of polyunsaturated fatty acids in the prevention of cardiovascular diseases

Cardiovascular diseases are one of the most important problems of modern medicine. They are associated with a large number of health care visits, hospitalizations and mortality. Prevention of atherosclerosis is one of the most effective strategies and should start as early as possible. Correction of lipid metabolism disorders is associated with definite clinical successes, both in primary prevention and in the prevention of complications of many cardiovascular diseases. A growing body of evidence suggests a multifaceted role for polyunsaturated fatty acids. They demonstrate a variety of functions in inflammation, both participating directly in a number of cellular processes and acting as a precursor for subsequent biosynthesis of lipid mediators. Extensive clinical data also support the importance of polyunsaturated fatty acids, but all questions have not been answered to date, indicating the need for further research.

The role of oxidized lipid species in insulin resistance and NASH in children

During the last two decades, nonalcoholic fatty liver disease (NAFLD) has emerged as the most common hepatic disease in pediatrics, mainly owing to the rising prevalence of pediatric obesity. Epidemiological studies have shown that the progressive increase in NAFLD prevalence is associated not only with obesity but also with changes in dietary habits experienced by all age groups, characterized by the increased intake of added sugars and certain fatty acids. In this review article, we focus on the effect of oxidized fatty acids deriving from linoleic acid and arachidonic acid on the pathogenesis and progression of NAFLD in youth.

Impact of α-Linolenic Acid, the Vegetable ω-3 Fatty Acid, on Cardiovascular Disease and Cognition

Given the evidence of the health benefits of plant-based diets and long-chain n-3 (ω-3) fatty acids, there is keen interest in better understanding the role of α-linolenic acid (ALA), a plant-derived n-3 fatty acid, on cardiometabolic diseases and cognition. There is increasing evidence for ALA largely based on its major food sources (i.e., walnuts and flaxseed); however, this lags behind our understanding of long-chain n-3 fatty acids. Meta-analyses of observational studies have shown that increasing dietary ALA is associated with a 10% lower risk of total cardiovascular disease and a 20% reduced risk of fatal coronary heart disease. Three randomized controlled trials (RCTs) [AlphaOmega trial, Prevención con Dieta Mediterránea (PREDIMED) trial, and Lyon Diet Heart Study] all showed benefits of diets high in ALA on cardiovascular-related outcomes, but the AlphaOmega trial, designed to specifically evaluate ALA effects, only showed a trend for benefit. RCTs have shown that dietary ALA reduced total cholesterol, LDL cholesterol, triglycerides, and blood pressure, and epidemiologic studies and some trials also have shown an anti-inflammatory effect of ALA, which collectively account for, in part, the cardiovascular benefits of ALA. A meta-analysis reported a trend toward diabetes risk reduction with both dietary and biomarker ALA. For metabolic syndrome and obesity, the evidence for ALA benefits is inconclusive. The role of ALA in cognition is in the early stages but shows promising evidence of counteracting cognitive impairment. Much has been learned about the health benefits of ALA and with additional research we will be better positioned to make strong evidence-based dietary recommendations for the reduction of many chronic diseases.

Associations of Vitamin B6 Intake and Plasma Pyridoxal 5'-Phosphate with Plasma Polyunsaturated Fatty Acids in US Older Adults: Findings from NHANES 2003-2004

Previous evidence suggests a potential dual impact of aging and vitamin B6 (B6) deficiency on polyunsaturated fatty acid (PUFA) metabolism; gender may influence PUFA biosynthesis. Perturbation of PUFA compositions during B6 deficiency could be linked to age-related health outcomes. However, little is known about the interrelationships between vitamin B6, PUFA, and gender in the older population. Therefore, we investigated whether gender-specific associations of B6 intake and plasma pyridoxal 5’-phosphate (PLP) concentration, respectively, with plasma PUFA concentrations and ratios (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), EPA + DHA, EPA/AA, and (EPA + DHA)/AA) existed in older adults. We further examined the relationships of adequate B6 status (PLP ≥ 20 nmol/L) with high (above median) plasma PUFA relative to deficient B6 status. This cross-sectional study analyzed 461 participants aged ≥60 years from NHANES 2003−2004. Nutrient intakes were assessed using two 24-h recalls and supplement questionnaires. PLP and PUFA concentrations were measured. Multivariate linear regression assessed the association of B6 intake and PLP with PUFA; multivariate logistic regression evaluated the relationship of adequate B6 status with high plasma PUFA, adjusting for demographic, socioeconomic, and dietary factors; physical activity; smoking; alcohol; medication; and BMI. There were interactions between gender and B6 intake on EPA (P-interaction = 0.008) and AA (P-interaction = 0.004) only, whereas no interaction existed between gender and PLP on PUFA. PLP was directly associated with EPA (β = 0.181, P = 0.002), DHA (β = 0.109, P = 0.005), EPA + DHA (β = 0.14, P = 0.002), EPA/AA (β = 0.186, P = 0.004), and (EPA + DHA)/AA (β = 0.13, P = 0.026). The odds of having high plasma EPA (adjusted (a) OR: 2.03, P = 0.049) and EPA/AA (aOR: 3.83, P < 0.0001) were greater in those with adequate B6 status compared to those with deficient B6 status. In conclusion, in US older adults, a higher PLP level was associated with a greater level of EPA, DHA, EPA + DHA, EPA/AA, and (EPA + DHA)/AA. Adequate B6 status was associated with high EPA and EPA/AA status. These findings suggest that sufficient vitamin B6 status may positively influence PUFA metabolism in older adults.

Changes in eicosapentaenoic acid and docosahexaenoic acid and risk of cardiovascular events and atrial fibrillation: A secondary analysis of the OMEMI trial

BACKGROUND

The cardiovascular benefit from n-3 polyunsaturated fatty acids (PUFAs) after acute myocardial infarction (AMI) is controversial, and the importance of serum eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations for clinical events is unclear.

OBJECTIVES

To assess changes in EPA and DHA serum concentrations during n-3 PUFA supplementation and their association with incident cardiovascular events.

METHODS

In the OMEMI trial, elderly patients with a recent AMI were randomized to 1.8 g/day of EPA/DHA or control (corn oil) for 2 years. The primary outcome was a composite of AMI, coronary revascularization, stroke, heart failure hospitalization, or all-cause death (major adverse cardiovascular event [MACE]) and the secondary outcome was new-onset atrial fibrillation (AF).

RESULTS

EPA and DHA measurements were available in 881 (92% of survivors) participants at randomization and study completion. EPA and DHA increased in the active treatment arm (n = 438) by a median of 87% and 16%, respectively. Greater on-treatment increases in EPA and DHA were associated with decreasing triglycerides, increasing high-density lipoprotein cholesterol, and lower baseline EPA and DHA concentrations. Greater on-treatment increases in EPA were associated with lower risk of MACE (adjusted hazard ratio 0.86 [95% confidence interval, CI, 0.75-0.99], p = 0.034), and higher risk of AF (adjusted hazard ratio (HR) 1.36 [95% CI 1.07-1.72], p = 0.011). Although there were similar tendencies for DHA changes and outcomes, these associations were not statistically significant (HR 0.84 [0.66-1.06] for MACE and 1.39 [0.90-2.13] for AF).

CONCLUSION

Greater on-treatment increases in EPA were associated with lower risk of MACE and higher risk of new-onset AF. These data suggest that the cardiovascular effects of increasing n-3 PUFA levels through supplements are complex, involving both potential benefits and harm.

