Arachidonic acid status correlates with first year growth in preterm infants

Nutritional interventions to prevent retinopathy of prematurity

Very preterm infants are at high risk of growth failure. Poor weight gain is a prominent risk factor for retinopathy of prematurity (ROP) and optimizing nutrition could potentially promote growth and reduce ROP. Most infants at risk of ROP need parenteral nutrition initially and studies of enhanced parenteral provision of lipids and amino acids have suggested a beneficial effect on ROP. Higher amino acid intake was associated with lower incidence of hyperglycemia, a risk factor for ROP. For very preterm infants, providing unpasteurized fortified raw maternal breast milk appears to have a dose-dependent preventive effect on ROP. These infants become deficient in arachidonic acid (ArA) and docosahexaenoic acid (DHA) after birth when the maternal supply is lost. Earlier studies have investigated the impact of omega-3 fatty acids on ROP with mixed results. In a recent study, early enteral supplementation of ArA 100 mg/kg/d and DHA 50 mg/kg/d until term equivalent age reduced the incidence of severe ROP by 50%. IMPACT: Previous reviews of nutritional interventions to prevent morbidities in preterm infants have mainly addressed bronchopulmonary dysplasia, brain lesions and neurodevelopmental outcome. This review focusses on ROP. Neonatal enteral supplementation with arachidonic acid and docosahexaenoic acid, at levels similar to the fetal accretion rate, has been found to reduce severe ROP by 50% in randomized controlled trials.

Differential Effects of n-3 and n-6 Polyunsaturated Fatty Acids on Placental and Embryonic Growth and Development in Diabetic Pregnant Mice

The present study aimed to investigate the differential effects of n-3 and n-6 polyunsaturated fatty acids (PUFAs) on placental and embryonic development. Pregnant mice were assigned to five groups: healthy control (HC), diabetes mellitus control (DMC), diabetes + low-dose n-3 PUFA (Ln-3), diabetes + high-dose n-3 PUFA (Hn-3), and diabetes + n-6 PUFA (n-6). On E12.5d, the Hn-3 group, but not the n-6 group, had a higher placenta weight. The weight ratio of embryo to placenta in the n-6 group was significantly lower than in the Hn-3 group but higher than in the DMC group. The Hn-3 group had significantly higher protein levels of VEGF, IGF-1, and IGFBP3, while the n-6 group had lower VEGF than the DMC group. Compared with the DMC group, embryonic Cer-16:0 was significantly higher in the Hn-3 group, while embryonic PC (36:6), PC (38:7), and PE (40:7) were significantly lower in the n-6 group. The embryo and placenta weights were positively correlated with placental VEGF, IGFBP3, and embryonic Cer-16:0, and they were negatively correlated with embryonic PC (36:6) and PE (40:7). The weight ratio of embryo to placenta was negatively correlated with embryonic PC (36:6). In addition, embryonic Cer-16:0 was positively correlated with placental VEGF and IGFBP3. In conclusion, n-3 PUFA and n-6 PUFA improved placental and embryonic growth through different mechanisms.

Dietary Implications of Polyunsaturated Fatty Acids during Pregnancy and in Neonates

Certain limitations exist for animals to modify fatty acid changes. Besides the role of arachidonic acid (AA), docosahexaenoic acid (DHA) and other 20-carbon long-chain polyunsaturated fatty acids (LCPUFAs) for the synthesis of inflammatory mediators as eicosanoids, different LCPUFAs have many other effects, including their abilities to regulate gene expression and downstream events. LCPUFAs are susceptible to autoxidation, which is prevented by the action of antioxidants in the form of enzymes like superoxide dismutases, catalases and peroxidases, as well as antioxidant compounds that protect against oxidation or repair the damage caused. Under normal conditions, the fetus needs both essential fatty acids (EFAs) and LCPUFAs, which are obtained from its mother by placental transfer. In early pregnancy, dietary derived fatty acids are accumulated in maternal adipose tissue. However, during late pregnancy, corresponding to the period of the highest fetal growth, maternal adipose tissue becomes catabolic and LCPUFAs are released into the circulation by adipose lipolytic activity. The released LCPUFAs are taken up by maternal liver to be esterified and released back to the circulation as triacylglycerides (TAGs) in very-low-density lipoprotein (VLDL) that become available to the placenta to be transferred to the fetus in the form of non-esterified fatty acids (NEFAs). An enhanced adipose tissue lipolysis is maintained around parturition and esterified LCPUFAs are diverted to mammary glands thanks to an increased activity of lipoprotein lipase for milk production. Throughout this process, LCPUFAs become available to the newborn during suckling. The important role of both DHA and AA for the development of the nervous system and for growth has motivated their dietary supplement during different postnatal stages. This has been especially important in preterm infants both because under normal conditions, the fetus acquires most of these fatty acids during late pregnancy, and because the immaturity of the enzyme systems for the synthesis of AA and DHA from their respective EFAs.

The essential role of docosahexaenoic acid and its derivatives for retinal integrity

The fatty acid composition of photoreceptor outer segment (POS) phospholipids diverges from other membranes, being highly enriched in polyunsaturated fatty acids (PUFAs). The most abundant PUFA is docosahexaenoic acid (DHA, C22:6n-3), an omega-3 PUFA that amounts to over 50% of the POS phospholipid fatty acid side chains. Interestingly, DHA is the precursor of other bioactive lipids such as elongated PUFAs and oxygenated derivatives. In this review, we present the current view on metabolism, trafficking and function of DHA and very long chain polyunsaturated fatty acids (VLC-PUFAs) in the retina. New insights on pathological features generated from PUFA deficient mouse models with enzyme or transporter defects and corresponding patients are discussed. Not only the neural retina, but also abnormalities in the retinal pigment epithelium are considered. Furthermore, the potential involvement of PUFAs in more common retinal degeneration diseases such as diabetic retinopathy, retinitis pigmentosa and age-related macular degeneration are evaluated. Supplementation treatment strategies and their outcome are summarized.

Dietary Fatty Acids and Inflammation: Focus on the n-6 Series

Among the polyunsaturated fatty acids (PUFAs), those belonging to the n-3 (or ω3) series, i.e., alpha-linolenic (ALA), eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids have been studied for decades from a pharma-nutritional viewpoint, namely in relation to cardiovascular health. More recent research is focusing on n-6 PUFAs, e.g., linoleic acid (LA), whose levels of consumption are much higher than those of n-3 and that cannot be used "pharmacologically". Perhaps because of this, the biological actions of n-6 PUFAs have not been investigated in details as those of their n-3 counterparts. However, an increasing body of evidence underscores their healthful actions on the cardiovascular system. Among the critiques to n-6 PUFAs and, particularly, LA there is the fact that they are precursors of pro-inflammatory eicosanoids. Hence, the hypothesis posits that we should reduce their intakes precisely to avoid increasing systemic, low-grade inflammation, i.e., one of the major etiological agents in degenerative diseases. In this narrative review, we address the issue of whether n-6 PUFAs are indeed pro-inflammatory, we discuss the most recent evidence of their role(s) in human health and prognosis, and we conclude that adequate intakes of n-6 fatty acids are associated with better cardiovascular health and child development.

Joint analyses of human milk fatty acids, phospholipids, and choline in association with cognition and temperament traits during the first 6 months of life

Early dietary exposure via human milk nutrients offers a window of opportunity to support cognitive and temperament development. While several studies have focused on associations of few pre-selected human milk nutrients with cognition and temperament, it is highly plausible that human milk nutrients synergistically and jointly support cognitive and behavioral development in early life. We aimed to discern the combined associations of three major classes of human milk nutrients with cognition and temperament during the first 6 months of life when human milk is the primary source of an infant’s nutrition and explore whether there were persistent effects up to 18 months old. The Mullen Scales of Early Learning and Infant Behavior Questionnaires—Revised were used to assess cognition and temperament, respectively, of 54 exclusively/predominantly breastfed infants in the first 6 months of life, whose follow-ups were conducted at 6–9, 9–12, and 12–18 months old. Human milk samples were obtained from the mothers of the participants at less than 6 months of age and analyzed for fatty acids [total monounsaturated fatty acids, polyunsaturated fatty acid, total saturated fatty acid (TSFA), arachidonic acid (ARA), docosahexaenoic acid (DHA), ARA/DHA, omega-6/omega-3 polyunsaturated fatty acids ratio (n-6/n-3)], phospholipids [phosphatidylcholine, phosphatidylethanolamine (PE), phosphatidylinositol (PI), sphingomyelin], and choline [free choline, phosphocholine (PCho), glycerophosphocholine]. Feature selection was performed to select nutrients associated with cognition and temperament. The combined effects of selected nutrients were analyzed using multiple regression. A positive association between the arachidonic acid (ARA) and surgency was observed (p = 0.024). A significant effect of DHA, n-6/n-3, PE, and TSFA concentrations on receptive language (R² = 0.39, p = 0.025) and the elevated ARA, PCho, and PI with increased surgency (R² = 0.43, p = 0.003) was identified, suggesting that DHA and ARA may have distinct roles for temperament and language functions. Furthermore, the exploratory association analyses suggest that the effects of human milk nutrients on R.L. and surgency may persist beyond the first 6 months of life, particularly surgency at 12–18 months (p = 0.002). Our study highlighted that various human milk nutrients work together to support the development of cognition and temperament traits during early infancy.

