Bioequivalence of dietary alpha-linolenic and docosahexaenoic acids as sources of docosahexaenoate accretion in brain and associated organs of neonatal baboons

Omega-3 pleiad: The multipoint anti-inflammatory strategy

Omega 3 (ω3) fatty acids have been described since the 1980s as promising anti-inflammatory substances. Prostaglandin and leukotriene modulation were exhaustively explored as the main reason for ω3 beneficial outcomes. However, during the early 2000s, after the human genome decoding advent, the nutrigenomic approaches exhibited an impressive plethora of ω3 targets, now under the molecular point of view. Different G protein-coupled receptors (GPCRs) recognizing ω3 and its derivatives appear to be responsible for blocking inflammation and insulin-sensitizing effects. A new class of ω3-derived substances, such as maresins, resolvins, and protectins, increases ω3 actions. Inflammasome disruption, the presence of GPR120 on immune cell surfaces, and intracellular crosstalk signaling mediated by PPARγ compose the last discoveries regarding the multipoint anti-inflammatory targets for this nutrient. This review shows a detailed mechanistic proposal to understand ω3 fatty acid action over the inflammatory environment in the background of several chronic diseases.

Pharmacokinetics and metabolism in mouse retina of bis-allylic deuterated docosahexaenoic acid (D-DHA), a new dry AMD drug candidate

Docosahexaenoic acid (DHA; 22:6n-3) rich photoreceptors function in a highly oxidizing microenvironment. Lipid peroxidation and inflammation contribute to initiation and progression of eye diseases including age-related macular degeneration (AMD). Deuteration of DHA at the bis-allylic positions (D-DHA) increases its resilience to oxidative damage in vitro. We studied the pharmacokinetics of dietary D-DHA as a therapy for replacing natural retinal DHA in vivo. Mice were fed 0.5% D-DHA for 77 days then switched to natural DHA (H-DHA) for 74 days. Tissue were harvested for analyses at various time points. D-DHA substitution levels were 75%-80% in the CNS and above 90% in all other tissues by day 77. D-DHA accretion was rapid in plasma and liver (t1/2a ∼2.8 d), followed by heart and red blood cells (t1/2a ∼8.5 d), then ocular tissues (choroid-RPE, neural retina, and optic nerve with t1/2a of 10.1, 23.4, and 26.3 days, respectively), while CNS accretion was slowest (t1/2a of 29.0-44.3 days). D-DHA elimination rates were comparable to, or slower than, accretion rates except for optic nerve. Retina had very long chain D-PUFA (D-VLC-PUFA) with 5 and 6 double bonds up to C36, as well as D-EPA and D-DPA derived metabolically from D-DHA. The neural retina and optic nerve reached the therapeutic target window (20%-50%) in 2-4 weeks. Biosynthesis of D-VLC-PUFA is consistent with normal metabolism. D-DHA crosses the blood-retina-barrier, enters visually active tissues, and is metabolized as its natural DHA parent where, as shown previously (Liu et al., 2022), it protects against lipid peroxidation.

Low linoleic acid foods with added DHA given to Malawian children with severe acute malnutrition improve cognition: a randomized, triple-blinded, controlled clinical trial

BACKGROUND

There is concern that the PUFA composition of ready-to-use therapeutic food (RUTF) for the treatment of severe acute malnutrition (SAM) is suboptimal for neurocognitive recovery.

OBJECTIVES

We tested the hypothesis that RUTF made with reduced amounts of linoleic acid, achieved using high-oleic (HO) peanuts without added DHA (HO-RUTF) or with added DHA (DHA-HO-RUTF), improves cognition when compared with standard RUTF (S-RUTF).

METHODS

A triple-blind, randomized, controlled clinical feeding trial was conducted among children with uncomplicated SAM in Malawi with 3 types of RUTF: DHA-HO-RUTF, HO-RUTF, and S-RUTF. The primary outcomes, measured in a subset of subjects, were the Malawi Developmental Assessment Tool (MDAT) global z-score and a modified Willatts problem-solving assessment (PSA) intention score for 3 standardized problems, measured 6 mo and immediately after completing RUTF therapy, respectively. MDAT domain z-scores, plasma fatty acid content, anthropometry, and eye tracking were secondary outcomes. Comparisons were made between the novel PUFA RUTFs and S-RUTF.

RESULTS

Among the 2565 SAM children enrolled, mean global MDAT z-scores were -0.69 ± 1.19 and -0.88 ± 1.27 for children receiving DHA-HO-RUTF and S-RUTF, respectively (difference 0.19, 95% CI: 0.01, 0.38). Children receiving DHA-HO-RUTF had higher gross motor and social domain z-scores than those receiving S-RUTF. The PSA problem 3 scores did not differ by dietary group (OR: 0.92, 95% CI: 0.67, 1.26 for DHA-HO-RUTF). After 4 wk of treatment, plasma phospholipid EPA and α-linolenic acid were greater in children consuming DHA-HO-RUTF or HO-RUTF when compared with S-RUTF (for all 4 comparisons P values < 0.001), but only plasma DHA was greater in DHA-HO-RUTF than S-RUTF (P < 0.001).

CONCLUSIONS

Treatment of uncomplicated SAM with DHA-HO-RUTF resulted in an improved MDAT score, conferring a cognitive benefit 6 mo after completing diet therapy. This treatment should be explored in operational settings. This trial was registered at clinicaltrials.gov as NCT03094247.

Natural abundance carbon isotope ratio analysis and its application in the study of diet and metabolism

Due to differences in carbon assimilation pathways between plants, there are subtle but distinct variations in the carbon isotope ratios of foods and animal products throughout the food supply. Although it is well understood that the carbon isotope ratio composition of the diet influences that of the consumers' tissues, the application of natural abundance carbon isotope ratio analysis in nutrition has long been underappreciated. Over the past decade, however, several studies have investigated the utility of carbon isotope ratio analysis for evaluation of nutritional biomarker status, primarily focusing on its application as an objective indicator of sugar and animal protein intake. More recently, research investigating the application of natural abundance measurements has been extended to study fatty acid metabolism and has yielded encouraging results. Collectively, data from large-scale observational studies and experimental animal studies highlight the potential for carbon isotope ratio analysis as an additional and effective tool to study diet and metabolism. The purpose of this review is to provide an overview of natural abundance carbon isotope ratio analysis, its application to studying nutrition, and an update of the research in the field.

Turnover of brain DHA in mice is accurately determined by tracer-free natural abundance carbon isotope ratio analysis

The brain is highly enriched in the long-chain omega-3 (n-3) PUFA DHA. Due to the limited capacity for local DHA synthesis in the brain, it relies on a continual supply from the circulation to replenish metabolized DHA. Previous studies investigating brain DHA turnover and metabolism have relied on isotope tracers to determine brain fatty acid kinetics; however, this approach is cumbersome and costly. We applied natural abundance carbon isotope ratio analysis via high-precision gas chromatography combustion isotope ratio mass spectrometry, without the use of labeled tracers, to determine the half-life of brain DHA in mice following a dietary switch experiment. Mice fed diets containing either α-linolenic acid (ALA) or DHA as the sole dietary n-3 PUFA were switched onto diets containing ALA, DHA, or ALA + DHA at 6 weeks of age, while control mice were maintained on their respective background diet. We measured brain DHA carbon isotope ratios (reported as δ13CDHA signatures) over a 168-day time course. Brain δ13CDHA signatures of control mice maintained on background diets over the time course were stable (P > 0.05). Brain δ13CDHA signatures of mice switched to the DHA or ALA + DHA diet from the ALA diet changed over time, yielding brain incorporation half-lives of 40 and 34 days, respectively. These half-lives determined by natural abundance carbon isotope ratio analysis were consistent with estimates from kinetic isotope tracer studies. Our results demonstrate the feasibility of natural abundance carbon isotope ratio analysis in the study of fatty acid metabolism without the use of isotopically labeled fatty acid tracers.