The associations of circulating common and uncommon polyunsaturated fatty acids and modification effects on dietary quality with all-cause and disease-specific mortality in NHANES 2003-2004 and 2011-2012

BACKGROUND

Associations of dietary or supplementary intake of several unsaturated fatty acids and mortality have been widely studied but the results were still hitherto inconsistent or limited. It is still need to explore the effects of these fatty acids by using the objective biomarkers.

OBJECTIVE

We aimed to investigate the relevancy of several serum n-3 and n-6 fatty acids with all-cause and disease-specific mortality to confirm their health effects and effects on the associations between dietary quality and all-cause mortality.

METHODS

A total of 4132 people from NHANES 2003-2004 and 2011-2012 and the mortality information was confirmed from the NDI. CPH models adjusted for known risk factors were conducted to explore the associations between circulating n-3 and n-6 fatty acids and all-cause or CVD or cancer mortality under complex sampling. We further evaluated their effects on association between dietary quality and all-cause mortality.

RESULTS

A total of 437 deaths occurred during the mean follow-up of 83.34 months, including 157 CVD death and 100 cancer death. Serum LA, ALA, EPA and DHA were associated with all-cause mortality (HR in quintile5: LA:0.584, 95%CI: 0.387-0.882, Ptrend = 0.011; ALA:0.626, 95%CI: 0.432-0.907, Ptrend = 0.008; EPA:0.535, 95%CI: 0.375-0.764, Ptrend = 0.001; DHA:0.669, 95%CI: 0.468-0.955, Ptrend = 0.031). Additionally, serum EPA and ALA were respectively related to CVD and cancer mortality (Q5 HR: EPA:0.450, 95%CI: 0.23-0.854, Ptrend = 0.009; ALA:0.387, 95%CI: 0.167-0.900, Ptrend = 0.022). Serum AA, GLA, DGLA and SDA were not associated with any risk of mortality. The effect on all-cause mortality of the lower AHEI scores can be improved by adherence to a higher serum LA, EPA and DHA (in the lowest AHEI strata, LA in tertile3 compared to tertile1 HR:0.596, 95%CI: 0.366-0.970; EPA:0.660, 95%CI: 0.454-0.959; DHA:0.666, 95%CI; 0.444-1.000).

CONCLUSIONS

Our results support the recent dietary recommendations to increase the intake of plant-derived and marine-derived n-6 and n-3 to improve the ability of primary and secondary prevention.

Dietary Intake and Biomarkers of α-Linolenic Acid and Mortality: A Meta-Analysis of Prospective Cohort Studies

Background: The association between α-linolenic acid (ALA) and mortality is inconsistent and has not been summarized systematically.

Objective: The purpose was to conduct a meta-analysis that synthesized the results of prospective cohort studies to investigate associations between ALA intake and mortality.

Methods: We conducted a comprehensive search on PubMed, Embase, and Web of Science databases on May 1, 2021, for relevant prospective cohort studies which reported associations of ALA (assessed by dietary surveys and/or ALA concentrations in body tissues) with mortality from all-cause, cardiovascular disease (CVD), and other diseases. Multivariable-adjusted relative risks (RRs) were pooled by a random or fixed-effects model.

Results: A total of 34 prospective cohort studies, of which 17 reported dietary ALA intake, 14 for ALA biomarkers, and the remaining 3 reported both of intake and biomarkers. The studies included 6,58,634 participants, and deaths were classified into all-cause mortality (56,898), CVD mortality (19,123), and other diseases mortality (19,061). Pooled RRs of ALA intake were 0.93 (95% CI: 0.86, 1.01, I² = 71.2%) for all-cause mortality, 0.90 (95% CI: 0.83, 0.98, I² = 22.1%) for CVD mortality, and 0.94 (95% CI: 0.83, 1.06, I² = 73.3%) for other diseases mortality. The two-stage random-effects dose-response analysis showed a linear relationship between dietary ALA intake and CVD-mortality and each 0.5% energy increment of ALA intake was associated with a 5% lower risk of CVD-mortality (RR: 0.95; 95% CI: 0.90, 1.00). Pooled RRs per SD increment of ALA biomarkers were 0.99 (95% CI: 0.96, 1.01, I² = 27%) for all-cause mortality, 1.00 (95% CI: 0.98, 1.03, I² = 0%) for CVD mortality and 0.98 (95% CI: 0.95, 1.01, I² = 0%) for other diseases mortality.

Conclusions: This meta-analysis summarizing the available prospective cohort studies indicated that ALA intake was associated with reduced risk of mortality, especially CVD mortality. Our findings suggest that ALA consumption may be beneficial for death prevention. Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO; identifier: CRD42021264532.

Altered Plasma Fatty Acids Associate with Gut Microbial Composition in Common Variable Immunodeficiency

PURPOSE

Fatty acid (FA) abnormalities are found in various inflammatory disorders and have been related to disturbed gut microbiota. Patients with common variable immunodeficiency (CVID) have inflammatory complications associated with altered gut microbial composition. We hypothesized that there is an altered FA profile in CVID patients, related to gut microbial dysbiosis.

METHODS

Plasma FAs were measured in 39 CVID patients and 30 healthy controls. Gut microbial profile, a food frequency questionnaire, and the effect of the oral antibiotic rifaximin were investigated in CVID patients.

RESULTS

The n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) (1.4 [1.0-1.8] vs. 1.9 [1.2-2.5], median (IQR), P < 0.05), and docosahexaenoic acid (DHA) (3.2 [2.4-3.9] vs. 3.5 [2.9-4.3], P < 0.05), all values expressed as weight percent of total plasma FAs, were reduced in CVID compared to controls. Also, n-6 PUFAs (34.3 ± 3.4 vs. 37.1 ± 2.8, mean ± SD, P < 0.001) and linoleic acid (LA) (24.5 ± 3.3 vs. 28.1 ± 2.7, P < 0.0001) and the FA anti-inflammatory index (98.9 [82.1-119.4] vs. 117.0 [88.7-153.1], median (IQR), P < 0.05) were reduced in CVID. The microbial alpha diversity was positively associated with plasma n-6 PUFAs (r = 0.41, P < 0.001) and LA (r = 0.51, P < 0.001), but not n-3 PUFAs (P = 0.78). Moreover, a 2-week course of rifaximin significantly reduced the proportion of n-6 PUFAs (P = 0.04, UNIANOVA). Serum immunoglobulin G (IgG) levels correlated with plasma n-3 PUFAs (rho = 0.36, P = 0.03) and DHA (rho = 0.41, P = 0.009).

CONCLUSION

We found a potentially unfavorable FA profile in CVID, related to low IgG levels. High plasma n-6 PUFAs were related to increased gut microbial diversity and altered by rifaximin therapy.

Exploring the Links between Diet and Inflammation: Dairy Foods as Case Studies

Systemic chronic inflammation may be a contributing factor to many noncommunicable diseases, including diabetes, cardiovascular disease, and obesity. With the rapid rise of these conditions, identifying the causes of and treatment for chronic inflammation is an important research priority, especially with regard to modifiable lifestyle factors such as diet. An emerging body of evidence indicates that consuming certain foods, including dairy foods like milk, cheese, and yogurt, may be linked to a decreased risk for inflammation. To discuss both broader research on diet and inflammation as well as research on links between individual foods and inflammation, the National Dairy Council sponsored a satellite session entitled "Exploring the Links between Diet and Inflammation: Dairy Foods as Case Studies" at the American Society for Nutrition's 2020 LIVE ONLINE Conference. This article, a review based on the topics discussed during that session, explores the links between diet and inflammation, focusing most closely on the relations between intake of dairy fat and dairy foods like milk, cheese, and yogurt, and biomarkers of inflammation from clinical trials. While there is currently insufficient evidence to prove an "anti-inflammatory" effect of dairy foods, the substantial body of clinical research discussed in this review indicates that dairy foods do not increase concentrations of biomarkers of chronic systemic inflammation.

