Effects of n-3 Long-Chain Polyunsaturated Fatty Acid Supplementation during Pregnancy and/or Lactation on Neurodevelopment and Visual Function in Children: A Systematic Review of Randomized Controlled Trials

Nutritional Quality Implications: Exploring the Impact of a Fatty Acid-Rich Diet on Central Nervous System Development

Given the comprehensive examination of the role of fatty acid-rich diets in central nervous system development in children, this study bridges significant gaps in the understanding of dietary effects on neurodevelopment. It delves into the essential functions of fatty acids in neurodevelopment, including their contributions to neuronal membrane formation, neuroinflammatory modulation, neurogenesis, and synaptic plasticity. Despite the acknowledged importance of these nutrients, this review reveals a lack of comprehensive synthesis in current research, particularly regarding the broader spectrum of fatty acids and their optimal levels throughout childhood. By consolidating the existing knowledge and highlighting critical research gaps, such as the effects of fatty acid metabolism on neurodevelopmental disorders and the need for age-specific dietary guidelines, this study sets a foundation for future studies. This underscores the potential of nutritional strategies to significantly influence neurodevelopmental trajectories, advocating an enriched academic and clinical understanding that can inform dietary recommendations and interventions aimed at optimizing neurological health from infancy.

Promising Sources of Plant-Derived Polyunsaturated Fatty Acids: A Narrative Review

(1) Background: Polyunsaturated fatty acids (PUFAs) are known for their ability to protect against numerous metabolic disorders. The consumption of oily fish is the main source of PUFAs in human nutrition and is commonly used for supplement production. However, seafood is an overexploited source that cannot be guaranteed to cover the global demands. Furthermore, it is not consumed by everyone for ecological, economic, ethical, geographical and taste reasons. The growing demand for natural dietary sources of PUFAs suggests that current nutritional sources are insufficient to meet global needs, and less and less will be. Therefore, it is crucial to find sustainable sources that are acceptable to all, meeting the world population's needs. (2) Scope: This review aims to evaluate the recent evidence about alternative plant sources of essential fatty acids, focusing on long-chain omega-3 (n-3) PUFAs. (3) Method: A structured search was performed on the PubMed search engine to select available human data from interventional studies using omega-3 fatty acids of non-animal origin. (4) Results: Several promising sources have emerged from the literature, such as algae, microorganisms, plants rich in stearidonic acid and GM plants. However, the costs, acceptance and adequate formulation deserve further investigation.

Does antenatal supplementation with omega-3 affect child development and behavior during the first six months of life? A randomized double-blind placebo-controlled trial

BACKGROUND

Omega-3 fatty acids, especially docosahexaenoic acid (DHA), are found in different cell membranes, but more concentrated in the brain, playing an important role in child's behavior and development.

AIMS

To evaluate the effect of antenatal omega-3 supplementation on child development and behavior during the first six months of life.

STUDY DESIGN

Randomized double-blind placebo-controlled trial.

SUBJECTS

Low-risk pregnant women with gestational age between 22 and 24 weeks were randomized in placebo (olive oil; n = 30) or omega-3 (fish oil; 1440 mg/day of DHA; n = 30) groups and supplemented until childbirth.

OUTCOME MEASURES

Child development was assessed using the Survey of Well-being of Young Children in the first, fourth and sixth month of life.

RESULTS

The comparison between groups showed no differences in the Developmental Milestones score at any time, but when compared to the first month, the omega-3 group showed an increase at the fourth and sixth month. Such increase was not observed in the placebo group. No differences were found between groups for Irritability and Inflexibility scores, however, higher scores for Difficulty with Routine were observed in the placebo group when compared to omega-3 at first, fourth and sixth month.

CONCLUSION

There were no differences between groups for child development, but the omega-3 group showed an increase in this score over time. The placebo group had greater difficulty with routine than the omega-3 group, indicating a beneficial effect of antenatal supplementation on child behavior.

TRIAL REGISTRATION

ReBec U1111-1215-7952 (June 16th 2018).

