Fatty acid composition of plasma, erythrocytes and adipose: their correlations and effects of age and sex

Sex, Body Mass Index, and APOE4 Increase Plasma Phospholipid-Eicosapentaenoic Acid Response During an ω-3 Fatty Acid Supplementation: A Secondary Analysis

BACKGROUND

The brain is concentrated with omega (ω)-3 (n-3) fatty acids (FAs), and these FAs must come from the plasma pool. The 2 main ω-3 FAs, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), must be in the form of nonesterified fatty acid (NEFA) or esterified within phospholipids (PLs) to reach the brain. We hypothesized that the plasma concentrations of these ω-3 FAs can be modulated by sex, body mass index (BMI, kg/m2), age, and the presence of the apolipoprotein (APO) E-ε4 allele in response to the supplementation.

OBJECTIVES

This secondary analysis aimed to determine the concentration of EPA and DHA within plasma PL and in the NEFA form after an ω-3 FA or a placebo supplementation and to investigate whether the factors change the response to the supplement.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted. Participants were randomly assigned to either an ω-3 FA supplement (DHA 0.8 g and EPA 1.7 g daily) or to a placebo for 6 mo. FAs from fasting plasma samples were extracted and subsequently separated into PLs with esterified FAs and NEFAs using solid-phase extraction. DHA and EPA concentrations in plasma PLs and as NEFAs were quantified using gas chromatography.

RESULTS

EPA and DHA concentrations in the NEFA pool significantly increased by 31%-71% and 42%-82%, respectively, after 1 and 6 mo of ω-3 FA supplementation. No factors influenced plasma DHA and EPA responses in the NEFA pool. In the plasma PL pool, DHA increased by 83%-109% and EPA by 387%-463% after 1 and 6 mo of ω-3 FA supplementation. APOE4 carriers, females, and individuals with a BMI of ≤25 had higher EPA concentrations than noncarriers, males, and those with a BMI of >25, respectively.

CONCLUSIONS

The concentration of EPA in plasma PLs are modulated by APOE4, sex, and BMI. These factors should be considered when designing clinical trials involving ω-3 FA supplementation. This trial was registered at clinicaltrials.gov as NCT01625195.

Effects of Long-Chain Polyunsaturated Fatty Acids in Combination with Lutein and Zeaxanthin on Episodic Memory in Healthy Older Adults

Arachidonic acid (ARA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), which are long-chain polyunsaturated fatty acids (LCPUFAs), as well as lutein (L) and zeaxanthin (Z), can potentially improve brain function. However, the effect of a combination of these components (LCPUFAs + LZ) on memory function in healthy older individuals remains unclear. This study aimed to determine if LCPUFAs + LZ-supplemented food could improve memory function. Exploratory and confirmatory trials (Trials 1 and 2, respectively) were conducted in healthy older Japanese individuals with memory complaints. We conducted randomized, double-blind, placebo-controlled, parallel-group trials. Participants were randomly allocated to two groups: placebo or LCPUFAs + LZ. LCPUFAs + LZ participants were provided with supplements containing ARA, DHA, EPA, L, and Z for 24 weeks in Trial 1 and 12 weeks in Trial 2. Memory functions were evaluated using Cognitrax before and after each trial. Combined analyses were performed for subgroups of participants with cognitive decline in Trials 1 and 2. The results showed that supplementation with LCPUFAs + LZ did not significantly affect memory function in healthy, non-demented, older individuals with memory complaints whereas it improved memory function in healthy, non-demented, older individuals with cognitive decline.

Adipose tissue n-3/n-6 fatty acids ratios versus n-3 fatty acids fractions as predictors of myocardial infarction

BACKGROUND

Tissue levels of n-3 polyunsaturated fatty acids (PUFAs) have been inversely related with risk of myocardial infarction (MI). Whether ratios of n-3 to n-6 PUFAs, reflecting both dietary intake of n-3 PUFAs and competing n-6 PUFAs, are better predictors of future MI than n-3 PUFA fractions is unclear. We aimed at investigating whether such ratios in adipose tissue better predict MI than n-3 PUFA fractions.

METHODS

Subcutaneous adipose tissue biopsies were obtained in a random sample (n=3,500) of the Diet, Cancer and Health cohort (n=57,053). Adipose tissue content of eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), alpha-linolenic acid (ALA), arachidonic acid (AA) and linoleic acid (LA) was determined using gas chromatography. Fractions of selected n-3 PUFAs and n-3/n-6 PUFA ratios were correlated to the 15-year occurrence of MI in a case-cohort design.

RESULTS

A total of 2,406 participants experienced an MI during follow-up. Adipose tissue total marine n-3 PUFAs, EPA+DHA, EPA, EPA/AA, DHA/AA and (EPA+DPA+DHA)/AA were all inversely associated with risk of incident MI. Evaluating the predictive power (Harrel's C-index) of the selected metrics, fractions of marine n-3 PUFAs and ratios of EPA/AA, DHA/AA, (EPA+DHA)/AA and (EPA+DPA+DHA)/AA all refined risk prediction over age and sex alone. At multivariable analyses, however, the above ratios were the only metrics providing additional risk prediction. Differences in ratios were related to differences in food intake.

