Plasma n-6 and n-3 polyunsaturated fatty acids as biomarkers of their dietary intakes: a cross-sectional study within a cohort of middle-aged French men and women

Fish oil supplement use modifies the relationship between dietary oily fish intake and plasma n-3 PUFA levels: an analysis of the UK Biobank

Observational evidence linking dietary n-3 PUFA intake and health outcomes is limited by a lack of robust validation of dietary intake using blood n-3 PUFA levels and potential confounding by fish oil supplement (FOS) use. We investigated the relationship between oily fish intake, FOS use and plasma n-3 PUFA levels in 121 650 UK Biobank (UKBB) participants. Ordinal logistic regression models, adjusted for clinical and lifestyle factors, were used to quantify the contribution of dietary oily fish intake and FOS use to plasma n-3 PUFA levels (measured by NMR spectroscopy). Oily fish intake and FOS use were reported by 38 % and 31 % of participants, respectively. Increasing oily fish intake was associated with a higher likelihood of FOS use (P < 0·001). Oily fish intake ≥ twice a week was the strongest predictor of high total n-3 PUFA (OR 6·7 (95 % CI 6·3, 7·1)) and DHA levels (6·6 (6·3, 7·1). FOS use was an independent predictor of high plasma n-3 PUFA levels (2·0 (2·0, 2·1)) with a similar OR to that associated with eating oily fish < once a week (1·9 (1·8, 2·0)). FOS use was associated with plasma n-3 PUFA levels that were similar to individuals in the next highest oily fish intake category. In conclusion, FOS use is more common in frequent fish consumers and modifies the relationship between oily fish intake and plasma n-3 PUFA levels in UKBB participants. If unaccounted for, FOS use may confound the relationship between dietary n-3 PUFA intake, blood levels of n-3 PUFAs and health outcomes.

Dietary habits and plasma lipid concentrations in a general Japanese population

INTRODUCTION

Accumulating data on the associations between food consumption and lipid composition in the body is essential for understanding the effects of dietary habits on health.

OBJECTIVES

As part of omics research in the Tohoku Medical Megabank Community-Based Cohort Study, this study sought to reveal the dietary impact on plasma lipid concentration in a Japanese population.

METHODS

We conducted a correlation analysis of food consumption and plasma lipid concentrations measured using mass spectrometry, for 4032 participants in Miyagi Prefecture, Japan.

RESULTS

Our analysis revealed 83 marked correlations between six food categories and the concentrations of plasma lipids in nine subclasses. Previously reported associations, including those between seafood consumption and omega-3 fatty acids, were validated, while those between dairy product consumption and odd-carbon-number fatty acids (odd-FAs) were validated for the first time in an Asian population. Further analysis suggested that dairy product consumption is associated with odd-FAs via sphingomyelin (SM), which suggests that SM is a carrier of odd-FAs. These results are important for understanding odd-FA metabolism with regards to dairy product consumption.

CONCLUSION

This study provides insight into the dietary impact on plasma lipid concentration in a Japanese population.

Association between serum polyunsaturated fatty acids and bone mineral density in US adults: NHANES 2011-2014

Objective

The purpose of this study was to investigate the association between serum polyunsaturated fatty acids (PUFAs) and bone mineral density (BMD).

Methods

We performed a cross-sectional study based on data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014. The weighted multiple linear regression model was utilized to determine the association between serum PUFAs and BMD. Further smoothed curve fitting and threshold effect analysis were conducted. Finally, we performed a subgroup analysis.

Results

In total, 1979 participants aged 20-59 years were enrolled. After adjusting for all covariates, we found that serum docosapentaenoic acid (DPA) was positively associated with head BMD (β = 0.0015, 95% Cl: 0.0004, 0.0026, P = 0.008296) and lumbar spine BMD (β = 0.0005, 95% Cl: 0.0000, 0.0010, P = 0.036093), and serum eicosadienoic acid (EDA) was negatively associated with thoracic spine BMD (β = -0.0008, 95% Cl: -0.0016, -0.0000, P = 0.045355). Smoothed curve fitting revealed a nonlinear positive association between serum DPA and lumbar spine BMD. Threshold effect analysis indicated that the threshold of serum DPA was 81.4 µmol/L. Subgroup analysis revealed a positive correlation between serum DPA and head BMD in the subgroup aged 50-59 years (β = 0.0025, 95% Cl: 0.0002, 0.0049, P = 0.035249) and females (β = 0.0026, 95% Cl: 0.0008, 0.0044, P = 0.005005). There was a positive relationship between serum DPA and lumbar spine BMD in females (β = 0.0008, 95% Cl: 0.0001, 0.0015, P = 0.017900) and a negative association between serum EDA and thoracic spine BMD in the subgroup aged 30-39 years (β = -0.0016, 95% Cl: -0.0031, -0.0001, P = 0.041331), males (β = -0.0012, 95% Cl: -0.0023, -0.0001, P = 0.039364) and other races (β = -0.0021, 95% Cl: -0.0037, -0.0006, P = 0.008059).

Conclusion

This study demonstrated a linear positive relationship between serum DPA and head BMD, a nonlinear positive association between serum DPA and lumbar spine BMD, and a linear negative correlation between serum EDA and thoracic spine BMD in US adults.

Dietary biomarkers and food records indicate compliance to study diets in the ADIRA (Anti-inflammatory Diet In Rheumatoid Arthritis) trial

Background

In the ADIRA (Anti-inflammatory Diet In Rheumatoid arthritis) trial, compliance to the study diets has previously been described primarily with a score based on reported intake of trial foods from telephone interviews. The aim of this study was to evaluate compliance using objective dietary biomarkers for whole grain, fruit and vegetables, margarine and oil, seafood and overall fat quality, as well as reported intake from food records of key components of the study diets.

Methods

Fifty patients with rheumatoid arthritis were randomized to begin with the intervention diet (rich in whole grain, fruit and vegetables, margarine/oil and seafood) or the control diet (rich in meat and high-fat dairy) for 10 weeks, followed by a ~ 4 months wash-out period, and then switched diet. Compliance was evaluated using plasma alkylresorcinols (AR) as biomarkers for intake of whole grain wheat and rye, serum carotenoids for fruit and vegetables, plasma linoleic acid (LA, 18:2 n-6) and -α-linolenic acid (18:3, n-3) for margarine and cooking oil, plasma eicosapentaenoic acid (EPA, 20:5 n-3), -docosahexaenoic acid (DHA 22:6, n-3) and -docosapentaenoic acid (22:5 n-3) for seafood, and plasma fatty acid pattern for the overall dietary fat quality. Reported intake of whole grain, fruit, berries and vegetables, seafood, red meat, and fat quality was extracted from 3-d food records.

Results

Plasma AR C21:0 and C23:0, LA, EPA, and DHA were higher while total serum carotenoids were lower after the intervention diet period compared to the control diet period (AR and carotenoids: p = <0.05, fatty acids: p = <0.001). Reported intake of whole grain, fruit, berries and vegetables, and seafood was higher and reported intake of red meat was lower during the intervention diet period compared to the control diet period (p = <0.001). Plasma- and reported fatty acid pattern differed as intended between the diet periods.

Conclusion

This study indicates that the participants in the ADIRA trial were compliant to the study diets regarding intake of whole grain, cooking fat, seafood, and red meat, and the intended overall dietary fat quality. Compliance to instructions on fruit- and vegetable intake remains uncertain.

Clinical trial registration

https://clinicaltrials.gov/ct2/show/NCT02941055?term=NCT02941055&draw=2&rank=1, NCT02941055.

Validation of an omega-3 substrate challenge absorption test as an indicator of global fat lipolysis

INTRODUCTION

The coefficient of fat absorption (CFA) quantifies fat that remains in stool after digestion and is not a direct measure of lipolysis. CFA has been used to assess treatment of pancreatic insufficiency but does not correlate with pancreatic enzyme replacement therapy dose. We explored use of an omega-3 substrate absorption challenge test as a sensitive test of lipolysis and absorption.

METHODS

We studied a novel microbially-derived lipase (SNSP003) employing an established surgical model commonly used to study the uptake of macronutrients, the exocrine pancreatic insufficient pig. Pigs were fed a high-fat diet and given a standardized omega-3 substrate challenge to test the effect of lipolysis on its absorption. Blood was drawn at 0, 1, 2, 4, 6, 8, 12, and 24 hours following the substrate challenge and was analyzed for omega-3 and total fat levels (c14:c24). SNSP003 was also compard to porcine pancrelipase.

RESULTS

The absorption of omega-3 fats was significantly increased following administration of 40, 80 and 120 mg SNSP003 lipase by 51% (p = 0.02), 89%, (p = 0.001) and 64% (p = 0.01), respectively, compared to that observed when no lipase was administered to the pigs, with Tmax at 4 hours. The two highest SNSP003 doses were compared to porcine pancrelipase and no significant differences were observed. Both doses increased plasma total fatty acids (141% for the 80 mg dose (p = 0.001) and 133% for the 120 mg dose (p = 0.006), compared to no lipase) and no significant differences were observed between the SNSP003 lipase doses and porcine pancrelipase.