Maternal Malnutrition in the Etiopathogenesis of Psychiatric Diseases: Role of Polyunsaturated Fatty Acids

Evidence from human studies indicates that maternal metabolic state and malnutrition dramatically influence the risk for developing psychiatric complications in later adulthood. In this regard, the central role of polyunsaturated fatty acids (PUFAs), and particularly n-3 PUFAs, is emerging considering that epidemiological evidences have established a negative correlation between n-3 PUFA consumption and development of mood disorders. These findings were supported by clinical studies indicating that low content of n-3 PUFAs in diet is linked to an increased susceptibility to psychiatric disorders. PUFAs regulate membrane fluidity and exert their central action by modulating synaptogenesis and neurotrophic factor expression, neurogenesis, and neurotransmission. Moreover, they are precursors of molecules implicated in modulating immune and inflammatory processes in the brain. Importantly, their tissue concentrations are closely related to diet intake, especially to maternal consumption during embryonal life, considering that their synthesis from essential precursors has been shown to be inefficient in mammals. The scope of this review is to highlight the possible mechanisms of PUFA functions in the brain during pre- and post-natal period and to evaluate their role in the pathogenesis of psychiatric diseases.

Arachidonic acid needed in infant formula when docosahexaenoic acid is present

Recently, the European Food Safety Authority asserted that arachidonic acid (ARA) is an optional nutrient for the term infant even when docosahexaenoic acid (DHA) is present. The brief rationale is based on an explicit, widespread misapplication of the concept of "essential fatty acids" to linoleic acid that implies it is uniquely required as a nutrient per se. Linoleic acid prevents acute clinical symptoms caused by polyunsaturated fatty acid-deficient diets and is the major precursor for ARA in most human diets. Experimental diets with ARA as the sole n-6 similarly prevent symptoms but at a lower energy percentage than linoleic acid and show ARA is a precursor for linoleic acid. The absence of consistent evidence of ARA benefit from randomized controlled trials is apparently an issue as well. This review highlights basic and clinical research relevant to ARA requirements as an adjunct to DHA in infancy. ARA is a major structural central nervous system component, where it rapidly accumulates perinatally and is required for signaling. Tracer studies show that ARA-fed infants derive about half of their total body ARA from dietary preformed ARA. Clinically, of the 3 cohorts of term infants studied with designs isolating the effects of ARA (DHA-only vs DHA+ARA), none considered ARA-specific outcomes such as vascular or immune function; the study with the highest ARA level showed significant neurocognitive benefit. All breastfed term infants of adequately nourished mothers consume both DHA and ARA. The burden of proof to substantially deviate from the composition of breastmilk is greater than that available from inherently empirical human randomized controlled trial evidence. Infant formulas with DHA but without ARA risk harm from suppression of ARA-mediated metabolism manifest among the many unstudied functions of ARA.

Detection and treatment of omega-3 fatty acid deficiency in psychiatric practice: Rationale and implementation

A body of translational evidence has implicated dietary deficiency in long-chain omega-3 (LCn-3) fatty acids, including eicosapenaenoic acid (EPA) and docosahexaenoic acid (DHA), in the pathophysiology and potentially etiology of different psychiatric disorders. Case–control studies have consistently observed low erythrocyte (red blood cell) EPA and/or DHA levels in patients with major depressive disorder, bipolar disorder, schizophrenia, and attention deficit hyperactivity disorder. Low erythrocyte EPA + DHA biostatus can be treated with fish oil-based formulations containing preformed EPA + DHA, and extant evidence suggests that fish oil supplementation is safe and well-tolerated and may have therapeutic benefits. These and other data provide a rationale for screening for and treating LCn-3 fatty acid deficiency in patients with psychiatric illness. To this end, we have implemented a pilot program that routinely measures blood fatty acid levels in psychiatric patients entering a residential inpatient clinic. To date over 130 blood samples, primarily from patients with treatment-refractory mood or anxiety disorders, have been collected and analyzed. Our initial results indicate that the majority (75 %) of patients exhibit whole blood EPA + DHA levels at ≤4 percent of total fatty acid composition, a rate that is significantly higher than general population norms (25 %). In a sub-set of cases, corrective treatment with fish oil-based products has resulted in improvements in psychiatric symptoms without notable side effects. In view of the urgent need for improvements in conventional treatment algorithms, these preliminary findings provide important support for expanding this approach in routine psychiatric practice.

Long-chain polyunsaturated fatty acids and the preterm infant: a case study in developmentally sensitive nutrient needs in the United States

The vast majority of infant formulas in the United States contain the long-chain polyunsaturated fatty acids (PUFAs) docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6), which were first permitted by the US Food and Drug Administration in 2001. As a scientific case study, preclinical animal studies of these nutrients definitively influenced the design and interpretation of human clinical studies. Early studies were tied to the availability of test substances, and in hindsight suggest re-evaluation of the essential fatty acid concept in light of the totality of available evidence. Research in the 1950s established the essentiality of n-6 PUFAs for skin integrity; however, widespread recognition of the essentiality of n-3 PUFAs came decades later despite compelling evidence of their significance. Barriers to an understanding of the essentiality of n-3 PUFAs were as follows: 1) their role is in neural function, which is measured only with difficulty compared with skin lesions and growth faltering that are apparent for n-6 PUFAs; 2) the experimental use of vegetable oils as PUFA sources that contain the inefficiently used C18 PUFAs rather than the operative C20 and C22 PUFAs; 3) the shift from reliance on high-quality animal studies to define mechanisms that established the required nutrients in the first part of the 20th century to inherently challenging human studies. Advances in nutrition of premature infants require the best practices and opinions available, taking into account the totality of preclinical and clinical evidence.

The European Food Safety Authority recommendation for polyunsaturated fatty acid composition of infant formula overrules breast milk, puts infants at risk, and should be revised

The European Food Safety Authority (EFSA) has concluded from a limited review of the literature that although docosahexaenoic acid (DHA) is required for infant formula, arachidonic acid is not required "even in the presence of DHA" (EFSA Journal, 12 (2014) 3760). This flawed opinion is grounded in human trials which tested functionality of DHA in neural outcomes and included arachidonic acid ostensibly to support growth. The EFSA report mistakes a nutrient ubiquitous in the diets of newborn infants, through breast milk and with wide-ranging health and neurodevelopmental effects, for an optional drug targeted to a particular outcome that is properly excluded when no benefit is found for that particular outcome. Arachidonic acid has very different biological functions compared to DHA, for example, arachidonic acid has unique functions in the vasculature and in specific aspects of immunity. Indeed, the overwhelming majority of trials include both DHA and arachidonic acid, and test development specific to DHA such as neural and visual development. DHA suppresses membrane arachidonic acid concentrations and its function. An infant formula with DHA and no arachidonic acid runs the risk of cardio and cerebrovascular morbidity and even mortality through suppression of the favorable oxylipin derivatives of arachidonic acid. The EFSA recommendation overruling breast milk composition should be revised forthwith, otherwise being unsafe, ungrounded in most of the evidence, and risking lifelong disability.