CONCLUSIONS

Both adipose tissue n-3 PUFAs fractions and ratios of n-3 PUFAs/AA were associated with a lower occurrence of MI, but ratios provided superior risk prediction. Dietary strategies affecting n-3/n-6 PUFA ratios should be further investigated for prediction of MI with dietary interventions at the population level and in intervention studies.

Why Have the Benefits of DHA Not Been Borne Out in the Treatment and Prevention of Alzheimer's Disease? A Narrative Review Focused on DHA Metabolism and Adipose Tissue

Docosahexaenoic acid (DHA), an omega-3 fatty acid rich in seafood, is linked to Alzheimer's Disease via strong epidemiological and pre-clinical evidence, yet fish oil or other DHA supplementation has not consistently shown benefit to the prevention or treatment of Alzheimer's Disease. Furthermore, autopsy studies of Alzheimer's Disease brain show variable DHA status, demonstrating that the relationship between DHA and neurodegeneration is complex and not fully understood. Recently, it has been suggested that the forms of DHA in the diet and plasma have specific metabolic fates that may affect brain uptake; however, the effect of DHA form on brain uptake is less pronounced in studies of longer duration. One major confounder of studies relating dietary DHA and Alzheimer's Disease may be that adipose tissue acts as a long-term depot of DHA for the brain, but this is poorly understood in the context of neurodegeneration. Future work is required to develop biomarkers of brain DHA and better understand DHA-based therapies in the setting of altered brain DHA uptake to help determine whether brain DHA should remain an important target in the prevention of Alzheimer's Disease.

ω-3 and ω-6 Polyunsaturated Fatty Acids, Obesity and Cancer

Recently, nutraceutical bioactive compounds in foods have been discovered for their potential health benefits regarding the prevention of chronic disorders, such as cancer, and inflammatory, cardiovascular, and metabolic diseases. Dietary omega-3 polyunsaturated fatty acids (ω-3PUFAs), including alpha-linolenic acid, docosapentaenoic acid, and eicosapentaenoic acid, are mostly attractive. They are available for the customers worldwide from commonly used foods and/or as components of commercial food supplements. The anti-inflammatory and hypotriglyceridemic effects of these fatty acids are well known, whereas pro-inflammatory properties have been recognized in their dietary counterparts, the ω-6PUFAs. Both ω-3 and ω-6PUFAs contribute to the production of lipid mediators such as endocannabinoids that are notably involved in control of food intake, energy sensing, and food-related disorders. In this review, we present ω-3 and ω-6PUFAs and their derivatives, endocannabinoids; discuss the anti-obesity effects of ω-3PUFAs; their roles in inflammation and colorectal cancer development; and how their action can be co-preventative and co-therapeutic.

Effects of combining exercise with long-chain polyunsaturated fatty acid supplementation on cognitive function in the elderly: a randomised controlled trial

Multifactorial lifestyle intervention is known to be more effective for ameliorating cognitive decline than single factor intervention; however, the effects of combining exercise with long-chain polyunsaturated fatty acids (LCPUFA) on the elderlies' cognitive function remain unclear. We conducted a randomised, single-masked placebo-controlled trial in non-demented elderly Japanese individuals. Participants were randomly allocated to the exercise with LCPUFA, placebo, or no exercise with placebo (control) groups. Participants in the exercise groups performed 150 min of exercise per week, comprised resistance and aerobic training, for 24 weeks with supplements of either LCPUFA (docosahexaenoic acid, 300 mg/day; eicosapentaenoic acid, 100 mg/day; arachidonic acid, 120 mg/day) or placebo. Cognitive functions were evaluated by neuropsychological tests prior to and following the intervention. The per-protocol set analysis (n = 76) revealed no significant differences between the exercise and the control groups in changes of neuropsychological tests. Subgroup analysis for participants with low skeletal muscle mass index (SMI) corresponding to sarcopenia cut-off value showed changes in selective attention, while working memory in the exercise with LCPUFA group was better than in the control group. These findings suggest that exercise with LCPUFA supplementation potentially improves attention and working memory in the elderly with low SMI.

Relationship between whole blood omega-3 fatty acid levels and dorsal cingulate gray matter volume: Sex differences and implications for impulse control

During adolescence, the prefrontal cortex (PFC) undergoes substantial structural development, including cortical thinning, a process associated with improvements in behavioral control. The cingulate cortex is among the regions recruited in response inhibition and mounting evidence suggests cingulate function may be sensitive to availability of an essential dietary nutrient, omega-3 fatty acids (N3; i.e. EPA + DHA). Our primary aim was to investigate the relationship between a biomarker of omega-3 fatty acids -- percent of whole blood fatty acids as EPA + DHA (N3 Index) -- and cingulate morphology, in typically developing adolescent males (n = 29) and females (n = 33). Voxel-based morphometry (VBM) was used to quantify gray matter volume (GMV) in the dorsal region of the cingulate (dCC). Impulse control was assessed via caregiver report (BRIEF) and Go/No-Go task performance. We predicted that greater N3 Index in adolescents would be associated with less dCC GMV and better impulse control. Results revealed that N3 Index was inversely related to GMV in males, but not in females. Furthermore, males with less right dCC GMV exhibited better caregiver-rated impulse control. A simple mediation model revealed that, in males, N3 Index may indirectly impact impulse control through its association with right dCC GMV. Findings suggest a sex-specific link between levels of N3 and dCC structural development, with adolescent males more impacted by lower N3 levels than females. Identifying factors such as omega-3 fatty acid levels, which may modulate the neurodevelopment of response inhibition, is critical for understanding typical and atypical developmental trajectories associated with this core executive function.