CONCLUSION

The omega-3 substrate absorption challenge test differentiates among different doses of a novel microbially-derived lipase and correlates with global fat lipolysis and absorption in exocrine pancreatic insufficient pigs. No significant differences were observed between the two highest novel lipase doses and porcine pancrelipase. Studies in humans should be designed to support the evidence presented here that suggests the omega-3 substrate absorption challenge test has advantages over the coefficient of fat absorption test to study lipase activity.

Relationship between dietary intake and erythrocyte PUFA in adolescents from a Western Australian cohort

BACKGROUND

Population-based studies show that the intake of omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFA) are associated with a range of health conditions. Therefore, the reliability of food frequency questionnaires (FFQ) as rapid and easily accessible screening tools for PUFA intake deserve investigation.

OBJECTIVE

We aimed to assess the relationship between erythrocyte fatty acids and fatty acid intake collected using the Commonwealth Scientific and Industrial Research Organisation (CSIRO) food frequency questionnaire in an adolescent cohort.

DESIGN

A cross-sectional study using data from 1155 young adolescents participating in the 14-year follow-up of the Raine Study. Bland-Altman plots were used to determine the agreement between dietary intake and erythrocyte levels of each fatty acid.

RESULTS

The main dietary source of n-3 long-chain (LC) PUFA was 'fresh fish' (53% of total n-3 LC-PUFA). Docosahexaenoic acid (DHA) showed the strongest correlation between erythrocyte and diet assessment (r = 0.274; p < 0.001), whilst linoleic acid (LA) (r = 0.103; p < 0.001) and arachidonic acid (AA) (r = -0.06; p = 0.042) showed weaker correlations, with limits of agreement relatively narrow. Bland-Altman plots showed a dose-dependent bias between the FFQ fatty acid data and corresponding erythrocyte data.

CONCLUSIONS

For the major n-3 and n-6 PUFA, dietary intakes derived from the FFQ showed weaker correlations and poorer agreement with erythrocyte levels, and the deviation between the two increased with higher intake levels.

Circulating plasma phospholipid fatty acid levels as a biomarker of habitual dietary fat intake: The INTERMAP/INTERLIPID Study

BACKGROUND

Accurate assessment of fat intake is essential to examine relationships between diet and disease risk. However, estimating individual intakes of fat quantity by dietary assessment is difficult.

OBJECTIVE

We assessed the association of plasma phospholipid fatty acid levels with dietary intake of fatty acids in the INTERMAP/INTERLIPID study, conducted with a standardized protocol.

METHODS

The study participants were 1339 men and women ages 40-59 years from five Japanese populations one from Hawaii; four from Japan. Fatty acid intake was estimated from four standardized 24-hour dietary recalls. Plasma phospholipid fatty acid composition was analyzed by gas chromatography. We illustrated the relationship between intake and circulating fatty acid levels using Spearman's rank-correlation coefficients, mean, and median values.

RESULTS

Spearman's rank-correlation coefficients between intake (g/d) and circulating fatty acid levels (µg/ml) were -0.03 to 0.21 for saturated fatty acids and monounsaturated fatty acids and -0.04 to 0.32 for trans fatty acids. The coefficients for essential n-3 and n-6 fatty acids were moderate to high, especially for eicosapentaenoic acid (EPA), 0.60; docosahexaenoic acid (DHA), 0.41; and EPA+DHA, 0.51. The circulating levels and intake of marine-derived n-3 fatty acids showed a linear association, at least for the intake of EPA+DHA up to 2.1 g/d.

CONCLUSION

We observed high correlation between intake and circulating levels of marine-derived n-3 fatty acids in participants from Japanese and Japanese-American populations with high and low fish intake. Plasma phospholipid marine-derived n-3 fatty acid measurements are a simple and reliable biomarker for assessing dietary intake.

Impact of the Mediterranean Dietary pattern on n-3 fatty acid tissue levels-A systematic review

INTRODUCTION

The Mediterranean Diet (MedDiet) is described as a plant-based dietary pattern with adherence associated with reductions in chronic disease risk and longevity. Although the nutrient profile is diverse and complex, the MedDiet is often described as a rich source of n-3 polyunsaturated fatty acids (PUFA) derived from fish, seafood and nuts. However, whether MedDiet adherence results in appreciable increases in tissue levels of n-3 PUFAs is yet to be systematically investigated. This systematic review synthesized the literature to determine the impact of the MedDiet on n-3 PUFA tissue levels.

MATERIALS AND METHODS

Medline, Embase, Amed, and CINAHL databases were searched for studies reporting on adherence to a MedDiet and tissue levels of n-3 PUFAs. PROSPERO registration number is CRD 42020162114.

RESULTS

Twenty-two studies were included. Seven were observational studies and 15 were randomised controlled trials (RCTs). All observational studies reported a positive relationship between adherence and higher tissue n-3 PUFA levels. Two-thirds (10/15) of RCTs reported significant increases in n-3 PUFA concentrations.

DISCUSSION

MedDiet adherence is associated with higher tissue levels of n-3 PUFA. However, we report heterogeneity in the description across all MedDiet interventions.

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.

The relationship between dietary intakes and plasma concentrations of PUFA in school-age children from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort

An adequate intake of PUFA plays a vital role in human health. Therefore, it is important to assess PUFA intakes in different populations and validate them with biomarkers, but only a few small studies are in paediatric populations. We calculated the dietary intake of PUFA and their main food sources in children and assessed associations between PUFA intakes and plasma proportions. Dietary intakes of 7-year-old children (n 8242) enrolled in the Avon Longitudinal Study of Parents and Children were calculated from the parental-completed FFQ. Plasma PUFA were measured in 5571 children 8 months later, and 4380 children had complete dietary and plasma data. The association between dietary and plasma PUFA proportions was estimated using Spearman's correlation coefficients, quintile cross-classification and Cohen's κ coefficients. Mean total PUFA intake was 13·2 g/d (sd 4·2), contributing 6·5 % of total energy intake; n-6 PUFA contributed 5·2 % and n-3 PUFA 0·7 %. The n-6:n-3 ratio was 7·9:1. Mean intakes of EPA and DHA were 35·7 mg/d and 49·7 mg/d, respectively. Most n-3 and n-6 PUFA intakes were weakly correlated with their respective plasma lipids (0·07 ≤ r ≤ 0·16, P < 0·001). The correlation between dietary and plasma DHA was stronger though (r = 0·34, P < 0·001), supported by a modest level of agreement between quintiles (k = 0·32). The results indicate that the FFQ was able to reasonably rank the long-chain (LC) PUFA, DHA, in this paediatric population. Public health initiatives need to address the suboptimal ratio of n-6:n-3 PUFA and very low n-3 LC-PUFA intakes in school-age children in the UK.

Plasma Fatty Acids and Quantitative Ultrasound, DXA and pQCT Derived Parameters in Postmenopausal Spanish Women

Different factors may contribute to the development of osteopenia or osteoporosis. Fatty acids are key nutrients for health, and a number of studies have reported an association between bone mineral density (BMD) and fatty acid intake. We aimed to investigate the relationships between serum levels of different fatty acids and bone parameters determined by quantitative bone ultrasound (QUS), peripheral quantitative computed tomography (pQCT), and dual-energy X-ray absorptiometry (DXA) in a sample of Spanish postmenopausal women. We enrolled a total of 301 postmenopausal women (median age 59 years; interquartile range (IQR) 7) in this study. All participants underwent full densitometric screening, including calcaneal quantitative ultrasound (QUS), peripheral quantitative computed tomography (pQCT), and dual-energy X-ray absorptiometry (DXA), as well as plasma fatty acid measurement. After adjustment for potential confounders, plasma n-3 polyunsaturated fatty acid (PUFA) levels correlated with BMD in the spine (r = 0.150; p = 0.014) and femoral neck (r = 0.143; p = 0.019). By multiple linear regression, an independent statistically significant positive relationship was observed between BMD in the spine and BMI (β = 0.288; p = 0.001) as well as total plasma n-3 PUFAs (β = 0.155; p = 0.009). The plasma n-3 PUFA level was also a significant and positive predictor of BMD at the femoral neck (β = 0.146; p = 0.009). Independent risk factors for low BMD (T-score ≤ 1) were determined by logistic regression analysis, and a relatively high level of plasma n-3 PUFAs (OR = 0.751; 95% CI 0.587-0.960, p = 0.022) was identified as a protective factor against low bone mass. In this single-center sample of Spanish postmenopausal women, we reported a significant positive and statistically independent association between BMD and plasma levels of n-3 PUFAs.