New European Food Safety Authority recommendation for infant formulae contradicts the physiology of human milk and infant development

The European Food Safety Authority (EFSA) has concluded from a limited review of the literature that although docosahexaenoic acid (DHA) was required for infant formula, arachidonic acid was not 'even in the presence of DHA'. The EFSA report mistakes a nutrient ubiquitous in the diets of infants, and with wide-ranging effects, for an optional drug targeted to a particular outcome that is properly excluded when no benefit is found for that particular outcome. The EFSA's conclusion is not evidence-based. Its conclusions are grounded in trials which tested functionality of DHA, not arachidonic acid. Arachidonic acid has very different biological functions, for instance, in the vasculature and in specific aspects of immunity. None of the trials cited tested any property specific to arachidonic acid. The test of time through natural selection and human evolution has resulted in milk composition in which arachidonic acid and its long-chain polyenoic family members are conserved and occupy a prominent position. As DHA suppresses arachidonic acid, an infant formula with DHA and no arachidonic acid runs the risk of cardio- and cerebrovascular morbidity through suppression of the favourable eicosanoid derivatives of arachidonic acid and cell structural integrity. The EFSA recommendation should be rejected forthwith as unsafe and risking lifelong disability.

Dietary supplement enriched in antioxidants and omega-3 protects from progressive light-induced retinal degeneration

In the present study, we have evaluated one of the dietary supplements enriched with antioxidants and fish oil used in clinical care for patient with age-related macular degeneration. Rats were orally fed by a gastric canula daily with 0.2 ml of water or dietary supplement until they were sacrificed. After one week of treatment, animals were either sacrificed for lipid analysis in plasma and retina, or used for evaluation of rod-response recovery by electroretinography (ERG) followed by their sacrifice to measure rhodopsin content, or used for progressive light-induced retinal degeneration (PLIRD). For PLIRD, animals were transferred to bright cyclic light for one week. Retinal damage was quantified by ERG, histology and detection of apoptotic nuclei. Animals kept in dim-cyclic-light were processed in parallel. PLIRD induced a thinning of the outer nuclear layer and a reduction of the b-wave amplitude of the ERG in the water group. Retinal structure and function were preserved in supplemented animals. Supplement induced a significant increase in omega-3 fatty acids in plasma by 168% for eicosapentaenoic acid (EPA), 142% for docosapentaenoic acid (DPA) and 19% for docosahexaenoic acid (DHA) and a decrease in the omega-6 fatty acids, DPA by 28%. In the retina, supplement induced significant reduction of linolenic acid by 67% and an increase in EPA and DPA by 80% and 72%, respectively, associated with significant decrease in omega-6 DPA by 42%. Supplement did not affect rhodopsin content or rod-response recovery. The present data indicate that supplement rapidly modified the fatty acid content and induced an accumulation of EPA in the retina without affecting rhodopsin content or recovery. In addition, it protected the retina from oxidative stress induced by light. Therefore, this supplement might be beneficial to slow down progression of certain retinal degeneration.

Docosahexaenoic acid and human brain development: evidence that a dietary supply is needed for optimal development

Humans evolved a uniquely large brain among terrestrial mammals. Brain and nervous tissue is rich in the omega-3 polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA). Docosahexaenoic acid is required for lower and high order functions in humans because of understood and emerging molecular mechanisms. Among brain components that depend on dietary components, DHA is limiting because its synthesis from terrestrial plant food precursors is low but its utilization when consumed in diet is very efficient. Negligible DHA is found in terrestrial plants, but in contrast, DHA is plentiful at the shoreline where it is made by single-celled organisms and plants, and in the seas supports development of very large marine mammal brains. Modern human brains accumulate DHA up to age 18, most aggressively from about half-way through gestation to about two years of age. Studies in modern humans and non-human primates show that modern infants consuming infant formulas that include only DHA precursors have lower DHA levels than for those with a source of preformed DHA. Functional measures show that infants consuming preformed DHA have improved visual and cognitive function. Dietary preformed DHA in the breast milk of modern mothers supports many-fold greater breast milk DHA than is found in the breast milk of vegans, a phenomenon linked to consumption of shore-based foods. Most current evidence suggests that the DHA-rich human brain required an ample and sustained source of dietary DHA to reach its full potential.

Omega-3 fatty acid deficiency in infants before birth identified using a randomized trial of maternal DHA supplementation in pregnancy

Background

DHA is accumulated in the central nervous system (CNS) before birth and is involved in early developmental processes, such as neurite outgrowth and gene expression.

Objective

To determine whether fetal DHA insufficiency occurs and constrains CNS development in term gestation infants.

Design

A risk reduction model using a randomized prospective study of term gestation single birth healthy infants born to women (n = 270) given a placebo or 400 mg/day DHA from 16 wk gestation to delivery. Fetal DHA deficiency sufficient to constrain CNS development was assessed based on increased risk that infants in the placebo group would not achieve neurodevelopment scores in the top quartile of all infants in the study.

Results

Infants in the placebo group were at increased risk of lower language development assessed as words understood (OR 3.22, CL 1.49–6.94, P = 0.002) and produced (OR 2.61, CL 1.22–5.58, P = 0.01) at 14 mo, and words understood (OR 2.77, CL 1.23–6.28, P = 0.03) and sentences produced (OR 2.60, CL 1.15–5.89, P = 0.02) at 18 mo using the McArthur Communicative Developmental Inventory; receptive (OR 2.23, CL 1.08–4.60, P = 0.02) and expressive language (OR 1.89, CL 0.94–3.83, P = 0.05) at 18 mo using the Bayley Scales of Infant Development III; and visual acuity (OR 2.69, CL 1.10–6.54, P = 0.03) at 2 mo.

Trial Registration

ClinicalTrials.gov NCT00620672

Bioconversion of α-linolenic acid into n-3 long-chain polyunsaturated fatty acid in hepatocytes and ad hoc cell culture optimisation

This study aimed to establish optimal conditions for a cell culture system that would allow the measurement of 18∶3n-3 (ALA) bioconversion into n-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA), and to determine the overall pathway kinetics. Using rat hepatocytes (FaO) as model cells, it was established that a maximum 20∶5n-3 (EPA) production from 50 µM ALA initial concentration was achieved after 3 days of incubation. Next, it was established that a gradual increase in the ALA concentration from 0 up to 125µM lead to a proportional increase in EPA, without concomitant increase in further elongated or desaturated products, such as 22∶5n-3 (DPA) and 22∶6n-3 (DHA) in 3 day incubations. Of interest, ALA bioconversion products were observed in the culture medium. Therefore, in vitro experiments disregarding the medium fatty acid content are underestimating the metabolism efficiency. The novel application of the fatty acid mass balance (FAMB) method on cell culture system (cells with medium) enabled quantifying the apparent enzymatic activities for the biosynthesis of n-3 LC-PUFA. The activity of the key enzymes was estimated and showed that, under these conditions, 50% (Km) of the theoretical maximal (V_max = 3654 µmol.g⁻¹ of cell protein.hour⁻¹) Fads2 activity on ALA can be achieved with 81 µM initial ALA. Interestingly, the apparent activity of Elovl2 (20∶5n-3 elongation) was the slowest amongst other biosynthesis steps. Therefore, the possible improvement of Elovl2 activity is suggested toward a more efficient DHA production from ALA. The present study proposed and described an ad hoc optimised cell culture conditions and methodology towards achieving a reliable experimental platform, using FAMB, to assist in studying the efficiency of ALA bioconversion into n-3 LC-PUFA in vitro. The FAMB proved to be a powerful and inexpensive method to generate a detailed description of the kinetics of n-3 LC-PUFA biosynthesis enzymes activities in vitro.