ISSFAL Official Statement Number 6: The importance of measuring blood omega-3 long chain polyunsaturated fatty acid levels in research

A statement on measuring blood omega-3 long chain polyunsaturated fatty acid levels was developed and edited based on input from ISSFAL members and accepted by vote of the ISSFAL Board of Directors. Summary of Statement: Omega-3 long chain polyunsaturated fatty acid (n-3 LCPUFA) levels at baseline and post-intervention should be assessed and reported in future research to evaluate the efficacy of n-3 LCPUFA supplementation: b ecause; 1. there are numerous factors that affect n-3 LCPUFA levels in humans as described in the systematic literature review [1]; 2. assessing intake of n-3 LCPUFA from the diet and/or supplements is not sufficient to accurately determine n-3 LCPUFA levels in humans; 3. some studies do not provide sufficient doses of n-3 LCPUFA to produce a significant impact on bloodstream/organ content and there is substantial variability in the uptake of n-3 LPCUFA into tissues between individuals. In secondary analyses, clinical trials should consider the influence of fatty acid status (baseline, endpoint and change from baseline to endpoint) on the outcome variables.

Omega-3 PUFA metabolism and brain modifications during aging

In Canada, 5.5 million (16% of Canadians) adults are >65 years old and projections suggest this number will be approximately 20% of Canadians by 2024. A major concern regarding old age is a decline in health, especially if this entails a loss of self-sufficiency and independence caused by a decline in cognition. The brain contains 60% of fat and is one of the most concentrated organs in long chain omega-3 fatty acids such as docosahexaenoic acid (DHA). During aging, there are physiological modifications in the metabolism of lipids that could also have consequences on brain structure and levels of DHA. This review will hence discuss the physiological modifications in the metabolism of lipids during aging with a focus on long chain omega-3 and omega-6 fatty acids and also outline the structural and functional modifications of the brain during aging including brain lipid modifications and its relation to higher levels of DHA and cognition. Therefore, in this review, we outline the importance of collecting more data on the biology of aging since it might highly improve our understanding about what are «normal» modifications occurring during aging and what can become pathological.

Non-dietary factors associated with n-3 long-chain PUFA levels in humans - a systematic literature review

Numerous health benefits are attributed to the n-3 long-chain PUFA (n-3 LCPUFA); EPA and DHA. A systematic literature review was conducted to investigate factors, other than diet, that are associated with the n-3 LCPUFA levels. The inclusion criteria were papers written in English, carried out in adult non-pregnant humans, n-3 LCPUFA measured in blood or tissue, data from cross-sectional studies, or baseline data from intervention studies. The search revealed 5076 unique articles of which seventy were included in the qualitative synthesis. Three main groups of factors potentially associated with n-3 LCPUFA levels were identified: (1) unmodifiable factors (sex, genetics, age), (2) modifiable factors (body size, physical activity, alcohol, smoking) and (3) bioavailability factors (chemically bound form of supplements, krill oil v. fish oil, and conversion of plant-derived α-linolenic acid (ALA) to n-3 LCPUFA). Results showed that factors positively associated with n-3 LCPUFA levels were age, female sex (women younger than 50 years), wine consumption and the TAG form. Factors negatively associated with n-3 LCPUFA levels were genetics, BMI (if erythrocyte EPA and DHA levels are <5·6 %) and smoking. The evidence for girth, physical activity and krill oil v. fish oil associated with n-3 LCPUFA levels is inconclusive. There is also evidence that higher ALA consumption leads to increased levels of EPA but not DHA. In conclusion, sex, age, BMI, alcohol consumption, smoking and the form of n-3 LCPUFA are all factors that need to be taken into account in n-3 LCPUFA research.

Whole blood omega-3 fatty acid concentrations are inversely associated with blood pressure in young, healthy adults

BACKGROUND

Omega-3 fatty acids (n - 3 FA) may have blood pressure (BP)-lowering effects in untreated hypertensive and elderly patients. The effect of n - 3 FA on BP in young, healthy adults remains unknown. The Omega-3 Index reliably reflects an individuals' omega-3 status. We hypothesized that the Omega-3 Index is inversely associated with BP levels in young healthy adults.