Comparison of dimension reduction methods on fatty acids food source study

Serum fatty acids (FAs) exist in the four lipid fractions of triglycerides (TGs), phospholipids (PLs), cholesteryl esters (CEs) and free fatty acids (FFAs). Total fatty acids (TFAs) indicate the sum of FAs in them. In this study, four statistical analysis methods, which are independent component analysis (ICA), factor analysis, common principal component analysis (CPCA) and principal component analysis (PCA), were conducted to uncover food sources of FAs among the four lipid fractions (CE, FFA, and TG + PL). Among the methods, ICA provided the most suggestive results. To distinguish the animal fat intake from endogenous fatty acids, FFA variables in ICA and factor analysis were studied. ICA provided more distinct suggestions of FA food sources (endogenous, plant oil intake, animal fat intake, and fish oil intake) than factor analysis. Moreover, ICA was discovered as a new approach to distinguish animal FAs from endogenous FAs, which will have an impact on epidemiological studies. In addition, the correlation coefficients between a published dataset of food FA compositions and the loading values obtained in the present ICA study suggested specific foods as serum FA sources. In conclusion, we found that ICA is a useful tool to uncover food sources of serum FAs.

Lipoproteins and fatty acids in chronic kidney disease: molecular and metabolic alterations

Chronic kidney disease (CKD) induces modifications in lipid and lipoprotein metabolism and homeostasis. These modifications can promote, modulate and/or accelerate CKD and secondary cardiovascular disease (CVD). Lipid and lipoprotein abnormalities - involving triglyceride-rich lipoproteins, LDL and/or HDL - not only involve changes in concentration but also changes in molecular structure, including protein composition, incorporation of small molecules and post-translational modifications. These alterations modify the function of lipoproteins and can trigger pro-inflammatory and pro-atherogenic processes, as well as oxidative stress. Serum fatty acid levels are also often altered in patients with CKD and lead to changes in fatty acid metabolism - a key process in intracellular energy production - that induce mitochondrial dysfunction and cellular damage. These fatty acid changes might not only have a negative impact on the heart, but also contribute to the progression of kidney damage. The presence of these lipoprotein alterations within a biological environment characterized by increased inflammation and oxidative stress, as well as the competing risk of non-atherosclerotic cardiovascular death as kidney function declines, has important therapeutic implications. Additional research is needed to clarify the pathophysiological link between lipid and lipoprotein modifications, and kidney dysfunction, as well as the genesis and/or progression of CVD in patients with kidney disease.

Tissue and Circulating Fatty Acids as Biomarkers to Evaluate Long-Term Fat Intake Are Tissue and Sex Dependent in CD-1 Mice

BACKGROUND

There is currently no consensus on which tissues are optimal for assessing specific diet-derived fatty acids (FAs) as biomarkers for long-term dietary studies.

OBJECTIVES

This study measured the content of unique diet-derived FAs from dairy, echium, and fish in tissues (adipose, muscle, liver, erythrocyte membranes, and plasma phospholipids, cholesterol esters, triglycerides, and free fatty acids) after long-term feeding in CD-1 mice.

METHODS

Beginning at weaning, mice (n = 10-11/sex/diet) were fed 1 of 4 diets (40% kcal/total energy) that only differed in FA composition: control fat blend (CON), reflecting the FA profile of the average US American diet, or CON supplemented with 30% of fish oil (FO), dairy fat (DF), or echium oil (EO). After 13 mo, tissues were collected to determine FAs via gas-liquid chromatography. Tissue FAs were analyzed via 2-factor ANOVA, and relationships between FA intake and tissue content were assessed with Spearman correlations.

RESULTS

As anticipated, 20:5n-3 (ω-3) tissue content was ≤32-fold greater in FO- compared with CON-fed mice (P < 0.05). In addition, 20:5n-3 intake strongly correlated with its content in all tissues (ρ = 0.67-0.76; P < 0.05). Echium oil intake also influenced tissue FA content in mice as expected. For example, 18:3n-6 was ≤25-fold greater in adipose, muscle, and liver tissues of EO-fed compared with CON-fed mice (P < 0.05). Tissue content of FAs typically considered biomarkers of dairy fat intake (15:0, 16:1 t9, and 17:0) was often not greater in mice fed DF than other diet groups, although 18:2 c9, t11 content was ≤6-fold greater in tissues from DF-fed compared with CON-fed mice (P < 0.05). The content of dairy-derived FAs in blood fractions of females was up to 2-fold greater compared with males, whereas docosapentaenoic acid content was up to 1-fold greater in all blood fractions and in liver tissue of males compared with females (P < 0.05). In adipose, muscle, and liver tissue, the content of γ-linolenic acid and stearidonic acid was less than 1-fold greater in females than in males (P < 0.05).

CONCLUSIONS

Our study indicates that the distribution of dietary FAs is tissue and sex dependent in aged CD-1 mice. Research using FA biomarkers should assess a combination of FA biomarkers to accurately validate patterns of FA intake and source.

Plasma ω-3 and ω-6 PUFA Concentrations and Risk of Atrial Fibrillation: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Current literature examining the prospective relation of circulating omega-3 (n-3) and omega-6 (n-6) PUFAs and atrial fibrillation (AF) is limited to predominantly white populations.

OBJECTIVES

We investigated the association of circulating n-3 and n-6 PUFAs with incident AF in participants from the Multi-Ethnic Study of Atherosclerosis.

METHODS

A total of 6229 participants (mean age = 62 y; 53% female; 39% white, 27% black, 22% Hispanic, and 12% Chinese) who were free of baseline AF and with plasma phospholipid PUFAs measured at baseline using GC were prospectively followed for the development of AF. Incident AF was ascertained using International Classification of Diseases-9 codes from hospital discharge records and Medicare claims data with follow-up through 2014. Multivariable Cox proportional hazards regression analysis was performed to determine the risk of incident AF.

RESULTS

During a median follow-up of 12.9 y, 813 (13%) participants developed AF. Each higher SD increment in arachidonic acid (AA; 20:4n-6) concentrations was associated with an 11% decreased risk of incident AF (HR: 0.89; 95% CI: 0.82, 0.96). Similarly, higher overall n-6 PUFA concentrations were also associated with a reduced AF risk (HR per SD increment: 0.93; 95% CI: 0.87, 1.00). Although no significant overall associations were observed for any individual n-3 PUFAs, higher circulating concentrations of DHA (22:6n-3) and EPA (20:5n-3) were associated with a decreased AF risk in blacks and Hispanics (DHA only) but not whites or Chinese Americans.

CONCLUSIONS

In a multiethnic cohort of individuals free of baseline cardiovascular disease, higher plasma concentrations of n-6 PUFAs, particularly AA, were associated with a reduced risk of incident AF. Important differences in AF risk were also noted across race/ethnicity for the n-3 PUFAs DHA and EPA.

A Study Protocol for a Parallel-Designed Trial Evaluating the Impact of Plant-Based Diets in Comparison to Animal-Based Diets on Health Status and Prevention of Non-communicable Diseases-The Nutritional Evaluation (NuEva) Study

Background and Aims: Currently, there is a continuing upward trend for plant-based lifestyles in Germany and Europe. The implementation of vegetarian and vegan lifestyles is characterized by omitting defined food groups such as fish, meat, sausage (vegetarians), or dairy products and honey (vegans). This carries the risk of an undersupply of valuable nutrients. The NuEva study is designed to examine this hypothesis and to evaluate the impact of plant-based diets on health status and disease risk.