Fingertip Whole Blood as an Indicator of Omega-3 Long-Chain Polyunsaturated Fatty Acid Changes during Dose-Response Supplementation in Women: Comparison with Plasma and Erythrocyte Fatty Acids

The sensitivity of fingertip whole blood to reflect habitual dietary and dose-dependent supplemental omega-3 long-chain polyunsaturated fatty acid (n-3 LCPUFA) intake in premenopausal women was compared to that of venous erythrocytes and plasma fatty acids. Samples were obtained from women in a randomised, double-blind, placebo-controlled trial in which premenopausal women (n = 53) were supplemented with DHA-rich tuna oil capsules and/or placebo (Sunola oil) capsules (6 capsules per day) for 8 weeks to achieve doses of either 0, 0.35, 0.7 or 1.05 g/day n-3 LCPUFA. All blood biomarkers were very similar in their ability to reflect dietary n-3 LCPUFA intake (r = 0.38–0.46 for EPA and DHA intake), and in their dose-dependent increases in n-3 LCPUFA levels after supplementation (R² = 0.41–0.51 for dose effect on biomarker EPA and DHA levels (mol %)). Fingertip whole blood is an effective alternative to erythrocytes and plasma as a biomarker n-3 LCPUFA intake in premenopausal women.

The pre-clinical phase of rheumatoid arthritis: From risk factors to prevention of arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease considered as a multistep process spanning from the interaction of genetic (e.g., shared epitope or non-HLA loci), environmental and behavioral risk factors (e.g., smoking) leading to breaking immune tolerance and autoimmune processes such as the production of autoantibodies (e.g., antibodies against citrullinated proteins ACPA or rheumatoid factors, RF), development of the first symptoms without clinical arthritis, and, finally, the manifestation of arthritis. Despite the typical joint involvement in established RA, the pathogenesis of the disease likely begins far from joint structures: in the lungs or periodontium in association with citrullination, intestinal microbiome, or adipose tissue, which supports normal findings in synovial tissue in ACPA+ patients with arthralgia. The presence of ACPA is detectable even years before the first manifestation of RA. The pre-clinical phase of RA is the period preceding clinically apparent RA with ACPA contributing to the symptoms without subclinical inflammation. While the combination of ACPA and RF increases the risk of progression to RA by up to 10 times, increasing numbers of novel autoantibodies are to be investigated to contribute to the increased risk and pathogenesis of RA. With growing knowledge about the course of RA, new aspiration emerges to cure and even prevent RA, shifting the "window of opportunity" to the pre-clinical phases of RA. The clinical definition of individuals at risk of developing RA (clinically suspect arthralgia, CSA) makes it possible to unify these at-risk individuals' clinical characteristics for "preventive" treatment in ongoing clinical trials using mostly biological or conventional synthetic disease-modifying drugs. However, the combination of symptoms, laboratory, and imaging biomarkers may be the best approach to select the correct target at-risk population. The current review aims to explore different phases of RA and discuss the potential of (non)pharmacological intervention aiming to prevent RA.

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.

Genome-Wide Association Study for Serum Omega-3 and Omega-6 Polyunsaturated Fatty Acids: Exploratory Analysis of the Sex-Specific Effects and Dietary Modulation in Mediterranean Subjects with Metabolic Syndrome

Many early studies presented beneficial effects of polyunsaturated fatty acids (PUFA) on cardiovascular risk factors and disease. However, results from recent meta-analyses indicate that this effect would be very low or nil. One of the factors that may contribute to the inconsistency of the results is that, in most studies, genetic factors have not been taken into consideration. It is known that fatty acid desaturase (FADS) gene cluster in chromosome 11 is a very important determinant of plasma PUFA, and that the prevalence of the single nucleotide polymorphisms (SNPs) varies greatly between populations and may constitute a bias in meta-analyses. Previous genome-wide association studies (GWAS) have been carried out in other populations and none of them have investigated sex and Mediterranean dietary pattern interactions at the genome-wide level. Our aims were to undertake a GWAS to discover the genes most associated with serum PUFA concentrations (omega-3, omega-6, and some fatty acids) in a scarcely studied Mediterranean population with metabolic syndrome, and to explore sex and adherence to Mediterranean diet (MedDiet) interactions at the genome-wide level. Serum PUFA were determined by NMR spectroscopy. We found strong robust associations between various SNPs in the FADS cluster and omega-3 concentrations (top-ranked in the adjusted model: FADS1-rs174547, p = 3.34 × 10-14; FADS1-rs174550, p = 5.35 × 10-14; FADS2-rs1535, p = 5.85 × 10-14; FADS1-rs174546, p = 6.72 × 10-14; FADS2-rs174546, p = 9.75 × 10-14; FADS2- rs174576, p = 1.17 × 10-13; FADS2-rs174577, p = 1.12 × 10-12, among others). We also detected a genome-wide significant association with other genes in chromosome 11: MYRF (myelin regulatory factor)-rs174535, p = 1.49 × 10-12; TMEM258 (transmembrane protein 258)-rs102275, p = 2.43 × 10-12; FEN1 (flap structure-specific endonuclease 1)-rs174538, p = 1.96 × 10-11). Similar genome-wide statistically significant results were found for docosahexaenoic fatty acid (DHA). However, no such associations were detected for omega-6 PUFAs or linoleic acid (LA). For total PUFA, we observed a consistent gene*sex interaction with the DNTTIP2 (deoxynucleotidyl transferase terminal interacting protein 2)-rs3747965 p = 1.36 × 10-8. For adherence to MedDiet, we obtained a relevant interaction with the ME1 (malic enzyme 1) gene (a gene strongly regulated by fat) in determining serum omega-3. The top-ranked SNP for this interaction was ME1-rs3798890 (p = 2.15 × 10-7). In the regional-wide association study, specifically focused on the FADS1/FASD2/FADS3 and ELOVL (fatty acid elongase) 2/ELOVL 5 regions, we detected several statistically significant associations at p < 0.05. In conclusion, our results confirm a robust role of the FADS cluster on serum PUFA in this population, but the associations vary depending on the PUFA. Moreover, the detection of some sex and diet interactions underlines the need for these associations/interactions to be studied in all specific populations so as to better understand the complex metabolism of PUFA.

Validation of a Food Frequency Questionnaire to Assess Intake of n-3 Polyunsaturated Fatty Acids in Switzerland

Population-based data suggest that high intake of omega-3 (n-3) polyunsaturated fatty acids (PUFA) may be beneficial in a variety of health conditions. It is likely that mainly those patients with preexisting n-3 deficiency are those that benefit most from n-3 fatty acid supplementation. Therefore, for targeted interventions, a fast and reliable screening tool for n-3 PUFA intake is necessary. Thus, the aim of this project was to adapt and validate a food frequency questionnaire (FFQ) for n-3 PUFA intake in Switzerland while using as references the following: (1) 7-day food records (FR), and (2) n-3 fatty acid composition of red blood cells (RBC). We recruited 46 healthy adults for the first part of the study and 152 for the second. We used the dietary software EBISpro for the analysis of n-3 PUFA intake. RBC fatty acid composition was determined by gas chromatography mass spectrometry (GC-MS). Using correlation analysis, we found a moderate significant association between FFQ and FR for α-linolenic acid (ALA), eicosapentanoic acid (EPA), docosahexanoic acid (DHA), and total n-3 fatty acids (all r between 0.523 and 0.586, all p < 0.001). Bland Altman analysis further showed good agreement between the two methods and no proportional bias. Correlations between FFQ and RBC fatty acid composition were also moderate for EPA and DHA (r = 0.430 and r = 0.605, p < 0.001), but weaker for ALA and total n-3 (r = 0.314 and r = 0.211, p < 0.01). The efficacy of the FFQ to classify individuals into the same or adjacent quartile of RBC PUFA content ranged between 70% and 87% for the different fatty acids. In conclusion, we showed that the Swiss n-3 PUFA FFQ is a valid tool to assess dietary n-3 PUFA intake, especially DHA and EPA, to determine population groups at risk for low intake.

Circulating n-3 fatty acids and linoleic acid as indicators of dietary fatty acid intake in post-myocardial infarction patients

BACKGROUND AND AIMS

Population-based studies often use plasma fatty acids (FAs) as objective indicators of FA intake, especially for n-3 FA and linoleic acid (LA). The relation between dietary and circulating FA in cardiometabolic patients is largely unknown. We examined whether dietary n-3 FA and LA were reflected in plasma lipid pools in post-myocardial infarction (MI) patients.

METHODS AND RESULTS

Patients in Alpha Omega Cohort filled out a 203-item food-frequency questionnaire from which eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), alpha-linolenic acid (ALA), and LA intake were calculated. Circulating individual FA (% total FA) were assessed in cholesteryl esters (CE; n = 4066), phospholipids (PL; n = 838), and additionally in total plasma for DHA and LA (n = 739). Spearman correlation coefficients (r_s) were calculated for dietary vs. circulating FA. Circulating FA were also compared across dietary FA quintiles, overall and in subgroups by sex, obesity, diabetes, statin use, and high alcohol intake. Patients were on average 69 years old and 79% was male. Moderate correlations between dietary and circulating levels were observed for EPA (r_s∼0.4 in CE and PL) and DHA (r_s ∼0.5 in CE and PL, ∼0.4 in total plasma), but not for ALA (r_s ∼0.0). Weak correlations were observed for LA (r_s 0.1 to 0.2). Plasma LA was significantly lower in statin users and in patients with a high alcohol intake.

CONCLUSIONS

In post-MI patients, dietary EPA and DHA were well reflected in circulating levels. This was not the case for LA, which may partly be influenced by alcohol use and statins.