METHODS

The current study (n = 2036) is a cross-sectional study investigating the baseline characteristics of a cohort, which includes healthy adults, age 25-41 years. Individuals with cardiovascular disease, known diabetes or a BMI higher than 35 kg/m were excluded. The Omega-3 Index was determined in whole blood using gas chromatography. Association with office and 24-h BP was assessed using multivariable linear regression models adjusted for potential confounders.

RESULTS

Median Omega-3 Index was 4.58% (interquartile range 4.08; 5.25). Compared with individuals in the lowest Omega-3 Index quartile, individuals in the highest had a SBP and DBP that was 4 and 2 mmHg lower, respectively (P < 0.01). A significant linear inverse relationship of the Omega-3 Index with 24-h and office BP was observed. Per 1-U increase in log-transformed Omega-3 Index the lowering in BP (given as multivariable adjusted β coefficients; 95% confidence interval) was -2.67 mmHg (-4.83; -0.51; P = 0.02) and -2.30 mmHg (-3.92; -0.68; P = 0.005) for 24-h SBP and DBP, respectively.

CONCLUSION

A higher Omega-3 Index is associated with statistically significant, clinically relevant lower SBP and DBP levels in normotensive young and healthy individuals. Diets rich in n - 3 FA may be a strategy for primary prevention of hypertension.

Composition and Concentration of Serum Fatty Acids of Phospholipids Depend on Tumour Location and Disease Progression in Colorectal Patients

BACKGROUND

Polyunsaturated fatty acids (PUFAs) play a role in the development/progression of colon cancer. The aim of the study was to assess the relation between serum phospholipids PUFAs, colorectal tumour localization and disease progression.

METHODS

A total of 67 patients (18 with proximal colon, 17 with distal colon and 32 with rectal tumour localization) as well as 16 controls were studied. One year after surgery, 33 patients had disease progression. Serum levels of C16:1(n-7), C18:1(n-9), C18:3(n-3), C20:5(n-3), C22:6(n- 3), C18:2(n-6), C20:2(n-6), C20:4(n-6) fatty acids of se - rum phospholipids were quantitatively measured before surgery by gas-chromatography.

RESULTS

Significantly higher mean value of C18:2, as compared to control, has been noted only for patients with proximal (p<0.05) and distal tumour (p<0.03) localization. The lower mean level of C20:5 and unsaturation index (UI) were observed in colorectal cancer patients regardless the tumour localization, but the statistical difference was noted only for patients with proximal tumours (p<0.05, p<0.03). In patients with proximal tumours, significantly lower mean level of C20:4 and UI were noted in patients with disease progression, as compared to patients with proximal tumours without disease progression (p<0.05).

CONCLUSION

The evaluation of PUFAs as a risk/prognostic factor in colorectal cancer patients should take into account tumour localization as a dependent variable.

Erythrocyte Omega-3 Fatty Acid Content in Elite Athletes in Response to Omega-3 Supplementation: A Dose-Response Pilot Study

Introduction

Supplementation of Omega-3 fatty acids (n-3FA) in athletes is related to the anti-inflammatory and/or antioxidant effect and consequently its action on all the processes of tissue restoration and adaptation to physical stress.

Objective

Evaluate the Omega-3 Index (O3Ix) response, in red blood cells, to supplemental EPA + DHA intake in the form of high purity and stable composition gums (G), in elite summer athletes.

Method

Twenty-four summer sport athletes of both sexes, pertaining to the Olympic Training Center in Spain, were randomized to two groups (2G = 760 or 3G = 1140 mg of n-3 FA in Omegafort OKids, Ferrer Intl.) for 4 months. Five athletes and four training staff volunteers were control group.

Results

The O3Ix was lower than 8% in 93.1% of all the athletes. The supplementation worked in a dose-dependent manner: 144% for the 3G dose and 135% for the 2G, both p < 0.001, with a 3% significant decrease of Omega-6 FAs. No changes were observed for the control group.

Conclusions

Supplementation with n-3FA increases the content of EPA DHA in the red blood cells at 4 months in a dose-dependent manner. Athletes with lower basal O3Ix were more prone to increment their levels. The study is registered with Protocol Registration and Results System (ClinicalTrials.gov) number NCT02610270.

Conversion ratios of n-3 fatty acids between plasma and erythrocytes: a systematic review and meta-regression

As biomarkers of dietary intake or disease risk factor, n-3 fatty acid (FA) can be measured in plasma phospholipids (PL), total lipids (TL) or erythrocytes. However, the numeric relationships between n-3 FA in these lipid pools are not clear. Our goal was to derive conversion ratios for plasma and erythrocyte n-3 FA. Potential studies were identified through systematic literature search in PubMed, Embase and the Cochrane Library of Systematic reviews (1950 to October 2014). In all, fifty-six studies reporting n-3 in healthy individuals were included, of which thirty-four articles reported plasma PL and erythrocytes, and twenty-two reported plasma TL and erythrocytes. Meta-regressions were performed to quantify the ratio between plasma and erythrocyte n-3 FA weight percentages, controlling for covariates including age, sex and study design. The conversion ratios from plasma PL to erythrocytes for EPA, DHA, DPA and total n-3 PUFA are 0·75, 1·16, 2·32 and 1·22; the corresponding conversion ratios from plasma TL to erythrocytes are 1·00, 2·10, 3·85 and 2·08, respectively. The conversion ratios were validated using reported values from the literature and measured data from fifty individuals. The relative error of the predicted results were within 10 % of the mean reported values except for EPA, and the individual measured data except for DPA, in plasma TL. The conversion ratios between plasma PL and erythrocytes were more stable compared with plasma TL. Such conversion ratios will be useful for nutritionists or public health professionals to assess FA profiles of different populations using data collected with different methodologies.