Co-existence of type I fatty acid synthase and polyketide synthase metabolons in Aurantiochytrium SW1 and their implications for lipid biosynthesis

The key enzymes of lipid biosynthesis in oleaginous filamentous fungi exist as metabolons. However, the existence of a similar organization in other groups of oleaginous microorganisms is still unknown. In this study, we confirmed the occurrence of two separate and distinct lipogenic metabolons in a thraustochytrid, Aurantiochytrium SW1. These involve the Type I Fatty Acid Synthase (FAS) pathway, consisting of six enzymes: fatty acid synthase, malic enzyme (ME), ATP: citrate lyase (ACL), acetyl-CoA carboxylase (ACC), malate dehydrogenase (MD) and pyruvate carboxylase (PC), and the Polyketide Synthase-like (PKS) pathway, consisting of PKS subunits a, b, c, glucose-6-phosphate dehydrogenase (G6PDH) 6-phosphogluconate dehydrogenase (6PGDH), ACL and ACC. This suggests that the NADPH requirement for the FAS pathway is primarily generated and channelled by ME whereas G6PDH and 6PGDH fulfil this role for the PKS pathway. Diminished biosynthesis of palmitic acid (16:0), docosahexaenoic acid (22:6 n-3, DHA) and docosapentaenoic acid (22:5 n-6, DPA) correlated with the dissociation of their respective metabolons thereby suggesting that regulation of the pathways is achieved through the formation and dissociation of the metabolons.

Hypertriglyceridemia in Preterm Infants

Preterm and critically ill infants are at risk for hypertriglyceridemia (HTG). Common risk factors for HTG include prematurity, intravenous lipid emulsion dose and oil composition, reduced lipoprotein lipase activity, fetal growth restriction, sepsis, and renal failure. Despite these risk factors, clinicians lack a universally agreed upon definition for HTG and evidence-based approach to HTG management. This review provides a detailed overview of triglyceride and intravenous lipid emulsion metabolism and how this relates to specific HTG risk factors, along with some practical considerations for managing HTG in the neonatal population.

NADPH–Cytochrome P450 Reductase Mediates the Fatty Acid Desaturation of ω3 and ω6 Desaturases from Mortierella alpina

Fatty acid desaturases play an important role in maintaining the appropriate structure and function of biological membranes. The biochemical characterization of integral membrane desaturases, particularly ω3 and ω6 desaturases, has been limited by technical difficulties relating to the acquisition of large quantities of purified proteins, and by the fact that functional activities of these proteins were only tested in an NADH-initiated reaction system. The main aim of this study was to reconstitute an NADPH-dependent reaction system in vitro and investigate the kinetic properties of Mortierella alpina ω3 and ω6 desaturases in this system. After expression and purification of the soluble catalytic domain of NADPH–cytochrome P450 reductase, the NADPH-dependent fatty acid desaturation was reconstituted for the first time in a system containing NADPH, NADPH–cytochrome P450 reductase, cytochrome b5, M. alpina ω3 and ω6 desaturase and detergent. In this system, the maximum activity of ω3 and ω6 desaturase was 213.4 ± 9.0 nmol min⁻¹ mg⁻¹ and 10.0 ± 0.5 nmol min⁻¹ mg⁻¹, respectively. The highest k_cat/K_m value of ω3 and ω6 desaturase was 0.41 µM⁻¹ min⁻¹ and 0.09 µM⁻¹ min⁻¹ when using linoleoyl CoA (18:2 ω6) and oleoyl CoA (18:1 ω9) as substrates, respectively. M. alpina ω3 and ω6 desaturases were capable of using NADPH as reductant when mediated by NADPH–cytochrome P450 reductase; although, their efficiency is distinguishable from NADH-dependent desaturation. These results provide insights into the mechanisms underlying ω3 and ω6 fatty acid desaturation and may facilitate the production of important fatty acids in M. alpina.

Cumulative Metabolic and Epigenetic Effects of Paternal and/or Maternal Supplementation with Arachidonic Acid across Three Consecutive Generations in Mice

Apart from the known associations between arachidonic acid (AA), weight gain, and neurological and immune function, AA exposure leads to alterations in global and gene-specific DNA methylation (DNAm) and fatty acid (FA) content in human cultured cells. However, it is unknown as to whether the latter effects occur in vivo and are maintained over extended periods of time and across generations. To address this issue, we asked whether AA supplementation for three consecutive generations (prior to coitus in sires or in utero in dams) affected offspring growth phenotypes, in addition to liver DNAm and FA profiles in mice. Twelve-week-old BALB/c mice were exposed daily to AA dissolved in soybean oil (vehicle, VH), or VH only, for 10 days prior to mating or during the entire pregnancy (20 days). On average, 15 mice were supplemented per generation, followed by analysis of offspring body weight and liver traits (x average = 36 and 10 per generation, respectively). Body weight cumulatively increased in F2 and F3 offspring generations and positively correlated with milligrams of paternal or maternal offspring AA exposure. A concomitant increase in liver weight was observed. Notably, akin to AA-challenged cultured cells, global DNAm and cis-7-hexadecenoic acid (16:1n-9), an anti-inflammatory FA that is dependent on stearoyl-CoA desaturase 1 (SCD1) activity, increased with milligrams of AA exposure. In accordance, liver Scd1 promoter methylation decreased with milligrams of germline AA exposure and was negatively correlated with liver weight. Our results show that mice retain cellular memories of AA exposure across generations that could potentially be beneficial to the innate immune system.

Inhibited maturation of astrocytes caused by maternal n-3 polyunsaturated fatty acid intake deficiency hinders the development of brain glial cells in neonatal rats

The brain is rich in long chain polyunsaturated fatty acids (PUFAs), which play an essential role in its development and functions. Here we examined the impact of maternal n-3 PUFA intake deficiency during gestation and lactation on the development of glial cells in the pup's developing cerebral cortex. In addition, using myelination as indicator and the anti-myelin basic protein (MBP) as measurement to establish the relationship between the number of glial fibrillary acidic protein (GFAP)-positive cells and the development of oligodendrocytes, we determined the myelination state of the somatosensory cortex at day 14 postnatal. Rat dams were fed either a control (Cont) or an n-3 PUFA-deficient (Def) diet for 60 days (acclimatisation :14 days; gestation: 21 days; lactation:21 days). Pups lactated from dams throughout the experiment. The distribution pattern of astrocytes in pups on day 7 postnatal was immunohistochemically analysed using GFAP and brain lipid binding protein (BLBP) as markers for mature astrocytes and astrocyte-specific radial glial cells, respectively. It was observed that, when compared with Cont pups, GFAP-positive cells decreased, BLBP-positive cells increased and myelinated structures were sparser in the somatosensory cortices of Def pups. In the open field test on day 21 postnatal, behavioural parameters did not differ between groups. Our results indicated that inhibited maturation of astrocytes caused by maternal n-3 PUFA deficiency hindered the development of brain glial cells of neonatal rats and hence, maternal n-3 PUFA intake during the gestation and lactation periods may have been crucial for the brain cell composition of pups.

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.

Unique Biomarker Characteristics in Gestational Diabetes Mellitus Identified by LC-MS-Based Metabolic Profiling

BACKGROUND

Gestational diabetes mellitus (GDM) is a type of glucose intolerance disorder that first occurs during women's pregnancy. The main diagnostic method for GDM is based on the midpregnancy oral glucose tolerance test. The rise of metabolomics has expanded the opportunity to better identify early diagnostic biomarkers and explore possible pathogenesis.

METHODS

We collected blood serum from 34 GDM patients and 34 normal controls for a LC-MS-based metabolomics study.

RESULTS

184 metabolites were increased and 86 metabolites were decreased in the positive ion mode, and 65 metabolites were increased and 71 were decreased in the negative ion mode. Also, it was found that the unsaturated fatty acid metabolism was disordered in GDM. Ten metabolites with the most significant differences were selected for follow-up studies. Since the diagnostic specificity and sensitivity of a single differential metabolite are not definitive, we combined these metabolites to prepare a ROC curve. We found a set of metabolite combination with the highest sensitivity and specificity, which included eicosapentaenoic acid, docosahexaenoic acid, docosapentaenoic acid, arachidonic acid, citric acid, α-ketoglutaric acid, and genistein. The area under the curves (AUC) value of those metabolites was 0.984 between the GDM and control group.

CONCLUSIONS

Our results provide a direction for the mechanism of GDM research and demonstrate the feasibility of developing a diagnostic test that can distinguish between GDM and normal controls clearly. Our findings were helpful to develop novel biomarkers for precision or personalized diagnosis for GDM. In addition, we provide a critical insight into the pathological and biological mechanisms for GDM.

Incorporation of Caprylic Acid into a Single Cell Oil Rich in Docosahexaenoic Acid for the Production of Specialty Lipids

Research background

New sources of docosahexaenoic acid have recently been investigated aiming at infant formula fortification and dietary supplementation, among which the single cell oil with 40-50% of this acid.

Experimental approach

For this purpose, such an oil was blended with caprylic acid in amount substance ratio ranging from 1:1 to 5:1 and the blends were interesterified using either Novozym 435 or Lipozyme TL IM as the catalyst. The influence of the amount of excess free caprylic acid in the substrate, as well as the type of enzyme on the triacylglycerol rearrangement resulting from the synthesis of the structured lipids were evaluated.

Results and conclusions

The regiospecific lipase Lipozyme TL IM seemed to induce transesterification among single cell oil triacylglycerols preferably by acidolysis with caprylic acid, which was directly proportional to the ratio of this acid in the substrate. In reactions catalyzed by the non-regiospecific lipase Novozym 435, a higher incorporation of caprylic acid into single cell oil triacylglycerols was observed than when using Lipozyme TL IM, independently of the oil/caprylic acid molar ratio.

