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

Lipidomic studies reveal two specific circulating phosphatidylcholines as surrogate biomarkers of the omega-3 index

Optimal dietary intake of omega-3 long-chain polyunsaturated fatty acids (n3-LCPUFAs) is critical to human health across the lifespan. However, omega-3 index (O3I) determination is not routinely assessed due to complicated procedures for n3-LCPUFA analysis from the phospholipid (PL) fraction of erythrocytes. Herein, a high-throughput method for lipidomics based on multisegment injection-nonaqueous capillary electrophoresis-mass spectrometry was applied to identify circulating PLs as surrogate biomarkers of O3I in two randomized placebo-controlled trials. An untargeted lipidomic data workflow using a subgroup analysis of serum extracts from sunflower oil versus high-dose fish oil (FO)-supplemented participants revealed that ingested n3-LCPUFAs were primarily distributed as their phosphatidylcholines (PCs) relative to other PL classes. In both high-dose FO (5.0 g/day) and EPA-only trials (3.0 g/day), PC (16:0_20:5) was the most responsive PL, whereas PC (16:0_22:6) was selective to DHA-only supplementation. We also demonstrated that the sum concentration of both these PCs in fasting serum or plasma samples was positively correlated to the O3I following FO (r = 0.708, P = 1.02 × 10-11, n = 69) and EPA- or DHA-only supplementation (r = 0.768, P = 1.01 × 10-33, n = 167). Overall, DHA was more effective in improving the O3I (ΔO3I = 4.90 ± 1.33%) compared to EPA (ΔO3I = 2.99 ± 1.19%) in young Canadian adults who had a poor nutritional status with an O3I (3.50 ± 0.68%) at baseline. Our method enables the rapid assessment of the O3I by directly measuring two circulating PC species in small volumes of blood, which may facilitate screening applications for population and precision health.

Biomarker-based validation of a food frequency questionnaire for the assessment of omega-3 fatty acid status in a healthy Iranian population

There is no valid instrument to assess n-3 polyunsaturated fatty acids (n-3 PUFAs) intake in Iran. This study aims to develop a food frequency questionnaire (FFQ) that estimates the intake of n-3 PUFA and validate it in a healthy Iranian population based on the n-3 PUFA content of red blood cells (RBCs) and a 3-day food record (FR). A healthy population (n = 221) was recruited between February and July 2021. Participants completed the new FFQ and 3-day FR to evaluate the average intake of n-3 PUFAs. We used gas chromatography to assess the n-3 PUFA content of RBCs. To validate the FFQ based on FR and biomarker as references, the correlation coefficient was calculated. According to the Bland-Altman plots, a good agreement was found between the new FFQ and FR. Moreover, absolute intake values of ALA, EPA, DPA, DHA, and total n-3 PUFAs based on FFQ were positively correlated to their respective RBC membrane levels (coefficients between 0.205 and 0.508, p < 0.005) and FR (coefficients between 0.771 and 0.827, p < 0.001). This new FFQ is a valid instrument that can be applied to estimate the n-3 PUFA status of healthy Iranian adults.

Sex differences in hippocampal-dependent memory and the hippocampal lipidome in adolescent rats raised on diets with or without DHA

Recent studies suggest the effects of DHA supplementation on human memory may differ between females and males during infancy, adolescence, and early adulthood, but the underlying mechanisms are not clear. As a result, this study sought to examine the spatial memory and brain lipidomic profiles in female and male adolescent rats with or without a DHA-enriched diet that began perinatally with the supplementation of dams. Spatial learning and memory were examined in adolescent rats using the Morris Water Maze beginning at 6 weeks of age and animals were sacrificed at 7 weeks of age to permit isolation of brain tissue and blood samples. Behavioral testing showed that there was a significant diet x sex interaction for two key measures of spatial memory (distance to zone and time spent in the correct quadrant during the probe test), with female rats benefiting the most from DHA supplementation. Lipidomic analyses suggest levels of arachidonic acid (ARA) and n-6 docosapentaenoic acid (DPA) containing phospholipid species were lower in the hippocampus of DHA supplemented compared with control animals, and principal component analyses revealed a potential dietary treatment effect for hippocampal PUFA. Females fed DHA had slightly more PE P-18:0_22:6 and maintained levels of PE 18:0_20:4 in the hippocampus in contrast with males fed DHA. Understanding how DHA supplementation during the perinatal and adolescent periods changes cognitive function in a sex-specific manner has important implications for determining the dietary requirements of DHA. This study adds to previous work highlighting the importance of DHA for spatial memory and provides evidence that further research needs to consider how DHA supplementation can cause sex-specific changes.

