Diverse, region-specific effects of addition of arachidonic and docosahexanoic acids to formula with low or adequate linoleic and alpha-linolenic acids on piglet brain monoaminergic neurotransmitters

Lipid organization and turnover in the plasma membrane of human differentiating neural progenitor cells revealed by time-of-flight secondary ion mass spectrometry imaging

Membrane lipids have been known to influence multiple signalling and cellular processes. Dysregulation of lipids at the neuronal membrane is connected to a significant alteration of the brain function and morphology, leading to brain diseases and neurodegeneration. Understanding the lipid composition and turnover of neuronal membrane will provide a significant insight into the molecular events underlying the regulatory effects of these biomolecules in a neuronal system. In this study, we aimed to characterize the composition and turnover of the plasma membrane lipids in human neural progenitor cells (NPCs) at an early differentiation stage into midbrain neurons using ToF-SIMS imaging. Lipid composition of the native plasma membrane was explored, followed by an examination of the lipid turnover using different isotopically labelled lipid precursors, including 13C-choline, 13C-lauric acid, 15N-linoleic, and 13C-stearic. Our results showed that differentiating NPCs contain a high abundance of ceramides, glycerophosphoserines, neutral glycosphingolipids, diradylglycerols, and glycerophosphocholines at the plasma membrane. In addition, different precursors were found to incorporate into different membrane lipids which are specific for the short- or long-carbon chains, and the unsaturation or saturation stage of the precursors. The lipid structure of neuronal membrane reflects the differentiation status of NPCs, and it can be altered significantly using a particular lipid precursor. Our study illustrates a potential of ToF-SIMS imaging to study native plasma membrane lipids and elucidate complex cellular processes by providing molecular -rich information at a single cell level.

Impact of Arachidonic and Docosahexaenoic Acid Supplementation on Neural and Immune Development in the Young Pig

Background: Human milk contains both arachidonic acid (ARA) and docosahexaenoic acid (DHA). Supplementation of infant formula with ARA and DHA results in fatty acid (FA) profiles, neurodevelopmental outcomes, and immune responses in formula-fed infants that are more like those observed in breastfed infants. Consequently, ARA and DHA have been historically added together to infant formula. This study investigated the impact of ARA or DHA supplementation alone or in combination on tissue FA incorporation, immune responses, and neurodevelopment in the young pig.

Methods: Male pigs (N = 48 total) received one of four dietary treatments from postnatal day (PND) 2–30. Treatments targeted the following ARA/DHA levels (% of total FA): CON (0.00/0.00), ARA (0.80/0.00), DHA (0.00/0.80), and ARA+DHA (0.80/0.80). Plasma, red blood cells (RBC), and prefrontal cortex (PFC) were collected for FA analysis. Blood was collected for T cell immunophenotyping and to quantify a panel of immune outcomes. Myelin thickness in the corpus callosum was measured by transmission electron microscopy and pig movement was measured by actigraphy.

Results: There were no differences in formula intake or growth between dietary groups. DHA supplementation increased brain DHA, but decreased ARA, compared with all other groups. ARA supplementation increased brain ARA compared with all other groups but did not affect brain DHA. Combined supplementation increased brain DHA levels but did not affect brain ARA levels compared with the control. Pigs fed ARA or ARA+DHA exhibited more activity than those fed CON or DHA. Diet-dependent differences in activity suggested pigs fed ARA had the lowest percent time asleep, while those fed DHA had the highest. No differences were observed for immune or myelination outcomes.

Conclusion: Supplementation with ARA and DHA did not differentially affect immune responses, but ARA levels in RBC and PFC were reduced when DHA was provided without ARA. Supplementation of either ARA or DHA alone induced differences in time spent asleep, and ARA inclusion increased general activity. Therefore, the current data support the combined supplementation with both ARA and DHA in infant formula and raise questions regarding the safety and nutritional suitability of ARA or DHA supplementation individually.

The sociodemographic characteristics and dietary and blood plasma fatty acid profiles of elderly Saudi women with Alzheimer disease

Background

Alzheimer’s disease (AD) is a progressive neurodegenerative disease, and due to various physiological and psychological factors the patients are at risk of nutritional insufficiencies. The purpose of this study was to assess the dietary fatty acid intake and its effect on plasma fatty acids in elderly Saudi women and to compare the differences in their food and plasma fatty acid profile on the basis of their residence.

