Association between Blood Omega-3 Index and Cognition in Typically Developing Dutch Adolescents

ω-3 Polyunsaturated Fatty Acid Status Testing in Humans: A Narrative Review of Commercially Available Options

There is an increasing body of evidence supporting a link between low intakes of ω-3 long-chain polyunsaturated fatty acids (LCPUFA) and numerous diseases and health conditions. However, few people are achieving the levels of fish/seafood or eicosapentaenoic acid and docosahexaenoic acid intake recommended in national and international guidelines. Knowledge of a person's ω-3 LCPUFA status will benefit the interpretation of research results and could be expected to lead to an increased effort to increase intake. Dietary intake survey methods are often used as a surrogate for measuring ω-3 PUFA tissue status and its impact on health and functional outcomes. However, because individuals vary widely in their ability to digest and absorb ω-3 PUFA, analytical testing of biological samples is desirable to accurately evaluate ω-3 PUFA status. Adipose tissue is the reference biospecimen for measuring tissue fatty acids, but less-invasive methods, such as measurements in whole blood or its components (e.g., plasma, serum, red blood cell membranes) or breast milk are often used. Numerous commercial laboratories provide fatty acid testing of blood and breast milk samples by different methods and present their results in a variety of reports such as a full fatty acid profile, ω-3 and ω-6 fatty acid profiles, fatty acid ratios, as well as the Omega-3 Index, the Holman Omega-3 Test, OmegaScore, and OmegaCheck, among others. This narrative review provides information about the different ways to measure ω-3 LCPUFA status (including both dietary assessments and selected commercially available analytical tests of blood and breast milk samples) and discusses evidence linking increased ω-3 LCPUFA intake or status to improved health, focusing on cardiovascular, neurological, pregnancy, and eye health, in support of recommendations to increase ω-3 LCPUFA intake and testing.

Red blood cell omega-3 fatty acids and attention scores in healthy adolescents

Omega-3 fatty acids are critical for brain function. Adolescence is increasingly believed to entail brain vulnerability to dietary intake. In contrast to the abundant research on the omega-3 docosahexaenoic acid (DHA) in cognition, research on DHA and attention in healthy adolescents is scarce. In addition, the role of alpha-linolenic acid (ALA), the vegetable omega-3 fatty acid, is unexplored. We examined associations between DHA and ALA and attention function among a healthy young population. In this cross-sectional study conducted in 372 adolescents (13.8 ± 0.9 years-old), we determined the red blood cell proportions of DHA and ALA by gas chromatography (objective biomarkers of their long-term dietary intake) and measured attention scores through the Attention Network Test. We constructed multivariable linear regression models to analyze associations, controlling for known confounders. Compared to participants at the lowest DHA tertile (reference), those at the highest DHA tertile showed significantly lower hit reaction time-standard error (higher attentiveness) (28.13 ms, 95% confidence interval [CI] =  - 52.30;  - 3.97), lower hit reaction time ( - 38.30 ms, 95% CI =  - 73.28;  - 3.33) and lower executive conflict response ( - 5.77 ms, 95% CI =  - 11.44;  - 0.09). In contrast, higher values were observed in those at the top tertile of ALA in hit reaction time compared to the lowest one (46.14 ms, 95% CI = 9.90; 82.34). However, a beneficial association was observed for ALA, with decreasing impulsivity index across tertiles. Overall, our results suggest that DHA (reflecting its dietary intake) is associated with attention performance in typically developing adolescents. The role of dietary ALA in attention is less clear, although higher blood levels of ALA appear to result in lower impulsivity. Future intervention studies are needed to determine the causality of these associations and to better shape dietary recommendations for brain health during the adolescence period.

A Systematic Review of Omega-3 Fatty Acid Consumption and Cognitive Outcomes in Neurodevelopment

INTRODUCTION

This systematic review addresses the effects of n-3 long-chain polyunsaturated fatty acids consumption on human neurodevelopment. It evaluates articles published between 2000 and 2022 investigating the cognitive outcomes during the period of neurodevelopment: from fetal development to adolescence. For the purpose of this review the terms LC PUFA and omega-3 fatty acid will be used interchangeably.