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.

The Omega-3 Index Response to an 8 Week Randomized Intervention Containing Three Fatty Fish Meals Per Week Is Influenced by Adiposity in Overweight to Obese Women

Background

The Dietary Guidelines for Americans (DGA) recommends consuming ~225 g/wk of a variety of seafood providing &gt;1.75 g/wk of long-chain omega-3 fatty acids to reduce cardiovascular disease risk, however individual responses to treatment vary.

Objective

This study had three main objectives. First, to determine if a DGA-conforming diet (DGAD), in comparison to a typical American diet (TAD), can increase the omega-3 index (OM3I), i.e., the red blood cell mol% of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA). Second, to identify factors explaining variability in the OM3I response to dietary treatment. Third to identify factors associated with the baseline OM3I.

Design

This is a secondary analysis of a randomized, double-blind 8 wk dietary intervention of overweight/obese women fed an 8d rotating TAD (n = 20) or DGAD (n = 22) registered at www.clinicaltrials.gov as NCT02298725. The DGAD-group consumed 240 g/wk of Atlantic farmed salmon and albacore tuna in three meals with an estimated EPA + DHA of 3.7 ± 0.6 g/wk. The TAD-group consumed ~160 g/wk of farmed white shrimp and a seafood salad containing imitation crab in three meal with an estimated EPA + DHA of 0.45 ± 0.05 g/wk. Habitual diet was determined at baseline, and body composition was determined at 0 and 8wks. Red blood cell fatty acids were measured at 0, 2 and 8 wk.

Results

At 8 wk, the TAD-group OM3I was unchanged (5.90 ± 1.35–5.80 ± 0.76%), while the DGAD-group OM3I increased (5.63 ± 1.27–7.33 ± 1.36%; p &lt; 0.001). In the DGAD-group 9 of 22 participants achieved an OM3I &gt;8%. Together, body composition and the baseline OM3I explained 83% of the response to treatment variability. Baseline OM3I (5.8 ± 1.3%; n = 42) was negatively correlated to the android fat mass (p = 0.0007) and positively correlated to the FFQ estimated habitual (EPA+DHA) when expressed as a ratio to total dietary fat (p = 0.006).

Conclusions

An 8 wk TAD did not change the OM3I of ~6%, while a DGAD with 240 g/wk of salmon and albacore tuna increased the OM3I. Body fat distribution and basal omega-3 status are primary factors influencing the OM3I response to dietary intake in overweight/obese women.

Omega-3 polyunsaturated fatty acid intake and plasma fatty acids of school going Indian children - a cross-sectional study

Long-chain omega-3 polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) play an essential role in cognitive and behavioural changes among school going children. This study delineates the dietary omega-3 PUFA [alpha-Linolenic acid (ALA), DHA, and EPA] intake and plasma fatty acids levels among school-going children. This is a cross-sectional study purely observational in nature, wherein 625 apparently healthy boys and girls aged between 7 and 13 years were selected from five different schools of Hyderabad. Dietary information on omega-3 PUFA (ALA, DHA, and EPA) intake was collected using a food frequency questionnaire. Plasma fatty acid concentrations were measured in 34% of sub-sample using standard gas chromatography. The study revealed that the average dietary intakes of omega-3 PUFA, ALA, DHA, and EPA were 55.46, 15.82, 35.59, 4.06 mg/day, respectively. There was a significant difference in mean DHA intake among gender and age group [girls (38.64±1.45 mg/day), boys (31.80±1.38 mg/day) p < 0.001] and [7-10 years (31.75±1.38 mg/day), 11-13 years (38.07±1.40 mg/day) p < 0.01]. The mean plasma DHA and DPA levels of overall subjects were 0.98 nmol% and 0.18nmol% respectively which was comparable among different gender, age and BMI-for age groups. There was a positive correlation between dietary DHA intake and plasma DHA level [ρ=0.376 (p < 0.001)]. The current study demonstrated that the omega-3 PUFA intake in school going children was less and reinforces the importance of increasing the omega-3 PUFA intake through diet and supplements.