The sociodemographic characteristics and dietary and blood plasma fatty acid profiles of elderly Saudi women with Alzheimer disease

Background

Alzheimer’s disease (AD) is a progressive neurodegenerative disease, and due to various physiological and psychological factors the patients are at risk of nutritional insufficiencies. The purpose of this study was to assess the dietary fatty acid intake and its effect on plasma fatty acids in elderly Saudi women and to compare the differences in their food and plasma fatty acid profile on the basis of their residence.

Methods

A total of 76 elderly women (50–100 years) were recruited through a random sampling method. A structured proforma was designed to gather information related to their age, income, dietary habits, and presence of any disease and awareness of AD. A 24-h dietary recall method for 3 days and food frequency questionnaire, concentrating on fish consumption and consumption of foods rich in ω-3 fatty acids, which was planned by dietitians, was used for dietary assessment. The gathered data were then analyzed using food processor software. The blood samples were collected to determine plasma fatty acids.

Results

The mean age of women diagnosed with AD was more than 75 years, and the prevalence of illiteracy was higher among AD subjects. As compared to the AD group, the concentration of LA and total ω-6 was significantly (p ≤ 0.05) higher in the control group from both recruitment sites [National Guard Health Affairs, King Abdulaziz Medical City, Riyadh (NGH) and Social Welfare Homes for the Elderly (SWH)]. Similarly, the concentrations of EPA, DHA, and ω-3 were also slightly higher in the control group at both sites, but the difference between the control and AD subjects was only significant (p ≤ 0.05) in subjects from NGH. We found no significant difference in the ω-6/ ω-3 ratio between groups. Also, no significant difference was found in the mean level of the plasma fatty acid when comparing the control and AD groups. The concentration of DHA in controls only and AA, EPA and ω-6 in both control and AD were significant (although weakly) correlated with their respective dietary intakes. No correlations were found between the intake of 18 C precursors (LA and ALA) and plasma levels of their long chain derivatives (AA, EPA, and DHA). Education, income, overall health status and the concentration of various fatty acids from food was higher and better in subjects from SWH than NGH. The lower plasma level indicates lower impaired systemic availability of several nutrients.

Conclusion

We found that dietary intervention might play a role in the prevention of AD.

Serum Omega-6 Fatty Acids and Immunology-Related Gene Expression in Peripheral Blood Mononuclear Cells: A Cross-Sectional Analysis in Healthy Children

SCOPE

Some studies suggest that a high dietary intake of omega-6 fatty acids is pro-inflammatory. However, whether omega-6 fatty acids actually cause pathogenic inflammation in humans is debated. Therefore, the associations between expression of immunology-related genes in peripheral blood mononuclear cells (PBMCs) and serum total omega-6 PUFA status are investigated.

METHODS AND RESULTS

Serum fatty acid profile and expression of 460 immunology-related genes in PBMCs from 58 healthy children (6-13 years) is measured, and examined the expression differences between children with high or low total omega-6 PUFA status (upper vs lower tertile). Taken together, both univariate analyses and integrated omics analyses support that while high omega-6 PUFA level associated with higher expressing of genes related to innate immune responses, it also associated with lower expression of several genes related to adaptive immune responses.

CONCLUSION

Omega-6 PUFA status associated both positively and negatively with expression of specific immunology-related genes in PBMCs in healthy children. The results may suggest a nuanced role for omega-6 fatty acids in the interphase of lipids and inflammation, and warrants further examination in gene-environment studies and randomized controlled trials.

Preconception Plasma Phospholipid Fatty Acids and Fecundability

CONTEXT

Fatty acids (FAs) are important for reproductive processes, including steroidogenesis, though associations with fecundability, as measured by time to pregnancy (TTP), are unclear.

OBJECTIVE

To investigate the relationship between preconception plasma phospholipid FA (PPFA) levels and time to human chorionic gonadotropin-pregnancy among women with prior pregnancy loss.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort of 1228 women attempting pregnancy (aged 18 to 40 years, with one or two prior pregnancy losses) followed for up to six cycles at four US university medical centers during 2006 to 2012. PPFA levels were measured at baseline.

MAIN OUTCOME MEASURES

Associations with fecundability overall and by body mass index (BMI) group after adjusting for confounders were estimated using fecundability odds ratios (FORs) and 95% CIs. False discovery rate (FDR) was used to account for multiple comparisons.

RESULTS

Monounsaturated fatty acids (MUFAs) were associated with increased fecundability or shorter TTP [FOR, 1.08 (95% CI, 1.01 to 1.16) per unit increase in percentage of total FAs], whereas polyunsaturated fatty acids (PUFAs) were associated with decreased fecundability or longer TTP [FOR, 0.95 (95% CI, 0.91 to 1.00) per 1% change], though associations only remained significant after FDR adjustment among women with BMI <25 kg/m2. Saturated FA and trans FA were not associated with fecundability. Omega-3 FAs and omega-6 linoleic acid were not associated with fecundability.

CONCLUSION

We observed associations between preconception MUFA and PUFA levels and fecundability among women with normal BMI, highlighting the importance of FA composition among normal-weight women with prior pregnancy loss.

Diet quality as assessed by the Healthy Food Intake Index and relationship with serum lipoprotein particles and serum fatty acids in pregnant women at increased risk for gestational diabetes

The importance of overall diet in modifying circulating lipoprotein particles and fatty acids during pregnancy is unclear. We examined the relationships of diet quality as assessed by the validated Healthy Food Intake Index (HFII) with serum HDL, LDL and VLDL particle concentrations and sizes and proportions of serum fatty acids in pregnant women at high risk for gestational diabetes mellitus (GDM). Overall, 161 women with a BMI of ≥30 kg/m2 and/or a history of GDM were drawn from the Finnish Gestational Diabetes Prevention Study, which is a dietary and exercise intervention trial to prevent GDM. At baseline, the HFII score was inversely related to concentrations of HDL particles (P=0·010) and MUFA (P=0·010) and positively related to concentrations of n-3 (P<0·001) and n-6 (P=0·003) PUFA. The significance for MUFA disappeared after adjustments. An increase in the HFII score from the first to second trimester of pregnancy correlated with reduced VLDL particle size (r −0·16, 95 % CI −0·31, −0·01), decreased MUFA concentrations (r −0·17, 95 % CI −0·31, −0·01) and elevated n-6 PUFA concentrations (r 0·16, 95 % CI 0·01, 0·31). In the maximum-adjusted model, the results remained significant except for VLDL particle size. These findings suggest that higher diet quality as defined by the HFII is related to a more favourable serum fatty acid profile, whereas the relationship with serum lipoprotein profile is limited in pregnant women at increased GDM risk.

Validation of an equation predicting highly unsaturated fatty acid (HUFA) compositions of human blood fractions from dietary intakes of both HUFAs and their precursors

Proportions of omega-3 (n-3) and omega-6 (n-6) in 20- and 22-carbon highly unsaturated fatty acids with 3 or more double bonds (HUFA) accumulated in tissue HUFA (e.g., the %n-6 in HUFA) are biomarkers reflecting intakes of n-6 and n-3 fatty acids. An empirical equation, referred to here as the Lands' Equation, was developed previously to use dietary intakes of n-6 and n-3 HUFA and their 18-carbon precursors to estimate the %n-6 in HUFA of humans. From the PubMed database, we identified clinical trials reporting (a) dietary intake of at least linoleic acid (18:2n-6) and alpha-linolenic acid (18:3n-3), and (b) the amounts of at least arachidonic acid (20:4n-6), eicosapentaenoic acid (20:5n-3), and docosahexaenoic acid (22:6n-3) in lipids of plasma, serum, or red blood cell. Linear regression analyses comparing reported and predicted %n-6 in HUFA gave a correlation coefficient of 0.73 (p<0.000000) for 34 studies with 92 subject groups. These results indicate that circulating HUFA compositions can be reliably estimated from dietary intake data that not only includes n-3 and n-6 HUFA consumption, but also includes consumption of 18 carbon n-3 and n-6 precursor fatty acids.

Plasma fatty acid levels and gene expression related to lipid metabolism in peripheral blood mononuclear cells: a cross-sectional study in healthy subjects

Background

Solid evidence indicates that intake of marine n-3 fatty acids lowers serum triglycerides and that replacing saturated fatty acids (SFA) with polyunsaturated fatty acids (PUFA) reduces plasma total cholesterol and LDL cholesterol. The molecular mechanisms underlying these health beneficial effects are however not completely elucidated. The aim of this study was therefore to investigate the expression of genes related to lipid metabolism in peripheral blood mononuclear cells (PBMC) depending on the plasma levels of n-6 and n-3 fatty acids and the SFA to PUFA ratio.

Methods

Fifty-four healthy subjects were grouped into tertiles (n = 18) based on plasma levels of n-6 and n-3 fatty acids and the SFA to PUFA ratio. The PBMC gene expression levels among subjects in the highest versus the lowest tertiles were compared. In total, 285 genes related to cholesterol and triglyceride metabolism were selected for this explorative study.