Impact of omega-3 fatty acid DHA and EPA supplementation in pregnant or breast-feeding women on cognitive performance of children: systematic review and meta-analysis

INTRODUCTION

The omega-3 long-chain polyunsaturated fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are important for brain development and cognitive performance. Because they are semi-essential fatty acids, they must be obtained from food. However, the dietary reference intakes of DHA and EPA have not yet been established. In women, a low DHA and/or EPA serum level during pregnancy or breastfeeding might negatively affect their children. For this study, we conducted a systematic review and meta-analysis of randomized control trials on the association between the consumption of fish oil supplements in pregnant and/or breastfeeding women and the cognitive performance of their children.

METHODS

The PubMed, Embase, and Central literature databases were systematically searched. We included and extracted relevant studies in duplicate and assessed study quality. Cognitive outcomes were grouped according to published criteria and according to time elapsed after the intervention. We performed fixed-effects meta-analyses for each cognitive outcome and for birth weight. We assessed potential confounding with meta-regressions and sensitivity analyses.

RESULTS

A total of 11 trials were included. No significant association was found between DHA/EPA supplementation and any of the assessed cognitive parameters or birth weight.

DISCUSSION

Our results confirm previous reviews on the studied topic. Reasons for inconclusive results may be small sample sizes for each assessed category, questionable quality of included studies, and the difficulty of reliably measuring cognitive performance in small children. Blood levels of omega-3 long-chain polyunsaturated fatty acids were mostly not comparable. Furthermore, the influence of genetic and environmental factors could not be assessed. Studies in this field should address such shortcomings.

Milk Fat Globule Membrane Supplementation in Children: Systematic Review with Meta-Analysis

(1) Background: Milk fat globule membrane (MFGM), composing fat droplets responsible for lipid transport in breast milk, has been shown to possess immunological and antimicrobial effects. Standard formulas (SF) are devoid of MFGMs during the production process. The study’s aim was to evaluate the safety and benefits of MFGMs supplementation in children. (2) Methods: We searched four databases for randomized controlled trials evaluating the supplementation of MFGMs in children. Growth parameters were chosen as the primary outcome. (3) Results: Twenty-four publications of seventeen studies were included. Meta-analyses assessing the primary outcomes at the age of 4 months included four studies (814 children) comparing the MFGM-supplemented formulas and SF, and two trials (549 children) comparing the MFGM-supplemented formulas and breastfeeding. The primary outcomes were non-inferior in all the experimental MFGM formulas compared to SF, or even represented more similar results to breastfed infants. The promising effects, including a lower incidence of acute otitis media and improved cognitive development, cannot be firmly confirmed due to the small amount of existing evidence. No significant adverse effects were reported in any of the assessed products. (4) Conclusions: The available data signaled beneficial effects and a good safety profile, requiring future research with well-designed trials.

Dietary Intake of DHA and EPA in a Group of Pregnant Women in the Moncton Area

Purpose: To compare docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and fish intake of pregnant women at 30 weeks of gestation to current recommendations and to determine the factors associated with omega-3 (ω-3) intake.

Methods: A food frequency questionnaire was completed by 54 women (54/131 = 41%) at 30 ± 0.8 weeks gestation. Supplement intake, sociodemographic characteristics, and ω-3 food habits were evaluated.

Results: Among this high socioeconomic status (SES) group, 66.7% and 64.8% met the Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO) recommendation of 200 mg/d DHA and 300 mg/d DHA + EPA, respectively, and only 48.1% met the Academy of Nutrition and Dietetics (Academy) recommendation of 500 mg/d DHA + EPA. Eighteen of the 54 women took a ω-3 supplement during the third trimester. This significantly improved their total intake to meet the FAO/WHO (88.9% ≥200 mg/d DHA and 94.4% ≥300 mg/d DHA + EPA) and the Academy (77.8% ≥500 mg/d DHA + EPA) recommendations. Among nonsupplement users (36/54), 50% met the FAO/WHO recommendations and only 33.3% met the Academy recommendations.

Conclusions: Results suggest that the majority of high SES women did not meet ω-3 recommendations from food alone. Continued prenatal education on the importance of fish intake and on the addition of ω-3 prenatal supplement is essential.