Methods

A total of 76 elderly women (50–100 years) were recruited through a random sampling method. A structured proforma was designed to gather information related to their age, income, dietary habits, and presence of any disease and awareness of AD. A 24-h dietary recall method for 3 days and food frequency questionnaire, concentrating on fish consumption and consumption of foods rich in ω-3 fatty acids, which was planned by dietitians, was used for dietary assessment. The gathered data were then analyzed using food processor software. The blood samples were collected to determine plasma fatty acids.

Results

The mean age of women diagnosed with AD was more than 75 years, and the prevalence of illiteracy was higher among AD subjects. As compared to the AD group, the concentration of LA and total ω-6 was significantly (p ≤ 0.05) higher in the control group from both recruitment sites [National Guard Health Affairs, King Abdulaziz Medical City, Riyadh (NGH) and Social Welfare Homes for the Elderly (SWH)]. Similarly, the concentrations of EPA, DHA, and ω-3 were also slightly higher in the control group at both sites, but the difference between the control and AD subjects was only significant (p ≤ 0.05) in subjects from NGH. We found no significant difference in the ω-6/ ω-3 ratio between groups. Also, no significant difference was found in the mean level of the plasma fatty acid when comparing the control and AD groups. The concentration of DHA in controls only and AA, EPA and ω-6 in both control and AD were significant (although weakly) correlated with their respective dietary intakes. No correlations were found between the intake of 18 C precursors (LA and ALA) and plasma levels of their long chain derivatives (AA, EPA, and DHA). Education, income, overall health status and the concentration of various fatty acids from food was higher and better in subjects from SWH than NGH. The lower plasma level indicates lower impaired systemic availability of several nutrients.

Conclusion

We found that dietary intervention might play a role in the prevention of AD.

Early-Life Nutrition and Neurodevelopment: Use of the Piglet as a Translational Model

Optimal nutrition early in life is critical to ensure proper structural and functional development of infant organ systems. Although pediatric nutrition historically has emphasized research on the relation between nutrition, growth rates, and gastrointestinal maturation, efforts increasingly have focused on how nutrition influences neurodevelopment. The provision of human milk is considered the gold standard in pediatric nutrition; thus, there is interest in understanding how functional nutrients and bioactive components in milk may modulate developmental processes. The piglet has emerged as an important translational model for studying neurodevelopmental outcomes influenced by pediatric nutrition. Given the comparable nutritional requirements and strikingly similar brain developmental patterns between young pigs and humans, the piglet is being used increasingly in developmental nutritional neuroscience studies. The piglet primarily has been used to assess the effects of dietary fatty acids and their accretion in the brain throughout neurodevelopment. However, recent research indicates that other dietary components, including choline, iron, cholesterol, gangliosides, and sialic acid, among other compounds, also affect neurodevelopment in the pig model. Moreover, novel analytical techniques, including but not limited to MRI, behavioral assessments, and molecular quantification, allow for a more holistic understanding of how nutrition affects neurodevelopmental patterns. By combining early-life nutritional interventions with innovative analytical approaches, opportunities abound to quantify factors affecting neurodevelopmental trajectories in the neonate. This review discusses research using the translational pig model with primary emphasis on early-life nutrition interventions assessing neurodevelopment outcomes, while also discussing nutritionally-sensitive methods to characterize brain maturation.

Critical review evaluating the pig as a model for human nutritional physiology

The present review examines the pig as a model for physiological studies in human subjects related to nutrient sensing, appetite regulation, gut barrier function, intestinal microbiota and nutritional neuroscience. The nutrient-sensing mechanisms regarding acids (sour), carbohydrates (sweet), glutamic acid (umami) and fatty acids are conserved between humans and pigs. In contrast, pigs show limited perception of high-intensity sweeteners and NaCl and sense a wider array of amino acids than humans. Differences on bitter taste may reflect the adaptation to ecosystems. In relation to appetite regulation, plasma concentrations of cholecystokinin and glucagon-like peptide-1 are similar in pigs and humans, while peptide YY in pigs is ten to twenty times higher and ghrelin two to five times lower than in humans. Pigs are an excellent model for human studies for vagal nerve function related to the hormonal regulation of food intake. Similarly, the study of gut barrier functions reveals conserved defence mechanisms between the two species particularly in functional permeability. However, human data are scant for some of the defence systems and nutritional programming. The pig model has been valuable for studying the changes in human microbiota following nutritional interventions. In particular, the use of human flora-associated pigs is a useful model for infants, but the long-term stability of the implanted human microbiota in pigs remains to be investigated. The similarity of the pig and human brain anatomy and development is paradigmatic. Brain explorations and therapies described in pig, when compared with available human data, highlight their value in nutritional neuroscience, particularly regarding functional neuroimaging techniques.