Results

Among the 285 selected genes, 161 were defined as expressed in the PBMCs. The plasma SFA to PUFA ratio was associated with the highest number of significantly different expressed genes (25 gene transcripts), followed by plasma n-6 fatty acid level (15 gene transcripts) and plasma n-3 fatty acid level (8 gene transcripts). In particular, genes involved in cholesterol homeostasis were significantly different expressed among subjects with high compared to low plasma SFA to PUFA ratio.

Conclusion

Genes involved in lipid metabolism were differentially expressed in PBMCs depending on the plasma fatty acid levels. This finding may increase our understanding of how fatty acids influence lipid metabolism at a molecular level in humans.

Electronic supplementary material

The online version of this article (10.1186/s12263-018-0600-z) contains supplementary material, which is available to authorized users.

High erythrocyte levels of the n-6 polyunsaturated fatty acid linoleic acid are associated with lower risk of subsequent rheumatoid arthritis in a southern European nested case–control study

Objectives

Findings relating to dietary intake of n-3 polyunsaturated fatty acids (PUFA) and risk of rheumatoid arthritis (RA) are mixed. Erythrocyte membrane PUFA is an accurate objective biomarker of PUFA status; however, there are little data on erythrocyte membrane PUFA and risk of RA. The objective was therefore to compare erythrocyte membrane PUFA between pre-RA individuals and matched controls from a population-based sample, and specifically to test the hypothesis that higher levels of longer chain n-3 PUFA are associated with lower risk of RA.

Methods

The European Prospective Investigation into Cancer and Nutrition (EPIC) is a large European prospective cohort study of apparently healthy populations. We undertook a nested case–control study by identifying RA cases with onset after enrolment (pre-RA) in four EPIC cohorts in Italy and Spain. Confirmed pre-RA cases were matched with controls by age, sex, centre, and date, time and fasting status at blood collection. Conditional logistic regression analysis was used to estimate associations of PUFA with the development of RA, adjusting for potential confounders including body mass index, waist circumference, education level, physical activity, smoking status and alcohol intake.

Results

The study analysed samples from 96 pre-RA subjects and 258 matched controls. In this analysis, the median time to diagnosis (defined as time between date of blood sample and date of diagnosis) was 6.71 years (range 0.8–15). A significant inverse association was observed with n-6 PUFA linoleic acid (LA) levels and pre-RA in the fully adjusted model (highest tertile: OR 0.29; 95% CI 0.12 to 0.75; P for trend 0.01). No association was observed with any individual n-3 PUFA, total n-3 PUFA or total n-3:n-6 ratio.

Conclusions

Erythrocyte levels of the n-6 PUFA LA were inversely associated with risk of RA, whereas no associations were observed for other n-6 or n-3 PUFA. Further work is warranted to replicate these findings and to investigate if lower LA levels are a bystander or contributor to the process of RA development.

Dietary omega-3 and omega-6 polyunsaturated fatty acids modulate hepatic pathology

Recent evidence has suggested that dietary polyunsaturated fatty acids (PUFAs) modulate inflammation; however, few studies have focused on the pathobiology of PUFA using isocaloric and isolipidic diets and it is unclear if the associated pathologies are due to dietary PUFA composition, lipid metabolism or obesity, as most studies compare diets fed ad libitum. Our studies used isocaloric and isolipidic liquid diets (35% of calories from fat), with differing compositions of omega (ω)-6 or long chain (Lc) ω-3 PUFA that were pair-fed and assessed hepatic pathology, inflammation and lipid metabolism. Consistent with an isocaloric, pair-fed model we observed no significant difference in diet consumption between the groups. In contrast, the body and liver weight, total lipid level and abdominal fat deposits were significantly higher in mice fed an ω-6 diet. An analysis of the fatty acid profile in plasma and liver showed that mice on the ω-6 diet had significantly more arachidonic acid (AA) in the plasma and liver, whereas, in these mice ω-3 fatty acids such as eicosapentaenoic acid (EPA) were not detected and docosahexaenoic acid (DHA) was significantly lower. Histopathologic analyses documented that mice on the ω-6 diet had a significant increase in macrovesicular steatosis, extramedullary myelopoiesis (EMM), apoptotic hepatocytes and decreased glycogen storage in lobular hepatocytes, and hepatocyte proliferation relative to mice fed the Lc ω-3 diet. Together, these results support PUFA dietary regulation of hepatic pathology and inflammation with implications for enteral feeding regulation of steatosis and other hepatic lesions.

Increased Fat Absorption From Enteral Formula Through an In-line Digestive Cartridge in Patients With Cystic Fibrosis

OBJECTIVES

Supplemental enteral nutrition (EN) is used by approximately 12% of people with cystic fibrosis (CF). The objective of this study was to evaluate the safety, tolerability, and fat absorption of a new in-line digestive cartridge (Relizorb) that hydrolyzes fat in enteral formula provided to patients with CF.

METHODS

Patients with CF receiving EN participated in a multicenter, randomized, double-blind, crossover trial with an open-label safety evaluation period. Plasma omega-3 fatty acid (FA) concentrations were measured and used as markers of fat absorption. Gastrointestinal symptoms were recorded to evaluate safety and tolerability. Information regarding the effect of EN on appetite and breakfast consumption was also collected.

RESULTS

Before study entry, participants had received EN for a mean of 6.6 years at a mean volume of approximately 800 mL, yet had a mean body mass index of only 17.5 kg/m and omega-3 FA plasma concentrations were only 60% of levels found in normal healthy subjects. Compared with placebo, cartridge use resulted in a statistically significant 2.8-fold increase in plasma omega-3 FA concentrations. There were no adverse experiences associated with cartridge use, and a decrease in the frequency and severity of most symptoms of malabsorption was observed with cartridge use. Participants reported increased preservation of appetite and breakfast consumption with cartridge use compared with their pre-study regimen.

CONCLUSIONS

Use of this in-line digestive cartridge was safe and well tolerated, and resulted in significantly increased levels of plasma omega-3 FA used with enteral formula, suggesting an overall increased fat absorption.

Alterations of specific lipid groups in serum of obese humans: a review

Obesity is a major contributor to the dysfunction of liver, cardiac, pulmonary, endocrine and reproductive system, as well as a component of metabolic syndrome. Although development of obesity-related disorders is associated with lipid abnormalities, most previous studies dealing with the problem in question were limited to routinely determined parameters, such as serum concentrations of triacylglycerols, total cholesterol, low-density and high-density lipoprotein cholesterol. Many authors postulated to extend the scope of analysed lipid compounds and to study obesity-related alterations in other, previously non-examined groups of lipids. Comprehensive quantitative, structural and functional analysis of specific lipid groups may result in identification of new obesity-related alterations. The review summarizes available evidence of obesity-related alterations in various groups of lipids and their impact on health status of obese subjects. Further, the role of diet and endogenous lipid synthesis in the development of serum lipid alterations is discussed, along with potential application of various lipid compounds as risk markers for obesity-related comorbidities.

A Novel Selective Inhibitor of Delta-5 Desaturase Lowers Insulin Resistance and Reduces Body Weight in Diet-Induced Obese C57BL/6J Mice

Obesity is now recognized as a state of chronic low-grade inflammation and is called as metabolic inflammation. Delta-5 desaturase (D5D) is an enzyme that metabolizes dihomo-γ-linolenic acid (DGLA) to arachidonic acid (AA). Thus, D5D inhibition increases DGLA (precursor to anti-inflammatory eicosanoids) while decreasing AA (precursor to pro-inflammatory eicosanoids), and could result in synergistic improvement in the low-grade inflammatory state. Here, we demonstrate reduced insulin resistance and the anti-obesity effect of a D5D selective inhibitor (compound-326), an orally active small-molecule, in a high-fat diet-induced obese (DIO) mouse model. In vivo D5D inhibition was confirmed by determining changes in blood AA/DGLA profiles. In DIO mice, chronic treatment with compound-326 lowered insulin resistance and caused body weight loss without significant impact on cumulative calorie intake. Decreased macrophage infiltration into adipose tissue was expected from mRNA analysis. Increased daily energy expenditure was also observed following administration of compound-326, in line with sustained body weight loss. These data indicate that the novel D5D selective inhibitor, compound-326, will be a new class of drug for the treatment of obese and diabetic patients.

Global survey of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid in the blood stream of healthy adults

Studies reporting blood levels of the omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were systematically identified in order to create a global map identifying countries and regions with different blood levels. Included studies were those of healthy adults, published in 1980 or later. A total of 298 studies met all inclusion criteria. Studies reported fatty acids in various blood fractions including plasma total lipids (33%), plasma phospholipid (32%), erythrocytes (32%) and whole blood (3.0%). Fatty acid data from each blood fraction were converted to relative weight percentages (wt.%) and then assigned to one of four discrete ranges (high, moderate, low, very low) corresponding to wt.% EPA+DHA in erythrocyte equivalents. Regions with high EPA+DHA blood levels (>8%) included the Sea of Japan, Scandinavia, and areas with indigenous populations or populations not fully adapted to Westernized food habits. Very low blood levels (≤4%) were observed in North America, Central and South America, Europe, the Middle East, Southeast Asia, and Africa. The present review reveals considerable variability in blood levels of EPA+DHA and the very low to low range of blood EPA+DHA for most of the world may increase global risk for chronic disease.