Impact of the n-6:n-3 long-chain PUFA ratio during pregnancy and lactation on offspring neurodevelopment: 5-year follow-up of a randomized controlled trial

BACKGROUND/OBJECTIVES

Evidence regarding the effect of n-3 long-chain polyunsaturated fatty acid (LCPUFA) supplementation during pregnancy on offspring's neurodevelopment is not conclusive.

SUBJECTS/METHODS

In this analysis, the effect of a reduced n-6:n-3 LCPUFA ratio in the diet of pregnant/lactating women (1.2 g n-3 LCPUFA together with an arachidonic acid (AA)-balanced diet between 15th wk of gestation-4 months postpartum vs control diet) on child neurodevelopment at 4 and 5 years of age was assessed. A child development inventory (CDI) questionnaire and a hand movement test measuring mirror movements (MMs) were applied and the association with cord blood LCPUFA concentrations examined.

RESULTS

CDI questionnaire data, which categorizes children as 'normal', 'borderline' or 'delayed' in different areas of development, showed no significant evidence between study groups at 4 (n=119) and 5 years (n=130) except for the area 'letters' at 5 years of age (P=0.043). Similarly, the results did not strongly support the hypothesis that the intervention has a beneficial effect on MMs (for example, at 5 years: dominant hand, fast: adjusted mean difference, -0.08 (-0.43, 0.26); P=0.631). Children exposed to higher cord blood concentrations of docosahexaenoic acid, eicosapentaenoic acid and AA, as well as a lower ratio of n-6:n-3 fatty acids appeared to show beneficial effects on MMs, but these results were largely not statistically significant.

CONCLUSIONS

Our results do not show clear benefits or harms of a change in the n-6:n-3 LCPUFA ratio during pregnancy on offspring's neurodevelopment at preschool age. Findings on cord blood LCPUFAs point to a potential influence on offspring development.

Effects of prenatal and/or postnatal supplementation with iron, PUFA or folic acid on neurodevelopment: update

Neurodevelopment has been linked, among other factors, to maternal and early infant diets. The objective of this review, which is part of the NUTRIMENTHE research project ‘The effect of diet on the mental performance of children’ (www.nutrimenthe.com), was to update current evidence on the effects of nutritional interventions such as iron, folic acid or n-3 long-chain polyunsaturated fatty acid (LCPUFA) supplementation during pregnancy and/or in early life on the mental performance and psychomotor development of children. In May 2014, we searched MEDLINE and The Cochrane Database of Systematic Reviews for relevant studies published since 2009. The limited updated evidence suggests that iron supplementation of infants may positively influence the psychomotor development of children, although it does not seem to alter their mental development or behaviour. The use of multivitamin-containing folic acid supplements during pregnancy did not benefit the mental performance of the offspring. Evidence from randomised controlled trials (RCT) did not show a clear and consistent benefit of n-3 LCPUFA supplementation during pregnancy and/or lactation on childhood cognitive and visual development. Caution is needed when interpreting current evidence, as many of the included trials had methodological limitations such as small sample sizes, high attrition rates, and no intention-to-treat analyses. Taken together, the evidence is still inconclusive. Large, high-quality RCT to assess the effects of supplementation with iron, LCPUFA or folic acid are still needed to further clarify the effects of these, and other nutrients, on neurodevelopment. Recent recommendations from scientific societies are briefly presented.

Prenatal Docosahexaenoic Acid Supplementation and Offspring Development at 18 Months: Randomized Controlled Trial

OBJECTIVE

We evaluated the effects of prenatal docosahexaenoic acid (DHA) supplementation on offspring development at 18 months of age.

DESIGN

Randomized placebo double-blind controlled trial.

SETTINGS

Cuernavaca, Mexico.

PARTICIPANTS AND METHODS

We followed up offspring (n = 730; 75% of the birth cohort) of women in Mexico who participated in a trial of DHA supplementation during the latter half of pregnancy. We assessed the effect of the intervention on child development and the potential modifying effects of gravidity, gender, SES, and quality of the home environment.