Methods: The NuEva study is a parallel-designed trial with at least 55 participants for each diet (vegetarian, vegan, flexitarian [rare meat/sausage consumption, once or twice per week]), and participants who consume a traditional Western diet as the control group. In the screening period critical nutrients are identified for the studied diets by analysis of a broad spectrum of nutrients in the human samples (fatty acids, vitamins, minerals, trace elements, nutrient metabolites).

Results: Based on the data from the screening period, defined menu plans, ensuring an adequate nutrient intake in accordance with the nutritional guidelines are prepared for each group. The plans are adapted and personalized to individual energy requirements based on the basal metabolic rate and physical activity level. The compliance with the NuEva concept and their impact on nutrient status and cardiovascular risk factors are validated during the intervention period of the NuEva study over 1 year. To investigate the impact of the studied diets on the microbiome, feces samples are collected at the beginning and after the 12 months intervention period (follow up: 12 months).

Conclusion: The NuEva study is designed to investigate the impact of common diets on health and disease status, with focus on prevention of cardiovascular diseases. In addition, the effectiveness of the prepared nutritional coaching strategy, ensuring optimal nutrient intake in accordance with the guidelines, is validated during the intervention period of the NuEva study.

Clinical Trial Registration: Registered under ClinicalTrials.gov Identifier no. NCT03582020.

Gender Differences in the Associations of Plasma Pyridoxal 5'-Phosphate with Plasma Polyunsaturated Fatty Acids among US Young and Middle-Aged Adults: NHANES 2003-2004

Vitamin B6-restricted diets and low plasma pyridoxal 5'-phosphate (PLP) status altered plasma polyunsaturated fatty acids (PUFA) compositions. Evidence suggests the role of gender in the metabolism of vitamin B6 and PUFA. However, no epidemiologic study examined the impact of gender on the relationship between vitamin B6 and PUFA status in adults. Thus, we investigated whether there were gender differences in the association of vitamin B6 intake and plasma PLP concentration with plasma PUFA concentrations and ratios (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), EPA + DHA, EPA/AA, (EPA + DHA)/AA) in US young/middle-aged adults. In total, 864 participants (20-59 years; 484 men, 380 women) from the National Health and Nutrition Examination Survey (NHANES) 2003-2004 were used for this cross-sectional study. Nutrient intakes were estimated from two 24 h recalls and supplement questionnaires; plasma PLP and PUFA were measured. Multivariate linear regression was utilized to obtain unstandardized (b) and standardized (β) coefficients. Covariates included demographic, socioeconomic, dietary variables, physical activity level, cigarette smoking status, alcohol consumption, prescription medication use, and BMI. There were significant interactions between gender and PLP on EPA (P-interaction = 0.004), DHA (P-interaction = 0.020), EPA + DHA (P-interaction = 0.010), EPA/AA (P-interaction = 0.002), (EPA + DHA)/AA (P-interaction = 0.004), whereas no interaction between gender and B6 intake existed. In gender-stratified analyses, in men, PLP was positively associated with EPA (β = 0.138, b = 0.104, p = 0.0004), DHA (β = 0.101, b = 0.058, p = 0.036), EPA + DHA (β = 0.125, b = 0.073, p = 0.005), EPA/AA (β = 0.144, b = 0.099, p = 0.0002), (EPA + DHA)/AA (β = 0.123, b = 0.068, p = 0.005). However, no associations between PLP and PUFA existed in women. In conclusion, gender differences were found in the relationships between plasma PLP and plasma EPA, DHA, EPA + DHA, EPA/AA, and (EPA + DHA)/AA, with significant direct associations in men only among US young/middle-aged adults.

Prevention of Endothelial Dysfunction and Cardiovascular Disease by n-3 Fatty Acids-Inhibiting Action on Oxidative Stress and Inflammation

BACKGROUND

Prospective cohort studies and randomized controlled trials have shown the protective effect of n-3 fatty acids against cardiovascular disease (CVD). The effect of n-3 fatty acids on vascular endothelial cells indicates their possible role in CVD prevention.

OBJECTIVE

Here, we describe the effect of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on endothelial dysfunction-caused by inflammation and oxidative stress-and their role in the development of CVD.

METHODS

We reviewed epidemiological studies done on n-3 fatty acids in CVD. The effect of DHA and EPA on vascular endothelial cells was examined with regard to changes in various markers, such as arteriosclerosis, inflammation, and oxidative stress, using cell and animal models.

RESULTS

Epidemiological studies revealed that dietary intake of EPA and DHA was associated with a reduced risk of various CVDs. EPA and DHA inhibited various events involved in arteriosclerosis development by preventing oxidative stress and inflammation associated with endothelial cell damage. In particular, EPA and DHA prevented endothelial cell dysfunction mediated by inflammatory responses and oxidative stress induced by events related to CVD. DHA and EPA also increased eNOS activity and induced nitric oxide production.

CONCLUSION

The effects of DHA and EPA on vascular endothelial cell damage and dysfunction may involve the induction of nitric oxide, in addition to antioxidant and anti-inflammatory effects. n-3 fatty acids inhibit endothelial dysfunction and prevent arteriosclerosis. Therefore, the intake of n-3 fatty acids may prevent CVDs, like myocardial infarction and stroke.

Dietary fatty acids and CHD: from specific recommendations to dietary patterns

Several countries have issued dietary recommendations about total and specific fatty acid (FA) intake for the prevention of CHD. For many years until today, controversies have existed especially about the deleterious effect or not of SFA, and the protective effect or not of n-3 PUFA, so that some authors have criticised these recommendations. There are many reasons for these controversies, including the different conclusions of prospective cohort studies compared with randomised clinical trials (RCT), and the contradictory conclusions of meta-analyses depending on the quality, number and type of studies included. The interrelationships between different FA in the diet make it difficult to analyse the specific effect of a particular class of FA on CHD. Furthermore, based on clinical practice and effectiveness of population-based prevention, it is very difficult at the individual level to assess in personal dietary intake the actual percentage and/or amount of SFA contained in each meal or consumed daily/weekly. In this critical narrative review, we try to answer the question of whether it would not be more relevant, in 2020, to promote dietary patterns, rather than FA intake recommendations. We critically analyse past and recent data on the association of FA with CHD, then propose that the Mediterranean diet and Japanese diet should be revitalised for Westerners and Asian populations, respectively. This does not exclude the usefulness of continuing research about effects of FA towards CHD, and accepting that what seems true today might be revised, at least partially tomorrow.

Omega-3 polyunsaturated fatty acids focusing on eicosapentaenoic acid and docosahexaenoic acid in the prevention of cardiovascular diseases: a review of the state-of-the-art

INTRODUCTION

: An epidemiological study of Greenlandic Inuit suggested the importance of omega-3 polyunsaturated fatty acids (PUFAs) in preventing ischemic heart disease. After this landmark study, large-scale epidemiological studies have examined the benefits of omega-3 PUFAs in the prevention of cardiovascular diseases.

AREAS COVERED

: This article reviews studies on omega-3 PUFAs, and identifies issues relevant to cardiovascular risk.

EXPERT OPINION

: Recent studies have focused on the anti-inflammatory effects of omega-3 PUFAs and specialized pro-resolving mediators. High-purity eicosapentaenoic acid (EPA) ethyl ester and EPA/docosahexaenoic acid (DHA) preparations have been developed primarily for the treatment of hypertriglyceridemia. Various trials on the cardiovascular protective effects of omega-3 PUFAs have been reported, but the results have not been consistent. Some issues of the trials have been suggested, such as using low-dose omega-3 PUFAs and not including hypertriglyceridemia in subject selection criteria. REDUCE-IT study that used a high dose of high-purity EPA preparation showed a relative reduction in cardiovascular events, but, the STRENGTH study that used a high dose of EPA/DHA preparation did not support this benefit. This article reviews the roles of omega-3 PUFAs in cardiovascular diseases, including progress in understanding the molecular mechanisms and recent large-scale clinical trials.