Omega-6 to omega-3 fatty acid ratio and higher-order cognitive functions in 7- to 9-y-olds: a cross-sectional study

BACKGROUND

Biochemical and behavioral evidence has suggested that the ratio of n-6 (omega-6) to n-3 (omega-3) could be an important predictor of executive function abilities in children.

OBJECTIVE

We determined the relation between the ratio of n-6 to n-3 and cognitive function in children. We hypothesized that children with lower ratios of n-6 to n-3 fatty acids would perform better on tests of planning and working memory.

DESIGN

Seventy 7- to 9-y-old children completed three 24-h diet recalls and a subset of the Cambridge Neuropsychological Test Assessment Battery. Parents provided information on their demographics and children's diet histories.

RESULTS

Mean n-3 and mean n-6 intakes were related to the mean time spent on each action taken in the planning problem. The ratio of n-6 to n-3 significantly predicted performance on the working memory and planning problems. There was a significant interaction between the ratio and fatty acid intake; when children had high ratios, a higher intake of n-3 fatty acids predicted a better performance on the planning task than when children had lower n-3 intakes. When children had low ratios, a lower intake of n-3 and lower intake of n-6 predicted better performance than when intakes were higher.

CONCLUSIONS

The relation between cognitive abilities and the ratio of n-6 to n-3 may be mediated by an enzymatic affinity for n-3 fatty acids. The ratio of n-6 to n-3 should be considered an important factor in the study of fatty acids and cognitive development. This trial was registered at clinicaltrials.gov as NCT01823419.

Heart arachidonic acid is uniquely sensitive to dietary arachidonic acid and docosahexaenoic acid content in domestic piglets

This study determined the sensitivity of heart and brain arachidonic acid (ARA) and docosahexaenoic acid (DHA) to the dietary ARA level in a dose-response design with constant, high DHA in neonatal piglets. On day 3 of age, pigs were assigned to 1 of 6 dietary formulas varying in ARA/DHA as follows (% fatty acid, FA/FA): (A1) 0.1/1.0; (A2) 0.53/1.0; (A3-D3) 0.69/1.0; (A4) 1.1/1.0; (D2) 0.67/0.62; and (D1) 0.66/0.33. At necropsy (day 28) higher levels of dietary ARA were associated with increased heart and liver ARA, while brain ARA remained unaffected. Dietary ARA had no effect on tissue DHA accretion. Heart was particularly sensitive, with pigs in the intermediate groups having different ARA (A2, 18.6±0.7%; A3, 19.4±1.0%) and a 0.17% increase in dietary ARA resulted in a 0.84% increase in heart ARA. Further investigations are warranted to determine the clinical significance of heart ARA status in developing neonates.

Higher n-3 fatty acids are associated with more intense fenfluramine-induced ACTH and cortisol responses among cocaine-abusing men

Preclinical studies have shown that diets supplemented with or deficient in n-3 polyunsaturated fatty acids (PUFAs) could influence serotonergic neurotransmission, but information about their effects on the serotonergic function of humans is scant. Therefore, simultaneous assessments of n-3 PUFAs and of the adrenocorticotropic hormone (ACTH) and cortisol responses to challenges with the serotonin (5-HT) probe d,l-fenfluramine (FEN) were performed in 25 cocaine-abusing men and 12 control subjects. Cocaine abusers were tested 18 days after their admission to a closed ward. ACTH and cortisol were measured in plasma samples collected on two testing days separated by 48 h following the random administration of 60 mg of FEN or placebo. Fatty acids were measured in the first test day samples. Patients' FEN-induced ACTH rises were significantly and positively correlated with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Patients' cortisol rises were positively and significantly correlated with EPA but not with DHA. There were no significant correlations between hormonal responses and pre-hospitalization cocaine use parameters. Control subjects' responses to FEN were not correlated with any PUFA. In conclusion, higher EPA and DHA levels were associated with a more intense FEN-induced ACTH response and higher EPA levels with a more intense cortisol response in cocaine-abusing men withdrawn from cocaine but not in control subjects. These findings support and expand existing evidence that EPA and DHA could influence 5-HT function in some human subgroups.