Role of Long-Chain Omega-3 Fatty Acids in Psychiatric Practice

Nutrition plays a minor role in psychiatric practice which is currently dominated by a pharmacological treatment algorithm. An accumulating body of evidence has implicated deficits in the dietary essential long-chain omega-3 (LCn-3) fatty acids, eicosapenaenoic acid (EPA) and docosahexaenoic acid (DHA), in the pathophysiology of several major psychiatric disorders. LCn-3 fatty acids have an established long-term safety record in the general population, and existing evidence suggests that increasing LCn-3 fatty acid status may reduce the risk for cardiovascular disease morbidity and mortality. LCn-3 fatty acid supplementation has been shown to augment the therapeutic efficacy of antidepressant, mood-stabilizer, and second generation antipsychotic medications, and may additionally mitigate adverse cardiometabolic side-effects. Preliminary evidence also suggests that LCn-3 fatty acid supplementation may be efficacious as monotherapy for primary and early secondary prevention and for perinatal symptoms. The overall cost-benefit ratio endorses the incorporation of LCn-3 fatty acids into psychiatric treatment algorithms. The recent availability of laboratory facilities that specialize in determining blood LCn-3 fatty acid status and emerging evidence-based consensus guidelines regarding safe and efficacious LCn-3 fatty acid dose ranges provide the infrastructure necessary for implementation. This article outlines the rationale for incorporating LCn-3 fatty acid treatment into psychiatric practice.

Deciphering the role of docosahexaenoic acid in brain maturation and pathology with magnetic resonance imaging

Animal studies have found that deficits in brain docosahexaenoic acid (DHA, 22:6n-3) accrual during perinatal development leads to transient and enduring abnormalities in brain development and function. Determining the relevance of this evidence to brain disorders in humans has been hampered by an inability to determine antimortem brain DHA levels and limitations associated with a postmortem approach. Accordingly, there is a need for alternate or complementary approaches to better understand the role of DHA in cortical function and pathology, and conventional magnetic resonance imaging (MRI) techniques may be ideally suited for this application. A major advantage of neuroimaging is that it permits prospective evaluation of the effects of manipulating DHA status on both clinical and neuroimaging variables. Emerging evidence from MRI studies suggest that greater DHA status is associated with cortical structural and functional integrity, and suggest that reduced DHA status and abnormalities in cortical function observed in psychiatric disorders may be interrelated phenomenon. Preliminary evidence from animal MRI studies support a critical role of DHA in normal brain development. Neuroimaging research in both human and animals therefore holds tremendous promise for developing a better understanding of the role of DHA status in cortical function, as well as for elucidating the impact of DHA deficiency on neuropathological processes implicated in the etiology and progression of neurodevelopmental and psychiatric disorders.

Maternal high fat diet is associated with decreased plasma n-3 fatty acids and fetal hepatic apoptosis in nonhuman primates

To begin to understand the contributions of maternal obesity and over-nutrition to human development and the early origins of obesity, we utilized a non-human primate model to investigate the effects of maternal high-fat feeding and obesity on breast milk, maternal and fetal plasma fatty acid composition and fetal hepatic development. While the high-fat diet (HFD) contained equivalent levels of n-3 fatty acids (FA's) and higher levels of n-6 FA's than the control diet (CTR), we found significant decreases in docosahexaenoic acid (DHA) and total n-3 FA's in HFD maternal and fetal plasma. Furthermore, the HFD fetal plasma n-6∶n-3 ratio was elevated and was significantly correlated to the maternal plasma n-6∶n-3 ratio and maternal hyperinsulinemia. Hepatic apoptosis was also increased in the HFD fetal liver. Switching HFD females to a CTR diet during a subsequent pregnancy normalized fetal DHA, n-3 FA's and fetal hepatic apoptosis to CTR levels. Breast milk from HFD dams contained lower levels of eicosopentanoic acid (EPA) and DHA and lower levels of total protein than CTR breast milk. This study links chronic maternal consumption of a HFD with fetal hepatic apoptosis and suggests that a potentially pathological maternal fatty acid milieu is replicated in the developing fetal circulation in the nonhuman primate.

Altered essential fatty acid metabolism and composition in rat liver, plasma, heart and brain after microalgal DHA addition to the diet

To investigate the effect of docosahexaenoic acid (DHA) without other highly unsaturated fatty acids (HUFA) on n-3 and n-6 essential fatty acid (EFA) metabolism and fatty acid composition in mammals, a stable isotope tracer technique was used in adult rats fed diets with or without 1.3% of algal DHA in a base diet containing 15% of linoleic acid and 3% of alpha-linolenic acid over 8 weeks. The rats were administered orally a mixed oil containing 48 mg/kg body weight of deuterated linoleic and alpha-linolenic acids and euthanized at 4, 8, 24, 96, 168, 240, 360 and 600 h after administration of the isotopes. Fatty acid compositions and the concentrations of deuterated precursors and their respective metabolites were determined in rat liver, plasma, heart and brain as a function of time. DHA, docosapentaenoic acid and eicosapentaenoic acid in the n-3 EFA family were significantly increased in all organs tested in the DHA-fed group, ranging from 5% to 200% greater in comparison with the control group. The accumulation of the metabolites, deuterated-DHA and deuterated-docosapentaenoic acid n-6 was greatly decreased by 1.5- to 2.5-fold in the dietary DHA group. In summary, feeding preformed DHA led to a marked increase in n-3 HUFA content of rat organs at the expense of n-6 HUFA and also prevented the accumulation of newly synthesized deuterated end products. This is the first study which has isolated the effects of DHA on the de novo metabolism on both the n-6 and n-3 EFA pathways.

Docosahexaenoic acid (DHA) and the developing central nervous system (CNS) - Implications for dietary recommendations

The accretion of docosahexaenoic acid (DHA) in membranes of the central nervous system is required for the optimum development of retina and brain functions. DHA status is determined by the dietary intake of n-3 polyunsaturated fatty acids (PUFA), both the metabolic precursor α-linolenic acid (α-LNA) and DHA. Clinical studies have shown that feeding term or premature infants with formula low in total n-3 PUFA may alter the maturation of visual acuity. Moreover, feeding infants over the first 6 mon of life with formula containing adequate α-LNA, but no DHA, did not sustain the same cerebral accretion of DHA as that of breast-fed infants. Whether lower DHA accretion in brain of formula-fed term infants impairs neurophysiological performances is not clearly established. Contradictory data have been published, possibly owing to confounding factors such as maternal intakes and/or genetic variations in PUFA metabolism. Nevertheless, a large corpus of data is in favor of the recommendation of regular dietary intakes of DHA (during at least the first 6 mon of life) and suggest that DHA should be added in formulas at the level generally found in human milk (0.2-0.3 wt% of total fatty acids). The maternal intake of n-3 PUFA during pregnancy and lactation is also crucial, since the n-3 PUFA are provided during perinatal development through placental transfer and maternal milk, which determines the DHA status of the newborn and consequently impacts on post-natal development of brain and visual functions. Whether more clinical studies are needed to control and improve the impact of DHA maternal intakes on the progeny's neurodevelopment, several commissions recommended by precaution that DHA average intake for pregnant and lactating women should be of 200-300 mg/day.