INTERVENTIONS OR MAIN EXPOSURES

400 mg/day of algal DHA.

OUTCOME MEASURES

Child development at 18 months of age measured using the Spanish version of the Bayley Scales of Infant Development-II. We calculated standardized psychomotor and mental development indices, and behavior rating scale scores.

RESULTS

Intent-to-treat differences (DHA-control) were: Psychomotor Developmental Index -0.90 (95% CI: -2.35, 0.56), Mental Developmental Index -0.26 (95% CI: -1.63, 1.10) and Behavior Rating Scale -0.01 (95% CI: -0.95, 0.94). Prenatal DHA intake attenuated the positive association between home environment and psychomotor development index observed in the control group (p for interaction = 0.03) suggesting potential benefits for children living in home environments characterized by reduced caregiver interactions and opportunities for early childhood stimulation.

CONCLUSIONS

Prenatal DHA supplementation in a population with low intakes of DHA had no effects on offspring development at 18 months of age although there may be some benefit for infants from poor quality home environments.

TRIAL REGISTRATION

Clinicaltrials.gov NCT00646360.

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

OBJECTIVES

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

DESIGN

Cross-sectional study.

SETTING

Launceston and surrounding regions, Tasmania, Australia.

PARTICIPANTS

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

MEASUREMENTS

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

RESULTS

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

CONCLUSION

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

Fish intake during pregnancy and foetal neurodevelopment--a systematic review of the evidence

Fish is a source of several nutrients that are important for healthy foetal development. Guidelines from Australia, Europe and the USA encourage fish consumption during pregnancy. The potential for contamination by heavy metals, as well as risk of listeriosis requires careful consideration of the shaping of dietary messages related to fish intake during pregnancy. This review critically evaluates literature on fish intake in pregnant women, with a focus on the association between neurodevelopmental outcomes in the offspring and maternal fish intake during pregnancy. Peer-reviewed journal articles published between January 2000 and March 2014 were included. Eligible studies included those of healthy pregnant women who had experienced full term births and those that had measured fish or seafood intake and assessed neurodevelopmental outcomes in offspring. Medline, Scopus, Web of Science, ScienceDirect and the Cochrane Library were searched using the search terms: pregnant, neurodevelopment, cognition, fish and seafood. Of 279 papers sourced, eight were included in the final review. Due to heterogeneity in methodology and measured outcomes, a qualitative comparison of study findings was conducted. This review indicates that the benefits of diets providing moderate amounts of fish during pregnancy outweigh potential detrimental effects in regards to offspring neurodevelopment. It is important that the type of fish consumed is low in mercury.

Contribution of n-3 long-chain polyunsaturated fatty acids to human milk is still low in Hungarian mothers

Maternal diet has decisive influence on the fatty acid composition of human milk. Fifteen years ago, we found outstandingly low contribution of docosahexaenoic acid (DHA) to human milk in a small group of Hungarian mothers. The major aim of the present study was to investigate whether DHA status in human milk in Hungary changed during the last 15 years. We aimed to examine the fatty acid composition of human milk at three different stages of lactation (3rd day, 6th week, and 6th month) in healthy Hungarian mothers. Fatty acid composition of human milk lipids was determined by gas chromatograph with flame ionization detector. Contribution of arachidonic acid to the fatty acid composition of human milk significantly decreased during lactation (0.91 [0.38] in colostrum, 0.53 [0.17] at 6th week, and 0.46 [0.13] at 6th month, p < 0.01). The contribution of DHA significantly decreased from colostrum to the 6th week of lactation (0.29 [0.12] and 0.14 [0.04], p < 0.01), without further changes by 6 months (0.12 [0.10]).

CONCLUSION

The contribution of DHA to the fatty acid composition of mature human milk in Hungarian mothers is still among the lowest values ever reported in the literature.

n-3 LC-PUFA supplementation: effects on infant and maternal outcomes

BACKGROUND

Long-chain polyunsaturated fatty acids (LC-PUFA), particularly docosahexaenoic acid (DHA) and arachidonic acid, are, respectively, n-3 and n-6 family members and play an important role in fetal and infant growth and development. Pregnancy and lactation impose special nutritional needs for the mother-fetus situation. Since the LC-PUFA required by the fetus is supplied by preferential placental transfer of preformed LC-PUFA rather than their precursor, it has been hypothesized that additional maternal supply of LC-PUFA, especially DHA, during pregnancy may improve maternal and infant outcomes.

