Omega-3 supplementation during the first 5 years of life and later academic performance: a randomised controlled trial

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.

New Perspectives on the Associations between Blood Fatty Acids, Growth Parameters, and Cognitive Development in Global Child Populations

Malnutrition is prevalent in low-middle-income countries (LMICs), but it is usually clinically diagnosed through abnormal anthropometric parameters characteristic of protein energy malnutrition (PEM). In doing so, other contributors or byproducts of malnutrition, notably essential fatty acid deficiency (EFAD), are overlooked. Previous research performed mainly in high-income countries (HICs) shows that deficiencies in essential fatty acids (EFAs) and their n-3 and n-6 polyunsaturated fatty acid (PUFA) byproducts (also known as highly unsaturated fatty acids or HUFAs) lead to both abnormal linear growth and impaired cognitive development. These adverse developmental outcomes remain an important public health issue in LMICs. To identify EFAD before severe malnutrition develops, clinicians should perform blood fatty acid panels to measure levels of fatty acids associated with EFAD, notably Mead acid and HUFAs. This review demonstrates the importance of measuring endogenous fatty acid levels for measuring fatty acid intake in various child populations in LMICs. Featured topics include a comparison of fatty acid levels between global child populations, the relationships between growth and cognition and PUFAs and the possible mechanisms driving these relationships, and the potential importance of EFAD and HUFA scores as biomarkers of overall health and normal development.

Maternal Supply of Both Arachidonic and Docosahexaenoic Acids Is Required for Optimal Neurodevelopment

During the last trimester of gestation and for the first 18 months after birth, both docosahexaenoic acid,22:6n-3 (DHA) and arachidonic acid,20:4n-6 (ARA) are preferentially deposited within the cerebral cortex at a rapid rate. Although the structural and functional roles of DHA in brain development are well investigated, similar roles of ARA are not well documented. The mode of action of these two fatty acids and their derivatives at different structural-functional roles and their levels in the gene expression and signaling pathways of the brain have been continuously emanating. In addition to DHA, the importance of ARA has been much discussed in recent years for fetal and postnatal brain development and the maternal supply of ARA and DHA. These fatty acids are also involved in various brain developmental processes; however, their mechanistic cross talks are not clearly known yet. This review describes the importance of ARA, in addition to DHA, in supporting the optimal brain development and growth and functional roles in the brain.

Effect of omega-3 fatty acids on cognition: an updated systematic review of randomized clinical trials

Context

The increasing number of studies on the effects of n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) on health, particularly cognition, in the last 5 years reflects the growing interest in this area of research.

Objective

The aim for this systematic review was to evaluate the scientific evidence published in the last 5 years (2012-2017) on the effects of n-3 LC-PUFA intake on cognition, cognitive development, and cognitive decline to determine whether n-3 LC-PUFAs support cognitive development and prevent cognitive decline.

Data Sources

The PubMed database was searched.

Study Selection

The 51 articles included in this systematic review reported on healthy individuals with mild or moderate cognitive impairment and patients with Alzheimer's disease. Risk of bias was assessed using Cochrane methodology.

Data Extraction

The number of study participants, the type of study, the type and dose of n-3 LC-PUFAs, and the key results are reported here.

Results

Current evidence indicates that n-3 LC-PUFAs administered during pregnancy or breastfeeding have no effect on the skills or cognitive development of children in later stages of development. Evidence regarding the improvement of cognitive function during childhood and youth or in attention deficit/hyperactivity disorder is inconclusive. Moreover, it is still unclear if n-3 LC-PUFAs can improve cognitive development or prevent cognitive decline in young or older adults.

Fish, Shellfish, and Children's Health: An Assessment of Benefits, Risks, and Sustainability

American children eat relatively little fish and shellfish in comparison with other sources of animal protein, despite the health benefits that eating fish and shellfish may confer. At the same time, fish and shellfish may be sources of toxicants. This report serves to inform pediatricians about available research that elucidates health risks and benefits associated with fish and shellfish consumption in childhood as well as the sustainability of fish and shellfish harvests.

Periconceptional Maternal Mediterranean Diet Is Associated With Favorable Offspring Behaviors and Altered CpG Methylation of Imprinted Genes