Obesity: genes, brain, gut, and environment

Obesity, which is assuming alarming proportions, has been attributed to genetic factors, hypothalamic dysfunction, and intestinal gut bacteria and an increase in the consumption of energy-dense food. Obesity predisposes to the development of type 2 diabetes mellitus, hypertension, coronary heart disease, and certain forms of cancer. Recent studies have shown that the intestinal bacteria in obese humans and mice differ from those in lean that could trigger a low-grade systemic inflammation. Consumption of a calorie-dense diet that initiates and perpetuates obesity could be due to failure of homeostatic mechanisms that regulate appetite, food consumption, and energy balance. Hypothalamic factors that regulate energy needs of the body, control appetite and satiety, and gut bacteria that participate in food digestion play a critical role in the onset of obesity. Incretins, cholecystokinin, brain-derived neurotrophic factor, leptin, long-chain fatty acid coenzyme A, endocannabinoids and vagal neurotransmitter acetylcholine play a role in the regulation of energy intake, glucose homeostasis, insulin secretion, and pathobiology of obesity and type 2 diabetes mellitus. Thus, there is a cross-talk among the gut, liver, pancreas, adipose tissue, and hypothalamus. Based on these evidences, it is clear that management of obesity needs a multifactorial approach.

Essential fatty acids and attention-deficit-hyperactivity disorder: a systematic review

AIM

Essential fatty acids (EFAs), also known as omega-3 and omega-6 fatty acids, have been claimed to have beneficial effects as a treatment for attention-deficit-hyperactivity disorder (ADHD). Animal experiments have provided information about the role of EFA in the brain, and several mechanisms of EFA activity are well known. The current review provides an updated, systematic overview of the theory and use of EFA in ADHD.

METHOD

Clinical studies and review papers of EFA blood levels and EFA supplementation trials in children with ADHD were researched in the Medline PubMed database. Additional studies were found from the references of these reports.

RESULTS

Children with ADHD present lower levels of blood EFAs, and open-label EFA supplementation trials in ADHD raise EFA blood levels and improve symptoms of ADHD. Randomized controlled trials, however, have generally been unsuccessful in demonstrating any behavioural treatment effects.

INTERPRETATION

Current findings do not support the use of EFA supplements as a primary or supplementary treatment for children with ADHD.

Polyunsaturated fatty acids in the pathogenesis and treatment of multiple sclerosis

Epidemiological, biochemical, animal model and clinical trial data described in this overview strongly suggest that polyunsaturated fatty acids, particularly n-6 fatty acids, have a role in the pathogenesis and treatment of multiple sclerosis (MS). Data presented provides further evidence for a disturbance in n-6 fatty acid metabolism in MS. Disturbance of n-6 fatty acid metabolism and dysregulation of cytokines are shown to be linked and a "proof of concept clinical trial" further supports such a hypothesis. In a randomised double-blind, placebo controlled trial of a high dose and low dose selected GLA (18:3n-6)-rich oil and placebo control, the high dose had a marked clinical effect in relapsing-remitting MS, significantly decreasing the relapse rate and the progression of disease. Laboratory findings paralleled clinical changes in the placebo group in that production of mononuclear cell pro-inflammatory cytokines (TNF-alpha, IL-1beta) was increased and anti-inflammatory TGF-beta markedly decreased with loss of membrane n-6 fatty acids linoleic (18:2n-6) and arachidonic acids (20:4n-6). In contrast there were no such changes in the high dose group. The improvement in disability (Expanded Disability Status Scale) in the high dose suggests there maybe a beneficial effect on neuronal lipids and neural function in MS. Thus disturbed n-6 fatty acid metabolism in MS gives rise to loss of membrane long chain n-6 fatty acids and loss of the anti-inflammatory regulatory cytokine TGF-beta, particularly during the relapse phase, as well as loss of these important neural fatty acids for CNS structure and function and consequent long term neurological deficit in MS.