Adipose tissue α-linolenic acid is inversely associated with insulin resistance in adults

BACKGROUND

There is emerging evidence of the beneficial effects of n-3 (ω-3) fatty acids (FAs) on cardiometabolic risk factors. Nevertheless, not much is known about the association between adipose tissue α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) and insulin resistance.

OBJECTIVE

We determined the association between adipose tissue n-3 FAs (total n-3 FAs, ALA, and EPA plus DHA) and insulin resistance in healthy adults.

DESIGN

In this cross-sectional study, multivariable analyses were used to assess the association between adipose tissue FAs (ALA, EPA plus DHA, and total n-3 FAs) and the homeostasis model assessment of insulin resistance (HOMA-IR) in a subset of adult participants (n= 716; mean age: 58 y) from the Adventist Health Study-2 (AHS-2) cohort.

RESULTS

Compared with the lowest tertile, the third tertile (β = -0.13; 95% CI: -0.24, -0.01) of adipose tissue ALA was inversely associated with the HOMA-IR. When stratified by waist circumference, ALA continued to be inversely associated [third tertile: β = -0.17 (95% CI: -0.31, -0.02)] with the HOMA-IR in subjects with a waist circumference ≤88 cm in women or ≤102 cm in men but not in those with a larger waist circumference. No significant association was noted between adipose tissue EPA plus DHA and HOMA-IR.

CONCLUSIONS

Higher adipose tissue ALA was inversely associated with insulin resistance in this cohort of healthy adult men and women. This finding appears to be more pronounced in individuals with a normal waist circumference.

Processed meat: the real villain?

Meat is a food rich in protein, minerals such as iron and zinc as well as a variety of vitamins, in particular B vitamins. However, the content of cholesterol and saturated fat is higher than in some other food groups. Processed meat is defined as products usually made of red meat that are cured, salted or smoked (e.g. ham or bacon) in order to improve the durability of the food and/or to improve colour and taste, and often contain a high amount of minced fatty tissue (e.g. sausages). Hence, high consumption of processed foods may lead to an increased intake of saturated fats, cholesterol, salt, nitrite, haem iron, polycyclic aromatic hydrocarbons, and, depending upon the chosen food preparation method, also heterocyclic amines. Several large cohort studies have shown that a high consumption of processed (red) meat is related to increased overall and cause-specific mortality. A meta-analysis of nine cohort studies observed a higher mortality among high consumers of processed red meat (relative risk (RR) = 1·23; 95 % CI 1·17, 1·28, top v. bottom consumption category), but not unprocessed red meat (RR = 1·10; 95 % CI 0·98, 1·22). Similar associations were reported in a second meta-analysis. All studies argue that plausible mechanisms are available linking processed meat consumption and risk of chronic diseases such as CVD, diabetes mellitus or some types of cancer. However, the results of meta-analyses do show some degree of heterogeneity between studies, and it has to be taken into account that individuals with low red or processed meat consumption tend to have a healthier lifestyle in general. Hence, substantial residual confounding cannot be excluded. Information from other types of studies in man is needed to support a causal role of processed meat in the aetiology of chronic diseases, e.g. studies using the Mendelian randomisation approach.

Omega-3 dietary Fatty Acid status of healthy older adults in Tasmania, Australia: an observational study

OBJECTIVES

To determine the dietary and supplement intake of omega-3 (n-3) polyunsaturated fatty acids (PUFA) of older Tasmanian adults; their plasma n-3 PUFA status and the relationship between n-3 PUFA intake and plasma status.

DESIGN

Cross-sectional study.

SETTING

Launceston and surrounding regions, Tasmania, Australia.

PARTICIPANTS

Seventy-three community-dwelling older adults: 23 men aged 70 ± 6.1 years and 50 women aged 70 ± 6.7 years.

MEASUREMENTS

A validated, semi-quantitative food frequency questionnaire estimated dietary PUFA intake. The plasma phospholipid fraction of venous blood samples was analysed for fatty acid content. Anthropometric data was recorded.

RESULTS

Thirty-five participants (48%) regularly ingested a fish oil supplement. Their plasma n-3 PUFA profile contained significantly more eicosapentaenoic acid (EPA) (odds ratio 3.14; 95% CI 1.37% to 7.30%; p<0.05) and docosahexaenoic acid (DHA) (odds ratio 2.64; 95% CI 1.16% to 6.01%; p<0.05) than non-supplement users. Fish and meat were the main dietary sources of n-3 PUFAs. Participants most commonly consumed fish 3-4 times per week. Significant associations of dietary α-linolenic acid (ALA), EPA, docosapentaenoic acid (DPA) and DHA with plasma n-3 PUFAs were noted but not always between dietary and plasma counterparts.

CONCLUSION

Without the use of fish oil supplements, most study participants were unable to meet the recommended daily intake of 0.5g EPA and DHA combined; however, the plasma n-3 PUFA profile of non-supplement-users was still robust compared to other Australian and overseas studies.

Lower inter-partum interval and unhealthy life-style factors are inversely associated with n-3 essential fatty acids changes during pregnancy: a prospective cohort with Brazilian women

OBJECTIVE

To analyze serum fatty acids concentrations during healthy pregnancy and evaluate whether socioeconomic, demographic, obstetric, nutritional, anthropometric and lifestyle factors are associated with their longitudinal changes.

STUDY DESIGN

A prospective cohort of 225 pregnant women was followed in the 5th-13th, 20th-26th and 30th-36th weeks of gestation. Serum samples were collected in each trimester of pregnancy and analyzed to determine the fatty acids composition using a high-throughput robotic direct methylation method coupled with fast gas-liquid chromatography. The independent variables comprised the subjects' socioeconomic and demographic status, obstetric history, early pregnancy body mass index (BMI), dietary and lifestyle parameters. Analyses were performed using linear mixed-effects models.

RESULTS

The overall absolute concentrations of fatty acids increased from the 1st to the 2nd trimester and slightly increased from the 2nd to the 3rd trimester. Early pregnancy BMI, inter-partum interval and weekly fish intake were the factors associated with changes in eicosapentaenoic + docosahexaenoic acids (EPA+DHA) and total n-3 polyunsaturated fatty acids (PUFAs). Early pregnancy BMI, age and monthly per-capita income were inversely associated with the changes in the n-6/n-3 ratio. Alcohol consumption was positively associated with the n-6/n-3 ratio.

CONCLUSION

Early pregnancy BMI was positively associated with EPA+DHA and total n-3 PUFAs, while presenting a reduced weekly fish intake and a lower inter-partum interval were associated with lower levels of n-3 PUFAs. A lower per-capita family income and a drinking habit were factors that were positively associated with a higher n-6/n-3 ratio.

Determining the fatty acid composition in plasma and tissues as fatty acid methyl esters using gas chromatography – a comparison of different derivatization and extraction procedures

Analysis of the fatty acid (FA) composition in biological samples is commonly carried out using gas liquid chromatography (GC) after transesterification to volatile FA methyl esters (FAME). We compared the efficacy of six frequently used protocols for derivatization of different lipid classes as well as for plasma and tissue samples. Transesterification with trimethylsulfonium hydroxide (TMSH) led to insufficient derivatization efficacies for polyunsaturated FAs (PUFA, <50%). Derivatization in presence of potassium hydroxide (KOH) failed at derivatizing free FAs (FFAs). Boron trifluoride (BF3) 7% in hexane/MeOH (1:1) was insufficient for the transesterification of cholesterol ester (CE) as well as triacylglycerols (TGs). In contrast, methanolic hydrochloric acid (HCl) as well as a combination of BF3 with methanolic sodium hydroxide (NaOH+BF3) were suitable for the derivatization of FFAs, polar lipids, TGs, and CEs (derivatization rate >80% for all tested lipids). Regarding plasma samples, all methods led to an overall similar relative FA pattern. However, significant differences were observed, for example, for the relative amount of EPA+DHA (n3-index). Absolute FA plasma concentrations differed considerably among the methods, with low yields for KOH and BF3. We also demonstrate that lipid extraction with tert-butyl methyl ether/methanol (MTBE/MeOH) is as efficient as the classical method according to Bligh and Dyer, making it possible to replace (environmentally) toxic chloroform.We conclude that HCl-catalyzed derivatization in combination with MeOH/MTBE extraction is the most appropriate among the methods tested for the analysis of FA concentrations and FA pattern in small biological samples. A detailed protocol for the analysis of plasma and tissues is included in this article.