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.

n-3 Docosapentaenoic Acid Intake and Relationship with Plasma Long-Chain n-3 Fatty Acid Concentrations in the United States: NHANES 2003-2014

The long-chain n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), play a crucial role in health, but previous National Health and Nutrition Examination Survey (NHANES) analyses have shown that EPA and DHA intake in the United States is far below recommendations (~250-500 mg/day EPA + DHA). Less is known about docosapentaenoic acid (DPA), the metabolic intermediate of EPA and DHA; however, evidence suggests DPA may be an important contributor to long-chain n-3 fatty acid intake and impart unique benefits. We used NHANES 2003-2014 data (n = 45,347) to assess DPA intake and plasma concentrations, as well as the relationship between intake and plasma concentrations of EPA, DPA, and DHA. Mean DPA intake was 22.3 ± 0.8 mg/day from 2013 to 2014, and increased significantly over time (p < 0.001), with the lowest values from 2003 to 2004 (16.2 ± 1.2 mg/day). DPA intake was higher in adults (20-55 years) and seniors (55+ years) compared to younger individuals. In regression analyses, DPA intake was a significant predictor of plasma EPA (β = 138.5; p < 0.001) and DHA (β = 318.9; p < 0.001). Plasma DPA was predicted by EPA and DHA intake (β = 13.15; p = 0.001 and β = 7.4; p = 0.002), but not dietary DPA (p = 0.3). This indicates that DPA intake is not a good marker of plasma DPA status (or vice versa), and further research is needed to understand the factors that affect the interconversion of EPA and DPA. These findings have implications for future long-chain n-3 fatty acids dietary recommendations.

Omega-3 supplementation with resistance training does not improve body composition or lower biomarkers of inflammation more so than resistance training alone in older men

The purpose of this study was to evaluate the effectiveness of 3.0 g/d of omega-3 fatty acid (eicosapentaenoic acid and docosahexaenoic acid) supplementation combined with progressive resistance training to improve body composition and lower inflammatory cytokines in older men when compared to placebo and resistance training. We hypothesized that completing a 12-week omega-3 supplementation period along with whole body resistance exercise (3 times/wk) would result in a significantly greater improvement in lean tissue mass as well as a significant decrease in interleukin-6 and tumor necrosis factor-α when compared to placebo. A total of 23 older men (≥65 years old) were randomized to an omega-3 supplementation group (n = 11) or placebo group (n = 12), and all the participants completed the same whole body progressive resistance training program. Baseline and 12-week data collection included body composition, muscle strength, functional ability, and inflammatory cytokines. Results indicated a significant main effect for time (all P < .05) for percent body fat (-2.5%), lean tissue mass (+1.1%), lumbar bone mineral density (+1.1%), hip bone mineral content (+1.1%), chest press strength (+31%), leg press strength (+37%), timed-up-and-go (-6.6%), and 6-minute walk distance (+4.5%) from baseline to post 12 weeks. No significant effects were noted for the 2 inflammatory cytokines measured (P > .05). We conclude that progressive resistance training exercise is an excellent method to enhance parameters of body composition, skeletal muscle strength, and functional ability in older men, whereas omega-3 supplementation did nothing to enhance these parameters or influence inflammatory biomarkers.