METHOD

Data were sourced from several major databases including PubMed (MEDLINE), Web of Science, and ProQuest Central. Randomized controlled trials (RCTs), nonrandomized controlled trials, prospective or retrospective cohort studies, and observational studies investigating the effects of omega-3 fatty acid consumption from dietary supplements, multiple-nutrient supplement, or food questionnaire on neurodevelopment were considered. Study population was separated in three developmental phases: (1) in-utero, (2) lactation/infancy, and (3) childhood/adolescence. Each article was evaluated for several key factors such as study type, type/dosage of PUFAs, number of subjects, length of intervention, participant age range, population characteristics, outcome measure (both primary/cognitive and secondary/other), results, conclusion, and confounding variables/limitations.

RESULTS

A total of 88 articles were included in the review, 69 RCTs and 19 longitudinal or observational studies. The results indicate equivocal effect of intervention, with some short-term benefits observed in the areas of visual attention, working memory, executive function, and communication. Omega-3 supplement might have a short-term positive impact on neurodevelopment in all three phases. Supplementation is recommended throughout life, rather than only during the earliest developmental stage.

Omega-3 index and AA/EPA ratio as biomarkers of running-related injuries: An observational study in recreational runners

ABSTRACTThe aim of this study was to examine the association between biomarkers of polyunsaturated fatty acids (PUFA), such as omega-3 (ω-3) index and arachidonic acid (AA; 20:4 ω-6)/eicosapentaenoic acid (EPA; 20:5ω-3) ratio (AA/EPA), and the prevalence of running-related injuries (RRI) in a cohort of recreational runners. We performed a retrospective, observational study of 275 non-elite runners (mean age: 41.20 ± 12.47 years) who were not supplemented with ω-3 fatty acids. The training characteristics and RRI were recorded over a period of 12 months through a self-reported questionnaire. Using whole blood samples collected by finger prick, PUFA were quantified by gas chromatography and ω-3 index and AA/EPA ratio measured. A total of 191 RRI cases were reported, with an injury prevalence rate of 50.9% in the overall population. The injured runners ran a significantly greater weekly distance than uninjured subjects (53.54 ± 25.27 km/week; p = 0.007). In a multivariate regression analysis, the lowest number of RRI was associated with higher values of ω-3 index (β = - 0.237; 95% CI - 0.308 to - 0.164; R² = 0.172; p < 0.0001), while a higher AA/EPA ratio was correlated with higher number of RRI (β = 0.019; 95% CI 0.007-0.031; R² = 0.038; p = 0.003). This study identifies ω-3 index and AA/EPA ratio as potential parameters associated with the risk of RRI. Future research is needed to confirm these results and apply specific nutritional strategies to successfully modify these biochemical variables.Trial registration: ISRCTN.org identifier: ISRCTN12847156..

Fish oil supplementation may improve attention, working memory and attention-deficit/hyperactivity disorder symptoms in adults with autism spectrum disorder: a randomised crossover trial

Marine n-3 fatty acids (n-3LCPUFA) have shown neurocognitive benefits in children with attention-deficit/hyperactivity disorder (ADHD), but few trials have examined effects in adults with autism spectrum disorder (ASD). We explored, if n-3LCPUFA affect cognitive functions in adults with ASD, and if effects are modified by comorbid ADHD. In a 2 × 4 week crossover study, twenty-six participants were randomised to sequence of supplementation with fish oil (FO, 5·2 g/d n-3PUFA) and safflower oil (SO). At baseline and after each period, we measured primary outcomes: attention (d2-test) and spatial working memory (Corsi test) and secondary outcomes: flexibility (Stroop word-colour test), ADHD symptoms (Conners scales), executive functions (Behavioural Inventory of Executive Function) and social behaviour (Social Responsiveness Scale). The dropout rate was 15 %. Compliance was 94 % and correlated with whole-blood n-3LCPUFA. Corsi scores improved by ∼0·3 × sd (P = 0·032) after FO v. SO, and the odds for d2 errors were 30 % lower (P = 0·016), which was supported by improved Conners scores of attention (P = 0·023). Improvement in Conners ADHD symptom score was limited to participants with ADHD (-3·5(-6·0; -1·0), n 10 v. -0·2(-2·5;2·2), n 11 without ADHD, Pinteraction = 0·096), who also improved their behavioural regulation index by 0·3 × sd after FO (Pinteraction = 0·016). Participants without ADHD gained most in d2 test performance (OR = 0·4(0·2;0·7) v. 0·9(0·6;1·3) in those with ADHD, Pinteraction = 0·002), but their executive function score was exacerbated after FO (5·9(0·0,11·8), Pinteraction = 0·039). Our results did not show any effects on ASD symptoms, but suggest that FO may improve attention and working memory in adults with ASD and ameliorate ADHD symptoms in those with comorbid ADHD.