Protective activities of distinct omega-3 enriched oils are linked to their ability to upregulate specialized pro-resolving mediators

Clinical studies using a range of omega-3 supplements have yielded conflicting results on their efficacy to control inflammation. Omega-3 fatty acids are substrate for the formation of potent immune-protective mediators, termed as specialized pro-resolving mediators (SPM). Herein, we investigated whether observed differences in the potencies of distinct omega-3 supplements were linked with their ability to upregulate SPM formation. Using lipid mediator profiling we found that four commercially available supplements conferred a unique SPM signature profile to human macrophages, with the overall increases in SPM concentrations being different between the four supplements. These increases in SPM concentrations were linked with an upregulation of macrophage phagocytosis and a decreased uptake of oxidized low-density lipoproteins. Pharmacological inhibition of two key SPM biosynthetic enzymes 5-Lipoxygenase or 15-Lipoxygenase reversed the macrophage-directed actions of each of the omega-3 supplements. Furthermore, administration of the two supplements that most potently upregulated macrophage SPM formation and reprogrammed their responses in vitro, to APOE^-/- mice fed a western diet, increased plasma SPM concentrations and reduced vascular inflammation. Together these findings support the utility of SPM as potential prognostic markers in determining the utility of a given supplement to regulate macrophage responses and inflammation.

High Consumption of Red Meat Is Associated with Excess Mortality Among African-American Women

BACKGROUND

Red meat is a rich source of nutrients but is typically high in saturated fats. Carcinogenic chemicals can be formed during cooking and processing. Little is known about the relation of red meat consumption to mortality in African Americans (AAs), a group with excess mortality and high consumption of red meat relative to whites.

OBJECTIVE

Our objective was to assess the association between red meat consumption and mortality in AA women.

METHODS

The Black Women's Health Study (BWHS) is a prospective cohort study of AA women across the USA who completed health questionnaires at enrollment in 1995 (median age 38 y, median BMI 27.9 kg/m2) and every 2 y thereafter. The analyses included 56,314 women who completed a validated FFQ and were free of cardiovascular disease and cancer at baseline in 1995. Exposures were total red meat, processed red meat, and unprocessed red meat consumption. Outcomes were all-cause and cause-specific mortality. Cox proportional hazards models with control for age, socioeconomic status, lifestyle factors, medical history, and dietary factors were used to estimate HRs with 95% CIs.

RESULTS

During 22 y of follow-up through to 2017, we identified 5054 deaths, which included 1354 cardiovascular deaths and 1801 cancer deaths. The HR for all-cause mortality was 1.47 (95% CI: 1.33, 1.62) for the highest quintile of total red meat consumption relative to the lowest. Each 1 serving/d increase in red meat consumption was associated with a 7% (95% CI: 5%, 9%) increased risk of all-cause mortality. Red meat consumption was also associated with increased cardiovascular mortality, but not with cancer mortality. Results were similar for the consumption of processed and unprocessed red meat.

CONCLUSIONS

Red meat consumption is associated with increased all-cause and cardiovascular mortality among AA women.

Circulating Concentrations of Essential Fatty Acids, Linoleic and α-Linolenic Acid, in US Adults in 2003-2004 and 2011-2012 and the Relation with Risk Factors for Cardiometabolic Disease: An NHANES Analysis

BACKGROUND

The increased use of high-oleic oils to replace trans fat has led to concern about declining intake of PUFA and the potential for essential fatty acid insufficiency or even deficiency.

OBJECTIVES

The aim of this study was to examine circulating concentrations of essential and poorly biosynthesized fatty acids, as biomarkers of dietary intake, in the NHANES data sets prior to (2003-2004 cycle) and following (2011-2012 cycle) legislation to reduce trans fat in the food supply and also to explore the associations between these fatty acids and markers of cardiometabolic health.

METHODS

Fasting circulating concentrations of fatty acids from adults (aged ≥20 y) in the 2003-2004 and 2011-2012 NHANES cycles were used for analysis. Dietary data from one day of both the 2003-2004 and 2011-2012 cycles were used to examine differences in dietary fatty acid intake between these cycles. Regression analyses were used to assess relations between circulating concentrations of fatty acids and cardiometabolic health.

RESULTS

Between 2003-2004 and 2011-2012, circulating concentrations of linoleic acid (LA) increased (1.38%, P = 0.002); no difference in dietary intake was observed. α-Linolenic acid (ALA), measured by dietary intake (0.14 g, P < 0.001) and circulating concentrations (0.23%, P < 0.01), increased from 2003-2004 to 2011-2012. Circulating LA was inversely associated with BMI (in kg/m2; regression coefficient per percentage point change in LA ± SE: -0.22 ± 0.04), waist circumference (-0.62 ± 0.09 cm), systolic blood pressure (-0.38 ± 0.09 mm Hg), triglycerides (-9.92 ± 0.63 mg/dL), glucose (-3.34 ± 0.13 mg/dL), insulin (-0.18 ± 0.05 µU/mL), and HOMA-IR (-0.29 ± 0.05).

CONCLUSIONS

In a nationally representative sample of US adults, no declines in circulating concentrations of essential fatty acids, LA and ALA, were observed between 2003-2004 and 2011-2012, a time when high-oleic oils were increasingly used in the food supply. Higher amounts of circulating LA were correlated with lower risk of cardiometabolic dysfunction, which underscores the importance of monitoring consumption in the United States.

Membrane modulatory effects of omega-3 fatty acids: Analysis of molecular level interactions

Bioactive omega-3 polyunsaturated fatty acids have been shown to reduce the risk of death in patients with cardiovascular disease and alleviate the symptoms of other inflammatory diseases. However, the mechanisms of action of these effects remain unclear. It has been postulated that omega-3 polyunsaturated fatty acids modify cell membranes by incorporation into the membrane and altering the signaling properties of cellular receptors. In this chapter, we explore the effects of omega-3 polyunsaturated fatty acids on cell membrane structure and function. We present a review of the current evidence for the health benefits of these compounds and explore the molecular mechanisms through which omega-3 polyunsaturated fatty acids interact with membrane lipids and modulate bilayer structure. Using computational models of multicomponent phospholipid bilayers, we assess the consequences of incorporation of these fatty acids on membrane lipid packing, water permeation, and membrane structure.

Omega-3 supplementation and cardiovascular disease: formulation-based systematic review and meta-analysis with trial sequential analysis

BACKGROUND

Omega-3 supplements are popular for cardiovascular disease (CVD) prevention. We aimed to assess the association between dose-specific omega-3 supplementation and CVD outcomes.

DESIGN

We included double-blind randomised clinical trials with duration ≥1 year assessing omega-3 supplementation and estimated the relative risk (RR) for all-cause mortality, cardiac death, sudden death, myocardial infarction and stroke. Primary analysis was a stratified random-effects meta-analysis by omega-3 dose in 4 a priori defined categories (<1, 1, 2, ≥3 of 1 g capsules/day). Complementary approaches were trial sequential analysis and sensitivity analyses for triglycerides, prevention setting, intention-to-treat analysis, eicosapentaenoic acid, sample size, statin use, study duration.