Impact of red and processed meat and fibre intake on treatment outcomes among patients with chronic inflammatory diseases: protocol for a prospective cohort study of prognostic factors and personalised medicine

INTRODUCTION

Chronic inflammatory diseases (CIDs) are frequently treated with biological medications, specifically tumour necrosis factor inhibitors (TNFi)). These medications inhibit the pro-inflammatory molecule TNF alpha, which has been strongly implicated in the aetiology of these diseases. Up to one-third of patients do not, however, respond to biologics, and lifestyle factors are assumed to affect treatment outcomes. Little is known about the effects of dietary lifestyle as a prognostic factor that may enable personalised medicine. The primary outcome of this multidisciplinary collaborative study will be to identify dietary lifestyle factors that support optimal treatment outcomes.

METHODS AND ANALYSIS

This prospective cohort study will enrol 320 patients with CID who are prescribed a TNFi between June 2017 and March 2019. Included among the patients with CID will be patients with inflammatory bowel disease (Crohn's disease and ulcerative colitis), rheumatic disorders (rheumatoid arthritis, axial spondyloarthritis, psoriatic arthritis), inflammatory skin diseases (psoriasis, hidradenitis suppurativa) and non-infectious uveitis. At baseline (pretreatment), patient characteristics will be assessed using patient-reported outcome measures, clinical assessments of disease activity, quality of life and lifestyle, in addition to registry data on comorbidity and concomitant medication(s). In accordance with current Danish standards, follow-up will be conducted 14-16 weeks after treatment initiation. For each disease, evaluation of successful treatment response will be based on established primary and secondary endpoints, including disease-specific core outcome sets. The major outcome of the analyses will be to detect variability in treatment effectiveness between patients with different lifestyle characteristics.

ETHICS AND DISSEMINATION

The principle goal of this project is to improve the quality of life of patients suffering from CID by providing evidence to support dietary and other lifestyle recommendations that may improve clinical outcomes. The study is approved by the Ethics Committee (S-20160124) and the Danish Data Protecting Agency (2008-58-035). Study findings will be disseminated through peer-reviewed journals, patient associations and presentations at international conferences.

TRIAL REGISTRATION NUMBER

NCT03173144; Pre-results.

Palmitate and oleate co-treatment increases myocellular protein content via impaired protein degradation

OBJECTIVES

Protein balance is a crucial determinant of myocellular size and function. The effects of fatty acids on myocellular protein balance remain controversial. The aim of this study was to determine the direct effects of a mixed-species fatty acid environment on myocellular protein synthesis and degradation.

METHODS

C2C12 myotubes were cultured in media containing equimolar (250 μM) palmitic acid and oleate (PO) or bovine serum albumin control for ≤72 h. Myocellular protein balance was determined via incorporation (synthesis) or release (degradation) of ³H-tyrosine after 24, 48, and 72 h of treatment. Expression of major proteolytic genes was measured by reverse transcription polymerase chain reaction.

RESULTS

PO significantly increased myocellular protein content at 24, 48, and 72 h. Basal myocellular protein synthesis was unchanged by PO. However, PO significantly decreased basal rate of protein degradation at 24 h and this effect persisted throughout 72 h of treatment. Expression of the proteolytic genes Atrogin-1 (MAFbx), MuRF-1, LC3, and ATG4 B, was reduced during the 72 h PO.

CONCLUSIONS

A mixed-species fatty acid environment increases myocellular protein content by decreasing the rate of protein degradation, which may be regulated at the level of gene transcription.

DHA Mitigates Autistic Behaviors Accompanied by Dopaminergic Change in a Gene/Prenatal Stress Mouse Model

Autism Spectrum Disorder (ASD) is characterized by impairments in social interaction, social communication, and repetitive and stereotyped behaviors. Recent work has begun to explore gene × environmental interactions in the etiology of ASD. We previously reported that prenatal stress exposure in stress-susceptible heterozygous serotonin transporter (SERT) KO pregnant dams in a mouse model resulted in autism-like behavior in the offspring (SERT/S mice). The association between prenatal stress and ASD appears to be affected by maternal SERT genotype in clinical populations as well. Using the mouse model, we examined autistic-like behaviors in greater detail, and additionally explored whether diet supplementation with docosahexaenoic acid (DHA) may mitigate the behavioral changes. Only male SERT/S mice showed social impairment and stereotyped behavior, and DHA supplementation ameliorated some of these behaviors. We also measured monoamine levels in the SERT/S mice after three treatment paradigms: DHA-rich diet continuously from breeding (DHA diet), DHA-rich diet only after weaning (CTL/DHA diet) and control diet only (CTL diet). The dopamine (DA) content in the striatum was significantly increased in the SERT/S mice compared with wild-type (WT) mice, whereas no difference was observed with noradrenaline and serotonin content. Moreover, DA content in the striatum was significantly reduced in the SERT/S mice with the DHA-rich diet provided continuously from breeding. The results indicate that autism-associated behaviors and changes in the dopaminergic system in this setting can be mitigated with DHA supplementation.