Association between dietary patterns and cognitive ability in Chinese children aged 10-15 years: evidence from the 2010 China Family Panel Studies

Background

Limited information is available concerning the association between dietary patterns and cognitive ability during adolescence, especially in regards to the epidemiological studies in China. Therefore, this study aimed to analyze the association between dietary patterns and cognitive ability in Chinese children aged 10–15 years.

Methods

The dietary information, cognitive ability and sociodemographic data of 2029 children were retrieved from the 2010 China Family Panel Studies. Dietary patterns were assessed by principal component analysis. Ordinal logistic regression models were used to determine the association between dietary patterns and cognitive ability in these children.

Results

Three dietary patterns were identified, namely, ‘High protein’, ‘High fat’ and ‘High salt-oil’. Following adjustment for gender, age, nationality, household registration, school type, parental education level, family learning environment, annual household income and family size, we found that an increase in ‘High protein’ pattern score was significantly associated with higher mathematics test scores (OR = 1.62, CI: 1.23 ~ 2.15; P = 0.001), but not with vocabulary test scores (OR = 1.21, CI: 0.93 ~ 1.58; P = 0.149). On the contrary, an increase in ‘High fat’ pattern score was significantly associated with lower scores of mathematics (OR = 0.76, CI: 0.59 ~ 0.98; P = 0.031) and vocabulary (OR = 0.77, CI: 0.61 ~ 0.97; P = 0.029) tests. However, there was no significant association between ‘High salt-oil’ pattern and the scores of mathematics (OR = 0.99, CI: 0.77 ~ 1.27; P = 0.915) and vocabulary (OR = 0.93, CI: 0.73 ~ 1.18; P = 0.544) tests.

Conclusion

The findings of this study demonstrated that ‘High protein’ pattern was positively associated with cognitive ability in Chinese children, while ‘High fat’ pattern exhibited a negative association.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-12209-2.

Effect of Omega-3 Supplementation on Self-Regulation in Typically Developing Preschool-Aged Children: Results of the Omega Kid Pilot Study-A Randomised, Double-Blind, Placebo-Controlled Trial

Supplementation of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) may enhance self-regulation (SR) and executive functioning (EF) in children of preschool age. The aim of the Omega Kid Study was to investigate the effect of n-3 LCPUFA supplementation on SR and EF in typically developing preschool-aged children. A double-blind placebo-controlled pilot trial was undertaken, the intervention was 12 weeks and consisted of 1.6 g of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per day compared to placebo. The HS-Omega-3 Index^® was assessed by capillary blood samples at baseline and post-intervention. Seventy-eight children were enrolled and randomised to either the n-3 LCPUFA treatment (n = 39) or placebo (n = 39) group. Post intervention, there was a significant three-fold increase in the HS-Omega-3 Index^® in the n-3 LCPUFA group (p < 0.001). There were no improvements in SR or EF outcome variables for the n-3 LCPUFA group post intervention compared to the placebo group determined by linear mixed models. At baseline, there were significant modest positive Spearman correlations found between the HS-Omega-3 index^® and both behavioural self-regulation and cognitive self-regulation (r = 0.287, p = 0.015 and r = 0.242, p = 0.015 respectively). Although no treatment effects were found in typically developing children, further research is required to target children with sub-optimal self-regulation who may benefit most from n-3 LCPUFA supplementation.

The Feasibility of the "Omega Kid" Study Protocol: A Double-Blind, Randomised, Placebo-Controlled Trial Investigating the Effect of Omega-3 Supplementation on Self-Regulation in Preschool-Aged Children