A dietary biomarker approach captures compliance and cardiometabolic effects of a healthy Nordic diet in individuals with metabolic syndrome

Assessment of compliance with dietary interventions is necessary to understand the observed magnitude of the health effects of the diet per se. To avoid reporting bias, different dietary biomarkers (DBs) could be used instead of self-reported data. However, few studies investigated a combination of DBs to assess compliance and its influence on cardiometabolic risk factors. The objectives of this study were to use a combination of DBs to assess compliance and to investigate how a healthy Nordic diet (ND) influences cardiometabolic risk factors in participants with high apparent compliance compared with the whole study population. From a recently conducted isocaloric randomized trial, SYSDIET (Systems Biology in Controlled Dietary Interventions and Cohort Studies), in 166 individuals with metabolic syndrome, several DBs were assessed to reflect different key components of the ND: canola oil (serum phospholipid α-linolenic acid), fatty fish [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)], vegetables (plasma β-carotene), and whole grains (plasma alkylresorcinols). High-fat dairy intake (expectedly low in the ND) was reflected by serum pentadecanoic acid. All participants with biomarker data (n = 154) were included in the analyses. Biomarkers were combined by using a biomarker rank score (DB score) and principal component analysis (PCA). The DB score was then used to assess compliance. During the intervention, median concentrations of alkylresorcinols, α-linolenic acid, EPA, and DHA were >25% higher in the ND individuals than in the controls (P < 0.05), whereas median concentrations of pentadecanoic acid were 14% higher in controls (P < 0.05). Median DB score was 57% higher in the ND than in controls (P < 0.001) during the intervention, and participants were ranked similarly by DB score and PCA score. Overall, estimates of group difference in cardiometabolic effects generally appeared to be greater among compliant participants than in the whole study population (e.g., estimates of treatment effects on blood pressure and lipoproteins were ∼1.5- to 2-fold greater in the most compliant participants), suggesting that poor compliance attenuated the dietary effects. With adequate consideration of their limitations, DB combinations (e.g., DB score) could be useful for assessing compliance in intervention studies investigating cardiometabolic effects of healthy dietary patterns. The study was registered at clinicaltrials.gov as NCT00992641.

Contribution of cod liver oil-related nutrients (vitamins A, D, E and eicosapentaenoic acid and docosahexaenoic acid) to daily nutrient intake and their associations with plasma concentrations in the EPIC-Norfolk cohort

Background

Total nutrient intake (TNI) is intake from food and supplements. This provides an assessment of nutrient adequacy and the prevalence of excessive intake, as well as the response with respect to biomarkers. Cod liver oil (CLO) is the most frequently consumed supplement in the UK, containing nutrients that might have varying influences on health. We calculated TNI for vitamins A, D and E, as well as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and assessed associations with the respective blood concentrations.

Methods

Seven-day diet diaries and blood samples were taken from two subsets of the European Prospective Investigation into Cancer (EPIC-Norfolk) cohort (age range 39–79 years; n = 1400 for vitamin D; n = 6656 for remaining nutrients). TNI was calculated for the subgroups: nonsupplement users, those consuming the nutrient in supplement form and those consuming a supplement without this nutrient.

Results

CLO-related nutrients were supplemented by 15%–33%, which approximately doubled median intakes. Almost everyone in the supplement + vitamin A group reached the estimated average requirement; however, guideline levels were likely to be exceeded. Partial correlations between intake of vitamins A and D and biomarkers were low and modestly strengthened by the inclusion of supplement sources (correlation = 0.01–0.13). Correlations between biomarker and TNI of vitamin E and EPA+DHA were in the range 0.40–0.46; however, vitamin E exceeding food intake resulted in attenuated coefficients. Linear associations between food or TNI EPA+DHA and plasma were weak but consistent across subgroups.

Conclusions

CLO-related nutrients contribute substantially to nutrient intake, with a risk of over-consumption. Apart from EPA+DHA, biomarker data suggest that CLO-related nutrients in supplements are not linearly associated with vitamin status.

Plasma phospholipid fatty acid biomarkers of dietary fat quality and endogenous metabolism predict coronary heart disease risk: a nested case-control study within the Women's Health Initiative observational study

Background

Although the relationship between dietary fat quality and coronary heart disease (CHD) risk has been evaluated, typically using diet questionnaires, results are inconsistent and data in postmenopausal women are limited. Plasma phospholipid fatty acid (PL‐FA) profiles, reflecting dietary intake and endogenous FA metabolism, may better predict diet–CHD risk.

Methods and Results

Using a nested case‐control design, we assessed the association between plasma PL‐FA profiles and CHD risk in 2448 postmenopausal women (1224 cases with confirmed CHD and 1224 controls matched for age, enrollment date, race/ethnicity, and absence of CHD at baseline and after 4.5 years of follow‐up) participating in the Women's Health Initiative observational study. PL‐FA profile was measured using gas chromatography. Product/precursor ratios were used to estimate stearoyl‐CoA‐desaturase (16:1n‐7/16:0, 18:1n‐9/18:0), Δ6‐desaturase (20:3n‐6/18:2n‐6), and Δ5‐desaturase (20:4n‐6/20:3n‐6) activities, indicators of endogenous FA metabolism. Multivariate conditional logistic regression was used to obtain odds ratios (95% CIs) for CHD risk. While no associations were observed for the predominant PL fatty acid (16:0, 18:0, 18:1n‐9, and 18:2n‐6), plasma PL–saturated fatty acid (1.20 [1.08 to 1.32]) and endogenously synthesized PL ω6 fatty acids (20:3n‐6; 3.22 [1.95 to 5.32]), 22:5n‐6; 1.63 [1.20 to 2.23]) and Δ6‐desaturase (1.25 [1.11 to 1.41]) were positively associated with CHD risk. PL‐ω3 fatty acids (20:5n‐3; 0.73 [0.58 to 0.93], 22:5n‐3; 0.56 [0.33 to 0.94], 22:6n‐3; 0.56 [0.39 to 0.80]), 18:1n‐7 (0.54 [0.29 to 0.99]), and Δ5‐desaturase (0.78 [0.70 to 0.88]) were inversely associated with CHD risk. Results support current guidelines regarding regular fish consumption. Additional findings include associations between endogenously synthesized fatty acids and CHD risk, which were partly explained by changes in Δ6‐desaturase and Δ5‐desaturase indexes, suggesting that in vivo metabolism may also play an important role in predicting CHD risk in this cohort of postmenopausal women.

Clinical Trial Registration

URL: http://ClinicalTrials.gov, Unique identifier: NCT01864122.

Exposure of fatty acids after a single oral administration of sacha inchi (Plukenetia volubilis L.) and sunflower oil in human adult subjects

CONTEXT

Sacha inchi (Plukenetia volubilis L.) is a potential oilseed crop because it is rich in α-linolenic acid (ALA) (omega-3 fatty acid).

OBJECTIVE

To evaluate the exposure of fatty acids after a single oral administration of sacha inchi or sunflower oil in healthy volunteers.

MATERIAL AND METHODS

Plasma fatty acids concentrations were assayed by Gas Chromatography with Flame Ionization Detector in 18 adult subjects. After fasting, blood samples were obtained at 0, 0.5, 1, 2, 4, 8 and 24 h after ingestion of 10 or 15 ml of sacha inchi oil or sunflower oil.

RESULTS

The proportion ALA/linoleic acid was 1.37 in sacha inchi oil and 0.01 in sunflower oil. ALA, lauric acid, palmitic acid, linolelaidic acid, cis-8,11,14-eicosatrienoic acid, cis-13,16-docosadienoic acid and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) levels changed over time after sacha inchi oil ingestion but not with sunflower oil. The time at maximal concentration (tmax) for ALA was 2 h after sacha inchi oil ingestion. No ALA in plasma was observed after sunflower oil consumption. The maximal concentration of ALA was 2.84 ± 0.36 mg/ml in women and 0.94 ± 0.57 mg/ml in men, p < 0.05, whereas maximal concentration of DHA was 2.60 ± 0.84 mg/ml in women and 1.00 ± 0.38 mg/ml in men (p > 0.05). There is a trend for higher plasma ALA levels with 15 ml sacha inchi oil. After 2 h of consumption, plasma delta triacylglycerol were reduced with sunflower oil but slightly increased with sacha inchi oil. A reduction in plasma delta triacylglycerol-rich lipoprotein cholesterol was observed with both oils.

CONCLUSION

Consumption of sacha inchi oil increased ALA and DHA in plasma.

Maternal milk DHA content predicts cognitive performance in a sample of 28 nations

Convergent evidence from neuronal biology and hominin brain hypertrophy suggests that omega-3 fatty acids are a limiting resource for neural and cognitive development in Homo sapiens, and therefore that children from populations with higher omega-3 availability should display superior cognitive performance. Using multiple regression, we tested this prediction in a sample of 28 countries, with Programme for International Student Assessment (PISA) math scores in 2009 as an index of cognitive performance, and country-specific breast milk levels of omega-3 docosahexaenoic acid (DHA) as an index of omega-3 availability. Breast milk DHA makes a highly significant contribution to math scores (β = 0.462, P = 0.006), greater in magnitude than the control variables of per capita Gross Domestic Product (PCGDP) and educational expenditures per pupil. Together, dietary fish (positively) and total fat (negatively) explain 61% of the variance in maternal milk DHA in a larger sample of 39 countries.

Fatty-acid composition of maternal and umbilical cord plasma and early childhood atopic eczema in a Spanish cohort

BACKGROUND/OBJECTIVES

Fatty-acid status during in-utero development might influence the risk of atopic diseases in early childhood. The aim of this work was to identify the relationship between maternal plasma and cord blood fatty acid (FA) composition and the risk of atopic eczema in the offspring at 14 months of age.