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.

Mercury Exposure and Heart Rate Variability: a Systematic Review

BACKGROUND

Mercury affects the nervous system and has been implicated in altering heart rhythm and function. We sought to better define its role in modulating heart rate variability, a well-known marker of cardiac autonomic function.

DESIGN

This is a systematic review study.

METHODS

We searched PubMed, Embase, TOXLINE, and DART databases without language restriction. We report findings as a qualitative systematic review because heterogeneity in study design and assessment of exposures and outcomes across studies, as well as other methodological limitations of the literature, precluded a quantitative meta-analysis.

RESULTS

We identified 12 studies of mercury exposure and heart rate variability in human populations (ten studies involving primarily environmental methylmercury exposure and two studies involving occupational exposure to inorganic mercury) conducted in Japan, the Faroe Islands, Canada, Korea, French Polynesia, Finland, and Egypt. The association of prenatal mercury exposure with lower high-frequency band scores (thought to reflect parasympathetic activity) in several studies, in particular the inverse association of cord blood mercury levels with the coefficient of variation of the R-R intervals and with low-frequency and high-frequency bands at 14 years of age in the Faroe Islands birth cohort study, suggests that early mercury exposure could have a long-lasting effect on cardiac parasympathetic activity. Studies with later environmental exposures to mercury in children or in adults were heterogeneous and did not show consistent associations.

CONCLUSIONS

The evidence was too limited to draw firm causal inferences. Additional research is needed to elucidate the effects of mercury on cardiac autonomic function, particularly as early-life exposures might have lasting impacts on cardiac parasympathetic function.

Red Blood Cell Docosapentaenoic Acid (DPA n-3) is Inversely Associated with Triglycerides and C-reactive Protein (CRP) in Healthy Adults and Dose-Dependently Increases Following n-3 Fatty Acid Supplementation

The role of the long-chain omega-3 (n-3) fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in lipid metabolism and inflammation has been extensively studied; however, little is known about the relationship between docosapentaenoic acid (DPA, 22:5 n-3) and inflammation and triglycerides (TG). We evaluated whether n-3 DPA content of red blood cells (RBC) was associated with markers of inflammation (interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), and C-reactive protein (CRP) and fasting TG prior to n-3 supplementation in two studies (Study 1: n = 115, aged 20-44 years, body mass index (BMI) 20-30 kg/m2, TG = 34-176 mg/dL; Study 2: n = 28, aged 22-65 years, BMI 24-37 kg/m2, TG = 141-339 mg/dL). We also characterized the dose-response effects of n-3 fatty acid supplementation on RBC n-3 DPA after five months of supplementation with fish oil (Study 1: 0, 300, 600, 900, and 1800 mg/day EPA + DHA) and eight weeks of prescription n-3 ethyl esters (Study 2: 0, 850, and 3400 mg/day EPA + DHA). In Study 1, RBC n-3 DPA was inversely correlated with CRP (R2 = 36%, p < 0.001) and with fasting TG (r = -0.30, p = 0.001). The latter finding was replicated in Study 2 (r = -0.33, p = 0.04). In both studies, n-3 supplementation significantly increased RBC n-3 DPA dose-dependently. Relative increases were greater for Study 1, with increases of 29%-61% vs. 14%-26% for Study 2. The associations between RBC n-3 DPA, CRP, and fasting TG may have important implications for the prevention of atherosclerosis and chronic inflammatory diseases and warrant further study.