Novelty and scientific contribution

These results revealed the importance of combining the choice of the type of lipase, either regiospecific or not, with the amount ratios of free fatty acids and the substrate in acidolysis when aiming to produce structured lipids as a source of docosahexaenoic acid.

Intravenous Lipid Emulsions in the NICU

The clinical goals of intravenous lipid emulsions (ILEs) have changed since their initial development. In the past, 100% soybean oil was used to provide energy and prevent an essential fatty acid deficiency. Now, different oil sources are used with the goal of improving nutritional status and preventing common neonatal comorbidities. We now have a better understanding of specific ILE constituents, namely, fatty acids, vitamin E, and phytosterols, and how these components contribute to complications such as intestinal failure-associated liver disease. This review addresses the development and composition of different ILEs and summarizes how individual ILE ingredients affect infant metabolism and health.

Production of arachidonic acid by Mortierella alpina using wastes from potato chips industry

AIMS

This research aimed to determine the potential use of wastes from the potato chips industry as a carbon source to develop an economical culture medium for the production of biomass, lipids and arachidonic acid (ARA) by Mortierella alpina.

METHODS AND RESULTS

A synthetic culture medium was optimized using a Plackett-Burman and central composite rotatable design, and used as a base to evaluate and characterize the potential use of wastes from the potato chips industry as carbon sources for the production of biomass, lipids and ARA by M. alpina. The waste was selected among other solid and liquid hydrolysed residues/by-products, and local low-cost alternatives for nitrogen sources were also evaluated. After 6 days of fermentation, the biomass concentration reached 20 g l^-1 with 40% of total lipids, and a 35% ARA content in the lipids fraction. Savings in production were calculated using a sensitivity analysis for the alternative culture medium in different scenarios.

CONCLUSIONS

This study showed a 7% savings in culture media expenses in the production of ARA-enriched biomass of M. alpina, compared to the conventional synthetic culture medium, when waste from the potato chips industry was used as an alternative source of carbon and macro/microelements, supplemented with a low-cost yeast extract alternative.

SIGNIFICANCE AND IMPACT OF THE STUDY

The demonstration of the use of potato chips wastes as a low-cost carbon source for the biomass, lipids and ARA production, suggesting an eco-friendly alternative for the use of agri-food wastes for valuable metabolites production.

Fatty Acid Supplementation and Socioemotional Outcomes: Secondary Analysis of a Randomized Trial

BACKGROUND AND OBJECTIVES

Children born preterm experience socioemotional difficulties, including increased risk of autism spectrum disorder (ASD). In this secondary analysis, we tested the effect of combined docosahexaenoic acid (DHA) and arachidonic acid (AA) supplementation during toddlerhood on caregiver-reported socioemotional outcomes of children born preterm. We hypothesized that children randomly assigned to DHA + AA would display better socioemotional outcomes compared with those randomly assigned to a placebo.

METHODS

Omega Tots was a single-site randomized, fully masked, parallel-group, placebo-controlled trial. Children (N = 377) were 10 to 16 months at enrollment, born at <35 weeks' gestation, and assigned to 180 days of daily 200-mg DHA + 200-mg AA supplementation or a placebo (400 mg corn oil). Caregivers completed the Brief Infant-Toddler Social and Emotional Assessment and the Pervasive Developmental Disorders Screening Test-II, Stage 2 at the end of the trial. Liner mixed models and log-binomial regression compared socioemotional outcomes between the DHA + AA and placebo groups.

RESULTS

Outcome data were available for 83% of children (n _treatment = 161; n _placebo = 153). Differences between DHA + AA and placebo groups on Brief Infant-Toddler Social and Emotional Assessment scores were of small magnitude (Cohen's d ≤ 0.15) and not statistically significant. Children randomly assigned to DHA + AA had a decreased risk of scoring at-risk for ASD on the Pervasive Developmental Disorders Screening Test-II, Stage 2 (21% vs 32%; risk ratio = 0.66 [95% confidence interval: 0.45 to 0.97]; risk difference = -0.11 [95% confidence interval: -0.21 to -0.01]) compared with children randomly assigned to a placebo.

CONCLUSIONS

No evidence of benefit of DHA + AA supplementation on caregiver-reported outcomes of broad socioemotional development was observed. Supplementation resulted in decreased risk of clinical concern for ASD. Further exploration in larger samples of preterm children and continued follow-up of children who received DHA + AA supplementation as they approach school age is warranted.

Protective Effects and Molecular Signaling of n-3 Fatty Acids on Oxidative Stress and Inflammation in Retinal Diseases

Oxidative stress and inflammation play crucial roles in the development and progression of retinal diseases. Retinal damage by various etiologies can result in retinopathy of prematurity (ROP), diabetic retinopathy (DR), and age-related macular degeneration (AMD). n-3 fatty acids are essential fatty acids and are necessary for homeostasis. They are important retinal membrane components and are involved in energy storage. n-3 fatty acids also have antioxidant and anti-inflammatory properties, and their suppressive effects against ROP, DR, and AMD have been previously evaluated. α-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and their metabolites have been shown to alleviate retinal oxidative stress and inflammation involving various biological signaling pathways. In this review, we summarize the current understanding of the n-3 fatty acids effects on the mechanisms of these retinal diseases and how they exert their therapeutic effects, focusing on ALA, EPA, DHA, and their metabolites. This knowledge may provide new remedial strategies for n-3 fatty acids in the prevention and treatment of retinal diseases associated with oxidative stress and inflammation.

Should formula for infants provide arachidonic acid along with DHA? A position paper of the European Academy of Paediatrics and the Child Health Foundation

Recently adopted regulatory standards on infant and follow-on formula for the European Union stipulate that from February 2020 onwards, all such products marketed in the European Union must contain 20-50 mg omega-3 DHA (22:6n-3) per 100 kcal, which is equivalent to about 0.5-1% of fatty acids (FAs) and thus higher than typically found in human milk and current infant formula products, without the need to also include ω-6 arachidonic acid (AA; 20:4n-6). This novel concept of infant formula composition has given rise to concern and controversy because there is no accountable evidence on its suitability and safety in healthy infants. Therefore, international experts in the field of infant nutrition were invited to review the state of scientific research on DHA and AA, and to discuss the questions arising from the new European regulatory standards. Based on the available information, we recommend that infant and follow-on formula should provide both DHA and AA. The DHA should equal at least the mean content in human milk globally (0.3% of FAs) but preferably reach 0.5% of FAs. Although optimal AA intake amounts remain to be defined, we strongly recommend that AA should be provided along with DHA. At amounts of DHA in infant formula up to ∼0.64%, AA contents should at least equal the DHA contents. Further well-designed clinical studies should evaluate the optimal intakes of DHA and AA in infants at different ages based on relevant outcomes.

The evolving use of intravenous lipid emulsions in the neonatal intensive care unit

Parenteral nutrition and intravenous lipid emulsions are essential for promoting optimal nutrition in the neonatal intensive care unit. However, long-term use of a pure soybean lipid emulsion is associated with a liver disease known as intestinal failure associated liver disease. Over the past several years, the science of lipid emulsions has evolved with a focus on nutritional optimization and disease prevention. This review's purpose is to provide a general overview of the three main components of lipid emulsions, phytosterols, the antioxidant Vitamin E, and polyunsaturated fatty acids, and their contribution to health.

Association of Retinopathy of Prematurity With Low Levels of Arachidonic Acid: A Secondary Analysis of a Randomized Clinical Trial

Importance

Mice with oxygen-induced retinopathy fed matched diets except for ω-3 long-chain polyunsaturated fatty acids (LC-PUFAs) vs ω-6 LC-PUFAs demonstrate relative antiangiogenic and neuroprotective associations of ω-3 LC-PUFAs. However, supplementing preterm infants with LC-PUFAs has been inconsistent in reducing major preterm morbidities. However, few studies measured serum lipid levels after supplementation.

Objective

To examine the associated risk of retinopathy of prematurity (ROP) from the levels of circulating ω-3 and ω-6 LC-PUFAs.

Design, Setting, and Participants

This longitudinal clinical study was a further analysis of serum lipid levels from a randomized controlled trial cohort of 90 infants born at gestational age (GA) less than 28 weeks. From April 4, 2013, to September 22, 2015, cord blood samples, followed by venous blood samples, were obtained at birth and at 1, 7, 14, and 28 days after birth and then at postmenstrual age (PMA) 32, 36, and 40 weeks at the neonatal intensive care unit at Sahlgrenska University Hospital in Göteborg, Sweden.

Main Outcomes and Measures

Serum phospholipid fatty acids were transmethylated and measured by gas chromatography-mass spectrometry. Mann-Whitney test, logistic regression Spearman rank correlation, and receiver operating characteristic curve analysis were used to compare differences between infants with no ROP and infants who developed ROP.

Results

Serum levels from 78 infants (43 male [55%]; mean [SD] GA, 25.5 [1.4] weeks) with a known ROP outcome were evaluated. Lower area under the curve (AUC) of arachidonic acid (AA) (20:4 ω-6) was seen in infants with a later diagnosis of ROP compared with infants with no ROP in the first month of life (mean, 34.05 [95% CI, 32.10-36.00] vs 37.15 [95% CI, 34.85-39.46]; P < .05). In addition, lower levels of AA at 32 weeks' PMA were seen in infants with later severe ROP compared with in those without ROP (mean, 7.06 [95% CI, 6.60-7.52] vs 8.74 [95% CI, 7.80-9.67]; P < .001). In logistic modeling, low postnatal serum levels of AA and GA at birth identified with a sensitivity greater than 90% of infants who developed ROP.