Self-regulation, the regulation of behaviour in early childhood, impacts children's success at school and is a predictor of health, wealth, and criminal outcomes in adulthood. Self-regulation may be optimised by dietary supplementation of omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFAs). The aim of the "Omega Kid" study is to investigate the feasibility of a protocol to investigate whether n-3 LCPUFA supplementation enhances self-regulation in preschool-aged children. The protocol assessed involved a double-blind, randomised, placebo-controlled trial of 12 weeks duration, with an intervention of 1.6 g of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per day (0.3 g EPA and 1.3 g DHA) in a microencapsulated powder compared to placebo. Children (n = 78; 40 boys and 38 girls) aged 3-5 years old were recruited and randomly allocated to the treatment (n = 39) or placebo group (n = 39). The HS-Omega-3 Index^® served as a manipulation check on the delivery of either active (n-3 LCPUFAs) or placebo powders. Fifty-eight children (76%) completed the intervention (28-30 per group). Compliance to the study protocol was high, with 92% of children providing a finger-prick blood sample at baseline and high reported-adherence to the study intervention (88%). Results indicate that the protocol is feasible and may be employed in an adequately powered clinical trial to test the hypothesis that n-3 LCPUFA supplementation will improve the self-regulation of preschool-aged children.

Verbal Memory Performance in Depressed Children and Adolescents: Associations with EPA but Not DHA and Depression Severity

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been described as positively associated with cognitive functioning. Current meta-analyses have identified eicosapentaenoic acid (EPA) as potentially more effective than docosahexaenoic acid (DHA). An especially vulnerable subgroup that might benefit from these beneficial effects are depressed youths. In this study, we examined associations between red blood cell (RBC) DHA and EPA levels and depression severity and verbal memory performance in a sample of 107 moderately (n = 63) and severely (n = 44) depressed youths. The findings showed that youths with high RBC EPA levels had steeper learning curves compared to those with moderate or low RBC EPA levels (Pillai's Trace = 0.195, p = 0.027, η_p² = 0.097). No associations between RBC DHA levels or depression severity and verbal memory performance were observed. Our results further confirm previous findings indicating a more important role of EPA compared to DHA in relation to cognitive functioning. Future research should further investigate the differential role of EPA and DHA concerning cognitive functioning in depressed youths. Evidence supporting beneficial supplementation effects could potentially establish a recommendation for a natural and easily accessible intervention for cognitive improvement or remission.

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.

Metabolic indices of polyunsaturated fatty acids: current evidence, research controversies, and clinical utility

The n-3 and n-6 polyunsaturated fatty acids (PUFA) are among the most studied nutrients in human metabolism. In the past few decades, prospective studies and controlled trials have supported the view that the effects of these essential fatty acids are clinically relevant. PUFA profiles in different blood compartments are reflections of both diet and metabolism, and their levels may be related to disease risk. Despite widespread interest, there is no consensus regarding which biomarkers best reflect PUFA status in the body. The measurement of PUFA levels is not straight-forward, and a wide variety of indices have been used in clinical studies, producing conflicting results. A major source of heterogeneity among studies is associated with research design, sampling, and laboratory analyses. To date, the n-3 index, n-6/n-3 ratio, and arachidonic acid (AA)/eicosapentaenoic acid (EPA) ratio are the most promising biomarkers associated with PUFA metabolism. Although hotly debated, these indices may be considered at least markers, if not risk factors, for several diseases, especially cardiovascular events and brain disorders. Here, we summarize the most updated evidence of n-3 and n-6 PUFA effects on human health, reviewing current controversies on the aforementioned indices and whether they can be considered valuable predictors of clinical outcomes.

Validation of a Dietary Questionnaire to Screen Omega-3 Fatty Acids Levels in Healthy Adults

To facilitate a clinical observational study to identify healthy volunteers with low (defined as ≤4%) and high (defined as ≥5.5%) omega-3 indices, a dietary questionnaire to rapidly assess habitual dietary intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) was developed. This study aimed to determine the validity of this newly developed dietary questionnaire. One hundred and eight volunteers were included and were assessed for habitual dietary intake of EPA and DHA using the questionnaire. The United States Department of Agriculture food products database and nutrition fact label was referenced for calculation. Blood samples were collected for the analysis of fatty acids in whole blood specimens and to derive omega-3 indices. A linear correlation was observed between reported dietary consumption of EPA, DHA, EPA+DHA and the whole blood levels of EPA, DHA, and the omega-3 indices (r = 0.67, 0.62, 0.67, respectively, p < 0.001 for all). The findings also suggested that the questionnaire was substantially better at identifying volunteers with high omega-3 indices (sensitivity 89%, specificity 84%, and agreement 86%) compared to volunteers with low omega-3 indices (sensitivity 100%, specificity 66%, and agreement 42%). In conclusion, this newly developed questionnaire is an efficient tool for the assessment of omega-3 indices in study populations and is particularly effective in identifying individuals with high omega-3 indices.