Meta-Analysis of Long-Chain Omega-3 Polyunsaturated Fatty Acids (LCω-3PUFA) and Prostate Cancer

We conducted a systematic review and meta-analysis to estimate the potential association between LCω-3PUFAs and prostate cancer (PC). A comprehensive literature search was performed through 2013 to identify prospective studies that examined dietary intakes of long-chain omega-3 polyunsaturated fatty acids (LCω-3PUFA) or blood biomarkers of LCω-3PUFA status and risk of PC. Random-effects meta-analyses were conducted to generate summary relative risk estimates (SRREs) for LCω-3PUFAs and total PC, and by stage and grade. Subgroup analyses were also conducted for specific fatty acids and other study characteristics. Twelve self-reported dietary intake and 9 biomarker studies from independent study populations were included in the analysis, with 446,243 and 14,897 total participants, respectively. No association between LCω-3PUFAs and total PC was observed (SRRE = 1.00, 95% CI: 0.93–1.09) for the dietary intake studies (high vs. low LCω-3PUFAs category comparison) or for the biomarker studies (SRRE of 1.07, 95% CI: 0.94–1.20). In general, most summary associations for the dietary intake studies were in the inverse direction, whereas the majority of summary associations for the biomarker studies were in the positive direction, but all were weak in magnitude. The results from this meta-analysis do not support an association between LCω-3PUFAs and PC.

Women who take n-3 long-chain polyunsaturated fatty acid supplements during pregnancy and lactation meet the recommended intake

The aim of the current study was to estimate total intake and dietary sources of eicosapentaenoic acid (EPA), docosapentanoic (DPA), and docosahexaenoic acid (DHA) and compare DHA intakes with the recommended intakes in a cohort of pregnant and lactating women. Twenty-four-hour dietary recalls and supplement intake questionnaires were collected from 600 women in the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort at each trimester of pregnancy and 3 months postpartum. Dietary intake was estimated in 2 ways: by using a commercial software program and by using a database created for APrON. Only 27% of women during pregnancy and 25% at 3 months postpartum met the current European Union (EU) consensus recommendation for DHA. Seafood, fish, and seaweed products contributed to 79% of overall n-3 long-chain polyunsaturated fatty acids intake from foods, with the majority from salmon. The estimated intake of DHA and EPA was similar between databases, but the estimated DPA intake was 20%-30% higher using the comprehensive database built for this study. Women who took a supplement containing DHA were 10.6 and 11.1 times more likely to meet the current EU consensus recommendation for pregnancy (95% confidence interval (CI): 6.952-16.07; P<0.001) and postpartum (95% CI: 6.803-18.14; P<0.001), respectively. Our results suggest that the majority of women in the cohort were not meeting the EU recommendation for DHA during pregnancy and lactation, but taking a supplement significantly improved the likelihood that they would meet recommendations.

Comprehensive profiling of plasma fatty acid concentrations in young healthy Canadian adults

Circulating fatty acids (FA) are associated with a multitude of chronic diseases. However, a major gap in establishing such relationships is the lack of accepted fatty acid reference ranges representing healthy individuals. Data on validated FA reference ranges would provide a better understanding of study baseline measures and aid in the evaluation and interpretation of pharmaceutical or dietary interventions. Reference ranges for plasma FA levels have been reported in a few small studies and on a limited number of FA. Therefore, we determined the average and percentiles of a broad set of 61 FA (C14 - C24:1) from plasma total lipids from an ethnically diverse population of healthy young Canadian males and females (Total n = 826). Plasma concentrations of some of the major FA ranged from 0.3 to 4.1 mmol/L for palmitic acid, 0.1 to 1.0 mmol/L for stearic acid, 0.03 to 3.2 mmol/L for oleic acid, 0.2 to 5.0 mmol/L for linoleic acid (LA), 12.0 to 186.9 μmol/L for α-linolenic acid, and 7.2 to 237.5 μmol/L for docosahexaenoic acid (DHA). Males had significantly higher plasma concentrations of γ-linolenic acid (GLA) and n-3 docosapentaenoic acid and lower concentrations of palmitoleic acid, LA and DHA than females. Comparison of FA concentrations between Caucasians, East Asians and South Asians revealed that South Asians had significantly lower levels of palmitoleic acid (p < 0.01) and oleic acid (p = 0.01) while East Asians had lower levels of GLA (p = 0.02) and dihomo-γ-linolenic acid (p = 0.03). Overall, these data provide a comprehensive set of quantitative values that profiles a small cohort of Canadians which highlights the utility of establishing validated FA reference ranges that may be used to understand how deficient, suboptimal, or excess amounts of a given FA may be associated with chronic disease.