Conclusions and Relevance

Low postnatal levels of the ω-6 LC-PUFAs (AA) are strongly associated with ROP development. Evaluating postnatal AA fraction after birth in addition to GA may be useful for ROP prediction.

Trial Registration

clinicaltrials.gov Identifier: NCT02760472.

Early Enteral Administration of a Complex Lipid Emulsion Supplement Prevents Postnatal Deficits in Docosahexaenoic and Arachidonic Acids and Increases Tissue Accretion of Lipophilic Nutrients in Preterm Piglets

BACKGROUND

Preterm delivery and current nutrition strategies result in deficiencies of critical long-chain fatty acids (FAs) and lipophilic nutrients, increasing the risk of preterm morbidities. We sought to determine the efficacy of preventing postnatal deficits in FAs and lipophilic nutrients using an enteral concentrated lipid supplement in preterm piglets.

METHODS

Preterm piglets were fed a baseline diet devoid of arachidonic acid (AA) and docosahexaenoic acid (DHA) and randomized to enteral supplementation as follows: (1) Intralipid (IL), (2) complex lipid supplement 1 (CLS1) with an AA:DHA ratio of 0.25, or (3) CLS2 with an AA:DHA ratio of 1.2. On day 8, plasma and tissue levels of FAs and lipophilic nutrients were measured and ileum histology performed.

RESULTS

Plasma DHA levels decreased in the IL group by day 2. In contrast, DHA increased by day 2 compared with birth levels in both CLS1 and CLS2 groups. The IL and CLS1 groups demonstrated a continued decline in AA levels during the 8-day protocol, whereas AA levels in the CLS2 group on day 8 were comparable to birth levels. Preserving AA levels in the CLS2 group was associated with greater ileal villus height and muscular layer thickness. Lipophilic nutrients were effectively absorbed in plasma and tissues.

CONCLUSIONS

Enteral administration of CLS1 and CLS2 demonstrated similar increases in DHA levels compared with birth levels. Only CLS2 maintained AA birth levels. Providing a concentrated complex lipid emulsion with an AA:DHA ratio > 1 is important in preventing postnatal AA deficits.

Intravenous Fish Oil and Serum Fatty Acid Profiles in Pediatric Patients With Intestinal Failure-Associated Liver Disease

BACKGROUND

Intravenous fish oil (FO) treats pediatric intestinal failure-associated liver disease (IFALD). There are concerns that a lipid emulsion composed of ω-3 fatty acids will cause an essential fatty acid deficiency (EFAD). This study's objective was to quantify the risk for abnormal fatty acid concentrations in children treated with FO.

METHODS

Inclusion criteria for this prospective study were children with intestinal failure. Intravenous soybean oil (SO) was replaced with FO for no longer than 6 months. Serum fatty acids were analyzed using linear and logistic models, and compared with age-based norms to determine the percentage of subjects with low and high concentrations.

RESULTS

Subjects (n = 17) started receiving FO at a median of 3.6 months (interquartile range 2.4-9.6 months). Over time, α-linolenic, linoleic, arachidonic, and Mead acid decreased, whereas docosahexaenoic and eicosapentaenoic acid increased (P < 0.001 for all). Triene-tetraene ratios remained unchanged (P = 1). Although subjects were 1.8 times more likely to develop a low linoleic acid while receiving FO vs SO (95% CI: 1.4-2.3, P < 0.01), there was not a significant risk for low arachidonic acid. Subjects were 1.6 times more likely to develop high docosahexaenoic acid while receiving FO vs SO; however, this was not significant (95% CI: 0.9-2.6, P = 0.08).

CONCLUSION

In this cohort of parenteral nutrition-dependent children, switching from SO to FO led to a decrease in essential fatty acid concentrations, but an EFAD was not evident. Low and high levels of fatty acids developed. Further investigation is needed to clarify if this is clinically significant.

A More Comprehensive Approach to the Neuroprotective Potential of Long-Chain Polyunsaturated Fatty Acids in Preterm Infants Is Needed-Should We Consider Maternal Diet and the n-6:n-3 Fatty Acid Ratio?

There is growing evidence that long-chain polyunsaturated fatty acids (LCPUFAs) are of importance for normal brain development. Adequate supply of LCPUFAs may be particularly important for preterm infants, because the third trimester is an important period of brain growth and accumulation of arachidonic acid (n-6 LCPUFA) and docosahexaenoic acid (n-3 LCPUFA). Fatty acids from the n-6 and n-3 series, particularly, have important functions in the brain as well as in the immune system, and their absolute and relative intakes may alter both the risk of impaired neurodevelopment and response to injury. This narrative review focuses on the potential importance of the n-6:n-3 fatty acid ratio in preterm brain development. Randomized trials of post-natal LCPUFA supplementation in preterm infants are presented. Pre-clinical evidence, results from observational studies in preterm infants as well as studies in term infants and evidence related to maternal diet during pregnancy, focusing on the n-6:n-3 fatty acid ratio, are also summarized. Two randomized trials in preterm infants have compared different ratios of arachidonic acid and docosahexaenoic acid intakes. Most of the other studies in preterm infants have compared formula supplemented with arachidonic acid and docosahexaenoic acid to un-supplemented formula. No trial has had a comprehensive approach to differences in total intake of both n-6 and n-3 fatty acids during a longer period of neurodevelopment. The results from preclinical and clinical studies indicate that intake of LCPUFAs during pregnancy and post-natal development is of importance for neurodevelopment and neuroprotection in preterm infants, but the interplay between fatty acids and their metabolites is complex. The best clinical approach to LCPUFA supplementation and n-6 to n-3 fatty acid ratio is still far from evident, and requires in-depth future studies that investigate specific fatty acid supplementation in the context of other fatty acids in the diet.

The Role of Lipids in Human Milk and Infant Formulae

The quantity and quality of dietary lipids in infant formulae have a significant impact on health outcomes, especially when fat storing and/or absorption are limited (e.g., preterm birth and short bowel disease) or when fat byproducts may help to prevent some pathologies (e.g., atopy). The lipid composition of infant formulae varies according to the different fat sources used, and the potential biological effects are related to the variety of saturated and unsaturated fatty acids. For example, since lipids are the main source of energy when the normal absorptive capacity of the digestive tract is compromised, medium-chain saturated fatty acids might cover this requirement. Instead, ruminant-derived trans fatty acids and metabolites of n-3 long-chain polyunsaturated fatty acids with their anti-inflammatory properties can modulate immune function. Furthermore, dietary fats may influence the nutrient profile of formulae, improving the acceptance of these products and the compliance with dietary schedules.

Inpatient outcomes of preterm infants receiving ω-3 enriched lipid emulsion (SMOFlipid): an observational study

Neonatal units have started to switch from using conventional soy-based to alternate lipid emulsions, like SMOFlipid. SMOFlipid has been associated with an improvement in biochemical parameters and delays progression of parenteral nutrition-associated liver disease (PNALD). This retrospective epoch study aimed to compare clinically relevant neonatal outcomes in preterm infants (< 32 weeks), receiving SMOFlipid versus Intralipid. We compared clinical outcomes in two epochs-epoch 1 (Intralipid, October 2013-June 2015) versus epoch 2 (SMOFlipid, July 2015-March 2017). Primary outcome studied was mortality and rates of severe neonatal morbidities. Univariate and multivariate regression was conducted to determine risk for mortality and PNALD. A total of 222 infants (epoch 1, 123 versus epoch 2, 99) were included in the study. A higher incidence of late onset sepsis (56 versus 30%, p < 0.005) was observed in epoch 1. There was no significant difference in mortality or rates of any other severe neonatal morbidity. The type of lipid emulsion did not have a significant effect on mortality or PNALD on regression analysis.

CONCLUSION

Use of SMOFlipid as the primary lipid emulsion seems to have minimal effect on rates of clinically important neonatal outcomes; however, long-term effects need to be further evaluated. What is Known: • Many neonatal units have started replacing traditional soy-based lipid formulations with SMOFlipid (ω-3 enriched lipid emulsion), as the primary lipid component in parenteral nutrition for preterm infants. • While there is evidence associating improved liver function and balanced essential fatty acid levels in infants receiving SMOFlipid, there is a lack of evidence evaluating relevant clinical outcomes in infants receiving SMOFlipid versus traditional lipid formulations. What is New: • The influence of SMOFlipid on a series of clinical outcomes in an at-risk preterm population is presented. • SMOFlipid appears to be well tolerated in preterm infants with minimal side effects, and some growth benefits seen.

Omega-6/omega-3 fatty acid intake of children and older adults in the U.S.: dietary intake in comparison to current dietary recommendations and the Healthy Eating Index

BACKGROUND

Omega-6 and omega-3 fatty acids (FAs) and their ratio have been shown to affect cognitive function in children and older adults. With these analyses, we aimed to describe omega-6 and omega-3 FA intake among children and older adults in light of FA intake recommendations and with consideration of overall diet.

METHODS

Data were merged from two cross-sectional studies with 219 children 7 to 12 years old and one longitudinal study with 133 adults 65 to 79 years old. Demographic data, anthropometric data, and Healthy Eating Index scores were used to study relations among the omega-6 to omega-3 FA ratio and age, education, body mass index, and diet quality. FA intake, demographic, and anthropometric data were examined using partial correlations, t-tests, and analysis of variance.