Background: Maternal diet during pregnancy has been shown to influence the child neuro-developmental outcomes. Studies examining effects of dietary patterns on offspring behavior are sparse. Objective: Determine if maternal adherence to a Mediterranean diet is associated with child behavioral outcomes assessed early in life, and to evaluate the role of differentially methylated regions (DMRs) regulating genomically imprinted genes in these associations. Methods: Among 325 mother/infant pairs, we used regression models to evaluate the association between tertiles of maternal periconceptional Mediterranean diet adherence (MDA) scores derived from a Food Frequency Questionnaire, and social and emotional scores derived from the Infant Toddler Social and Emotional Assessment (ITSEA) questionnaire in the second year of life. Methylation of nine genomically imprinted genes was measured to determine if MDA was associated with CpG methylation. Results: Child depression was inversely associated with maternal MDA (Bonferroni-corrected p = 0.041). While controlling for false-discovery, compared to offspring of women with the lowest MDA tertile, those with MDA scores in middle and high MDA tertiles had decreased odds for atypical behaviors [OR (95% CI) = 0.40 (0.20, 0.78) for middle and 0.40 (0.17, 0.92) for highest tertile], for maladaptive behaviors [0.37 (0.18, 0.72) for middle tertile and 0.42 (0.18, 0.95) for highest tertile] and for an index of autism spectrum disorder behaviors [0.46 (0.23, 0.90) for middle and 0.35 (0.15, 0.80) for highest tertile]. Offspring of women with the highest MDA tertile were less likely to exhibit depressive [OR = 0.28 (0.12, 0.64)] and anxiety [0.42 (0.18, 0.97)] behaviors and increased odds of social relatedness [2.31 (1.04, 5.19)] behaviors when compared to low MDA mothers. Some associations varied by sex. Perinatal MDA score was associated with methylation differences for imprinted control regions of PEG10/SGCE [females: Beta (95% CI) = 1.66 (0.52, 2.80) - Bonferroni-corrected p = 0.048; males: -0.56 (-1.13, -0.00)], as well as both MEG3 and IGF2 in males [0.97 (0.00, 1.94)] and -0.92 (-1.65, -0.19) respectively. Conclusion: In this ethnically diverse cohort, maternal adherence to a Mediterranean diet in early pregnancy was associated with favorable neurobehavioral outcomes in early childhood and with sex-dependent methylation differences of MEG3, IGF2, and SGCE/PEG10 DMRs.

Brain Health across the Lifespan: A Systematic Review on the Role of Omega-3 Fatty Acid Supplements

The brain is the most significant and complex organ of the human body. Increasingly, we are becoming aware that certain nutrients may help to safeguard brain health. An expanse of research has investigated the effects of omega fatty acids in relation to brain health but effects across the lifespan have not been widely evaluated. The present systematic review collated evidence from 25 randomized controlled trials (n = 3633) published since 2013. Compared with control groups, omega-3 supplementation generally correlated with improvements in blood biomarkers. Subsequently, these appear to benefit those with lower baseline fatty acid levels, who are breastfeeding or who have neuropsychiatric conditions. Whilst multiple studies indicate that omega fatty acids can protect against neurodegeneration in older adults, more work is needed in the years preceding the diagnosis of such medical conditions. Bearing in mind the scale of ageing populations and rising healthcare costs linked to poor brain health, omega supplementation could be a useful strategy for helping to augment dietary intakes and support brain health across the lifespan. Ongoing research is now needed using harmonious methodologies, supplement dosages, ratios and intervention periods to help formulate congruent conclusions.

How does high DHA fish oil affect health? A systematic review of evidence

The health benefits of fish oil, and its omega-3 long chain polyunsaturated fatty acid content, have attracted much scientific attention in the last four decades. Fish oils that contain higher amounts of eicosapentaenoic acid (EPA; 20:5n-3) than docosahexaenoic acid (DHA; 22:6n-3), in a distinctive ratio of 18/12, are typically the most abundantly available and are commonly studied. Although the two fatty acids have traditionally been considered together, as though they were one entity, different physiological effects of EPA and DHA have recently been reported. New oils containing a higher quantity of DHA compared with EPA, such as fractionated and concentrated fish oil, tuna oil, calamari oil and microalgae oil, are increasingly becoming available on the market, and other oils, including those extracted from genetically modified oilseed crops, soon to come. This systematic review focuses on the effects of high DHA fish oils on various human health conditions, such as the heart and cardiovascular system, the brain and visual function, inflammation and immune function and growth/Body Mass Index. Although inconclusive results were reported in several instances, and inconsistent outcomes observed in others, current data provides substantiated evidence in support of DHA being a beneficial bioactive compound for heart, cardiovascular and brain function, with different, and at times complementary, effects compared with EPA. DHA has also been reported to be effective in slowing the rate of cognitive decline, while its possible effects on depression disorders are still unclear. Interestingly, gender- and age- specific divergent roles for DHA have also been reported. This review provides a comprehensive collection of evidence and a critical summary of the documented physiological effects of high DHA fish oils for human health.

Using fathers as a negative control exposure to test the Developmental Origins of Health and Disease Hypothesis: A case study on maternal distress and offspring asthma using Swedish register data

BACKGROUND

Developmental Origins of Health and Disease Hypothesis (DOHaD) studies are often observational in nature and are therefore prone to biases from loss to follow-up and unmeasured confounding. Register-based studies can reduce these issues since they allow almost complete follow-up and provide information on fathers that can be used in a negative control analysis to assess the impact of unmeasured confounding.

AIM

The aim of this study was to propose a causal model for testing DOHaD using paternal exposure as a negative control, and its application to maternal distress in pregnancy and offspring asthma.

METHODS

A causal diagram including shared and parent-specific measured and unmeasured confounders for maternal (fetal) and paternal exposures is proposed. The case study consisted of all children born in Sweden from July 2006 to December 2008 ( n=254,150). Information about childhood asthma, parental distress and covariates was obtained from the Swedish national health registers. Associations between maternal and paternal distress during pregnancy and offspring asthma at age five years were assessed separately and with mutual adjustment for the other parent's distress measure, as well as for shared confounders.