Long-chain n-3 polyunsaturated fatty acids decrease feelings of anger in substance abusers

It has been suggested that low levels of n-3 polyunsaturated fatty acids (PUFAs) play a role in the pathophysiology of some psychiatric disorders. In light of the existence of strong associations between high-frequency and high-severity aggressive behaviors and substance use disorders and of our observation that substance abusers have poor dietary habits, the possibility that the administration of supplements of n-3 PUFAs would decrease their anger levels was explored. A lifelong history of aggressive behaviors and problems with the law was obtained in 24 patients. Thirteen patients received on a daily basis capsules containing 3 g of n-3 PUFAs (EPA+DHA). Eleven patients received placebo capsules. The trial was double-blind, randomized, and lasted 3 months. An anger scale was administered at baseline and every month thereafter. Six PUFA group patients and eight placebo group patients were followed for an additional 3 months after treatment discontinuation. Four patients in each group had a history of assaultive behavior. The baseline fish and n-3 PUFA intakes of these eight patients were significantly lower than those of the non-aggressive patients. When given for 3 months, n-3 PUFAs were superior to placebo in diminishing anger scores. Scores remained decreased for 3 months following treatment discontinuation. These data provide further support for emerging evidence indicating that supplementation with long-chain n-3 PUFAs could be beneficial in the treatment of some individuals with aggressive tendencies.

Effects of Breast Milk and Milk Formula Diets on Synthesized Speech Sound-Induced Event-Related Potentials in 3- and 6-Month-Old Infants

Effects of breast milk and milk formula supplemented with docosahexaenoic acid and arachidonic acid on speech processing were investigated by recording event-related potentials (ERPs) to synthesized /pa/ and /ba/ (oddball paradigm, 80%:20%) at 3 and 6 months of age. Behavioral assessment was also obtained. A major positive component (P200) was elicited by both types of sounds. It had a maximal scalp distribution in the fronto-central areas in both groups of infants. The mean latencies did not differ between the groups or between the stimulus types. However, the latencies decreased across age in both groups. The mean P200 amplitude in the formula-fed infants was lower than that in the breast-fed infants, but the difference was not significant. The between-stimulus differences in frontal P200 amplitudes were positively correlated with the behavioral scores of Bayley Index of Infant Development. These data suggest that the processing of the present speech stimuli is not affected by the investigated diets in the early infancy.

Reduced brain DHA content after a single reproductive cycle in female rats fed a diet deficient in N-3 polyunsaturated fatty acids

BACKGROUND

Low levels of n-3 polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA, 22:6n3), are implicated in postpartum depression.

METHODS

The effects of pregnancy and lactation on brain phospholipid fatty acid content were determined in female rats fed diets containing sufficient (control) or negligible (deficient) alpha-linolenic acid (18:3n-3), the dietary precursor of DHA, beginning at conception. Female virgins, fed the diets for 6 weeks, served as control animals. Whole brain total phospholipid composition was determined at weaning by GC.

RESULTS

Brain DHA content of postpartum dams fed the deficient diet was decreased by 21% compared with age-matched virgin control animals, with a reciprocal increase in docosapentaenoic acid (22:5n6) to 243%.

CONCLUSIONS

Under dietary conditions supplying inadequate n-3 PUFAs, maternal brain DHA content can be reduced after a single reproductive cycle. This depletion may affect neuronal function and thus the sensitivity of the postpartum organism to stress.

Cultural symbolism of fish and the psychotropic properties of omega-3 fatty acids

Fish is a food with unique psychotropic properties. Consumption of long-chain omega-3 fatty acids, rich in seafood, reduces depression, aggression and anger while improving mental well-being. We posit that symbols of fish have become linked to the emotional states induced by long-chain fatty acid by associative pairings, both conscious and unconscious. The limbic and hippocampal activity necessary for memory formation containing emotional content and the labeling of social context by cortical processes appears to be optimized by diets rich in long-chain omega-3 fatty acid. In this critical literature survey, we find that fish have been culturally labeled as symbols of emotional well-being and social healing in religious and medical practices among independent cultures, for at least six millennia. This understanding of the perception of fish as a symbolically healing or purifying food can assist current messages improving public health.