Mechanisms of n-3 fatty acid-mediated development and maintenance of learning memory performance

Docosahexaenoic acid (DHA, 22:6n-3) is specifically enriched in the brain and mainly anchored in the neuronal membrane, where it is involved in the maintenance of normal neurological function. Most DHA accumulation in the brain takes place during brain development in the perinatal period. However, hippocampal DHA levels decrease with age and in the brain disorder Alzheimer's disease (AD), and this decrease is associated with reduced hippocampal-dependent spatial learning memory ability. A potential mechanism is proposed by which the n-3 fatty acids DHA and eicosapentaenoic acid (20:5n-3) aid the development and maintenance of spatial learning memory performance. The developing brain or hippocampal neurons can synthesize and take up DHA and incorporate it into membrane phospholipids, especially phosphatidylethanolamine, resulting in enhanced neurite outgrowth, synaptogenesis and neurogenesis. Exposure to n-3 fatty acids enhances synaptic plasticity by increasing long-term potentiation and synaptic protein expression to increase the dendritic spine density, number of c-Fos-positive neurons and neurogenesis in the hippocampus for learning memory processing. In aged rats, n-3 fatty acid supplementation reverses age-related changes and maintains learning memory performance. n-3 fatty acids have anti-oxidative stress, anti-inflammation, and anti-apoptosis effects, leading to neuron protection in the aged, damaged, and AD brain. Retinoid signaling may be involved in the effects of DHA on learning memory performance. Estrogen has similar effects to n-3 fatty acids on hippocampal function. It would be interesting to know if there is any interaction between DHA and estrogen so as to provide a better strategy for the development and maintenance of learning memory.

Evaluation of docosahexaenoic acid deficiency as a preventable risk factor for recurrent affective disorders: current status, future directions, and dietary recommendations

Major recurrent affective disorders, including major depressive disorder (MDD) and bipolar disorder, represent a growing public health crisis in the United States. Evidence from cross-national and cross-sectional epidemiological surveys, comparative peripheral and central composition studies, and placebo-controlled intervention trials suggest that n-3 fatty acid deficiency may contribute to the pathoaetiology of affective disorders. These data are reviewed with the objective of estimating a daily docosahexaenoic acid (DHA, 22:6n-3) intake value that is projected to be efficacious in mitigating vulnerability. It is proposed that daily DHA intake sufficient to increase erythrocyte DHA composition to a level found in healthy subjects from Japan (7%), where the lifetime prevalence rates of MDD and bipolar disorder are several fold lower than the US, represents an appropriate target. To achieve this target, preliminary DHA intervention trials indicate that a daily dose of 400-700 mg/d in children and 700-1000 mg/d in adults would be required. Based on the results of placebo-controlled intervention trials, a higher daily DHA dose in the order of 1000-1500 mg/d in a 2:1 eicosapentaenoic acid (EPA, 20:5n-3):DHA ratio may be optimal for the treatment of established affective disorders. These recommendations are intended to guide future dose-ranging placebo-controlled DHA intervention trials in patients with established affective disorders, as well as in asymptomatic subjects at elevated risk for developing affective disorders. Such early intervention studies are currently feasible and will ultimately be required to definitively evaluate whether DHA is a required nutrient for the prevention of affective disorders.

Dietary fish oil replacement with lard and soybean oil affects triacylglycerol and phospholipid muscle and liver docosahexaenoic acid content but not in the brain and eyes of surubim juveniles Pseudoplatystoma sp

Triplicate groups of juvenile suribim were fed for 183 days one of four different isonitrogenous (47.6% crude protein) and isolipidic (18.7% lipid) diets formulated using three different lipid sources: 100% fish oil (FO, diet 1); 100% pig lard (L, diet 2); 100% soybean oil (SO, diet 3), and FO/L/SO (1:1:1, w/w/w; diet 4). The tissue levels of fatty acids 18:2n-6 and 18:3n-3 decreased relative to corresponding dietary fatty acid values. The 20:5n-3 and 22:6n-3 composition of muscle and liver neutral lipids were linearly correlated with corresponding dietary fatty acid composition. In contrast, the 22:6n-3 composition of the brain and eye were similar among treatments. The 22:6n-3 level was enriched in all tissues, particularly in the neural tissues. Similar results were observed for tissue polar lipids: fatty acids content reflected dietary composition, with the exception of the 22:6n-3 level, which showed enrichment and no differences between groups. Given these results, the importance of the biochemical functions (transport and/or metabolism) of 22:6n-3 in the development of the neural system of surubim warrants further investigation.

Alpha-linolenic acid and its conversion to longer chain n-3 fatty acids: benefits for human health and a role in maintaining tissue n-3 fatty acid levels

There is little doubt regarding the essential nature of alpha-linolenic acid (ALA), yet the capacity of dietary ALA to maintain adequate tissue levels of long chain n-3 fatty acids remains quite controversial. This simple point remains highly debated despite evidence that removal of dietary ALA promotes n-3 fatty acid inadequacy, including that of docosahexaenoic acid (DHA), and that many experiments demonstrate that dietary inclusion of ALA raises n-3 tissue fatty acid content, including DHA. Herein we propose, based upon our previous work and that of others, that ALA is elongated and desaturated in a tissue-dependent manner. One important concept is to recognize that ALA, like many other fatty acids, rapidly undergoes beta-oxidation and that the carbons are conserved and reused for synthesis of other products including cholesterol and fatty acids. This process and the differences between utilization of dietary DHA or liver-derived DHA as compared to ALA have led to the dogma that ALA is not a useful fatty acid for maintaining tissue long chain n-3 fatty acids, including DHA. Herein, we propose that indeed dietary ALA is a crucial dietary source of n-3 fatty acids and its dietary inclusion is critical for maintaining tissue long chain n-3 levels.

Omega-3 Fatty acids and neural development to 2 years of age: do we know enough for dietary recommendations?

The omega (omega)-3 fatty acids are essential nutrients, explained by the absence of a Delta-15 desaturase in mammalian cells. The omega-3 fatty acids are found in the diet as alpha-linolenic acid (18:3omega-3) and eicosapentaenoic acid (20:5omega-3), as well as docosahexaenoic acid (DHA), with different functions of each of the omega-3 fatty acids in different cells. One essential role of the omega-3 fatty acids is fulfilled by the 22 carbon DHA (22:6omega-3). Depletion of DHA from brain and retina interferes with normal neurogenesis and neurological function, and visual signaling pathways. Observation and intervention studies with pregnant and lactating women, and with infants fed some formulas show that dietary DHA is associated with higher scores on tests of visual and neural development in infants and children. The estimated average requirement and variability in requirement among individuals both of which are needed to set dietary recommended intakes (DRIs) for the different omega-3 fatty acids are unknown. However, because omega-3 fatty acids are essential, adequate intakes to minimize risk of poor neural development and function can be justified, but dose-response data to provide a safe upper limit with different omega-6 fatty acid intakes are needed. Dietary recommendations do affect the food supply and supplements and are used in labeling, all impacting population health. When scientific information is incomplete, consideration must be given to the implications of recommendations that focus on individual nutrients, rather than dietary patterns such as breast-feeding and consuming fish that promote health and minimize disease risk.

alpha-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans

Blood levels of polyunsaturated fatty acids (PUFA) are considered biomarkers of status. Alpha-linolenic acid, ALA, the plant omega-3, is the dietary precursor for the long-chain omega-3 PUFA eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA). Studies in normal healthy adults consuming western diets, which are rich in linoleic acid (LA), show that supplemental ALA raises EPA and DPA status in the blood and in breast milk. However, ALA or EPA dietary supplements have little effect on blood or breast milk DHA levels, whereas consumption of preformed DHA is effective in raising blood DHA levels. Addition of ALA to the diets of formula-fed infants does raise DHA, but no level of ALA tested raises DHA to levels achievable with preformed DHA at intakes similar to typical human milk DHA supply. The DHA status of infants and adults consuming preformed DHA in their diets is, on average, greater than that of people who do not consume DHA. With no other changes in diet, improvement of blood DHA status can be achieved with dietary supplements of preformed DHA, but not with supplementation of ALA, EPA, or other precursors.