RESULTS

Seventeen studies (n=83 617) were included. Omega-3 supplementation as ≤1 capsule/day was not associated with any outcome under study; futility boundaries were crossed for all-cause mortality and cardiac death. For two capsules/day, we observed a statistically significant reduction of cardiac death (n=3, RR 0.55, 95% CI 0.33 to 0.90, I²=0%); for ≥3 capsules/day we observed a statistically significant reduction of cardiac death (n=3, RR 0.82, 95% CI 0.68 to 0.99, I²=0%), sudden death (n=1, RR 0.70, 95% CI 0.51 to 0.97) and stroke (n=2, RR 0.74, 95% CI 0.57 to 0.95, I²=0%).

CONCLUSION

Omega-3 supplementation at <2 1 g capsules/day showed no association with CVD outcomes; this seems unlikely to change from future research. Compared with the robust scientific evidence available for low doses, the evidence for higher doses (2-4 1 g capsules/day) is weak. The emerging postulated benefit from high-dose supplementation needs replication and further evaluation as to the precise formulation and indication.

Fatty acids and cardiometabolic health: a review of studies in Chinese populations

Rapid nutrition transition from plant-based traditional diet to westernized diet has led to dramatically heightening burdens of cardiometabolic diseases in China in past decades. Recently, national surveys reported that poor dietary quality including low marine n-3 fatty acids and high intakes of red meat and processed meat was associated with considerably elevated cardiometabolic deaths. Previous studies mainly from Western population-based cohorts have indicated that not only fat quantity but also quality linked with different cardiometabolic outcomes. Compared with Western peoples, Asian peoples, including Chinese, are known to have different dietary patterns and lifestyle, as well as genetic heterogeneities, which may modify fatty acid metabolism and disease susceptibility in certain degree. To date, there were limited prospective studies investigating the relationships between fatty acids and cardiometabolic disease outcomes in Chinese, and most existing studies were cross-sectional nature and within one or two region(s). Notably, shifting dietary patterns could change not only amount, types, and ratio of fatty acids accounting for overall energy intake, but also their food sources and ratio to other macronutrients. Moreover, large geographic and urban-rural variations in prevalence of cardiometabolic diseases among Chinese may also reflect the effects of socioeconomic development and local diets on health status. Therefore, current review will summarize available literatures with more focus on the Chinese-based studies which may extend current knowledge about the roles of fatty acids in pathogenesis of cardiometabolic diseases for Asian populations and also provide useful information for trans-ethnic comparisons with other populations.

Plasma fatty acids and the risk of vascular disease and mortality outcomes in individuals with type 2 diabetes: results from the ADVANCE study

AIMS/HYPOTHESIS

This biomarker study aimed to quantify the association of essential and other plasma fatty acid biomarkers with macrovascular disease, microvascular disease and death in individuals with type 2 diabetes.

METHODS

A case-cohort study (N = 3576), including 654 macrovascular events, 341 microvascular events and 631 deaths during 5 years of (median) follow-up, was undertaken as a secondary analysis of the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified-Release Controlled Evaluation (ADVANCE) study (full details of the study design and primary endpoints of the ADVANCE trial and its case-cohort have been published previously). This current study considers new data: fatty acids measured from baseline plasma samples by proton NMR analysis. The fatty acids measured were n-3, docosahexaenoic acid (DHA), n-6, linoleic acid, and polyunsaturated, monounsaturated and saturated fatty acids. HRs were modelled per SD higher (percentage) fatty acid. C statistics and continuous net reclassification improvement were used to test the added value of fatty acids compared with traditional cardiovascular risk factors.

RESULTS

After adjustment for traditional cardiovascular risk factors, an inverse association was observed for n-3 fatty acids and DHA with the risk of macrovascular events (HR [95% CI]: 0.87 [0.80, 0.95] and 0.88 [0.81, 0.96], respectively, per 1 SD higher percentage), and for n-3 fatty acids with the risk of death (HR 0.91 [95% CI 0.84, 0.99] per 1 SD higher percentage). Such associations were also evident when investigating absolute levels of fatty acids. There were no statistically significant associations between any fatty acids and microvascular disease after adjustment. However, there was limited improvement in the predictive ability of models when any fatty acid was added.

CONCLUSIONS/INTERPRETATION

Plasma n-3 fatty acids and DHA were found to be inversely associated with macrovascular disease, while n-3 fatty acids were also inversely associated with death. These results support the cardioprotective effects of n-3 fatty acids and DHA and further merit testing the role of high-dose supplementation with n-3 fatty acids in individuals with type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00145925. Graphical abstract.

Dietary treatment to lower cholesterol and triglyceride and reduce cardiovascular risk

PURPOSE OF REVIEW

To provide an update on dietary measures to lower levels of LDL-C and triglyceride and reduce cardiovascular (CVD) outcomes.

RECENT FINDINGS

Fifty-year follow-up in the Seven Countries Study confirmed that cholesterol levels correlate with saturated fat intake and all-cause mortality and age at death. In the PURE study, refined carbohydrate increased CVD risk whereas saturated fat did not despite increasing LDL-C levels; limitations are discussed. Reports on CVD risk with eggs provide conflicting results. Plant-based diets with healthful complex carbohydrates reduced CVD. The REDUCE-IT trial lowered triglyceride 21.6% and reduced CVD events 26.1% with an omega-3 fatty acid, An omega-3 fatty acid index at least 4% with EPA and docosahexaenoic acid prevented coronary plaque progression. A clinician guide to counsel patients on nutrition and heart healthy diets was recently published.

SUMMARY

Based on the evidence, individuals should continue to minimize saturated fats and refined carbohydrates, eliminate trans-fat and increase fruits, vegetables, whole grains, low-fat dairy, and fish or other omega-3 fatty acids. Adhering to a Mediterranean diet is strongly recommended because of lowering CVD and total mortality. High-dose omega-3 fatty acids lower triglyceride, reduce CVD and prevent coronary plaque progression.

The Short Overview on the Relevance of Fatty Acids for Human Cardiovascular Disorders

This review presents existing evidence of the influence of saturated and unsaturated fatty acids on cardiovascular diseases (CVD). Data are discussed regarding the roles of the most relevant fatty acids, such as myristic (C14:0), palmitic (C16:0), stearic (C18:0), palmitoleic (C16:1), oleic (C18:1), linoleic (C18:2), α-linolenic (C18:3, ω-3), γ-linolenic (C18:3, ω-6), arachidonic (C20:4), eicosapentaenoic (C20:5), docosahexaenoic (C22:6), and docosapentaenoic (C22:5) acid. The accumulated knowledge has expanded the understanding of the involvement of fatty acids in metabolic processes, thereby enabling the transition from basic exploratory studies to practical issues of application of these biomolecules to CVD treatment. In the future, these findings are expected to facilitate the interpretation and prognosis of changes in metabolic lipid aberrations in CVD.

Lipoproteins and lipids in cardiovascular disease: from mechanistic insights to therapeutic targeting

With cardiovascular disease being the leading cause of morbidity and mortality worldwide, effective and cost-efficient therapies to reduce cardiovascular risk are highly needed. Lipids and lipoprotein particles crucially contribute to atherosclerosis as underlying pathology of cardiovascular disease and influence inflammatory processes as well as function of leukocytes, vascular and cardiac cells, thereby impacting on vessels and heart. Statins form the first-line therapy with the aim to block cholesterol synthesis, but additional lipid-lowering drugs are sometimes needed to achieve low-density lipoprotein (LDL) cholesterol target values. Furthermore, beyond LDL cholesterol, also other lipid mediators contribute to cardiovascular risk. This review comprehensively discusses low- and high-density lipoprotein cholesterol, lipoprotein (a), triglycerides as well as fatty acids and derivatives in the context of cardiovascular disease, providing mechanistic insights into their role in pathological processes impacting on cardiovascular disease. Also, an overview of applied as well as emerging therapeutic strategies to reduce lipid-induced cardiovascular burden is provided.