SUBJECTS/METHODS

Two hundred and eleven non-atopic mothers and their children were studied. Mothers were recruited in their first trimester of gestation and children were monitored until 14 months of age. Samples of maternal plasma and cord blood plasma were analyzed to determine the FA profile of total lipids. Presence of atopic eczema in the infants was documented through questionnaires at 6 and 14 months of age.

RESULTS

Higher concentrations of total long-chain polyunsaturated FA (LC-PUFA) were found in maternal plasma of non-atopic children in relation to atopic group. Moreover, this maternal plasma LC-PUFA content was negatively correlated with the atopic eczema (odds ratios (OR)=0.83, P=0.04) in infants. Regarding cord blood samples, docosahexaenoic acid (DHA C22:6n3) and the sum of total n-3 and of LC-PUFA n-3 showed a negative correlation with the prevalence of the disease (OR=0.50, 0.49 and 0.49, respectively).

CONCLUSIONS

Our results show that the fatty-acid status of the fetus during pregnancy has an important role in the development of atopic eczema in early childhood. The prevalence of this atopic disorder is related to lower cord blood plasma levels of FA belonging to n-3 series, especially DHA.

Omega-3 fatty acids status in human subjects estimated using a food frequency questionnaire and plasma phospholipids levels

BACKGROUND

Intakes of omega-3 (n-3) fatty acids (FA) are associated with several health benefits. The aim of this study was to verify whether intakes of n-3 FA estimated from a food frequency questionnaire (FFQ) correlate with n-3 FA levels measured in plasma phospholipids (PL).

METHODS

The study sample consisted of 200 French-Canadians men and women aged between 18 to 55 years. Dietary data were collected using a validated FFQ. Fasting blood samples were collected and the plasma PL FA profile was measured by gas chromatography.

RESULTS

Low intakes of n-3 long-chain FA together with low percentages of n-3 long-chain FA in plasma PL were found in French-Canadian population. Daily intakes of eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) were similar between men and women. Yet, alpha-linolenic acid (ALA) and total n-3 FA intakes were significantly higher in men compared to women (ALA: 2.28 g and 1.69 g, p < 0.0001, total n-3 FA: 2.57 g and 1.99 g, p < 0.0001; respectively). In plasma PL, DPA and DHA percentages were significantly different between men and women (DPA: 1.03% and 0.88%, p < 0.0001, DHA: 3.00% and 3.43%, p = 0.0005; respectively). Moreover, DHA (men: r = 0.52, p < 0.0001; women: r = 0.57, p < 0.0001) and total n-3 FA (men: r = 0.47, p < 0.0001; women: r = 0.52, p < 0.0001) intakes were positively correlated to their respective plasma PL FA levels. In women, EPA (r = 0.44, p < 0.0001) and DPA (r = 0.23, p = 0.02) intakes were also correlated respectively with EPA and DPA plasma PL FA percentages.

CONCLUSION

Estimated n-3 long-chain FA intake among this young and well-educated French-Canadian population is lower than the recommendations. Further, FFQ data is comparable to plasma PL results to estimate DHA and total n-3 FA status in healthy individuals as well as to evaluate the EPA and DPA status in women. Overall, this FFQ could be used as a simple, low-cost tool in future studies to rank n-3 FA status of individuals.

Dietary methods and biomarkers of omega 3 fatty acids: a systematic review

The aims of the present study were to review the validity of dietary methods used to measure the usual long chain (LC) omega-3 polyunsaturated fatty acid (n-3 PUFA) intake of a population and to assess the usefulness of different biomarkers of n-3 PUFA in healthy humans. Two systematic literature searches were conducted until May 2011 to update previous systematic reviews. The first literature search aimed to find studies validating the methodology used for measuring the dietary intake of n-3 PUFA. The second search aimed to find human intervention studies in which n-3 PUFA status changed after 2 weeks of n-3 PUFA supplementation. Sixteen studies were identified for inclusion in the first review. Correlation coefficients between fatty acids in subcutaneous fat or blood lipids and dietary intake of n-3 PUFA from different questionnaires were similar. Subcutaneous fat has been reported as the best reference method for some authors, and these studies showed moderate correlation coefficients with no dietary intake method being superior to any other. As for the evaluation of biomarkers of docosahexaenoic acid (DHA, 22 : 6 n-3) and eicosapentaenoic acid (EPA, 20 : 5n-3) status in response to supplementation, the new search reaffirmed and reinforced the evidence supporting that plasma phospholipid DHA, erythrocyte DHA, and platelet DHA were all effective and robust biomarkers of DHA status. Our findings only confirmed earlier studies and did not provide evidence for reaching new conclusions.

A restricted cubic spline approach to assess the association between high fat fish intake and red blood cell EPA + DHA content

BACKGROUND AND AIMS

Fish, especially fatty fish, are the main contributor to eicosapentaenoic (EPA) and docosahexaenoic (DHA) intake. EPA and DHA concentrations in red blood cells (RBC) has been proposed as a cardiovascular risk factor, with <4% and >8% associated with the lowest and greatest protection, respectively. The relationship between high fat fish (HFF) intake and RBC EPA + DHA content has been little investigated on a wide range of fish intake, and may be non-linear. We aimed to study the shape of this relationship among high seafood consumers.

METHODS AND RESULTS

Seafood consumption records and blood were collected from 384 French heavy seafood consumers and EPA and DHA were measured in RBC. A multivariate linear regression was performed using restricted cubic splines to consider potential non-linear associations. Thirty-six percent of subjects had an RBC EPA + DHA content lower than 4% and only 5% exceeded 8%. HFF consumption was significantly associated with RBC EPA + DHA content (P [overall association] = 0.021) adjusted for sex, tobacco status, study area, socioeconomic status, age, alcohol, other seafood, meat, and meat product intakes. This relationship was non-linear: for intakes higher than 200 g/wk, EPA + DHA content tended to stagnate. Tobacco status and fish contaminants were negatively associated with RBC EPA + DHA content.

CONCLUSION

Because of the saturation for high intakes, and accounting for the concern with exposure to trace element contaminants, intake not exceeding 200 g should be considered.

Dietary patterns are associated with disease risk among participants in the Women's Health Initiative Observational Study

Coronary heart disease (CHD) is the leading cause of death in women. A nested case-control study tested whether dietary patterns predicted CHD events among 1224 participants in the Women's Health Initiative-Observational Study (WHI-OS) with centrally confirmed CHD, fatal or nonfatal myocardial infarct compared to 1224 WHI-OS controls matched for age, enrollment date, race/ethnicity, and absence of CHD at baseline or follow-up. The first six principal components explained >75% of variation in dietary intakes and K-mean analysis based on these six components produced three clusters. Diet cluster 1 was rich in carbohydrate, vegetable protein, fiber, dietary vitamin K, folate, carotenoids, α-linolenic acid [18:3(n-3)], linoleic acid [18:2(n-6)], and supplemental calcium and vitamin D. Diet cluster 2 was rich in total and animal protein, arachidonic acid [20:4(n-6)], DHA [22:6(n-3)], vitamin D, and calcium. Diet cluster 3 was rich in energy, total fat, and trans fatty acids (all P < 0.01). Conditional logistic regression analysis demonstrated diet cluster 1 was associated with lower CHD risk than diet cluster 2 (reference group) adjusted for smoking, education, and physical activity [OR = 0.79 (95% CI = 0.64, 0.99); P = 0.038]. This difference was not significant after adjustment for BMI and systolic blood pressure. Diet cluster 3 was associated with higher CHD risk than diet cluster 2 [OR = 1.28 (95% CI = 1.04, 1.57); P = 0.019], but this difference did not remain significant after adjustment for smoking, education, and physical activity. Within this WHI-OS cohort, distinct dietary patterns may be associated with subsequent CHD outcomes.

Associations of plasma phospholipid omega-6 and omega-3 polyunsaturated Fatty Acid levels and MRI measures of cardiovascular structure and function: the multiethnic study of atherosclerosis

Background. The association between plasma omega-6 fatty acids and cardiovascular disease (CVD) is unclear, and discrepancy remains concerning the cardiovascular benefit of the omega-3 fatty acid alpha-linolenic acid. Methods. Associations of plasma phospholipid fatty acid levels (arachidonic acid, linoleic acid, eicosapentaenoic acid, docosahexaenoic acid (DHA), and alpha-linolenic acid) with cardiac magnetic resonance imaging measures of left ventricular (LV) mass, LV volume, ejection fraction, stroke volume, and aortic distensibility were investigated in 1,274 adults. Results. Results of multivariate analysis showed no statistically significant associations of plasma omega-6 or omega-3 levels with cardiac magnetic resonance imaging measures. Stratification by gender revealed a positive association between DHA and LV mass in women (β = 1.89, P = 0.02; P interaction = 0.003) and a trend for a positive association between DHA and ejection fraction in men (β = 0.009, P = 0.05; P interaction = 0.03). Conclusion. Additional research is warranted to clarify the effects of plasma DHA on cardiac structure and function in women versus men.