Red blood cell polyunsaturated fatty acids and mortality in the Women's Health Initiative Memory Study

BACKGROUND

The prognostic value of circulating polyunsaturated fatty acid (PUFA) levels is unclear.

OBJECTIVES

To determine the associations between red blood cell (RBC) PUFA levels and risk for death.

METHODS

This prospective cohort study included 6501 women aged 65 to 80 years who participated in the Women's Health Initiative Memory Study (enrolment began 1996). RBC PUFA levels were measured at baseline and expressed as a percent of total RBC PUFAs. PUFAs of primary interest were the n-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and their sum (the Omega-3 Index). PUFAs of secondary interest included the 2 major n-6 PUFAs, linoleic acid and arachidonic acid, and the PUFA factor score (a calculated variable including 6 PUFAs that accounts for their intercorrelations). The primary outcome was total mortality through August 2014.

RESULTS

After a median of 14.9 years of follow-up, 1851 women (28.5%) had died. RBC levels of EPA and DHA were higher in the survivors (P < .002 for each). In the fully adjusted models, the hazard ratios (99% confidence intervals) for mortality associated with a 1 standard deviation PUFA increase for total mortality were 0.92 (0.85, 0.98) for the Omega-3 Index, 0.89 (0.82, 0.96) for EPA, 0.93 (0.87, 1.0) for DHA, and 0.76 (0.64, 0.90) for the PUFA factor score. There were no significant associations of alpha-linolenic acid, arachidonic acid or linoleic acid with total mortality.

CONCLUSIONS

Higher RBC levels of marine n-3 PUFAs were associated with reduced risk for all-cause mortality. These findings support the beneficial relationship between the Omega-3 Index and health outcomes.

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.

Translating plasma and whole blood fatty acid compositional data into the sum of eicosapentaenoic and docosahexaenoic acid in erythrocytes

Specific blood levels of eicosapentaenoic plus docosahexaenoic acid (EPA+DHA, wt% of total) in erythrocytes or "the omega-3 index" have been recommended for cardio-protection, but fatty acids are often measured in different blood fractions. The ability to estimate the % of EPA+DHA in erythrocytes from the fatty acid composition of other blood fractions would enable clinical assessments of omega-3 status when erythrocyte fractions are not available and increase the ability to compare blood levels of omega-3 fatty acids across clinical studies. The fatty acid composition of baseline plasma, erythrocytes and whole blood samples from participants (n=1104) in a prospective, multicenter study examining acute coronary syndrome were determined. The ability to predict the % of EPA+DHA in erythrocytes from other blood fractions were examined using bivariate and multiple linear regression modelling. Concordance analysis was also used to compare the actual erythrocytes EPA+DHA values to values estimated from other blood fractions. EPA+DHA in erythrocytes was significantly (p<0.001) correlated EPA+DHA in plasma (r(2)=0.54) and whole blood (r(2)=0.79). Using multiple linear regression to predict EPA+DHA in erythrocytes resulted in stronger coefficients of determination in both plasma (R(2)=0.70) and whole blood (R(2)=0.84). Concordance analyses indicated agreement between actual and estimated EPA+DHA in erythrocytes, although estimating from plasma fatty acids appears to require translation by categorization rather than by translation as continuous data. This study shows that the fatty acid composition of different blood fractions can be used to estimate erythrocyte EPA+DHA in a population with acute coronary syndrome.

The Effect of Marine Derived n-3 Fatty Acids on Adipose Tissue Metabolism and Function

Adipose tissue function is key determinant of metabolic health, with specific nutrients being suggested to play a role in tissue metabolism. One such group of nutrients are the n-3 fatty acids, specifically eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). Results from studies where human, animal and cellular models have been utilised to investigate the effects of EPA and/or DHA on white adipose tissue/adipocytes suggest anti-obesity and anti-inflammatory effects. We review here evidence for these effects, specifically focusing on studies that provide some insight into metabolic pathways or processes. Of note, limited work has been undertaken investigating the effects of EPA and DHA on white adipose tissue in humans whilst more work has been undertaken using animal and cellular models. Taken together it would appear that EPA and DHA have a positive effect on lowering lipogenesis, increasing lipolysis and decreasing inflammation, all of which would be beneficial for adipose tissue biology. What remains to be elucidated is the duration and dose required to see a favourable effect of EPA and DHA in vivo in humans, across a range of adiposity.