Validation of fatty acid intakes estimated by a food frequency questionnaire using erythrocyte fatty acid profiling in the Montreal Heart Institute Biobank

BACKGROUND

To improve the prevention, treatment and risk prediction of cardiovascular diseases, genetic markers and gene-diet interactions are currently being investigated. The Montreal Heart Institute (MHI) Biobank is suitable for such studies because of its large sample size (currently, n = 17 000), the availability of biospecimens, and the collection of data on dietary intakes of saturated (SFAs) and n-3 and n-6 polyunsaturated (PUFAs) fatty acids estimated from a 14-item food frequency questionnaire (FFQ). We tested the validity of the FFQ by correlating dietary intakes of these fatty acids with their red blood cell (RBC) content in MHI Biobank participants.

METHODS

Seventy-five men and 75 women were selected from the Biobank. We successfully obtained RBC fatty acids for 142 subjects using gas chromatography coupled to mass spectrometry. Spearman correlation coefficients were used to test whether SFA scores and daily intakes (g day(-1)) of n-3 and n-6 PUFAs correlate with their RBC content.

RESULTS

Based on covariate-adjusted analyses, intakes of n-3 PUFAs from vegetable sources were significantly correlated with RBC α-linolenic acid levels (ρ = 0.23, P = 0.007), whereas n-3 PUFA intakes from marine sources correlated significantly with RBC eicosapentaenoic acid (ρ = 0.29, P = 0.0008) and docosahexaenoic acid (ρ = 0.41, P = 9.2 × 10(-7)) levels. Intakes of n-6 PUFAs from vegetable sources correlated with RBC linoleic acid (ρ = 0.18, P = 0.04). SFA scores were not correlated with RBC total SFAs.

CONCLUSIONS

The MHI Biobank 14-item FFQ can appropriately estimate daily intakes of n-3 PUFAs from vegetable and marine sources, as well as vegetable n-6 PUFAs, which enables the possibility of using these data in future studies.

Potential of long-chain n-3 polyunsaturated fatty acids in melanoma prevention

The possible antineoplastic activity of dietary long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs) has been supported by ample preclinical studies that have identified a number of molecular factors and pathways affected by these fatty acids and involved in cell growth, apoptosis, invasion, and angiogenesis. The aim of this critical review is to assess the current state of knowledge on the potential anticancer effects of LC n-3 PUFAs against malignant melanoma, one of the most common cancers among Western populations. The results of preclinical as well as human observational and interventional studies investigating the effects of LC n-3 PUFAs in melanoma were examined. Overall, the analysis of the literature reveals that, even though a large body of information is available, further effort is needed to identify the main molecular targets of LC n-3 PUFAs in melanoma. Moreover, additional well-designed human observational studies are essential to shed further light on the issue. The results of these studies could provide support and specific information for the development of clinical studies, especially those performed in combination with conventional or innovative antineoplastic therapies.

Age and sex differences in the incorporation of EPA and DHA into plasma fractions, cells and adipose tissue in humans