RESULTS

Most children and adults consumed at least the recommended amount of alpha-linolenic acid (LNA; omega-3) for their age and gender without consuming high amounts of linoleic acid (LA; omega-6), but did not consume sufficient eicosapentaenoic acid (EPA; omega-) and docosahexaenoic acid (DHA; omega-3). The average omega-6 to omega-3 ratios in both groups were lower than previously reported. Eating lower ratios was associated with healthier diets and consuming adequate amounts of several other nutrients. No demographic or anthropometric variables were related to FA intake in children. Adults with a college degree had significantly lower ratios than those without a college degree.

CONCLUSIONS

American children and older adults are able to consume more balanced omega-6 to omega-3 ratios than has been indicated by commodity data. However, very few American children met even the lowest recommendations for EPA and DHA intake. Research is needed to clarify recommendations for the optimal ratio across development, which may aid in increasing EPA and DHA intake and improving health outcomes in the United States.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02199808 13 July 2014, NCT01823419 (retrospectively registered) 20 March 2013, and NCT01515098 18 January 2012.

A Mixed Lipid Emulsion for Prevention of Parenteral Nutrition Associated Cholestasis in Extremely Low Birth Weight Infants: A Randomized Clinical Trial

OBJECTIVES

To examine whether a mixed lipid emulsion reduces the incidence of parenteral nutrition associated cholestasis (PNAC) in extremely low birth weight (ELBW, <1000 g) infants.

STUDY DESIGN

This double-blind randomized trial of 230 ELBW infants (June 2012-October 2015) was performed at a single level IV neonatal intensive care unit. Patients received either a mixed lipid emulsion composed of soybean oil, medium chain triglycerides, olive oil, and fish oil-(intervention) or a soybean oil-based lipid emulsion (control) for parenteral nutrition. The primary outcome measure was PNAC (conjugated bilirubin >1.5 mg/dL [25 µmol/L] at 2 consecutive measurements). The study was powered to detect a reduction of PNAC from 25% to 10%.

RESULTS

Reasons for noneligibility of 274 infants screened were refusal to participate (n = 16), death (n = 10), withdrawal of treatment (n = 5), higher order multiples (n = 9), and parents not available for consent (n = 4). Intention to treat analysis was carried out in 223 infants (7 infants excluded after randomization). Parenteral nutrition associated cholestasis was 11 of 110 (10.1%) in the intervention and 18 of 113 (15.9%) in the control group (P = .20). Multivariable analyses showed no statistically significant difference in the intention to treat (aOR 0.428, 95% CI 0.155-1.187; P = .10) or per protocol population (aOR 0.457, 95% CI 0.155-1.347; P = .16). There was no statistically significant effect on any other neonatal morbidity.

CONCLUSIONS

The incidence of parenteral nutrition associated cholestasis was not significantly reduced using a mixed lipid emulsion in ELBW infants.

TRIAL REGISTRATION

ClinicalTrials.govNCT01585935.

Association of whole blood n-6 fatty acids with stunting in 2-to-6-year-old Northern Ghanaian children: A cross-sectional study

In Northern Ghana, 33% of children are stunted due to economic disparities. Dietary fatty acids (FA) are critical for growth, but whether blood FA levels are adequate in Ghanaian children is unknown. The objective of this study was to determine the association between whole blood FAs and growth parameters in Northern Ghanaian children 2-6 years of age. A drop of blood was collected on an antioxidant treated card and analyzed for FA composition. Weight and height were measured and z-scores were calculated. Relationships between FAs and growth parameters were analyzed by Spearman correlations, linear regressions, and factor analysis. Of the 307 children who participated, 29.7% were stunted and 8% were essential FA deficient (triene/tetraene ratio>0.02). Essential FA did not differ between stunted and non-stunted children and was not associated with height-for-age z-score (HAZ) or weight-for-age z-score (WAZ). In hemoglobin adjusted regression models, both HAZ and WAZ were positively associated with arachidonic acid (p≤0.01), dihomo-gamma-linolenic acid (DGLA, p≤0.05), docosatetraenoic acid (p≤0.01) and the ratio of DGLA/linoleic acid (p≤0.01). These data add to the growing body of evidence indicating n-6 FAs are critical in childhood linear growth. Our findings provide new insights into the health status of an understudied Northern Ghanaian population.

Arachidonic acid production by the oleaginous fungus Mortierella alpina 1S-4: A review

The filamentous fungus Mortierella alpina 1S-4 is capable of accumulating a large amount of triacylglycerol containing C20 polyunsaturated fatty acids (PUFAs). Indeed, triacylglycerol production by M. alpina 1S-4 can reach 20 g/L of culture broth, and the critical cellular signaling and structural PUFA arachidonic acid (ARA) comprises 30%–70% of the total fatty acid. The demonstrated health benefits of functional PUFAs have in turn encouraged the search for rich sources of these compounds, including fungal strains showing enhanced production of specific PUFAs. Screening for mutants and targeted gene manipulation of M. alpina 1S-4 have elucidated the functions of various enzymes involved in PUFA biosynthesis and established lines with improved PUFA productivity. In some cases, these strains have been used for indistrial-scale production of PUFAs, including ARA. In this review, we described practical ARA production through mutant breeding, functional analyses of genes encoding enzymes involved in PUFA biosynthesis, and recent advances in the production of specific PUFAs through molecular breeding of M. alpina 1S-4.

Low serum ω-3 and ω-6 polyunsaturated fatty acids and other metabolites are associated with poor linear growth in young children from rural Malawi

Background: Stunting affects ∼25% of children <5 y of age and is associated with impaired cognitive and motor development and increased morbidity and mortality. The pathogenesis of stunting is poorly understood.Objective: The purpose of this study was to identify altered metabolic pathways associated with child stunting.Design: We measured 677 serum metabolites using liquid chromatography-tandem mass spectrometry in a cross-sectional study of 400 Malawian children aged 12-59 mo, of whom 62% were stunted.Results: A low height-for-age z score (HAZ) was associated with lower serum concentrations of 1) ω-3 (n-3) and ω-6 (n-6) polyunsaturated fatty acids (PUFAs), 2) sulfated neurosteroids, which play a role in brain development, 3) carnitine, a conditionally essential nutrient with an important role in the carnitine shuttle for the metabolism of fatty acids and energy production, and 4) γ-glutamyl amino acids, which represent an altered γ-glutamyl cycle of glutathione metabolism. A low HAZ was associated with significantly higher serum concentrations of 5 biomarkers related to cigarette smoke exposure.Conclusions: This metabolomics study shows a cross-sectional association between stunting and low serum ω-3 and ω-6 long-chain PUFAs, which are essential for growth and development; low sulfated neurosteroids, which play a role in brain development; low carnitine, which is essential for β-oxidation of fatty acids; alterations in glutathione metabolism; and increased serum metabolites that are associated with secondhand tobacco smoke exposure. This trial was registered at www.controlled-trials.com as ISRCTN14597012.

Supplementing dams with both arachidonic and docosahexaenoic acid has beneficial effects on growth and immune development

Omega-3 long-chain polyunsaturated fatty acids (LCPUFAS) modulate immune cells in vitro and in vivo. This study investigated the effects of enriching the maternal diet with the n-6 and n-3 LCPUFAs, arachidonic (20:4n-6, 0.6%wt ARA) and docosahexaenoic acid (22:6n-3, 0.32%wt DHA), or 1:1 and 2:1 ratios (ARA: DHA) on total lipids in milk, total lipids, and immunophenotypes in plasma, lymph nodes, and spleen from isolated immune cells from 28d old pups. From day 15 of gestation to day 3 pp, Sprague-Dawley dams were fed a commercial chow. On day 3 pp litters were culled and pups (4 males and 2 females) randomly cross-fostered to dams who were randomized to one of the 5 experimental diets resulting in 20 male and 10 female pups/diet group. Dams fed ARA or ARA: DHA had 28-36% more 20:4n-6 in milk and feeding DHA or ARA: DHA doubled 22:6n-3 in milk lipids (P<0.05). Feeding 1:1 or 2:1 ARA: DHA resulted in greater pup weight at weaning (P<0.05). Compared to the control pups, ARA + DHA fed pups had a lower proportion of splenic CD45RA+ lymphocytes. In summary, postpartum supplementation with a combination of ARA + DHA, compared to ARA or DHA alone, resulted in a higher content of ARA and DHA in dam's milk and tissues and had positive effects on growth, accompanied by evidence of progression toward a mature immune phenotype, and suggests a need for ARA when DHA is supplemented in the early diet. Additional investigations are needed of ARA immunomodulation to better understand and estimate nutritional requirements for LCPUFAs during early development.

Is There a Role for Bioactive Lipids in the Pathobiology of Diabetes Mellitus?