Omega-3 index levels and associated factors in a middle-aged French population: the MONA LISA-NUT Study

BACKGROUND/OBJECTIVES

The omega-3 index (the summed percentage content of eicosapentaenoic and docosahexaenoic acids in red blood cells) is associated with a lower risk of fatal coronary heart disease and sudden cardiac death. We aimed to determine which socio-demographic, behavioural or clinical factors are independently associated with the omega-3 index and the extent to which seafood consumption mediates the index's association with socio-economic status (SES).

SUBJECTS/METHODS

As part of the cross-sectional MONA LISA-NUT survey (2005-2007), gas chromatography was used to analyse the red blood cell fatty acid composition in 503 French subjects aged 35-64 years. Dietary data were collected by trained dieticians via a validated food frequency questionnaire and a prospective 3-day food record. Risk factors were estimated with standardised measurements and questionnaires. SES was assessed through the self-reported educational and income tax levels.

RESULTS

The mean ± s.d. omega-3 index was 6.02 ± 1.75%. In the best parsimonious predictive model (which explained 32% of the variability in the omega-3 index), age, educational level and seafood servings were significantly and positively associated with the index. In contrast, waist circumference and smoking were inversely associated with the index. In a mediation analysis that took account of all these factors, seafood servings explained about 40% of the association between educational level and the omega-3 index. Similar results were obtained for the income tax level.

CONCLUSIONS

The inverse association between SES and omega-3 index is largely explained (40%) by an insufficient seafood intake. It remains to be seen which other factors mediate this association.

Achieving optimal n-3 fatty acid status: the vegetarian's challenge... or not

The long chain n-3 (omega-3) fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), although originally synthesized by microorganisms in the oceans, are primarily obtained from the consumption of fish. Vegetarians, by definition, do not eat fish and thus consume virtually no EPA and DHA. Because conversion of the plant-derived n-3 fatty acid α-linolenic acid (ALA) to EPA and DHA is very low, n-3 tissue concentrations in vegetarians are lower than in omnivores. This review asks 2 questions: what is the evidence that increased n-3 concentrations reduce the risk of cardiovascular disease in vegetarians, and, if it does, how can vegetarians increase their blood and tissue concentrations of these animal-derived fatty acids? At present, both cardiovascular risk markers and cardiovascular events appear to be significantly reduced in vegetarians compared with those in omnivores. If so, and in the absence of data to show that risk in vegetarians could be even lower with higher n-3 concentrations, then the second question becomes moot. However, the absence of evidence is not evidence of absence; therefore, at our present state of knowledge, increasing n-3 concentrations is not an unreasonable goal for vegetarians. This can be accomplished by a variety of approaches, including increased intakes of ALA, consumption of stearidonic acid-enriched soybean oil (if and when it comes to the market), and the use of supplements containing EPA, DHA, or both derived from nonanimal sources (microalgae, biotech yeast, and, in the future, biotech plant oils).

Serum docosahexaenoic and eicosapentaenoic acid and risk of cognitive decline over 10 years among elderly Japanese

BACKGROUND/OBJECTIVES

To clarify the association of serum docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) levels with cognitive decline over 10 years.

SUBJECTS/METHODS

This study was part of the National Institute for Longevity Sciences - Longitudinal Study of Aging, and was conducted with 232 male and 198 female Japanese community-dwelling subjects aged 60-79 years in the second wave (2000-2002). Cognitive function was assessed with the Mini-Mental State Examination (MMSE) in both the second and seventh (2010-2012) waves. Fasting venous blood samples were collected in the morning, and serum DHA and EPA levels were measured. Multiple logistic regression analysis was performed among participants with an MMSE score ≥ 24 in the second wave (n=430) to estimate the odds ratio (OR) and 95% confidence interval (CI) for MMSE score ≤ 23 or MMSE score decline ≥ 4 10 years later. These estimates were based on baseline tertiles of serum DHA or EPA levels, and controlled for age, sex, education, MMSE score at baseline, alcohol consumption, current smoking, body mass index and disease history.

RESULTS

Fifteen (3.5%) subjects whose MMSE score was ≤ 23 and 36 (8.3%) subjects whose MMSE score declined to ≥ 4 showed cognitive decline. Multivariate-adjusted OR (95% CI) for the lowest through highest tertiles of serum DHA to MMSE score ≤ 23 or decline ≥ 4 were 1.00 (reference), 0.11 (0.02-0.58) and 0.17 (0.04-0.74), or 1.00 (reference), 0.22 (0.08-0.61) and 0.31 (0.12-0.75), respectively (P for trend=0.01 or 0.04). Serum EPA was not associated with cognitive decline.

CONCLUSIONS

The study gives some indication that a moderately high level of serum DHA might prevent cognitive decline among community-dwelling elderly Japanese individuals.