Effect of 1 Year Krill Oil Supplementation on Cognitive Achievement of Dutch Adolescents: A Double-Blind Randomized Controlled Trial

Long-chain polyunsaturated fatty acids (LCPUFA) are important for brain development and function, maybe especially during adolescence. Observational studies have demonstrated an association between fish consumption (a source of LCPUFA) and cognition in adolescents, but intervention trials are lacking. The goal of the current study was to investigate the effect of one year of krill oil (a source of LCPUFA) supplementation on the cognitive performance of adolescents with a low Omega-3 Index (O3I ≤ 5%). A double-blind, randomized, and placebo-controlled supplementation trial with repeated measurements (baseline (T0), three months (T1), six months (T2), and 12 months (T3)) in adolescents (267 randomized) was executed. Participants were randomized to 400 mg eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per day in Cohort I or placebo and 800 mg EPA + DHA per day in Cohort II or placebo. O3I was monitored by a finger prick at all time points. At T0, T2, and T3, participants executed a neurocognitive test battery. Covariate corrected mixed models were run with either condition (krill or placebo) or O3I as predictors. Krill oil supplementation led to a small but significant increase in mean O3I, but few participants increased to the intended O3I range (8–11%). There was no significant effect of supplementation on the neurocognitive tests, nor a relationship between O3I and neurocognitive test scores. The increase in O3I was small in most participants, probably due to non-compliance. Possibly the increase in O3I was too small to demonstrate an effect. More research on the influence of LCPUFAs on cognition in adolescents is needed.

Dietary Long-Chain Omega-3 Fatty Acids Are Related to Impulse Control and Anterior Cingulate Function in Adolescents

Impulse control, an emergent function modulated by the prefrontal cortex (PFC), helps to dampen risky behaviors during adolescence. Influences on PFC maturation during this period may contribute to variations in impulse control. Availability of omega-3 fatty acids, an essential dietary nutrient integral to neuronal structure and function, may be one such influence. This study examined whether intake of energy-adjusted long-chain omega-3 fatty acids [eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)] was related to variation in impulse control and PFC activity during performance of an inhibitory task in adolescents (n = 87; 51.7% female, mean age 13.3 ± 1.1 years) enrolled in a longitudinal neuroimaging study. Intake of DHA + EPA was assessed using a food frequency questionnaire and adjusted for total energy intake. Inhibitory control was assessed using caregiver rating scale (BRIEF Inhibit subscale) and task performance (false alarm rate) on a Go/No-Go task performed during functional MRI. Reported intake of long-chain omega-3 was positively associated with caregiver ratings of adolescent ability to control impulses (p = 0.017) and there was a trend for an association between intake and task-based impulse control (p = 0.072). Furthermore, a regression of BOLD response within PFC during successful impulse control (Correct No-Go versus Incorrect No-Go) with energy-adjusted DHA + EPA intake revealed that adolescents reporting lower intakes display greater activation in the dorsal anterior cingulate, potentially suggestive of a possible lag in cortical development. The present results suggest that dietary omega-3 fatty acids are related to development of both impulse control and function of the dorsal anterior cingulate gyrus in normative adolescent development. Insufficiency of dietary omega-3 fatty acids during this developmental period may be a factor which hinders development of behavioral control.

Omega-3 Fatty Acids as a Treatment for Pediatric Depression. A Phase III, 36 Weeks, Multi-Center, Double-Blind, Placebo-Controlled Randomized Superiority Study