Long-chain fatty acids increase cellular dopamine in an immortalized cell line (MN9D) derived from mouse mesencephalon

The lysate of an immortalized monoclonal cell line derived from the striatum (X61) contains a dopaminergic stimulatory activity that is capable of increasing the dopamine content of an immortalized mouse mesencephalic cell line (MN9D) which expresses a dopaminergic phenotype. Purification of an isoamyl alcohol extract of this lysate and subsequent identification by NMR spectroscopic analysis demonstrated that the dopaminergic stimulatory activity contained within the lysate was a mixture of 80-90% cis-9-octadecenoic acid (oleic acid) and 10-20% cis-11-octadecenoic acid (cis-vaccenic acid). The effect of oleic acid on MN9D dopamine is a prolonged event. MN9D dopamine increases linearly over a 48 h period suggesting the induction of an increased dopaminergic phenotype in these dividing cells. The ability to increase MN9D dopamine by oleic and cis-vaccenic acids is shared by a number of other long-chain fatty acids including arachidonic, linoleic, linolenic, palmitoleic, and cis-13-octadecenoic acid. The possibility that oleic or other relatively innocuous fatty acids might affect dopaminergic function in primary neurons is intriguing with respect to possible therapeutic approaches to the treatment of dopaminergic cell loss and the motor sequelae of Parkinson's disease.

Auditory brainstem evoked response in juvenile rats fed rat milk formulas with high docosahexaenoic acid

Previous studies found that juvenile offspring of rats fed high docosahexaenoic acid (DHA; 22:6n-3) diets through gestation and lactation had longer auditory brainstem-evoked response (ABR) accompanied by higher 22:6n-3 and lower arachidonic acid (ARA; 20:4n-6) in brain. In the present study, ABR was assessed in juvenile rats fed high-DHA diets only postnatally.

METHODS

Rat pups were fed rat milk formulas with varying amounts of DHA and ARA to 19 days of age followed by diets with the corresponding fatty acids. The high-DHA group was fed 2.3% of fatty acids as DHA, the DHA + ARA group was fed DHA and ARA at 0.6 and 0.4% of fatty acids, levels similar to those in some infant formulas, and the unsupplemented group was fed no DHA or ARA. ABR and fatty acid and monoamine levels in brain were measured on postnatal days 26-28. Statistical analyses were measured by ANOVA.

RESULTS

ARA and DHA levels in brain increased with supplementation. ABR was shorter in the high-DHA group than the DHA + ARA group and not different from the unsupplemented or dam-reared suckling group. Norepinephrine levels in the inferior colliculus were lower in the high-DHA group than the DHA + ARA group and higher in all formula groups compared to the dam-reared group.

CONCLUSION

In contrast to the longer ABR in juvenile offspring of rats fed high-DHA through gestation and lactation, ABR was shorter in juvenile rats fed high-DHA diets only after birth than rats fed ARA + DHA. Further studies are needed to understand the relationship between dietary DHA, norepinephrine, and auditory system development over a range of DHA intakes and discrete periods of development.

Fatty acid alterations in liver and milk of cadmium exposed rats and in brain of their suckling offspring

Fatty acid composition was studied in milk at day 14 and in liver at day 24 after parturition of lactating rats exposed to 0 ppm, 5 ppm or 25 ppm cadmium (Cd) via drinking water for 17 days during lactation, and in the brain of their offspring at day 19 after birth. In the liver phospholipid fraction, 22:5(n-3) was significantly higher, while in the triacylglycerol fraction 22:6(n-3)/20:5(n-3) ratio was significantly lower in the 25 ppm group compared to the controls. Significantly higher proportions of 16:0 and lower proportions of medium-chain fatty acids, 8:0-14:0, were observed in milk of dams in the 25 ppm group, indicating decreased enzymatic activity of thiotransferase II in the mammary gland. Slightly increased levels of 20:3(n-6) were observed in brains of pups in the 25 ppm group compared to control. The results indicate that Cd exposure influences fatty acid metabolism in lactating rats.