Arachidonic acid-enriched triacylglycerol improves cognitive function in elderly with low serum levels of arachidonic acid

Arachidonic acid (ARA) is an n-6 PUFA and is thought to have an important role in various physiological and psychological functions. Recently, supplementation with ARA-enriched TAG was shown to improve age-related decreases in cognitive function in healthy elderly men. To investigate the influence of baseline serum ARA status on cognitive function and its improvement, we analyzed cognitive function stratified by serum ARA level. The stratified analysis was also conducted for the effects of ARA-enriched TAG supplementation on cognitive improvement. Cognitive function was evaluated by measuring event-related potentials (ERPs), including P300 latency and amplitude. When participants were stratified by baseline serum ARA level, P300 latency was significantly longer and P300 amplitude was generally lower in the low-ARA group than in the high-ARA group. No significant difference in P300 components was observed when participants were stratified by serum levels of any other fatty acid. ARA-enriched TAG supplementation significantly shortened P300 latency and increased P300 amplitude in the low-ARA group, although no significant differences were observed in the high-ARA group. These findings suggest that lower serum ARA levels were associated with cognitive function in elderly men and that ARA-enriched TAG supplementation is more effective in improving cognitive function in healthy elderly men with low serum ARA levels than in those with high serum ARA levels.

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.

Determinants of erythrocyte omega-3 fatty acid content in response to fish oil supplementation: a dose-response randomized controlled trial

Background

The erythrocyte membrane content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which constitutes the omega‐3 index (O3I), predicts cardiovascular disease mortality. The amount of EPA+DHA needed to achieve a target O3I is poorly defined, as are the determinants of the O3I response to a change in EPA+DHA intake. The objective of this study was to develop a predictive model of the O3I response to EPA+DHA supplementation in healthy adults, specifically identifying factors that determine the response.

Methods and Results

A randomized, placebo‐controlled, double‐blind, parallel‐group study was conducted in 115 healthy men and women. One of 5 doses (0, 300, 600, 900, 1800 mg) of EPA+DHA was given daily as placebo or fish oil supplements for ≈5 months. The O3I was measured at baseline and at the end of the study. There were no significant differences in the clinical characteristics between the groups at baseline. The O3I increased in a dose‐dependent manner (P<0.0001), with the dose of EPA+DHA alone accounting for 68% (quadratic, P<0.0001) of the variability in the O3I response. Dose adjusted per unit body weight (g/kg) accounted for 70% (linear, P<0.0001). Additional factors that improved prediction of treatment response were baseline O3I, age, sex, and physical activity. Collectively, these explained 78% of the response variability (P<0.0001).

Conclusions

Our findings validate the O3I as a biomarker of EPA+DHA consumption and identify additional factors, particularly body weight, that can be used to tailor EPA+DHA recommendations to achieve a target O3I.

Role of Long-Chain Omega-3 Fatty Acids in Psychiatric Practice

Nutrition plays a minor role in psychiatric practice which is currently dominated by a pharmacological treatment algorithm. An accumulating body of evidence has implicated deficits in the dietary essential long-chain omega-3 (LCn-3) fatty acids, eicosapenaenoic acid (EPA) and docosahexaenoic acid (DHA), in the pathophysiology of several major psychiatric disorders. LCn-3 fatty acids have an established long-term safety record in the general population, and existing evidence suggests that increasing LCn-3 fatty acid status may reduce the risk for cardiovascular disease morbidity and mortality. LCn-3 fatty acid supplementation has been shown to augment the therapeutic efficacy of antidepressant, mood-stabilizer, and second generation antipsychotic medications, and may additionally mitigate adverse cardiometabolic side-effects. Preliminary evidence also suggests that LCn-3 fatty acid supplementation may be efficacious as monotherapy for primary and early secondary prevention and for perinatal symptoms. The overall cost-benefit ratio endorses the incorporation of LCn-3 fatty acids into psychiatric treatment algorithms. The recent availability of laboratory facilities that specialize in determining blood LCn-3 fatty acid status and emerging evidence-based consensus guidelines regarding safe and efficacious LCn-3 fatty acid dose ranges provide the infrastructure necessary for implementation. This article outlines the rationale for incorporating LCn-3 fatty acid treatment into psychiatric practice.

Plasma levels of n-3 fatty acids in bipolar patients: deficit restricted to DHA

Epidemiological studies suggest that n-3 polyunsaturated fatty acid (n-3 FA) deficiency is a risk factor for bipolar disorders (BDs). The aim of this study was to determine whether such a deficit does exist in patients with BD and to characterize the overall plasma fatty acid (FA) profile in these patients. Using gas chromatography/mass spectrometry, we measured fasting plasma levels of 15 FAs in 42 patients diagnosed with BD according to DSM-IV criteria and in 57 age- and gender-matched healthy controls. Plasma docosahexaenoic acid (DHA) levels were significantly decreased in bipolar patients (p < 0.001 versus healthy controls). Compared with controls, patients had higher plasma levels of all other FAs, including arachidonic acid (AA, p < 0.001), alpha-linolenic acid (ALA, p < 0.001), and eicosapentaenoic acid (EPA) (p < 0.001). Although in the present study we observed significant DHA deficits in the plasma of bipolar patients our findings do not support the therapeutic use of ALA and/or EPA supplementation. DHA may provide a basis for possible pharmacological intervention in psychiatric disorders at the level of second messengers linked to the phosphatidylinositol cycle. Finally, measurement of FA levels in plasma seems to be more reliable and reproducible than assays of erythrocyte FA content.