Background: Depressive disorders in childhood and adolescence are a major health problem and often follow a chronic course with severe consequences in later life. Depressive disorders cause the highest burden of disease in this age group across all medical conditions. Treatment adherence is usually very poor, and the use of antidepressant drugs is heavily debated, as suicidal ideations may increase, in particular in the early phase of treatment. Omega-3 fatty acids rich in eicosapentaenoic acid have shown some promising results in over a dozen small scale randomized controlled trials (RCTs) in adult major depressive disorders, with only very few published RCTs in children and adolescents. High-quality phase III RCTs are missing. Methods and Design: The omega-3-pMDD trial is a carefully designed phase III RCT to assess the efficacy and safety of omega-3 fatty acids in the early course of pediatric major depressive disorder (MDD). The study is designed as a multi-center, double-blinded, placebo-controlled, randomized clinical trial enrolling 220 patients aged 8 to 17 years meeting DSM-IV criteria for major depressive disorder of at least moderate symptom severity. After a single-blinded placebo-lead-in phase (7 to 10 days) patients are randomly assigned to omega-3 fatty acids or placebo over 36 weeks. Primary outcomes are changes in depression severity, as well as remission and recovery rates. Secondary outcome measures include the omega-3 index and inflammatory parameters as predictors of response. Data analysis will be performed in the intention-to-treat sample using a (generalized) linear random intercept regression model. Through sampling of blood, hair, saliva, and urine, further putative biological markers for depression and omega-3 fatty response will be investigated. Discussion: This trial addresses if omega-3 fatty acids play a role in the pathogenesis of pediatric MDDs and have antidepressant properties, in particular in clinically depressed children and adolescents with a pre-existing omega-3 fatty acid deficiency, increased markers of oxidative stress, and/or markers of (low grade) inflammation. Ethics and Dissemination: The study was approved by the local ethics committees. The results will be published in peer-reviewed journals irrespective of specific outcomes. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03167307.

The effect of Atlantic salmon consumption on the cognitive performance of preschool children - A randomized controlled trial

BACKGROUND AND AIMS

Long chain polyunsaturated n-3 fatty acids (LC-PUFA) are of functional and structural importance for brain development. Observational studies have shown positive relations between fatty fish consumption and cognitive performance in children, but Results from intervention studies using supplementary n-3 LC-PUFA are conflicting. Salmon is a good source of n-3 LC-PUFA, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). We tested the hypothesis that an increased dietary salmon intake results in better cognitive outcomes than a meat based diet.

METHODS

Children (n = 205, age 4-6 years) in this trial were individually randomized to eating meals containing farmed Atlantic salmon or meat three times weekly for 16 weeks. Pre- and post-intervention a cognitive test (Wechsler Preschool and Primary Scale of Intelligence, 3rd edition, WPPSI-III) and a fine-motor coordination test (Nine Hole Peg Test, 9-HPT) were performed. Biochemical analyses included glycerophospholipid fatty acid profiles in plasma and cheek cells, serum 25-hydroxyvitamin D, and urinary iodine concentration. Dietary intake before and during the study were determined using food frequency questionnaires.

RESULTS

Intakes of EPA, DHA, vitamin D and iodine were higher in the salmon than the meat group, but on biomarker level only EPA and DHA increased significantly in the salmon group compared to the meat group (p < 0.001). In general linear models no significant differences between the intervention groups were found in the scale scores of the WPPSI-III tests and the 9-HPT. In analyses of the raw scores, the salmon group showed significantly better improvement in two of the eight raw scores compared to the meat group (symbol search p = 0.038, picture concepts p = 0.047).

CONCLUSIONS

Intake of farmed Atlantic salmon led to a greater increase of the raw scores of the picture concept and symbol search subtests, while in the six other subtests raw scores were not different between the groups. This might indicate a modest positive association of salmon intake with the performance of preschool children in some subtests evaluating fluid intelligence but does not suggest an influence on global IQ development.

CLINICAL TRIAL REGISTRY NUMBER AND WEBSITE

ClinicalTrials.gov registration number: NCT01951937.

The effects of fatty fish intake on adolescents' nutritional status and associations with attention performance: results from the FINS-TEENS randomized controlled trial

Background

Adolescence involves changes in dietary habits that may induce imbalances in the intake of different nutrients. Fish is an important dietary source of omega-3 (n-3) long-chain polyunsaturated fatty acids (LCPUFAs), vitamin D, several minerals and high-quality protein. By using secondary outcomes and exploratory analyses, the aims of this paper were to evaluate if nutritional biomarkers (red blood cell fatty acids, serum (s)-25(OH)D, s-ferritin and urinary iodine concentration (UIC)) were altered during a dietary intervention, and if they mediated previously reported changes in attention performance. In addition, to examine the status of the biomarkers and explore associations between dietary pattern, biomarkers and attention performance cross-sectionally at baseline.