AIM

To summarize evidences of the effect of n-3 LC-PUFA intake during pregnancy and lactation on maternal and infant outcomes in order to offer a comprehensive view of this issue that should be useful for clinical practice.

RESULTS

Maternal n-3 LC-PUFA supplementation may reduce risk for early preterm birth >34 weeks and seems very promising for primary allergy prevention during childhood. On the contrary, there are not sufficient data proving that the consumption of oils rich in n-3 LC-PUFA during pregnancy optimizes child's visual and neurodevelopment and reduces the risk for preeclampsia and perinatal depression; the implications of these findings remain to be elucidated.

CONCLUSION

The implications of n-3 LC-PUFA supplementation on fetal development, maternal outcomes and later infant growth is worth being elucidated and is promising in its potential for a positive impact on fetal and maternal outcomes.

Evidence-based interventions for improvement of maternal and child nutrition: what can be done and at what cost?

Maternal undernutrition contributes to 800,000 neonatal deaths annually through small for gestational age births; stunting, wasting, and micronutrient deficiencies are estimated to underlie nearly 3·1 million child deaths annually. Progress has been made with many interventions implemented at scale and the evidence for effectiveness of nutrition interventions and delivery strategies has grown since The Lancet Series on Maternal and Child Undernutrition in 2008. We did a comprehensive update of interventions to address undernutrition and micronutrient deficiencies in women and children and used standard methods to assess emerging new evidence for delivery platforms. We modelled the effect on lives saved and cost of these interventions in the 34 countries that have 90% of the world's children with stunted growth. We also examined the effect of various delivery platforms and delivery options using community health workers to engage poor populations and promote behaviour change, access and uptake of interventions. Our analysis suggests the current total of deaths in children younger than 5 years can be reduced by 15% if populations can access ten evidence-based nutrition interventions at 90% coverage. Additionally, access to and uptake of iodised salt can alleviate iodine deficiency and improve health outcomes. Accelerated gains are possible and about a fifth of the existing burden of stunting can be averted using these approaches, if access is improved in this way. The estimated total additional annual cost involved for scaling up access to these ten direct nutrition interventions in the 34 focus countries is Int$9·6 billion per year. Continued investments in nutrition-specific interventions to avert maternal and child undernutrition and micronutrient deficiencies through community engagement and delivery strategies that can reach poor segments of the population at greatest risk can make a great difference. If this improved access is linked to nutrition-sensitive approaches--ie, women's empowerment, agriculture, food systems, education, employment, social protection, and safety nets--they can greatly accelerate progress in countries with the highest burden of maternal and child undernutrition and mortality.

trans Isomeric fatty acids are inversely related to the availability of long-chain PUFAs in the perinatal period

We summarize data on the potential interaction of trans isomeric fatty acids [trans fatty acids (TFAs)] with the availability of long-chain polyunsaturated fatty acids (LC-PUFAs) in the perinatal period. Today, TFA intakes in pregnant and lactating women can be estimated to be ∼1% of energy in the majority of the population. The significant inverse associations seen between TFAs and LC-PUFAs in pregnant women in 3 different European populations investigated in a recent study raise doubts about the nutritional adequacy of high TFA intakes during pregnancy. In a recent study on the TFA content of human milk in a sizable group of mothers at the sixth week of lactation, both arachidonic and docosahexaenoic acids correlated significantly inversely to 18-carbon TFAs but not to 16-carbon TFAs, and at the sixth month of lactation arachidonic acid correlated significantly inversely to 18-carbon TFAs but not to 16-carbon TFAs. Similarly, significant inverse correlations were seen between 18-carbon TFAs and arachidonic and docosahexaenoic acids in both artery and vein wall lipids in a sizable group of healthy term infants. The TFA data obtained in umbilical blood vessel wall lipids were related to the neurologic condition of healthy children at 18 mo of age: children with minimal neurologic dysfunction at age 18 mo had significantly higher cord blood vein wall trans octadecadienoic acid values than did neurologically normal children. Total TFA values as well as total 18-carbon TFA values in umbilical vein wall lipids were significantly inversely associated with neurologic optimality score. Contradictory data renders it impossible to draw firm conclusions on the role of TFAs in modifying fetal growth; however, TFA exposure may be a confounding parameter in studies that investigate the relation between fetal fatty acid supply and intrauterine growth.