Inflammation, decreased levels of circulating endothelial nitric oxide (eNO) and brain-derived neurotrophic factor (BDNF), altered activity of hypothalamic neurotransmitters (including serotonin and vagal tone) and gut hormones, increased concentrations of free radicals, and imbalance in the levels of bioactive lipids and their pro- and anti-inflammatory metabolites have been suggested to play a role in diabetes mellitus (DM). Type 1 diabetes mellitus (type 1 DM) is due to autoimmune destruction of pancreatic β cells because of enhanced production of IL-6 and tumor necrosis factor-α (TNF-α) and other pro-inflammatory cytokines released by immunocytes infiltrating the pancreas in response to unknown exogenous and endogenous toxin(s). On the other hand, type 2 DM is due to increased peripheral insulin resistance secondary to enhanced production of IL-6 and TNF-α in response to high-fat and/or calorie-rich diet (rich in saturated and trans fats). Type 2 DM is also associated with significant alterations in the production and action of hypothalamic neurotransmitters, eNO, BDNF, free radicals, gut hormones, and vagus nerve activity. Thus, type 1 DM is because of excess production of pro-inflammatory cytokines close to β cells, whereas type 2 DM is due to excess of pro-inflammatory cytokines in the systemic circulation. Hence, methods designed to suppress excess production of pro-inflammatory cytokines may form a new approach to prevent both type 1 and type 2 DM. Roux-en-Y gastric bypass and similar surgeries ameliorate type 2 DM, partly by restoring to normal: gut hormones, hypothalamic neurotransmitters, eNO, vagal activity, gut microbiota, bioactive lipids, BDNF production in the gut and hypothalamus, concentrations of cytokines and free radicals that results in resetting glucose-stimulated insulin production by pancreatic β cells. Our recent studies suggested that bioactive lipids, such as arachidonic acid, eicosapentaneoic acid, and docosahexaenoic acid (which are unsaturated fatty acids) and their anti-inflammatory metabolites: lipoxin A4, resolvins, protectins, and maresins, may have antidiabetic actions. These bioactive lipids have anti-inflammatory actions, enhance eNO, BDNF production, restore hypothalamic dysfunction, enhance vagal tone, modulate production and action of ghrelin, leptin and adiponectin, and influence gut microbiota that may explain their antidiabetic action. These pieces of evidence suggest that methods designed to selectively deliver bioactive lipids to pancreatic β cells, gut, liver, and muscle may prevent type 1 and type 2 DM.

Effects of a lipid emulsion containing fish oil on polyunsaturated fatty acid profiles, growth and morbidities in extremely premature infants: A randomized controlled trial

BACKGROUND & AIMS

The purpose of the study was to compare the effects of the parenteral emulsion SMOFlipid^®, with 15% fish oil, with Clinoleic^® on retinopathy of prematurity (ROP) and other morbidities and growth, and to compare their impact on longitudinal serum levels of fatty acids. Retinopathy of prematurity, other morbidity and growth were correlated with each parenteral lipid supplement.

METHODS

Ninety infants born at gestational age <28 weeks were randomized to treatment with SMOFlipid^® or Clinoleic^®. Two thirds (66%) of the infants received parenteral nutrition for up to 14 days birth (median 8, range 2-14 days), and additional 25% of the infants received for up to 28 days after birth (median 21, range 15-28 days). Cord blood samples and then venous blood samples were obtained at ages 1, 7, 14, and 28 days and at postmenstrual age (PMA) 32, 36, and 40 weeks. Breastmilk was collected at postnatal day 7, and at PMA 32 and 40 weeks. Serum phospholipid and breastmilk total fatty acids were analyzed by gas chromatography-mass spectrometry. Treatment groups were compared with regard to ROP, bronchopulmonary dysplasia, necrotizing enterocolitis, patent ductus arteriosus sepsis and growth between birth and 36 weeks.

RESULTS

Infants on SMOFlipid^® had higher fractions of omega-3 LCPUFA eicosapentaenoic acid (EPA) and slightly higher omega-3 LCPUFA docosahexaenoic acid (DHA) fraction and a decreased arachidonic acid (AA) to DHA ratio from one week after birth up to 32 postmenstrual weeks compared to infants on Clinoleic^®. Treatment groups did not differ in morbidities or growth.

CONCLUSION

Supplementation with SMOFlipid^® containing 15% fish oil during parenteral nutrition increased EPA substantially, DHA marginally, reduced AA and decreased AA to DHA ratio. It did not reduce morbidity or affect growth. Since extremely preterm infants accumulate a large deficit of DHA and AA, studies on more prolonged or different levels of DHA and AA supplementation are warranted.

Maternal and fetal lipid metabolism under normal and gestational diabetic conditions

Maternal lipids are strong determinants of fetal fat mass. Here we review the overall lipid metabolism in normal and gestational diabetes mellitus (GDM) pregnancies. During early pregnancy, the increase in maternal fat depots is facilitated by insulin, followed by increased adipose tissue breakdown and subsequent hypertriglyceridemia, mainly as a result of insulin resistance (IR) and estrogen effects. The response to diabetes is variable as a result of greater IR but decreased estrogen levels. The vast majority of fatty acids (FAs) in the maternal circulation are esterified and associated with lipoproteins. These are taken up by the placenta and hydrolyzed by lipases. The released FAs enter various metabolic routes and are released into fetal circulation. Although these determinants are modified in maternal GDM, the fetus does not seem to receive more FAs than in non-GDM pregnancies. Long-chain polyunsaturated FAs are essential for fetal development and are obtained from the mother. Mitochondrial FA oxidation occurs in fetal tissue and in placenta and contributes to energy production. Fetal fat accretion during the last weeks of gestation occurs very rapidly and is sustained not only by FAs crossing the placenta, but also by fetal lipogenesis. Fetal hyperinsulinemia in GDM mothers promotes excess accretion of adipose tissue, which gives rise to altered adipocytokine profiles. Fetal lipoproteins are low at birth, but the GDM effects are unclear. The increase in body fat in neonates of GDM women is a risk factor for obesity in early childhood and later life.

Reduction of Arachidonate Is Associated With Increase in B-Cell Activation Marker in Infants: A Randomized Trial

BACKGROUND

Infants who are not breast-fed benefit from formula with both docosahexaenoic acid (C22:6n3) and arachidonic acid (ARA; C20:4n6). The amount of ARA needed to support immune function is unknown. Infants who carry specific fatty acid desaturase (FADS) polymorphisms may require more dietary ARA to maintain adequate ARA status.

OBJECTIVE

The aim of the study was to determine whether ARA intake or FADS polymorphisms alter ARA levels of lymphocytes, plasma, and red blood cells in term infants fed infant formula.

METHODS

Infants (N = 89) were enrolled in this prospective, double-blind controlled study. Infants were randomized to consume formula containing 17 mg docosahexaenoic acid and 0, 25, or 34 mg ARA/100 kcal for 10 weeks. Fatty acid composition of plasma phosphatidylcholine and phosphatidylethanolamine, total fatty acids of lymphocytes and red blood cells, activation markers of lymphocytes, and polymorphisms in FADS1 and FADS2 were determined.

RESULTS

Lymphocyte ARA was higher in the 25-ARA formula group than in the 0- or 34-ARA groups. In plasma, 16:0/20:4 and 18:0/20:4 species of phosphatidylcholine and phosphatidylethanolamine were highest and 16:0/18:2 and 18:0/18:2 were lowest in the 34-ARA formula group. In minor allele carriers of FADS1 and FADS2, plasma ARA content was elevated only at the highest level of ARA consumed. B-cell activation marker CD54 was elevated in infants who consumed formula containing no ARA.

CONCLUSIONS

ARA level in plasma is reduced by low ARA consumption and by minor alleles in FADS. Dietary ARA may exert an immunoregulatory role on B-cell activation by decreasing 16:0/18:2 and 18:0/18:2 species of phospholipids. ARA intake from 25 to 34 mg/100 kcal is sufficient to maintain cell ARA level in infants across genotypes.

Systematic Review on N-3 and N-6 Polyunsaturated Fatty Acid Intake in European Countries in Light of the Current Recommendations - Focus on Specific Population Groups

BACKGROUND

Earlier reviews indicated that in many countries adults, children and adolescents consume on an average less polyunsaturated fatty acids (PUFAs) than recommended by the Food and Agriculture Organisation/World Health Organisation.

SUMMARY

The intake of total and individual n-3 and n-6 PUFAs in European infants, children, adolescents, elderly and pregnant/lactating women was evaluated systematically.

RESULTS

The evaluations were done against recommendations of the European Food Safety Authority. Key Messages: Fifty-three studies from 17 different European countries reported an intake of total n-3 and n-6 PUFAs and/or individual n-3 or n-6 PUFAs in at least one of the specific population groups: 10 in pregnant women, 4 in lactating women, 3 in infants 6-12 months, 6 in children 1-3 years, 11 in children 4-9 years, 8 in adolescents 10-18 years and 11 in elderly >65 years. Mean linoleic acid intake was within the recommendation (4 energy percentage [E%]) in 52% of the countries, with inadequate intakes more likely in lactating women, adolescents and elderly. Mean α-linolenic acid intake was within the recommendation (0.5 E%) in 77% of the countries. In 26% of the countries, mean eicosapentaenoic acid and/or docosahexaenoic acid intake was as recommended. These results indicate that intake of n-3 and n-6 PUFAs may be suboptimal in specific population groups in Europe.

Physical Stability of 20% Lipid Injectable EmulsionsviaSimulated Syringe Infusion: Effects of GlassvsPlastic Product Packaging

BACKGROUND

The United States Pharmacopeia (USP) has proposed large-globule-size limits to ensure the physical stability of lipid injectable emulsions, expressed as the percent fat >5 microm, or PFAT(5), not exceeding 0.05%. Visibly obvious phase separation as free oil has been shown to occur in some samples if PFAT(5) is >0.4%. We recently found that lipids, newly packaged in plastic (P), exceed the proposed USP limits and seem to produce less stable total nutrient admixtures compared with those made from conventional glass (G), which do meet proposed USP standards. We tested the possible stability differences between 20% lipid injectable emulsions in either P or G in a simulated neonatal syringe infusion study.