Effect of dietary docosahexaenoic acid on biosynthesis of docosahexaenoic acid from alpha-linolenic acid in young rats

Docosahexaenoic acid (DHA), a crucial nervous system n-3 PUFA, may be obtained in the diet or synthesized in vivo from dietary alpha-linolenic acid (LNA). We addressed whether DHA synthesis is regulated by the availability of dietary DHA in artificially reared rat pups, during p8 to p28 development. Over 20 days, one group of rat pups was continuously fed deuterium-labeled LNA (d5-LNA) and no other n-3 PUFA (d5-LNA diet), and a second group of rat pups was fed a d5-LNA diet with unlabeled DHA (d5-LNA + DHA diet). The rat pups were then euthanized, and the total amount of deuterium-labeled docosahexaenoic acid (d5-DHA) (synthesized DHA) as well as other n-3 fatty acids present in various body tissues, was quantified. In the d5-LNA + DHA group, the presence of dietary DHA led to a marked decrease (3- to 5-fold) in the total amount of d5-DHA that accumulated in all tissues that we examined, except in adipose. Overall, DHA accretion from d5-DHA was generally diminished by availability of dietary preformed DHA, inasmuch as this was found to be the predominant source of tissue DHA. When preformed DHA was unavailable, d5-DHA and unlabeled DHA were preferentially accreted in some tissues along with a net loss of unlabeled DHA from other organs.

High-throughput analysis of plasma fatty acid methyl esters employing robotic transesterification and fast gas chromatography

Fatty acid analysis is an important research tool, and indices derived from essential fatty acid contents serve as useful biomarkers related to cardiovascular and other chronic disease risk. Both clinical and basic studies of essential fatty acid composition are becoming ever larger in magnitude leading to delays while the rather laborious lipid analyses are performed. A robotic transesterification procedure has been developed for high-throughput analysis of plasma fatty acid methyl esters. In this approach, robots perform most steps including plasma and reagent transfer, transesterification reaction via heating at 80 degrees C in open tubes with multiple reagent additions, followed by two-phase extraction and transfer of lipid extracts to GC vials. The vials are then placed directly onto a GC autosampler carousel for robotic sample injection. An improved fast GC method is presented in which the peaks of interest are eluted within 6 min. This method is readily scalable to prepare and analyze 200 samples per day (1,000 samples per week) so that large clinical trials can be accommodated.

Effect of fatty acids isolated from edible oils like mustard, linseed or coconut on astrocytes maturation

The omega-3 polyunsaturated fatty acid, docosahexaenoic acid (DHA, 22:6n-3) has been previously shown to facilitate some of the vital functions of astrocytes. Since some dietary oils contain alpha-linolenic acid (ALA, 18:3n-3), which is a precursor of DHA, we examined their effect on astrocyte development. Fatty acids (FAs) were isolated from commonly used oils and their compositions were determined by GLC. FAs from three oils, viz. coconut, mustard and linseed were studied for their effect on astrocyte morphology. Parallel studies were conducted with FAs from the same oils after heating for 72 h. Unlike coconut oil, FAs from mustard and linseed, both heated and raw, caused significant morphogenesis of astrocytes in culture. ss-AR binding was also substantially increased in astrocytes treated with FAs from raw mustard and linseed oils as compared to astrocytes grown in normal medium. The expression profile of the isoforms of GFAP showed that astrocyte maturation by FAs of mustard and linseed oil was associated with appearance of acidic variants of GFAP and disappearance of some neutral isoforms similar to that observed in cultures grown in serum containing medium or in the presence of DHA. Taken together, the study highlights the contribution of specific dietary oils in facilitating astrocyte development that can have potential impact on human health.

The influence of dietary docosahexaenoic acid and arachidonic acid on central nervous system polyunsaturated fatty acid composition

Numerous studies on perinatal long-chain polyunsaturated fatty acid nutrition have clarified the influence of dietary docosahexaenoic acid (DHA) and arachidonic acid (ARA) on central nervous system PUFA concentrations. In humans, omnivorous primates, and piglets, DHA and ARA plasma and red blood cells concentrations rise with dietary preformed DHA and ARA. Brain and retina DHA are responsive to diet while ARA is not. DHA is at highest concentration in cells and tissues associated with high energy consumption, consistent with high DHA levels in mitochondria and synaptosomes. DHA is a substrate for docosanoids, signaling compounds of intense current interest. The high concentration in tissues with high rates of oxidative metabolism may be explained by a critical role related to oxidative metabolism.

Differential tissue dose responses of (n-3) and (n-6) PUFA in neonatal piglets fed docosahexaenoate and arachidonoate

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are commonly added to infant formula worldwide; however, dietary concentrations needed to obtain optimal tissue levels have not been established. Hence, we studied tissue responses in piglets fed various doses of DHA and ARA. Doses were 0, 1, 2, and 5 times those used in U.S. infant formulas and DHA/ARA in Diet 0, Diet 1, Diet 2, and Diet 5 were 0, 4.1/8.1, 8.1/16.2, and 20.3/40.6 mg/100 kJ formula, respectively. Supplementation of dietary DHA and ARA increased DHA in brain, retina, liver, adipose tissue, plasma, and erythrocyte by 1.1- to 25.8-fold of Diet 0 (P-trend < 0.01). Tissue ARA (1.1- to 6.0-fold of Diet 0) responded to dietary ARA in liver, adipose tissue, plasma, and erythrocytes (P-trend < 0.05); brain and retina ARA was, however, unresponsive to dietary DHA and ARA. Plasma and erythrocyte DHA were positively associated with DHA in neural (brain and retina) and visceral (liver and adipose) tissues (r(2) = 0.11-0.56; P < 0.001-P = 0.042). Plasma and erythrocyte ARA did not correlate with neural ARA. Only plasma ARA was associated with liver ARA (r(2) = 0.222; P = 0.02) and adipose ARA (r(2) = 0.867; P < 0.001) and erythrocyte ARA correlated with adipose ARA (r(2) = 0.470; P < 0.001). We conclude that dietary DHA supplementation affords an effective strategy for enhancing tissue DHA, ARA in visceral but not neural tissues is sensitive to dietary ARA, and erythrocyte and plasma DHA can be used as proxies for tissue DHA, although blood-borne ARA is not an indicator of neural ARA.

Fatty acids in tea shoots (Camellia sinensis (L.) O. Kuntze) and their effects on the growth of retinal RF/6A endothelial cell lines

Chemo-protective effects of tea on ocular diseases were recorded in Chinese pharmacopoeia about 2000 years ago by eating tea. In the present study, contents of fatty acids (FAs) in tea shoots were determined by capillary GC; and the growth of RF/6A cells was also investigated by exposure to various representative FAs existing in tea shoots with pathologically relevant concentrations (40-500 microM) by ameliorated MTT assay and flow cytometry. Electron spin resonance (ESR) was used to measure oxygen consumption and investigate the free radical scavenging ability of linoleic acid (LA). Results showed that the most abundant long chain FAs were palmitic, linoleic, and alpha-linolenic acid in tea shoots; some RF/6A cells became suspended in culture medium treated by a high dose of both saturated and unsaturated FAs, but no apoptosis was observed. Moreover, it seemed that those FAs with different structure had various effects on the cell proliferation at their relatively low concentrations, LA expressed antioxidant activity in this study, which might be an important mechanism on the protection of eyes.