The aim of the present study was to determine whether age and sex influence both the status and incorporation of EPA and DHA into blood plasma, cells and tissues. The study was a double-blind, randomised, controlled intervention trial, providing EPA plus DHA equivalent to 0, 1, 2 or 4 portions of oily fish per week for 12 months. The participants were stratified by age and sex. A linear regression model was used to analyse baseline outcomes, with covariates for age or sex groups and by adjusting for BMI. The change in outcomes from baseline to 12 months was analysed with additional adjustment for treatment and average compliance. Fatty acid profiles in plasma phosphatidylcholine, cholesteryl esters, NEFA and TAG, mononuclear cells (MNC), erythrocyte membranes, platelets, buccal cells (BU) and adipose tissue (AT) were determined. At baseline, EPA concentrations in plasma NEFA and DHA concentrations in MNC, BU and AT were higher in females than in males (all P< 0·05). The concentrations of EPA in AT (P= 0·003) and those of DHA in plasma TAG (P< 0·01) and AT (P< 0·001) were higher with increasing age. Following 12-month supplementation with EPA plus DHA, adjusted mean difference for change in EPA concentrations in plasma TAG was significantly higher in females than in males (P< 0·05) and was greater with increasing age (P= 0·02). Adjusted mean difference for change in DHA concentrations in AT was significantly smaller with increasing age (P= 0·02). Although small differences in incorporation with age and sex were identified, these were not of sufficient magnitude to warrant a move away from population-level diet recommendations for n-3 PUFA.

Estimation of eicosapentaenoic acid and docosahexaenoic acid intakes in pregnant Japanese women without nausea by using a self-administered diet history questionnaire

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intakes during pregnancy affect fetal development and maternal mental health; therefore, an accurate assessment of EPA and DHA intakes is required. We hypothesized that a self-administered diet history questionnaire (DHQ) that was developed for non-pregnant adults could be used for estimating EPA and DHA intakes in pregnant Japanese women; thus, we evaluated the validity and reproducibility of the DHQ during pregnancy. We recruited 262 healthy participants with singleton pregnancies during their second trimester at a university hospital in Tokyo between June 2010 and July 2011. Plasma concentrations of EPA and DHA were measured as reference values. Fifty-eight women completed the DHQ twice, within a 4- to 5-week period to assess the reproducibility of the results. Among the participants without pregnancy-associated nausea (n = 180), significantly positive correlations were observed between energy-adjusted intakes and plasma concentrations of EPA (r(s) = 0.388), DHA (r(s) = 0.264), and EPA + DHA (r(s) = 0.328). More than 60% of the participants without nausea fell into the same or adjacent quintiles according to energy-adjusted intakes and plasma concentrations of EPA, DHA, and EPA + DHA. Meanwhile, among the participants with nausea, a low correlation for EPA and no correlation for DHA and EPA + DHA were found. Intraclass correlation coefficients for the 2-time DHQ measurements were 0.691 (EPA) and 0.663 (DHA). The results indicate that the DHQ has an acceptable level of validity and reproducibility for assessing EPA, DHA, and EPA + DHA intakes in pregnant Japanese women without nausea.

Association between plasma omega-3 fatty acids and cardiovascular disease risk factors

The consumption of omega-3 (n-3) fatty acids (FA), namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been linked to reduced cardiovascular disease (CVD) risk. The objective of this study was to examine the relation between n-3 FA in plasma phospholipid (PL) levels and CVD risk factors. n-3 FA levels in plasma PL were determined using gas chromatography in 100 obese (body mass index (BMI), ≥30 kg·m−2) and 100 nonobese selected individuals from the Quebec City metropolitan area. The CVD risk factors analysed were BMI, blood pressure, plasma lipids levels, and fasting plasma glucose. Significantly higher levels of alpha-linolenic acid (ALA) and docosapentaenoic acid (DPA) were observed in obese subjects, whereas significantly higher levels of DHA were observed in nonobese subjects. For CVD risk factors, ALA levels were positively correlated with plasma triglyceride concentrations and negatively associated with diastolic blood pressure. None of the CVD risk factors studied was linked to EPA levels. In addition, DPA was negatively related to high-density lipoprotein cholesterol (HDL-C) and positively correlated with the total cholesterol/HDL-C ratio. DHA levels were negatively correlated with BMI, waist circumference, and plasma triglyceride levels, whereas a positive association was observed with HDL-C levels. Total n-3 FA percentages were negatively correlated with BMI. In conclusion, higher DHA percentages in plasma PL are associated with a more favourable CVD risk profile, whereas higher DPA percentages in plasma PL are associated with a more deteriorated CVD risk profile.