Methods

The Fish Intervention Studies-TEENS (FINS-TEENS) was a three-armed intervention trial, including adolescents from eight secondary schools (n = 415; age: 14–15y) in Bergen, Norway. Participants were individually randomized to receive either fish meals, meat meals or n-3 LCPUFA supplements, three times a week for a total of 12 weeks. Blood and urine samples were collected pre and post intervention and attention performance was assessed with the d2 test of attention. Analyses of covariance (ANCOVA) assessed differences between groups in changes of biomarkers and linear mixed models were applied in analyses of attention performance and biomarkers. The trial is registered in ClinicalTrials.gov (NCT02350322).

Results

At baseline, the mean omega-3 index was 5.8 ± 1.3% and deficient status were identified for s-25(OH)D (54%), s-ferritin (10%) and UIC (40%). The intervention resulted in an increase in DHA and the omega-3 index which was larger in the supplement group compared to the fish and meat group (P < 0.01), and in the fish group compared to the meat group (P < 0.01). No differences between the groups were observed for changes in 25(OH)D, s-ferritin or UIC. None of the biomarkers mediated performance in the d2 test. The intake of fatty fish and a healthy dietary pattern was associated with scores in processing speed at baseline.

Conclusions

These results show that Norwegian adolescents have insufficient status of important nutrients, which may be improved with fatty fish consumption or n-3 LCPUFA supplements. However, nutritional status was not associated with scores in the d2 test of attention.

Discrepancy between Knowledge and Perceptions of Dietary Omega-3 Fatty Acid Intake Compared with the Omega-3 Index

Little is known about the relationship between perceptions of nutrient adequacy and biomarkers of nutrition status. This cross-sectional study of U.S. and German adults (n = 200; 18–80 years) compared dietary practices, knowledge, and beliefs of omega-3 fatty acids (O3-FA) with the omega-3 index (O3-I), an erythrocyte-based biomarker associated with cardiovascular disease (CVD) risk. More than half of adults believed that O3-FAs are beneficial for heart and brain health and could correctly identify the food sources of O3-FA. However, the mean O3-I in the U.S. (4.3%) and Germany (5.5%) puts the majority of adults sampled (99%) in intermediate or high CVD-risk categories. More Americans were considered at high CVD-risk (40%) when compared with Germans (10%). In the U.S., but not Germany, women had a significantly higher O3-I than men (4.8% vs. 3.8%, p < 0.001). In the intermediate CVD-risk group, about one-third of adults in both countries (30% in the U.S. and 27% in Germany) believed their diet was adequate in O3-FA. Notably, mean O3-I concentrations did not significantly differ with dietary perceptions of adequacy. More adults in Germany (26%) than in the U.S. (10%) believed that dietary supplements are needed to achieve a balanced diet. In spite of adequate knowledge about food sources and a consistent belief that O3-FA are important for health, very few participants had O3-I concentrations in the range for CVD protection.

Effects of Long-Chain Omega-3 Polyunsaturated Fatty Acids on Endothelial Vasodilator Function and Cognition-Are They Interrelated?

Long-chain omega-3 polyunsaturated fatty acids (LCn-3 PUFA) may improve brain functions by acting on endothelial cells in the cerebrovasculature to facilitate vasodilatation and perfusion. The aim of this review is to explore this hypothesis by analyzing the effect of LCn-3 PUFA supplementation on systemic vasodilator and cognitive function and finding evidence to link LCn-3 PUFA intake, vasodilator function and cognition. Forty randomized controlled trials examining the effect of LCn-3 PUFA supplementation in humans on either endothelial vasodilator function or cognition were identified and pooled effects measured with a weighted analysis. Compared to placebo, LCn-3 PUFA tended to increase flow-mediated dilatation and significantly improved cognitive function. Emerging evidence links vasodilator dysfunction to cognitive impairment, but evidence that LCn-3 PUFA can improve cognition through enhancements of vasodilator function is still lacking. Further research is needed to determine: (1) whether LCn-3 PUFA can enhance dilatation of cerebral vessels; (2) if improvements in cerebrovascular responsiveness by LCn-3 PUFA are accompanied by cognitive benefits; and (3) the target population groups.