Nutrition and neurodevelopment in children: focus on NUTRIMENTHE project

There is growing evidence that early nutrition affects later cognitive performance. The idea that the diet of mothers, infants, and children could affect later mental performance has major implications for public health practice and policy development and for our understanding of human biology as well as for food product development, economic progress, and future wealth creation. To date, however, much of the evidence is from animal, retrospective studies and short-term nutritional intervention studies in humans. The positive effect of micronutrients on health, especially of pregnant women eating well to maximise their child's cognitive and behavioural outcomes, is commonly acknowledged. The current evidence of an association between gestational nutrition and brain development in healthy children is more credible for folate, n-3 fatty acids, and iron. Recent findings highlight the fact that single-nutrient supplementation is less adequate than supplementation with more complex formulae. However, the optimal content of micronutrient supplementation and whether there is a long-term impact on child's neurodevelopment needs to be investigated further. Moreover, it is also evident that future studies should take into account genetic heterogeneity when evaluating nutritional effects and also nutritional recommendations. The objective of the present review is to provide a background and update on the current knowledge linking nutrition to cognition and behaviour in children, and to show how the large collaborative European Project NUTRIMENTHE is working towards this aim.

The effect of maternal omega-3 (n-3) LCPUFA supplementation during pregnancy on early childhood cognitive and visual development: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Maternal fish consumption during pregnancy has been positively associated with cognitive and visual abilities in the offspring, leading to the hypothesis that maternal omega-3 (n-3) long-chain PUFA (LCPUFA) supplementation improves children's neurologic and visual development.

OBJECTIVE

The objective was to evaluate the effect of maternal omega-3 LCPUFA supplementation in pregnancy on neurologic and visual development in the offspring.

DESIGN

Five electronic databases were searched. Human randomized controlled trials that supplemented the maternal diet with omega-3 LCPUFAs during pregnancy, or pregnancy and lactation, and that assessed either neurologic or visual development of the offspring were included. Trial quality was assessed, and the results of eligible trials were compared in meta-analyses.

RESULTS

Eleven RCTs involving 5272 participants were included in the review. Most trials had methodologic limitations. No differences in standardized psychometric test scores for cognitive, language, or motor development were observed between the LCPUFA-supplemented and control groups, except for cognitive scores in 2-5-y-old children, in whom supplementation resulted in higher Developmental Standard Scores (mean difference: 3.92; 95% CI: 0.77, 7.08; n = 156; P = 0.01). However, this effect was from 2 trials with a high risk of bias. Because of the variety of visual assessments and age ranges, it was not possible to combine studies with visual outcomes in a meta-analysis, although 6 of the 8 assessments in 5 trials reported no difference between the supplemented and control groups.

CONCLUSION

The evidence does not conclusively support or refute that omega-3 LCPUFA supplementation in pregnancy improves cognitive or visual development.

Cognitive enhancement by omega-3 fatty acids from child-hood to old age: findings from animal and clinical studies

Omega-(n)-3 polyunsaturated fatty acids (PUFAs), including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are major components of neuronal membranes and have a wide range of functions, from modulating synaptic plasticity and neurochemistry, to neuroimmune-modulation and neuroprotection. Thus, it is not surprising that n-3 PUFA are widely acknowledged to have cognitive-enhancing effects. Although clinical evidence is somewhat conflicting, probably in large part due to methodological issues, animal studies have consistently demonstrated that n-3 PUFA are indispensable for proper brain development, may enhance cognitive function in healthy, adult individuals and attenuate cognitive impairment in aging and age-related disorders, such as dementia. This review discusses and integrates up to date evidence from clinical and animal studies investigating the cognitive-enhancing effects of n-3 PUFA during development, child- and adult-hood, as well as old-age with associated neurodegenerative diseases, such as Alzheimer's disease. Furthermore, we cover the major underlying biochemical and neurophysiological mechanisms by which n-3 PUFA mediate these effects on cognition. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