METHODS

Eighteen individual syringes were prepared from each 20% lipid injectable emulsion product (n = 36) and attached to a syringe pump set at an infusion rate of 0.5 mL/hour. The starting PFAT(5) levels were measured at time 0 and after 24 hours of infusion, using a laser-based light obscuration technique as described by the USP Chapter <729>. The data were assessed by a 2-way analysis of variance (ANOVA) with Container (G vs P) and Time as the independent variables and PFAT as the dependent variable.

RESULTS

At time 0, the starting PFAT(5) level for lipids packaged in G was 0.006% +/- 0.001% vs 0.162% +/- 0.026% for P, whereas at the end of the infusion they were 0.013% +/- 0.003% and 0.328% +/- 0.046%, respectively. Significant differences were noted overall between groups for Container, Time, and Container-Time interaction (all p < .001). Bonferroni tests showed significant differences in PFAT(5) levels between Containers at time 0 (T-0; p < .001) and T-0 vs T-24 for P-based lipids (p < .001), whereas no such differences were noted for Time for the G-based lipids. Similar results were noted for PFAT(10) levels.

CONCLUSIONS

We confirm that presently available lipid injectable emulsions packaged in newly introduced plastic containers exceed the proposed USP <729> PFAT(5) limits and subsequently become significantly less stable during a simulated syringe-based infusion. Although modest growth (p = NS) in large-diameter fat globules was observed for the glass-based lipids, they remained within proposed USP globule size limits throughout the study. Glass-based lipids seem to be a more stable dosage form and potentially a safer way to deliver lipids via syringe infusion to critically ill neonates.

Longchain polyunsaturated fatty acid supplementation in preterm infants

BACKGROUND

Controversy exists over whether longchain polyunsaturated fatty acids (LCPUFA) are essential nutrients for preterm infants because they may not be able to synthesise sufficient amounts of LCPUFA to meet the needs of the developing brain and retina.

OBJECTIVES

To assess whether supplementation of formula milk with LCPUFA is safe and of benefit to preterm infants. The main areas of interest were the effects of supplementation on the visual function, development and growth of preterm infants.

SEARCH METHODS

Trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2) in the Cochrane Library (searched 28 February 2016), MEDLINE Ovid (1966 to 28 February 2016), Embase Ovid (1980 to 28 February 2016), CINAHL EBSCO (Cumulative Index to Nursing and Allied Health Literature; 1980 to 28 February 2016), MEDLINE In Process & Other Non-indexed Citations (1966 to 28 February 2016) and by checking reference lists of articles and conference proceedings. We also searched ClinicalTrials.gov (13 April 2016). No language restrictions were applied.

SELECTION CRITERIA

All randomised trials evaluating the effect of LCPUFA-supplemented formula in enterally-fed preterm infants (compared with standard formula) on visual development, neurodevelopment and physical growth. Trials reporting only biochemical outcomes were not included.

DATA COLLECTION AND ANALYSIS

All authors assessed eligibility and trial quality, two authors extracted data separately. Study authors were contacted for additional information.

MAIN RESULTS

Seventeen trials involving 2260 preterm infants were included in the review. The risk of bias varied across the included trials with 10 studies having low risk of bias in a majority of the domains. The median gestational age (GA) in the included trials was 30 weeks and median birth weight (BW) was 1300 g. The median concentration of docosahexaenoic acid (DHA) was 0.33% (range: 0.15% to 1%) and arachidonic acid (AA) 0.37% (range: 0.02% to 0.84%). Visual acuity Visual acuity over the first year was measured by Teller or Lea acuity cards in eight studies, by visual evoked potential (VEP) in six studies and by electroretinogram (ERG) in two studies. Most studies found no significant differences in visual acuity between supplemented and control infants. The form of data presentation and the varying assessment methods precluded the use of meta-analysis. A GRADE analysis for this outcome indicated that the overall quality of evidence was low. Neurodevelopment Three out of seven studies reported some benefit of LCPUFA on neurodevelopment at different postnatal ages. Meta-analysis of four studies evaluating Bayley Scales of Infant Development at 12 months (N = 364) showed no significant effect of supplementation (Mental Development Index (MDI): MD 0.96, 95% CI -1.42 to 3.34; P = 0.43; I² = 71% - Psychomotor DeveIopment Index (PDI): MD 0.23, 95% CI -2.77 to 3.22; P = 0.88; I² = 81%). Furthermore, three studies at 18 months (N = 494) also revealed no significant effect of LCPUFA on neurodevelopment (MDI: MD 2.40, 95% CI -0.33 to 5.12; P = 0.08; I² = 0% - PDI: MD 0.74, 95% CI -1.90 to 3.37; P = 0.58; I² = 54%). A GRADE analysis for these outcomes indicated that the overall quality of evidence was low. Physical growth Four out of 15 studies reported benefits of LCPUFA on growth of supplemented infants at different postmenstrual ages (PMAs), whereas two trials suggested that LCPUFA-supplemented infants grow less well. One trial reported mild reductions in length and weight z scores at 18 months. Meta-analysis of five studies (N = 297) showed increased weight and length at two months post-term in supplemented infants (Weight: MD 0.21, 95% CI 0.08 to 0.33; P = 0.0010; I² = 69% - Length: MD 0.47, 95% CI 0.00 to 0.94; P = 0.05; I² = 0%). Meta-analysis of four studies at a corrected age of 12 months (N = 271) showed no significant effect of supplementation on growth outcomes (Weight: MD -0.10, 95% CI -0.31 to 0.12; P = 0.34; I² = 65% - Length: MD 0.25; 95% CI -0.33 to 0.84; P = 0.40; I² = 71% - Head circumference: MD -0.15, 95% CI -0.53 to 0.23; P = 0.45; I² = 0%). No significant effect of LCPUFA on weight, length or head circumference was observed on meta-analysis of two studies (n = 396 infants) at 18 months (Weight: MD -0.14, 95% CI -0.39 to 0.10; P = 0.26; I² = 66% - Length: MD -0.28, 95% CI -0.91 to 0.35; P = 0.38; I² = 90% - Head circumference: MD -0.18, 95% CI -0.53 to 0.18; P = 0.32; I² = 0%). A GRADE analysis for this outcome indicated that the overall quality of evidence was low.

AUTHORS' CONCLUSIONS

Infants enrolled in the trials were relatively mature and healthy preterm infants. Assessment schedule and methodology, dose and source of supplementation and fatty acid composition of the control formula varied between trials. On pooling of results, no clear long-term benefits or harms were demonstrated for preterm infants receiving LCPUFA-supplemented formula.

Enhanced production of polyunsaturated fatty acids by enzyme engineering of tandem acyl carrier proteins

In some microorganisms, polyunsaturated fatty acids (PUFAs) are biosynthesized by PUFA synthases characterized by tandem acyl carrier proteins (ACPs) in subunit A. These ACPs were previously shown to be important for PUFA productivity. In this study, we examined their function in more detail. PUFA productivities increased depending on the number of ACPs without profile changes in each subunit A of eukaryotic and prokaryotic PUFA synthases. We also constructed derivative enzymes from subunit A with 5 × ACPs. Enzymes possessing one inactive ACP at any position produced ~30% PUFAs compared with the parental enzyme but unexpectedly had ~250% productivity compared with subunit A with 4 × ACPs. Enzymes constructed by replacing the 3^rd ACP with an inactive ACP from another subunit A or ACP-unrelated sequences produced ~100% and ~3% PUFAs compared with the parental 3^rd ACP-inactive enzyme, respectively. These results suggest that both the structure and number of ACP domains are important for PUFA productivity.

Early docosahexaenoic and arachidonic acid supplementation in extremely-low-birth-weight infants

BACKGROUND

Extremely-low-birth-weight (ELBW) infants accrue large deficits in docosahexaenoic acid (DHA) and arachidonic acid (ARA) and require improved supplementation strategies. We hypothesized that once daily DHA+ARA drops applied to buccal mucosa will increase blood levels.

METHODS

Thirty ELBW infants were randomized to receive DHA 20 mg/kg/d + ARA 40 or 60 mg/kg/d + ARA 120 mg/kg/d or placebo within 72 h of age for 8 wk duration. Red blood cell phospholipid levels of DHA (primary) and ARA (secondary) were measured at 2 and 8 wk of age.

RESULTS

Twenty-eight survivors with a median birth weight of 806 g completed dosing and sampling. Red blood cell levels were similar between the three groups at 2 wk (DHA: 4.62 wt% (interquartile range (IQR) 4.1-5.5) for all, P = 0.29 between groups; ARA: 21.1 wt% (IQR 18.78-22.6) for all, P = 0.41 between groups) and 8 wk (DHA: 6.0 wt% (IQR 5.1-7.1) for all, P = 0.57 between groups; ARA: 20.1 wt% (IQR 18.3-23.1) for all, P = 0.63 between groups). DHA in all infants showed a median increase of 31% from 2 to 8 wk (P < 0.04). ARA levels did not significantly change over time (P > 0.6).

CONCLUSION

Daily buccal DHA and ARA supplements did not affect fatty acid levels in ELBW infants.

Advances in the nutrition of preterm infants

The greatly improved survival rate of infants born both preterm and low birth weight (LBW) has led to the subsequent growth and development of these infants becoming an important focus for research. Preterm infants begin life with, or acquire as a result of their prematurity, greater morbidity than term born babies, growth deficits, an increased risk of developmental delay and an increased risk of later adult diseases compared with appropriate for gestational age (AGA) term born babies.