Dietary n-3 polyunsaturated fatty acids, fish intake and healthy ageing

BACKGROUND

Seafood consumption and dietary intake of n-3 polyunsaturated fatty acids (PUFA) protect from cardiovascular disease, muscle wasting and mortality; however, their role in delaying unhealthy ageing is uncertain.

METHODS

A prospective cohort study with 1592 community-dwelling individuals aged ≥60 years recruited in 2008-2010, and followed through 2015. Intake of seafood and n-3 PUFA [eicosapentanoic acid (EPA) and docosahexanoic acid (DHA)] was estimated using a validated diet history and food composition tables. Unhealthy ageing was assessed across the domains of physical and cognitive function, mental health, morbidity, self-rated health and vitality.

RESULTS

Higher blue fish consumption was negatively associated with unhealthy ageing in 2015 [multivariate ß (95% confidence interval) per interquartile range (IQR) increase of fish: -0.49 (-0.90; -0.08)] and, specifically, was associated with lower accumulation of functional impairments [-1.00 (-1.71; -0.28)] and morbidities [-0.30 (-0.73; 0.13)]. Individuals with high intakes of EPA (≥0.47 g/day) and DHA (≥0.89 g/day) presented the highest reductions in age-related deficits accumulation: -1.61 (-3.01; -0.22) and -1.34 (-2.76; 0.08), respectively. Intake of EPA and DHA were negatively associated with the accumulation of functional deficits [results per IQR increase: -0.79 (-1.64; -0.06) and -0.84 (-1.67; -0.01), respectively] and morbidities [-0.60 (-1.10; -1.11) and -0.60 (-1.09; -0.11)]. No associations were observed between n-3 PUFA and self-rated or mental health, or between white fish and unhealthy ageing.

CONCLUSIONS

In this cohort of Spanish individuals with elevated intake of fish and a high adherence to the Mediterranean diet, consumption of blue fish and n-3 PUFA had a prospective protective association with deficits accumulation.

Differential Effects of Roux-en-Y Gastric Bypass Surgery and Laparoscopic Sleeve Gastrectomy on Fatty Acid Levels

BACKGROUND

Bariatric surgery is associated with improved cardiovascular outcomes and also affects lipid levels, but few studies have compared the effects of Roux-en-Y gastric bypass (RYGB) surgery with those of laparoscopic sleeve gastrectomy (LSG) on serum fatty acid levels. The present study compares the effects of RYGB and LSG surgeries on serum fatty acid levels.

METHODS

The study participants were women who were undergoing either RYGB or LSG and body mass index (BMI)-matched controls. Fasting blood samples to measure glucose, insulin, and fatty acids were drawn at baseline and at 6 and 18 months from baseline.

RESULTS

Serum fatty acid data were available for 57 participants at baseline, of whom 56 had data at 6 months and 41 had data at 18 months from baseline. Compared with baseline, serum non-esterified fatty acids (NEFAs) levels were significantly higher at 6 and 18 months in the LSG group compared with the RYGB group. In the RYGB group, 2 saturated fatty acids (SFAs), 2 monounsaturated fatty acids (MUFAs), and 1 polyunsaturated fatty acid (PUFA) were significantly decreased after surgery, compared with those of the LSG group.

CONCLUSIONS

A significant increase in NEFAs was seen after LSG, compared with RYGB. Compared with the LSG group, several serum fatty acids were significantly reduced after RYGB.

TRIAL REGISTRATION

NCT01228097.

Association of Arachidonic Acid-derived Lipid Mediators with Subsequent Onset of Acute Myocardial Infarction in Patients with Coronary Artery Disease

Polyunsaturated fatty acids (PUFAs) have been suggested for cardiovascular health. This study was conducted to investigate the prognostic impacts of the PUFA metabolites, oxylipins, on clinical outcomes in coronary artery disease (CAD). A total of 2,239 patients with stable CAD were prospectively enrolled and followed up regularly. Among them, twenty-five consecutive patients with new onset of acute myocardial infarction (AMI) within 2-year follow-up were studied. Another 50 gender- and age-matched patients without clinical cardiovascular events for more than 2 years were studied for control. Baseline levels of specific arachidonic acid metabolites were significantly higher in patients with subsequent AMI than in the controls. In Kaplan-Meier analysis, the incidence of future AMI was more frequently seen in patients with higher baseline levels of 8-hydroxyeicosatetraenoic acid (HETE), 9-HETE, 11-HETE, 12-HETE, 15-HETE, 19-HETE, 20-HETE, 5,6-epoxyeicosatrienoic acid (EET), 8,9-EET, 11,12-EET, or 14-15-EET when compared to their counterparts (all the P < 0.01). Further, serum levels of these specific HETEs, except for 11,12-EET, were positively correlated to the levels of some inflammatory and cardiac biomarker such as tumor necrosis factor-α and N-terminal pro B-type natriuretic peptide. Accordingly, serum specific oxylipins levels are increased and associated with the consequent onset of AMI, suggesting their potential role for secondary prevention in clinically stable CAD.

Associations of fat and carbohydrate intake with cardiovascular disease and mortality: prospective cohort study of UK Biobank participants

OBJECTIVE

To investigate the association of macronutrient intake with all cause mortality and cardiovascular disease (CVD), and the implications for dietary advice.

DESIGN

Prospective population based study.

SETTING

UK Biobank.

PARTICIPANTS

195 658 of the 502 536 participants in UK Biobank completed at least one dietary questionnaire and were included in the analyses. Diet was assessed using Oxford WebQ, a web based 24 hour recall questionnaire, and nutrient intakes were estimated using standard methodology. Cox proportional models with penalised cubic splines were used to study non-linear associations.

MAIN OUTCOME MEASURES

All cause mortality and incidence of CVD.

RESULTS

4780 (2.4%) participants died over a mean 10.6 (range 9.4-13.9) years of follow-up, and 948 (0.5%) and 9776 (5.0%) experienced fatal and non-fatal CVD events, respectively, over a mean 9.7 (range 8.5-13.0) years of follow-up. Non-linear associations were found for many macronutrients. Carbohydrate intake showed a non-linear association with mortality; no association at 20-50% of total energy intake but a positive association at 50-70% of energy intake (3.14 v 2.75 per 1000 person years, average hazard ratio 1.14, 95% confidence interval 1.03 to 1.28 (60-70% v 50% of energy)). A similar pattern was observed for sugar but not for starch or fibre. A higher intake of monounsaturated fat (2.94 v 3.50 per 1000 person years, average hazard ratio 0.58, 0.51 to 0.66 (20-25% v 5% of energy)) and lower intake of polyunsaturated fat (2.66 v 3.04 per 1000 person years, 0.78, 0.75 to 0.81 (5-7% v 12% of energy)) and saturated fat (2.66 v 3.59 per 1000 person years, 0.67, 0.62 to 0.73 (5-10% v 20% of energy)) were associated with a lower risk of mortality. A dietary risk matrix was developed to illustrate how dietary advice can be given based on current intake.

CONCLUSION

Many associations between macronutrient intake and health outcomes are non-linear. Thus dietary advice could be tailored to current intake. Dietary guidelines on macronutrients (eg, carbohydrate) should also take account of differential associations of its components (eg, sugar and starch).