Omega-3 fatty acids and pregnancy: current implications for practice

PURPOSE OF REVIEW

We conducted this review to evaluate the evidence for maternal supplementation with omega-3 fatty acids during pregnancy for the prevention or treatment of common complications of pregnancy including preterm birth, pregnancy-induced hypertension and preeclampsia, as well as perinatal depression. We also evaluated the evidence supporting maternal omega-3 fatty acid supplementation to optimize infant neurocognitive development and for primary prevention of allergic diseases in childhood.

RECENT FINDINGS

Omega-3 fatty acids through diet or dietary supplementation may reduce the risk for early preterm birth. Preliminary findings from small randomized controlled trials suggest that maternal omega-3 fatty acid supplementation during pregnancy may reduce the risk for allergic disease in childhood, but this observation requires confirmation by large appropriately powered randomized controlled trials. More research is needed before routine maternal supplementation for this indication can be recommended.

SUMMARY

Although it is biologically plausible that maternal omega-3 fatty acid supplementation might prevent a number of pregnancy complications and optimize child health and development, indications for supplementation other than prevention of preterm births are currently investigational.

Omega 3 fatty acids on child growth, visual acuity and neurodevelopment

The aim of this review is to evaluate the effects of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) supplementation in pregnant and lactating women and infants during postnatal life, on the visual acuity, psychomotor development, mental performance and growth of infants and children. Eighteen publications (11 sets of randomized control clinical trial [RCTs]) assessed the effects of the n-3 LCPUFA supplementation duringpregnancyon neurodevelopment and growth, in the same subjects at different time points; 4 publications (2 data sets from RCTs) addressed physiological responses to n-3 LCPUFA supplementation duringpregnancy & lactationand 5 publications (3 data sets from RCTs) exclusively duringlactation. Some of these studies showed beneficial effects of docosahexaenoic acid (DHA) supplementation during pregnancy and/or lactation especially on visual acuity outcomes and some on long-term neurodevelopment; a few, showed positive effects on growth. There were also 15 RCTs involving term infants who received infant formula supplemented with DHA, which met our selection criteria. Many of these studies claimed a beneficial effect of such supplementation on visual, neural, or developmental outcomes and no effects on growth. Although new well designed and conducted studies are being published, evidence from RCTs does not demonstrate still a clear and consistent benefit of n-3 LCPUFA supplementation during pregnancy and/or lactation on term infants growth, neurodevelopment and visual acuity. These results should be interpreted with caution due to methodological limitations of the included studies.

The role of meta-analysis in the evaluation of the effects of early nutrition on mental and motor development in children

The role of early nutrition as a cost-effective measure to ensure optimal infant growth, development, and long-term health is gaining attention. In particular, the role of supplementation with nutrients such as n-3 (omega-3) fatty acids, iron, zinc, and B vitamins, which are relevant to brain structure and function, is of interest. However, for all of these nutrients, there is a lack of clarity and no consensus regarding their role in the mental and motor development of children. Systematic reviews with or without a meta-analysis are a well-established means of reviewing existing evidence and of integrating findings from various studies, including those related to infant nutrition. In this article, I provide an overview of the basic principles of systematic review and meta-analysis of randomized controlled trials (RCTs) and summarize such evidence related to the effects of early nutrition on mental and motor development. The inclusion of only RCTs in a systematic review could be considered the major strength. Randomization is the only means to control for unknown and unmeasured differences between comparison groups as well as for those that are known and measured. However, even if only RCTs are included, reviews are not free of potential biases. An understanding of the strengths and limitations of the meta-analytic approach, which I discuss in this article, is needed by everyone involved in decision making regarding interventions assessed by this approach.