Polyunsaturated Fatty Acids in Human Milk

The n-6 and n-3 fatty acids are essential dietary nutrients required for optimal growth and development, particularly of the brain and retina. Large amounts of the n-3 fatty acid docosahexaenoic acid (DHA) is accumulated in the brain grey matter and the visual elements of the retina during development, and reduced DHA in these tissues can result in decreased visual and psychomotor development. Although the possible importance of differences in n-6 and n-3 fatty acids, particularly DHA, between human milk and infant formulas has been the subject of intense clinical research, the variability in the essential fatty acid content of milk within and among different populations of women and implications of this to infant growth and development have received much less attention. Considerable research has shown that the DHA content of the maternal diet is the most important determinant of the amount of DHA secreted in milk, and thus the dietary intake of the breastfed infant. The DHA content of human milk varies over 10-fold, being lowest in women with no intake of DHA and highest in women with high intakes of DHA, which is found predominantly in fatty fish. The requirement for n-3 fatty acids, and the balance of n-6 and n-3 fatty acids for optimal growth and development of the brain and retina, and long-term minimization of risk of chronic disease remains as one of the most important questions in infant nutrition. Dietary recommendations to modifying dietary fat with the aim of reducing risk of chronic disease, including obesity and cardiovascular disease in adults, need to consider that when followed by pregnant women, these recommendations can have a marked effect on the amount and balance of n-6 and n-3 fatty acids secreted in milk.

Perinatal biochemistry and physiology of long-chain polyunsaturated fatty acids

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are important structural components of the central nervous system. These fatty acids are transferred across the placenta, are present in human milk, and are accumulated in the brain and retina during fetal and infant development. The high concentrations of DHA in the retina and of DHA and ARA in brain gray matter suggests that these fatty acids have important roles in retinal and neural function. Animal studies have shown that depletion of DHA from the retina and brain results in reduced visual function and learning deficits. The latter effects may be explained by changes in the membrane bilayer that alter membrane-associated receptors and signal transduction systems, ion channel activity, or direct effects on gene expression. DHA can be formed in the liver from alpha linolenic acid, but it is unclear if the rate of DHA synthesis in humans is sufficient to support optimal brain and retinal development. Although there is no evidence that the ability to form ARA from linoleic acid is limiting, supplementation with DHA reduces tissue ARA, possibly creating a conditional need for ARA in infants with a dietary intake of DHA. The amount of DHA in human milk varies widely and is positively correlated with visual and language development in breast-fed infants. Advances in understanding essential fatty acid requirements will benefit from intervention studies that use functionally relevant tests to probe the deficiency or adequacy of physiologically important pools of DHA and ARA in developing infants.

Polyunsaturated fatty acid status and relapse vulnerability in cocaine addicts

There is mounting evidence that low levels of some polyunsaturated fatty acids (PUFAs) play a role in the pathophysiology of depressive and aggressive disorders, including homicides. There is also evidence derived mostly from the animal literature that PUFAs could play a role in the abuse of substances through their action on central serotonergic and dopaminergic systems that are both known to play a role in reward mechanisms. In this study, we explored the possibility that the relapse rates of cocaine addicts discharged after a period of detoxification on an inpatient unit would be associated with their PUFA status. Thirty-eight patients were enrolled in the study. PUFA status was assessed only at baseline, shortly after admission. Resumption of substance use was assessed 3 months, 6 months and 1 year following discharge. Thirty-two patients remained available for follow-up for the duration of the study. Subjects who relapsed at 3 months had significantly lower baseline levels of total n-6 PUFAs, linoleic acid (LA, 18:2n-6), arachidonic acid (AA, 20:4n-6) and total n-3 PUFAs when compared to non-relapsers by ANCOVAs with age and weight as covariates. Lower baseline total n-6 PUFAs, LA and AA continued to predict relapse 6 months and 12 months following discharge. Age, marital status, educational level, cocaine use parameters or psychopathology did not differ between relapsers and non-relapsers. In conclusion, low PUFA status at baseline was a better predictor of relapse than cocaine use, sociodemographic or clinical parameters. These data suggest, but do not prove, the existence of a causal relationship between n-6 or n-3 status and relapse vulnerability in cocaine addicts, and provide a rationale for the exploration of possible relationships between relapse to addictive disorders and PUFA status in observational and interventional trials.