Prevention of Cardiovascular Events with Omega-3 Polyunsaturated Fatty Acids and the Mechanism Involved

An epidemiological study of Greenlandic Inuit suggested that fish oil, or omega-3 polyunsaturated fatty acids (PUFA), was important in preventing atherosclerotic disease. After this landmark study, many large-scale epidemiological studies and meta-analyses have examined the health benefits of omega-3 PUFA as part of a fatty acid-rich diet to demonstrate its beneficial roles in the prevention of cardiovascular diseases. Recent research has also focused attention on the anti-inflammatory effects of omega-3 PUFA and on specialized pro-resolving mediators. Findings of these studies have led to the development of omega-3 PUFA preparations for the treatment of dyslipidemia, including a highly purified eicosapentaenoic acid (EPA)-ethyl ester product (Epadel®) in Japan and an EPA/docosahexaenoic acid (DHA) preparation (Lotriga®) in the United States and Europe. Although various large-scale clinical trials on the cardiovascular preventive effect of omega-3 PUFA were conducted and reported, the results were not always consistent. The issues of not targeting subjects with hypertriglyceridemia and using low dose of omega-3 PUFA have been suggested to contribute to the failure of demonstrating the preventive effect of omega-3 PUFA in these clinical trials. Taking into account the above issues, the REDUCE-IT trial evaluated a highly purified EPA preparation at a high dose of 4 g/day in patients with hypertriglyceridemia and high cardiovascular risk, and demonstrated an extraordinary outcome of 25% relative reduction in cardiovascular events. This article reviews studies on omega-3 fatty acids during the last 50 years, including the progress in elucidating molecular mechanisms and recent large-scale clinical studies.

Association between erythrocyte membrane n-3 and n-6 polyunsaturated fatty acids and carotid atherosclerosis: A prospective study

BACKGROUND AND AIMS

The relationship of polyunsaturated fatty acids (PUFAs) with cardiovascular risk is still controversial. We aimed to determine whether erythrocyte n-3 and n-6 PUFAs are related to the risk of carotid atherosclerosis.

METHODS

From 2008 to 2019, baseline erythrocyte n-3 and n-6 PUFAs were determined in a cohort of 4040 Chinese adults (40-75 ys). The intima-media thickness (IMT) at the common carotid artery (CCA) and bifurcation of the carotid artery (BIF) and carotid plaque were assessed using ultrasonography at baseline and every 3 years.

RESULTS

During a median follow-up of 8.8 years, we identified the following newly diagnosed cases: 535 cases of CCAIMT thickening, 654 cases of BIFIMT thickening, and 850 cases of carotid plaque. Higher erythrocyte docosahexaenoic acid (DHA) and arachidonic acid (ARA) and lower gamma-linolenic acid (GLA) were associated with decreased risks of BIFIMT thickening. N-3 eicosatrienoic acid (ETrA), docosapentaenoic acid (DPA), and n-6 dodecylthioacetic acid (DTA) presented a significant beneficial association with carotid IMT thickening in the short-term (2.8 y) follow-up (all p trend <0.02), although the association was attenuated in the relatively long-term (8.8 y) follow-up. In addition, carotid plaque risk was found to be inversely associated with ETrA and DHA but positively associated with alpha-linolenic acid (ALA). N-6 linolenic acid (LA) and eicosadienoic acid (EDA) were not significantly associated with carotid atherosclerosis risk.

CONCLUSIONS

Higher erythrocyte very-long-chain n-3 and n-6 PUFAs (especially DHA and ARA) and lower erythrocyte GLA are associated with lower carotid atherosclerosis risk, suggesting potential cardioprotective roles of very-long-chain PUFAs.

Associations between omega-6 polyunsaturated fatty acids, hyperinsulinemia and incident diabetes by race/ethnicity: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND & AIMS

Omega-6 polyunsaturated fatty acids (PUFAs) have been shown to relate to insulin resistance and type 2 diabetes (T2D), but influence of race/ethnicity has not been investigated. The aim of this study was to determine whether omega-6 PUFAs, and estimated desaturase enzyme activity, are associated with fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and incident T2D, and whether associations differ by race/ethnicity.

METHODS

This study was conducted in the Multi-Ethnic Study of Atherosclerosis (MESA) (N = 6282). Associations between baseline plasma phospholipid fatty acids (LA, Linoleic Acid; GLA, γ-linoleic acid; DGLA, Dihomo-γ-linolenic acid; AA, arachidonic acid; D5D, delta-5 desaturase; D6D, delta-6 desaturase), fasting glucose, insulin, and HOMA-IR [(fasting insulin - fasting glucose)/22.5] were evaluated using linear regression. Associations between omega-6 PUFAs (N = 5508 after excluding diabetics at baseline) and T2D incidence were assessed using Cox proportional hazards regression. Analyses were replicated/stratified by race/ethnicity (White, Black, Chinese, Hispanic) and tests for interaction were assessed by inclusion of a cross-product term in models.

RESULTS

In fully adjusted models, insulin and HOMA-IR were positively associated with LA (insulin: 0.213 per SD, p = 0.01; HOMA-IR: 0.252 per SD, p < 0.001), GLA (insulin: 0.010 per SD, p < 0.001; HOMA-IR: 0.006 per SD, p < 0.001), DGLA (insulin: 0.279 per SD, p < 0.001; HOMA-IR: 0.175 per SD, p < 0.001) and D6D activity (insulin: 0.001 per SD, p < 0.001; HOMA-IR: 0.006 per SD, p < 0.001), and inversely associated with AA (insulin -0.272 per SD, p < 0.001; HOMA-IR: -0.125 per SD, p = 0.03) and D5D activity (insulin: -0.530 per SD, p < 0.001; HOMA-IR: -0.322 per SD, p < 0.001), while weak or no associations were observed with fasting glucose, and associations appeared to differ by race/ethnicity. After accounting for HOMA-IR at baseline, LA was inversely (HR: 0.87, p = 0.003) and DGLA (HR: 1.17, p < 0.001) and AA (HR: 1.15, p = 0.001) were positively associated with T2D in the overall population, but associations were attenuated or no longer present when stratified by race/ethnicity (P-interaction >0.05).

CONCLUSIONS

Results confirm previous reports that omega-6 PUFAs are associated with hyperinsulinemia. Findings suggest omega-6 PUFAs are more likely markers of hyperinsulinemia rather than a protective/risk factor for T2D and indicate racial/ethnic differences in associations, but further research is needed to confirm findings.

Dietary linoleic acid and human health: Focus on cardiovascular and cardiometabolic effects

This narrative review aims to discuss the more relevant evidence on the role of linoleic acid (LA), a n-6 essential fatty acid that constitutes the predominant proportion of dietary polyunsaturated fatty acids (PUFA), in cardiovascular health. Although LA can be metabolized into Arachidonic Acid (AA), a 20 carbon PUFA which is the precursor of eicosanoids, including some with proinflammatory or prothrombotic-vasoconstrictor action, the large majority of experimental and clinical studies have assessed the potential benefit of increasing dietary intake of LA. Overall, data from clinical studies and meta-analyses suggest an association between high dietary intakes or tissue levels of n-6 PUFA, and specifically LA, and the improvement of cardiovascular risk (mainly of the plasma lipid profile), as well as long-term glycaemic control and insulin resistance. Most observational data show that elevated/increased dietary intake or tissue levels of LA is associated with a reduced incidence of cardiovascular diseases (mainly coronary artery diseases) and of new onset metabolic syndrome or type 2 diabetes. The effects of LA (or n-6 PUFA) in other physio-pathological areas are less clear. High quality clinical trials are needed to assess both the actual amplitude and the underlying mechanisms of the health effects related to dietary intake of this essential fatty acid.