The influence of moderate and high dietary long chain polyunsaturated fatty acids (LCPUFA) on baboon neonate tissue fatty acids

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are now common ingredients in commercial infant formulas, however, the optimal levels have not been established. Our previous data showed that the current amount of DHA in U.S. term formulas, 0.3%w/w, is insufficient to normalize cerebral cortex DHA to levels in breastfed baboon neonate controls (Diau et al.: BMC Medicine 3: 11, 2005). Here, we report on the influence of higher formula DHA levels on 12-wk-old full-term baboon CNS and visceral organs. Fourteen nursery-reared baboons were randomized to one of three diets: control (C, no DHA-ARA); moderate LCPUFA (L, 0.33%DHA-0.67%ARA); high LCPUFA (L3, 1.00%DHA-0.67%ARA). DHA increased significantly in liver, heart, and plasma (all C < L < L3), RBC (C < L, L3), and CNS regions: precentral gyrus (C < L < L3), frontal cortex, inferior and superior colliculi, globus pallidus, and caudate (all C < L, L3). These data extend previous observations indicating that 1) tissue DHA is more sensitive to diet than ARA; 2) cerebral cortex DHA increases with higher levels of DHA than in present commercial formulas; and 3) basal ganglia and limbic system DHA saturate with levels of DHA currently available in formulas. These results imply that higher levels of DHA are necessary to normalize cortex DHA to those found in breastfed animals.

Docosahexaenoic acid, the aquatic diet, and hominin encephalization: difficulties in establishing evolutionary links

Distinctive characteristics of modern humans, including language, tool manufacture and use, culture, and behavioral plasticity, are linked to changes in the organization and size of the brain during hominin evolution. As brain tissue is metabolically and nutritionally costly to develop and maintain, early hominin encephalization has been linked to a release of energetic and nutritional constraints. One such nutrient-based approach has focused on the n-3 long-chained polyunsaturated fatty acid docosahexaenoic acid (DHA), which is a primary constituent of membrane phospholipids within the synaptic networks of the brain essential for optimal cognitive functioning. As biosynthesis of DHA from n-3 dietary precursors (alpha-linolenic acid, LNA) is relatively inefficient, it has been suggested that preformed DHA must have been an integral dietary constituent during evolution of the genus Homo to facilitate the growth and development of an encephalizing brain. Furthermore, preformed DHA has only been identified to an appreciable extent within aquatic resources (marine and freshwater), leading to speculation that hominin encephalization is linked specifically to access and consumption of aquatic resources. The key premise of this perspective is that biosynthesis of DHA from LNA is not only inefficient but also insufficient for the growth and maturation demands of an encephalized brain. However, this assumption is not well-supported, and much evidence instead suggests that consumption of LNA, available in a wider variety of sources within a number of terrestrial ecosystems, is sufficient for normal brain development and maintenance in modern humans and presumably our ancestors.

Role of omega-3 fatty acids in brain development and function: potential implications for the pathogenesis and prevention of psychopathology

The principle omega-3 fatty acid in brain, docosahexaenoic acid (DHA), accumulates in the brain during perinatal cortical expansion and maturation. Animal studies have demonstrated that reductions in perinatal brain DHA accrual are associated with deficits in neuronal arborization, multiple indices of synaptic pathology including deficits in serotonin and mesocorticolimbic dopamine neurotransmission, neurocognitive deficits, and elevated behavioral indices of anxiety, aggression, and depression. In primates and humans, preterm delivery is associated with deficits in fetal cortical DHA accrual, and children/adolescents born preterm exhibit deficits in cortical gray matter maturation, neurocognitive deficits particularly in the realm of attention, and increased risk for attention-deficit/hyperactivity disorder (ADHD) and schizophrenia. Individuals diagnosed with ADHD or schizophrenia exhibit deficits in cortical gray matter maturation, and medications found to be efficacious in the treatment of these disorders increase cortical and striatal dopamine neurotransmission. These associations in conjunction with intervention trials showing enhanced cortical visual acuity and cognitive outcomes in preterm and term infants fed DHA, suggest that perinatal deficits in brain DHA accrual may represent a preventable neurodevelopmental risk factor for the subsequent emergence of psychopathology.

Long-chain polyunsaturated fatty acids in maternal and infant nutrition

Homo sapiens has evolved on a diet rich in alpha-linolenic acid and long chain polyunsaturated fatty acids (LCP). We have, however, gradually changed our diet from about 10,000 years ago and accelerated this change from about 100 to 200 years ago. The many dietary changes, including lower intake of omega3-fatty acids, are related to 'typically Western' diseases. After a brief introduction in essential fatty acids (EFA), LCP and their functions, this contribution discusses our present low status of notably LCPomega3 in the context of our rapidly changing diet within an evolutionary short time frame. It then focuses on the consequences in pregnancy, lactation and neonatal nutrition, as illustrated by some recent data from our group. We discuss the concept of a 'relative' EFA/LCP deficiency in the fetus as the outcome of high transplacental glucose flux. This flux may in the fetus augment de novo synthesis of fatty acids, which not only dilutes transplacentally transported EFA/LCP, but also causes competition of de novo synthesized oleic acid with linoleic acid for delta-6 desaturation. Such conditions were encountered by us in mothers with high body mass indices, diabetes mellitus and preeclampsia. The unifying factor might be compromised glucose homeostasis. In search of the milk arachidonic acid (AA) and docosahexaenoic acid (DHA) contents of our African ancestors, we investigated women in Tanzania with high intakes of freshwater fish as only animal lipid source. These women had milk AA and DHA contents that were well above present recommendations for infant formulae. Both studies stimulate rethinking of 'optimal homeostasis'. Subtle signs of dysbalanced maternal glucose homeostasis may be important and observations from current Western societies may not provide us with an adequate basis for dietary recommendations.

A cholesterol-enriched diet induces ultrastructural changes in retinal and macroglial rabbit cells

The purpose of this study was to ascertain whether the excess of cholesterol in rabbits induces ultrastructural retinal changes similar to those observed in human age-related macular degeneration (AMD). New Zealand rabbits were divided into two groups: Control (GO; n=10), fed standard diet for 8 months; hypercholesterolemic (G1; n=10), fed with 0.5% cholesterol-enriched diet for 8 months. Eyes were processed for transmission electron microscopy (TEM) and immunohistochemistry (anti-glial fibrillary acidic protein, GPAP). In comparison with GO, G1 exhibited alterations in all the retinal layers that were more intense in areas overlying altered retinal pigment epithelium (RPE). RPE changes showed no preferential location. In G1, Bruch's membrane was thicker as a result particle build-up in the collagen layers; the cytoplasm of RPE showed dense bodies, debris from cell membranes, vacuoles and numerous clumps of lipids; necrosis and apoptosis were detected in different retinal layers; Müller cells and astrocytes were reactive with instances of apoptosis and necrosis; some Müller cells filled up the empty spaces left by degenerated neurons in all retinal layers; some Müller cell nuclei were displaced to the nerve-fiber layer (NFL); epiretinal perivascular astrocytes contained drops of lipids; the NFL had very few astrocytes and the basal membranes of capillaries in the NFL was thicker. Excess cholesterol induces ultrastructural changes in the rabbit retina similar to those in human AMD. Given that lipid intake is most dependent on food composition, dietary regimen could help induce or prevent retinal disease.