Higher serum EPA or DHA, and lower ARA compositions with age independent fatty acid intake in Japanese aged 40 to 79

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are the predominant long-chain polyunsaturated fatty acids (PUFA) among membrane phospholipids in the mammalian brain and neural tissues. This cross-sectional study examined age effects on serum eicosapentaenoic acid (EPA), DHA, and ARA compositions assessed with reference to dietary intakes among 1,014 Japanese men and 1,028 Japanese women aged 40-79 years. Venous blood was collected early in the morning after at least 12-h fasting. Serum fatty acid (FA) compositions were expressed as molar percentages of the total FA (mol% of total). Diet was assessed using a 3-day dietary record that included photographs. Participants were categorized into groups by sex and age (40-49, 50-59, 60-69, and 70-79 years). Intakes of fish, EPA, and DHA tended to increase with age. Significant positive correlations between serum FA composition and the corresponding weight percentage of total FA intake were observed for EPA and DHA in all sex and age groups, and for ARA among females in their 40s. Serum EPA and DHA compositions were higher, while ARA decreased with age, and these associations remained consistent even after adjusting for corresponding FA intake. These results suggest potential effects of age on differences in blood EPA, DHA, and ARA compositions, independent of corresponding FA intake among community-dwelling Japanese men and women.

Clinical correlates and heritability of erythrocyte eicosapentaenoic and docosahexaenoic acid content in the Framingham Heart Study

OBJECTIVES

Red blood cell (RBC) levels of eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA, the omega-3 index, expressed as a percent of total fatty acids) are inversely related to risk for cardiovascular disease (CVD). Although several mechanisms underlying this relationship have been proposed, understanding the associations between the omega-3 index and markers of CVD in the community can shed additional light on this question. The objectives of this study were to define the relations between the omega-3 index and clinical factors and to determine the heritability of the omega-3 index.

METHODS

RBC samples (n = 3196) drawn between 2005 and 2008 from participants in the Framingham Study [Examination 8 of the Offspring cohort plus Examination 3 of the Omni (minorities) cohort] were analyzed for fatty acid composition by gas chromatography.

RESULTS

The mean (SD) omega-3 index was 5.6% (1.7%). In multivariable regression models, the factors significantly and directly associated with the omega-3 index were age, female sex, higher education, fish oil supplementation, dietary intake of EPA + DHA, aspirin use, lipid pharmacotherapy, and LDL-cholesterol. Factors inversely associated were Offspring cohort, heart rate, waist girth, triglycerides and smoking. The total explained variability in the omega-3 index for the fully adjusted model was 73%, which included major components due to heritability (24%), EPA + DHA intake (25%), and fish oil supplementation (15%).

CONCLUSION

The variability in the omega-3 index is determined primarily by dietary and genetic factors. An increased omega-3 index is associated with a generally cardioprotective risk factor milieu.

Comparison of the incorporation of orally administered DHA into plasma, erythrocyte and cheek cell glycerophospholipids

Adequate intake of n-3 fatty acids plays an important role in human health. The analysis of various blood lipids is used as a measure of fatty acid status in humans. Cheek cell phospholipids (PL) have also been proposed as biological markers, but are rarely used in clinical studies due to limitations in sample quality and quantity. An improved method for the analysis of cheek cell glycerophospholipid fatty acids is applied in a 29 d supplementation trial with 510 mg DHA daily. The DHA increases in cheek cell, plasma and erythrocyte glycerophospholipids are compared. High correlations are shown for glycerophospholipid DHA between cheek cells and plasma (r 0·88) and erythrocytes (r 0·76) before study commencement. After the daily supplementation of DHA, the half-maximal glycerophospholipid DHA level is reached after about 4 d in plasma, 6 d in erythrocytes and 10 d in cheek cells. The mean DHA increase (mol%) relative to baseline was most prominent in plasma (186 %), followed by cheek cells (180 %) and erythrocytes (130 %). Considering a lag phase of about 5 d, cheek cells reflect short-term changes in dietary fat uptake. Based on the data of the present study, they can be used alternatively to plasma and erythrocyte PL as non-invasive n-3 fatty acid status markers.

The omega-3 index: clinical utility for therapeutic intervention

Red blood cell levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are a reflection of tissue levels and are determined by a complex interplay of metabolism and nutrition. Low levels of EPA+DHA in erythrocytes are associated with increased risk for sudden cardiac death. If levels of EPA+DHA in erythrocytes are determined using a strictly defined and standardized method, then the clinical significance of differing levels (previously defined in major research studies using this methodology) may be understood and applied in patient care. The Omega-3 Index, which is the EPA+DHA content of erythrocytes expressed as a percent of total identified fatty acids, was originally suggested as a marker of increased risk for death from coronary heart disease, but it can also be viewed as an actual risk factor, playing a pathophysiologic role in the disease. Optimal levels appear to be 8% or greater. At this stage of its development, the Omega-3 Index appears to fulfill many of the requirements for both a risk marker and a risk factor. Using the Omega-3 Index in the design of clinical studies might allow for a more efficient use of research resources.