RESULTS

Maternal distress during pregnancy was associated with offspring asthma risk; mutually adjusted odds ratio (OR) (OR 1.32, 95% CI 1.23, 1.43). The mutually adjusted paternal distress-offspring asthma analysis (OR 1.05, 95% CI 0.97, 1.13) indicated no evidence for unmeasured confounding shared by the mother and father.

CONCLUSIONS

Using paternal exposure in a negative control model to test the robustness of fetal programming hypotheses can be a relatively simple extension of conventional observational studies but limitations need to be considered.

Docosahexaenoic Acid and Cognition throughout the Lifespan

Docosahexaenoic acid (DHA) is the predominant omega-3 (n-3) polyunsaturated fatty acid (PUFA) found in the brain and can affect neurological function by modulating signal transduction pathways, neurotransmission, neurogenesis, myelination, membrane receptor function, synaptic plasticity, neuroinflammation, membrane integrity and membrane organization. DHA is rapidly accumulated in the brain during gestation and early infancy, and the availability of DHA via transfer from maternal stores impacts the degree of DHA incorporation into neural tissues. The consumption of DHA leads to many positive physiological and behavioral effects, including those on cognition. Advanced cognitive function is uniquely human, and the optimal development and aging of cognitive abilities has profound impacts on quality of life, productivity, and advancement of society in general. However, the modern diet typically lacks appreciable amounts of DHA. Therefore, in modern populations, maintaining optimal levels of DHA in the brain throughout the lifespan likely requires obtaining preformed DHA via dietary or supplemental sources. In this review, we examine the role of DHA in optimal cognition during development, adulthood, and aging with a focus on human evidence and putative mechanisms of action.

Docosahexaenoic Acid and Cognition throughout the Lifespan

Docosahexaenoic acid (DHA) is the predominant omega-3 (n-3) polyunsaturated fatty acid (PUFA) found in the brain and can affect neurological function by modulating signal transduction pathways, neurotransmission, neurogenesis, myelination, membrane receptor function, synaptic plasticity, neuroinflammation, membrane integrity and membrane organization. DHA is rapidly accumulated in the brain during gestation and early infancy, and the availability of DHA via transfer from maternal stores impacts the degree of DHA incorporation into neural tissues. The consumption of DHA leads to many positive physiological and behavioral effects, including those on cognition. Advanced cognitive function is uniquely human, and the optimal development and aging of cognitive abilities has profound impacts on quality of life, productivity, and advancement of society in general. However, the modern diet typically lacks appreciable amounts of DHA. Therefore, in modern populations, maintaining optimal levels of DHA in the brain throughout the lifespan likely requires obtaining preformed DHA via dietary or supplemental sources. In this review, we examine the role of DHA in optimal cognition during development, adulthood, and aging with a focus on human evidence and putative mechanisms of action.

Dietary marine fatty acids (fish oil) for asthma

BACKGROUND

Epidemiological studies suggest that a diet high in marine fatty acids (fish oil) may have beneficial effects on inflammatory conditions such as rheumatoid arthritis and possibly asthma.

OBJECTIVES

1. To determine the effect of marine n-3 fatty acid (fish oil) supplementation in asthma. 2. To determine the effect of a diet high in fish oil in asthma.

SEARCH STRATEGY

The Cochrane Airways Review Group register was search using the terms: marine fatty acids OR diet OR nutrition OR fish oil OR eicosapentaenoic acid OR EPA. Bibliographies of retrieved trials were searched and fish oil manufacturers contacted.

SELECTION CRITERIA

Randomised controlled trials in patients with asthma more than two years of age were included. The study duration had to be in excess of 4 weeks. Double blind trials were preferred, but single-blind and open trials were also reviewed for possible inclusion. Three reviewers read each paper, blind to its identity. Decisions concerning inclusion were made by simple majority. Quality assessment was performed by all three reviewers independently.

DATA COLLECTION AND ANALYSIS

The only comparison possible was between marine n-3 fatty acid supplementation and placebo. There were insufficient trials to examine dietary manipulation alone.

MAIN RESULTS

Eight randomised controlled trials conducted between 1986 and 1998 satisfied the inclusion criteria. Six were of parallel design and two were cross-over studies. Seven compared fish oil with placebo whilst one compared high dose vs low dose marine n-3 fatty acid supplementation. None of the included studies reported asthma exacerbations, health status or hospital admissions. There was no consistent effect on any of the analyzable outcomes: FEV1, peak flow rate, asthma symptoms, asthma medication use or bronchial hyper reactivity. The single study performed in children also combined dietary manipulation with fish oil supplementation and showed improved peak flow and reduced asthma medication use. There were no adverse events associated with fish oil supplements. Updated Search conducted August 2000. No new trials were found.

REVIEWER'S CONCLUSIONS

There is little evidence to recommend that people with asthma supplement or modify their dietary intake of marine n-3 fatty acids (fish oil) in order to improve their asthma control. Equally, there is no evidence that they are at risk if they do so.