The influence of prematurity and long chain polyunsaturate supplementation in 4-week adjusted age baboon neonate brain and related tissues

Clinical studies show that docosahexaenoic acid (DHA) and arachidonic acid (ARA) supplemented formula improve visual function in preterm infants, however improved fatty acid status is known only for plasma and red blood cells (RBC) since target organs cannot be sampled from humans. Baboons were randomized to one of four groups: Term breast-fed (B); Term formula-fed (T-); Preterm formula-fed (P-); and Preterm DHA/ARA-supplemented formula-fed (P+). The P+ contained 0.61 +/- 0.03% DHA and 1.21 +/- 0.09% ARA, and breast milk had 0.68 +/- 0.22% and 0.62 +/- 0.12% as DHA and ARA, respectively. The B and P+ groups had significantly higher DHA concentration in all tissues than T- and P-. The P- group showed dramatically lower DHA content of 35%, 27%, 66%, and 75% in the brain, retina, liver, and plasma, respectively, compared with B. Supplementation prevented declines in DHA levels in the retina, and liver, and attenuated the decline in brain, plasma and RBC of preterm animals. In contrast, ARA was not significantly lower compared with B in any group in any tissue but was significantly elevated in liver and brain. RBC and plasma DHA were correlated with DHA in tissues; RBC/plasma ARA were uncorrelated with tissue ARA. We conclude that 1) DHA drops precipitously in term and preterm primates consuming formula without long chain polyunsaturates, while 22:5n-6 concentration rises; 2) tissue ARA levels are insensitive to dietary LCP supplementation or prematurity, 3) plasma and RBC levels of ARA are uncorrelated with total ARA levels; 4) DHA levels are correlated with group effects and are uncorrelated within groups.

Metabolic alterations during inflammation and its modulation by central actions of omega-3 fatty acids

PURPOSE OF REVIEW

To discuss the possible relationship between long-chain polyunsaturated fatty acids, cytokines, anandamides, nitric oxide, leptin, various neurotransmitters in the brain, and their role in anorexia of acute and chronic inflammatory conditions and cancer.

RECENT FINDINGS

Recent studies have shown that long-chain polyunsaturated fatty acids, especially the omega-3 series, have antiinflammatory actions, increase the concentrations of anandamides, enhance the levels of acetylcholine and nitric oxide and modulate the concentrations and actions of various neurotransmitters, including leptin, in the brain. Patients suffering from acute and chronic inflammatory conditions have low tissue concentrations of various long-chain polyunsaturated fatty acids, and high levels of proinflammatory cytokines that can cause anorexia and decrease food intake.

SUMMARY

It is suggested that supplementation of long-chain polyunsaturated fatty acids may have a role in the prevention and treatment of acute and chronic inflammatory conditions, improving anorexia associated with these conditions.

Docosahexaenoic acid and arachidonic acid in infant development

Docosahaxaenoic acid and arachidonic acid are highly concentrated in the central nervous system. The amount of these fatty acids in the central nervous system increases dramatically during the last intrauterine trimester and the first year of life. A central question of research conducted during the past 20 years is if the essential fatty acid precursor of docosahexaenoic acid is sufficient to achieve optimal DHA accumulation in the central nervous system and, therefore, infant development. The important role of non-human primate studies in characterising the behavioral effects of n-3 essential fatty acid deficiency and subsequent low brain DHA accumulation, the difference between essential fatty acid deficiencies and conditional deficiencies of docosahexaenoic acid and arachidonic acid, and the evidence that human infants have a conditionally essential need for docosahexaenoic acid and, perhaps, for arachidonic acid are summarised. The current suggestive evidence for several possible mechanisms underlying behavioral effects are also provided.

Anandamide and diet: inclusion of dietary arachidonate and docosahexaenoate leads to increased brain levels of the corresponding N-acylethanolamines in piglets

Endogenous ligands of cannabinoid receptors have been discovered recently and include some N-acylethanolamines (NAEs; e.g., N-arachidonoylethanolamine) and some 2-acylglycerols (e.g., sn-2-arachidonoylglycerol). Previously, we found these compounds to be active biologically when administered per os in large quantities to mice. In the present work, piglets were fed diets with and without 20:4n-6 and 22:6n-3 fatty acid precursors of NAEs, in levels similar to those found in porcine milk, during the first 18 days of life, and corresponding brain NAEs were assessed. In piglets fed diets containing 20:4n-6 and 22:6n-3, there were increases in several biologically active NAEs in brain homogenates-20:4n-6 NAE (4-fold), 20:5n-3 NAE (5-fold), and 22:5n-3 and 22:6n-3 NAE (9- to 10-fold). These results support a mechanism we propose for dietary long-chain polyunsaturated fatty acids influences on brain biochemistry with presumed functional sequelae. This paradigm will enable targeted investigations to determine whether and why specific populations such as infants, elderly, or persons suffering from certain clinical conditions may benefit from dietary long-chain polyunsaturated fatty acids.