The effect of healthy dietary consumption on executive cognitive functioning in children and adolescents: a systematic review

A systematic review was conducted to evaluate whether healthier dietary consumption among children and adolescents impacts executive functioning. PubMed, Education Resources Information Center, PsychINFO and Thomson Reuters’ Web of Science databases were searched, and studies of executive functioning among children or adolescents aged 6–18 years, which examined food quality, macronutrients and/or foods, were included. Study quality was also assessed. In all, twenty-one studies met inclusion criteria. Among the twelve studies examining food quality (n 9) or macronutrient intakes (n 4), studies examining longer-term diet (n 6) showed positive associations between healthier overall diet quality and executive functioning, whereas the studies examining the acute impact of diet (n 6) were inconsistent but suggestive of improvements in executive functioning with better food quality. Among the ten studies examining foods, overall, there was a positive association between healthier foods (e.g. whole grains, fish, fruits and/or vegetables) and executive function, whereas less-healthy snack foods, sugar-sweetened beverages and red/processed meats were inversely associated with executive functioning. Taken together, evidence suggests a positive association between healthy dietary consumption and executive functioning. Additional studies examining the effects of healthier food consumption, as well as macronutrients, on executive functioning are warranted. These studies should ideally be conducted in controlled environments and use validated cognitive tests.

Nutrient reference value: non-communicable disease endpoints--a conference report

Nutrition is complex-and seemingly getting more complicated. Most consumers are familiar with "essential nutrients," e.g., vitamins and minerals, and more recently protein and important amino acids. These essential nutrients have nutrient reference values, referred to as dietary reference intakes (DRIs) developed by consensus committees of scientific experts convened by the Institute of Medicine of the National Academy of Sciences, Engineering, and Medicine and carried out by the Food and Nutrition Board. The DRIs comprise a set of four nutrient-based reverence values, the estimated average requirements, the recommended dietary allowances (RDAs), the adequate intakes and the tolerable upper intake levels for micronutrient intakes and an acceptable macronutrient distribution range for macronutrient intakes. From the RDA, the US Food and Drug Administration (FDA) derives a labeling value called the daily value (DV), which appears on the nutrition label of all foods for sale in the US. The DRI reports do not make recommendations about whether the DV labeling values can be set only for what have been defined to date as "essential nutrients." For example, the FDA set a labeling value for "dietary fiber" without having the DV. Nutrient reference values-requirements are set by Codex Alimentarius for essential nutrients, and regulatory bodies in many countries use these Codex values in setting national policy for recommended dietary intakes. However, the focus of this conference is not on essential nutrients, but on the "nonessential nutrients," also termed dietary bioactive components. They can be defined as "Constituents in foods or dietary supplements, other than those needed to meet basic human nutritional needs, which are responsible for changes in health status (Office of Disease Prevention and Health Promotion, Office of Public Health and Science, Department of Health and Human Services in Fed Regist 69:55821-55822, 2004)." Substantial and often persuasive scientific evidence does exist to confirm a relationship between the intake of a specific bioactive constituent and enhanced health conditions or reduced risk of a chronic disease. Further, research on the putative mechanisms of action of various classes of bioactives is supported by national and pan-national government agencies, and academic institutions, as well as functional food and dietary supplement manufacturers. Consumers are becoming educated and are seeking to purchase products containing bioactives, yet there is no evaluative process in place to let the public know how strong the science is behind the benefits or the quantitative amounts needed to achieve these beneficial health effects or to avoid exceeding the upper level (UL). When one lacks an essential nutrient, overt deficiency with concomitant physiological determents and eventually death are expected. The absence of bioactive substances from the diet results in suboptimal health, e.g., poor cellular and/or physiological function, which is relative and not absolute. Regrettably at this time, there is no DRI process to evaluate bioactives, although a recent workshop convened by the National Institutes of Health (Options for Consideration of Chronic Disease Endpoints for Dietary Reference Intakes (DRIs); March 10-11, 2015; http://health.gov/dietaryguidelines/dri/ ) did explore the process to develop DVs for nutrients, the lack of which result in increased risk of chronic disease (non-communicable disease) endpoints. A final report is expected soon. This conference (CRN-International Scientific Symposium; "Nutrient Reference Value-Non-Communicable Disease (NRV-NCD) Endpoints," 20 November in Kronberg, Germany; http://www.crn-i.ch/2015symposium/ ) explores concepts related to the Codex NRV process, the public health opportunities in setting NRVs for bioactive constituents, and further research and details on the specific class of bioactives, n-3 long-chain polyunsaturated fatty acids (also termed omega-3 fatty acids) and their constituents, specifically docosahexaenoic acid and eicosapentaenoic acid.