Research in recent decades has confirmed that there are marked differences in the nutritional requirements of preterm LBW infants compared with their AGA term born counterparts, both in the neonatal period and probably for all of infancy. In addition to the increased requirement for energy and protein, preterm LBW infants demonstrate a greatly increased requirement for some of the mineral elements, particularly iron, zinc and calcium, when compared with the needs of term AGA infants. In the UK, feeding practices for preterm infants in neonatal units and throughout infancy after hospital discharge are variable and many questions remain as to the optimal nutritional regimen for preterm LBW infants (and for subgroups of these infants) at different stages of infancy. There is some concern that the 2002 World Health Organization recommendations on infant feeding may be applied to all infants, including preterm infants, without consideration of their special nutritional needs, which may further compromise their growth and development.

A brief résumé of the work of prominent researchers in the field of preterm infant nutrition in the UK, notably Lucas, Cooke and Fewtrell, is included in the review, together with information from papers published by the authors of the review. The review concludes with a summary of the generally accepted recommendations on feeding preterm LBW infants after hospital discharge and information on some practical help available to the parents of these children and to health workers in the field.

Effect of offering maize, linseed or tuna oils throughout pregnancy and lactation on sow and piglet tissue composition and piglet performance

The effects of different dietary essential fatty acids on piglet tissue composition at birth and performance until 7 days post weaning were investigated by offering the sow diets containing (17·5 g oil per kg diet) either maize oil (MO) as a control treatment, tuna oil (TO) as a source of long chain n-3 polyunsaturated fatty acids, particularly 22:6 n-3, or a mixture of maize and linseed oils (LO) which supplied the same amount of n-3 acids as TO but in the form of 18:3 n-3. Ten sows were allocated to each treatment which was offered throughout pregnancy and lactation. Compared with MO, offering TO increased sow plasma and subcutaneous adipose tissue 22: 6 n-3 proportions whereas LO increased 18: 3 n-3 and, to a much lesser extent than TO, 22: 6 n-3. Offering TO to the sow increased the proportions of 20: 5 n-3 and 22: 6 n-3 in piglet brain and liver at birth and decreased the n-6 acids, 20: 4, 22: 4 and 22: 5. LO only increased piglet liver 20: 5 n-3 proportions but to a lesser extent than TO; however, LO also decreased the proportions of 20: 4, 22: 4 and 22: 5 n-6 in piglet tissues. Offering the pregnant sow dietary 18: 3 n-3 therefore increased deposition of 22: 6 n-3 in foetal piglet tissues to a much lesser extent than tuna oil and so it is necessary to offer the sow pre-formed 22: 6 n-3 in order to achieve maximum foetal 22: 6 n-3 deposition. By experimentally allocating piglets at birth, effects of sow nutrition during pregnancy and lactation were separated. Piglets sucking MO or TO sows were heavier than piglets sucking LO sows 7 days post weaning.

The effect of feeding salmon oil to sows throughout pregnancy on pre-weaning mortality of piglets

Salmon oil (16·5 kg /t), a source of long-chain polyunsaturated n-3 fatty acids, was included in diets offered to multiparous sows during pregnancy and lactation to measure responses in pre-weaning mortality and performance of piglets in two studies. The first study, carried out under commercial conditions, included 196 sows which were offered salmon oil and control diets from immediately post service until weaning. The same diets were also offered to 10 sows per treatment from day 58 of pregnancy in a controlled nutritional study which measured the effects of salmon oil on piglet tissue fatty acid composition. Offering salmon oil to the sow significantly increased gestation length and decreased individual piglet birth weight but had no effect on litter size at birth. Overall, salmon oil reduced pre-weaning mortality from 11·7% to 10·2% mainly by reducing the incidence of deaths from crushing by the sow. More detailed analysis of mortality using a general linear mixed model and 2294 piglet records, demonstrated that the incidence of pre-weaning mortality was significantly decreased with increasing individual piglet birth weight and by inclusion of salmon oil in the diet; the incidence of mortality increased with average piglet birth weight in a litter. Salmon oil inclusion had no effect on weight of litter weaned, sow lactation food intake or subsequent reproductive performance. In both studies, dietary salmon oil increased the proportions of long-chain n-3 polyunsaturated fatty acids in colostrum to a similar extent. In the nutritional study, inclusion of salmon oil reduced the proportions of 20: 4 n-6 in piglet liver and brain at birth and increased the proportions of long-chain n-3 polyunsaturated fatty acids. Therefore, despite reducing piglet birth weight, offering sows salmon oil reduced pre-weaning mortality of piglets. The nutritional study showed that the amount and type of marine oil used may not have been optimal.

Fatty Acid Composition in Feeds and Plasma of Canadian Premature Infants

OBJECTIVES

The objective of the present exploratory study was to investigate how the fatty acid (FA) composition of different food sources for preterm infants including breast milk (BM), formula (F), human milk fortifiers (HMFs), and total parenteral nutrition (TPN) impacted preterm infant's plasma FA. The associations between FA content of plasma with antioxidant enzyme activity and cognition were also evaluated.

METHODS

Thirty-two premature infants were included in the present study. Five different feeds (BM, F, BM + F, BM + HMF, and TPN) were provided. Foods and preterm infant plasma samples were collected at the same time on the same day biweekly where possible. Separation and identification of the plasma and food FA methyl esters were performed by gas-liquid chromatography. Antioxidant enzymes were measured. The Bayley Scale of Infant Development version III was used to evaluate cognition.

RESULTS

In food sources, BM contained significantly lower stearic acid (C18:0) (P < 0.05), oleic acid (C18:1n9) (P < 0.01), linoleic acid (C18:2n6) (P < 0.01), α-linoleic acid (C18:3n3) (P < 0.01), and arachidonic acid (C20:4n6) (P < 0.05) compared with the F. Palmitic acid (C16:0) was significantly higher (P < 0.05) in the BM + HMF compared with the BM. Stearic acid (C18:0) was significantly higher (P < 0.05) in the BM + F and BM + HMF compared with the BM. In the plasma lauric acid (C12:0) (P < 0.05) and myristic acid (C14:0) (P < 0.001) were higher in the BM-fed babies compared with the F-fed or TPN-recipient groups. Antioxidant enzymes, activities and cognition scores did not differ by feeding groups, however the study may not have been powered to detect these differences.

CONCLUSIONS

The type, and therefore quality, of fatty acids is an important consideration when selecting what is fed to premature infants because differences in feed fatty acids were seen in some plasma fatty acids in the study.

Essentiality of arachidonic acid intake in murine early development

We previously reported the importance of long-chain polyunsaturated fatty acid (LC-PUFA (>C20)) intake, including arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), for growth. This follow-up study focuses on ARA using a novel artificial rearing model during the lactation period in delta-6-desaturase knockout (D6D-KO) mice. Newborn D6D-KO male mouse pups were separated from dams within 48 hours and fed artificial milks containing 18-C essential fatty acids (EFAs) (16-17% LA, 3.8-4.1% ALA) with or without 1.2% ARA. After weaning, mice were maintained on similar diets: 15% LA, 2.3-2.4% ALA with or without 1.9% ARA. As a reference group, new born wild type (WT) male mouse pups were maintained by artificial milk and diet containing LA and ALA without ARA. Aspects of brain function were measured behaviorally (motor activity and rota-rod test) when mice were age 9 weeks. Body weight in the KO-Cont group was significantly lower (approximately 30%) than in the WT-Cont group, but this decrease was ameliorated by providing ARA in the KO-ARA group. The motor activity and coordination in the KO-Cont group decreased markedly compared to the WT-Cont group. The KO-ARA group had a tendency toward deteriorated motor coordination, although the motor activity was significantly enhanced compared to the KO-Cont group. In KO-ARA group brains, the level of ARA was increased and DHA decreased compared to WT-Cont. These results suggest that intake of LA and ALA only is insufficient to support healthy growth, and that ARA is also required, at least during the lactation period. These findings also suggested that continued intake of relatively high levels of ARA and without supplemental DHA during development led to an increased motor activity above that of WT animals. These studies indicate that both ARA dose and proper combination with DHA must be delineated to define optimal growth and behavioral function.

The Essentiality of Arachidonic Acid in Infant Development

Arachidonic acid (ARA, 20:4n-6) is an n-6 polyunsaturated 20-carbon fatty acid formed by the biosynthesis from linoleic acid (LA, 18:2n-6). This review considers the essential role that ARA plays in infant development. ARA is always present in human milk at a relatively fixed level and is accumulated in tissues throughout the body where it serves several important functions. Without the provision of preformed ARA in human milk or infant formula the growing infant cannot maintain ARA levels from synthetic pathways alone that are sufficient to meet metabolic demand. During late infancy and early childhood the amount of dietary ARA provided by solid foods is low. ARA serves as a precursor to leukotrienes, prostaglandins, and thromboxanes, collectively known as eicosanoids which are important for immunity and immune response. There is strong evidence based on animal and human studies that ARA is critical for infant growth, brain development, and health. These studies also demonstrate the importance of balancing the amounts of ARA and DHA as too much DHA may suppress the benefits provided by ARA. Both ARA and DHA have been added to infant formulas and follow-on formulas for more than two decades. The amounts and ratios of ARA and DHA needed in infant formula are discussed based on an in depth review of the available scientific evidence.