Changes of the transcriptional and fatty acid profiles in response to n-3 fatty acids in SH-SY5Y neuroblastoma cells

Synthesis of docosahexaenoic acid (DHA) from its metabolic precursors contributes to membrane incorporation of this FA within the central nervous system. Although cultured neural cells are able to produce DHA, the membrane DHA contents resulting from metabolic conversion do not match the high values of those resulting from supplementation with preformed DHA. We have examined whether the DHA precursors down-regulate the incorporation of newly formed DHA within human neuroblastoma cells. SH-SY5Y cells were incubated with gradual doses of alpha-linolenic acid (alpha-LNA), EPA, or docosapentaenoic acid (DPA), and the incorporation of DHA into ethanolamine glycerophospholipids was analyzed as a reflection of synthesizing activity. The incorporation of EPA, DPA, and preformed DHA followed a dose-response saturating curve, whereas that of DHA synthesized either from alpha-LNA, EPA, or DPA peaked at concentrations of precursors below 15-30 microM and sharply decreased with higher doses. The mRNA encoding for six FA metabolism genes were quantified using real-time PCR. Two enzymes of the peroxisomal beta-oxidation, L-bifunctional protein and peroxisomal acyl-CoA oxidase, were expressed at lower levels than fatty acyl-CoA ligase 3 (FACL3) and delta6-desaturase (delta6-D). The delta6-D mRNA slightly increased between 16 and 48 h of culture, and this effect was abolished in the presence of 70 microM EPA. In contrast, the EPA treatment resulted in a time-dependent increase of FACL3 mRNA. The terminal step of DHA synthesis seems to form a "metabolic bottleneck," resulting in accretion of EPA and DPA when the precursor concentration exceeds a specific threshold value. We conclude that the critical precursor- concentration window of responsiveness may originate from the low basal expression level of peroxisomal enzymes.

One generation of n-3 polyunsaturated fatty acid deprivation increases depression and aggression test scores in rats

Male rat pups at weaning (21 days of age) were subjected to a diet deficient or adequate in n-3 polyunsaturated fatty acids (n-3 PUFAs) for 15 weeks. Performance on tests of locomotor activity, depression, and aggression was measured in that order during the ensuing 3 weeks, after which brain lipid composition was determined. In the n-3 PUFA-deprived rats, compared with n-3 PUFA-adequate rats, docosahexaenoic acid (22:6n-3) in brain phospholipid was reduced by 36% and docosapentaenoic acid (22:5n-6) was elevated by 90%, whereas brain phospholipid concentrations were unchanged. N-3 PUFA-deprived rats had a significantly increased (P = 0.03) score on the Porsolt forced-swim test for depression, and increased blocking time (P = 0.03) and blocking number (P = 0.04) scores (uncorrected for multiple comparisons) on the isolation-induced resident-intruder test for aggression. Large effect sizes (d > 0.8) were found on the depression score and on the blocking time score of the aggression test. Scores on the open-field test for locomotor activity did not differ significantly between groups, and had only small to medium effect sizes. This single-generational n-3 PUFA-deprived rat model, which demonstrated significant changes in brain lipid composition and in test scores for depression and aggression, may be useful for elucidating the contribution of disturbed brain PUFA metabolism to human depression, aggression, and bipolar disorder.

Suckling rats actively recycle carbon from alpha-linolenate into newly synthesized lipids even during extreme dietary deficiency of n-3 polyunsaturates

Docosahexaenoate is usually considered to be the principal endpoint of alpha-linolenate metabolism in mammals. Nevertheless, several studies over the past 30 y have shown that more carbon from alpha-linolenate is recycled into newly synthesized lipids than is used to make docosahexaenoate. Our objective in this study was to assess carbon recycling from alpha-linolenate in suckling rats made deficient in n-3 polyunsaturated fatty acids (PUFA). Female Long-Evans rats were given a diet deficient in n-3 PUFA at weaning and then bred 8 wk later. Pups from the second generation were nursed by their respective dams and gavaged with 1 mg [U-13C]-alpha-linolenate at 10 d old. Brain and liver were obtained 24 h later, and the fatty acid profiles and 13C enrichment analyzed. Docosahexaenoate was markedly depleted in brain (-82%) and liver (-97%) of the n-3 PUFA-deficient rats. In the controls, 13C enrichment in products of carbon recycling (cholesterol and fatty acids other than n-3 PUFA) exceeded that in docosahexaenoate by 2.4-fold (liver) and 7.5-fold (brain). n-3 PUFA deficiency reduced the ratio of 13C enrichment in products of carbon recycling compared with 13C incorporated into docosahexaenoate by 63% in the brain but not in the liver. Despite severe n-3 PUFA deficiency, carbon recycling still consumed 50% more 13C from alpha-linolenate than went into docosahexaenoate in the liver and 2.8-fold more in the brain. We conclude that carbon recycling is an integral part of neonatal metabolism of alpha-linolenate and is not simply an overflow pathway arising from excess availability of preformed docosahexaenoate.

Essential fatty acid transfer and fetal development

Docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6) are important structural components of the central nervous system. These fatty acids are transferred across the placenta, and are accumulated in the brain and other organs during fetal development. Depletion of 22:6n-3 from the retina and brain results in reduced visual function and learning deficits: these may involve critical roles of 22:6n-3 in membrane-dependent signaling pathways and neurotransmitter metabolism. Transfer of 22:6n-3 across the placenta involves specific binding and transfer proteins that facilitate higher concentrations of 22:6n-3 and 20:4n-6, but lower linoleic acid (18:2n-6) in fetal compared with maternal plasma, or in the breast-fed or formula-fed infant. However, human and animal studies both demonstrate that maternal diet impacts fetal 22:6n-3 and 20:4n-6 accretion. After birth, parenteral lipid, human milk and infant formula feeding all result in a marked decrease in plasma 22:6n-3 and 20:4n-6 and an increase in 18:2n-6. Estimation of fetal tissue fatty acid accretion suggests that current preterm infant feeds are unlikely to meet in utero rates of 22:6n-3 accretion. Consideration needs to be given to whether fetal plasma 22:6n-3 and 20:4n-6 enrichment and the low 18:2n-6 facilitates accretion of 22:6n-3 and 20:4n-6 in developing tissues.

α-Linolenic acid does not contribute appreciably to docosahexaenoic acid within brain phospholipids of adult rats fed a diet enriched in docosahexaenoic acid

Adult male unanesthetized rats, reared on a diet enriched in both alpha-linolenic acid (alpha-LNA) and docosahexaenoic acid (DHA), were infused intravenously for 5 min with [1-(14)C]alpha-LNA. Timed arterial samples were collected until the animals were killed at 5 min and the brain was removed after microwaving. Plasma and brain lipid concentrations and radioactivities were measured. Within plasma lipids, > 99% of radioactivity was in the form of unchanged [1-(14)C]alpha-LNA. Eighty-six per cent of brain radioactivity at 5 min was present as beta-oxidation products, whereas the remainder was mainly in 'stable' phospholipid or triglyceride as alpha-LNA or DHA. Equations derived from kinetic modeling demonstrated that unesterified unlabeled alpha-LNA rapidly enters brain from plasma, but that its incorporation into brain phospholipid and triglyceride, as in the form of synthesized DHA, is < or = 0.2% of the amount that enters the brain. Thus, in rats fed a diet containing large amounts of both alpha-LNA and DHA, the alpha-LNA that enters brain from plasma largely undergoes beta-oxidation, and is not an appreciable source of DHA within brain phospholipids.