Proportions of trans fatty acids in erythrocytes of Canadian adults before the prohibition of partially hydrogenated oils in foods: results from the Canadian Health Measures Survey 2012-2015.

BACKGROUND: The partially hydrogenated oil (PHO) prohibition came into effect in Canada in September 2018 to reduce the intakes of total trans fatty acids (t-TFAs) and industrially produced TFAs (i-TFAs). OBJECTIVES: We aimed to estimate the red blood cell (RBC) proportions of t-TFA (primary objective) and total 18:1 TFA (secondary objective) of adults in Canada before the PHO prohibition and to identify the population subgroups at risk of higher TFA intakes. METHODS: We pooled data from 4025 adult participants of the cross-sectional Canadian Health Measures Survey cycles 3 and 4 (2012-2015). We estimated mean proportions, relative to total fatty acids (FAs), of RBC t-TFA and 18:1 TFA and their associations with sociodemographic, health, and lifestyle characteristics using multiple linear regression models. RESULTS: The nonadjusted mean RBC proportions of t-TFA and total 18:1 TFA were 0.59% (95% CI: 0.54, 0.63) and 0.27% (95% CI: 0.25, 0.29), respectively. In the adjusted models, the same participant characteristics were associated with t-TFA and 18:1 TFA but differences were generally smaller for 18:1 TFA than for t-TFA. Race, BMI, and alcohol intake were independently associated with RBC t-TFA and 18:1 TFA. Asian and Black participants had lower RBC t-TFA (-0.05% and -0.10% of total FA, respectively) than White participants. Obesity and high risk alcohol drinking were associated with slightly lower (≤0.06%) t-TFA proportions than lower adiposity and alcohol intake concentrations, respectively. CONCLUSIONS: Pre-PHO prohibition in food in Canada, t-TFA proportions were relatively low compared with a proposed threshold of 1% of total RBC FAs, over which cardiovascular disease risk may be higher. Previous voluntary initiatives to reduce i-TFA in the food supply may explain these relatively low RBC t-TFA concentrations. Some population subgroups had higher baseline RBC TFA than other subgroups, but the physiological implications of these small differences, at relatively low baseline RBC TFA proportions, remain to be determined.

Adherence to Vitamin D Supplementation Recommendations for Breastfed Infants and Young Children: An Analysis of Canadian Community Health Survey Data Cycles From 2015 to 2018.

BACKGROUND: In Canada, nutrition policy, as outlined in the Nutrition for Healthy Term Infants recommendations, includes a daily vitamin D supplement of 10 µg (400 IU) for breastfed infants and young children to support adequate vitamin D status. OBJECTIVES: This study aimed to report on adherence to vitamin D supplementation recommendations for breastfed infants (≤12 months); and for children breastfed >12 mo. METHODS: Canadian Community Health Survey (paired-cycles 2015/2016 and 2017/2018) maternal experiences data for infants born 2012-2018 who received any breastmilk formed the sample (n = 7079). Whether the infant was given a vitamin D supplement (yes/no) and the frequency (daily/almost every day, 1-2/wk, or <1/wk) were surveyed. Weighted data (95% CI) were summarized according to breastfeeding history (exclusive to 6 mo and continuing; partial to 6 mo and continuing; and stopped ≤6 mo). Correlates of supplement adherence were explored using logistic regression. RESULTS: Overall, 87.1% (95% CI: 85.9%, 88.3%) of participants reported giving their infant (≤12 mo) a vitamin D supplement, and of these, 83.3% (95% CI: 81.9%, 84.7%) did so daily/almost every day, 12.4% (95% CI: 11.1%, 13.7%) did so 1-2/wk, and 4.3% (95% CI: 3.6%, 5.0%) did so <1/wk. Lower adjusted odds of adherence were observed among participants reporting: stopped breastfeeding ≤6 mo, lower education or income, recent immigration, and overweight prepregnancy body mass index; higher odds of adherence were observed in the western provinces. Regarding mothers of children >12 mo and breastfed (n = 2312), 58.0% (95% CI: 54.9%, 61.1%) gave a vitamin D supplement daily/almost every day. CONCLUSIONS: Adherence to providing a vitamin D supplement to breastfed infants is high in Canada. Nonetheless, we estimate that ∼27% of mothers are nonadherent to daily/almost every day administration of a vitamin D supplement and that adherence declines in children breastfed >12 mo. Further promotion to support uptake of the current guidance may be necessary, particularly for parents of recent immigration or lower socioeconomic status.

Associations of maternal inflammatory states with human milk composition in mothers of preterm infants.

Introduction: Overweight/obesity (ow/ob) is increasing in prevalence in pregnant women, and it is associated with other pro-inflammatory states, such as pre-eclampsia, gestational diabetes, and preterm labor. Data are lacking if mothers experiencing inflammatory states who deliver preterm have mother's own milk (MOM) with differing inflammatory markers or pro-inflammatory fatty acid (FA) profiles. Methods: The aim was to explore associations of maternal pre- and perinatal inflammatory states with levels of inflammatory markers and/or FAs in longitudinal samples of MOM from mothers of preterm infants born <1,250 g. Inflammatory states included pre-pregnancy ow/ob, diabetes, chorioamnionitis (chorio), preterm labor (PTL), premature rupture of membranes (PROM), pre-eclampsia, and cesarian delivery. In MOM, inflammatory markers studied included c-reactive protein (CRP), free choline, IFN-Ɣ, IL-10, IL-1ß, IL-1ra, IL-6, IL-8, and TNF-α, and FAs included omega-6:omega-3 ratio, arachidonic acid, docosahexaenoic acid, linoleic acid, monounsaturated FAs, and saturated FAs. The above inflammatory states were assessed individually, and the healthiest mothers (normal BMI, no chorio, and ± no pre-eclampsia) were grouped. Regression analysis tested associations at baseline (day 5) and over time using generalized estimating equations. Results: A total of 92 infants were included who were delivered to mothers (42% ow/ob) at a median gestational age of 27.7 weeks and birth weight of 850 g. MOM CRP was 116% higher (relative change 2.16) in mothers with ow/ob at baseline than others (p = 0.01), and lower (relative change 0.46, 0.33, respectively) in mothers in the two "healthy groups" at baseline (both p < 0.05) than others. MOM IL-8 levels were lower with chorio and PTL at baseline. No significant associations were found for other individual or grouped inflammatory states nor for other MOM inflammatory markers nor FA profiles at baseline. Discussion: In conclusion, MOM CRP levels are positively associated with inflammatory states, such as ow/ob. Reassuringly, there was no association between FA profiles or most other inflammatory markers and maternal inflammatory states. Further studies are needed to determine potential associations or ramifications of MOM CRP in vulnerable preterm infants.

Perspective: Human Milk Composition and Related Data for National Health and Nutrition Monitoring and Related Research.

National health and nutrition monitoring is an important federal effort in the United States and Canada, and the basis for many of their nutrition and health policies. Understanding of child exposures through human milk (HM) remains out of reach due to lack of current and representative data on HM's composition and intake volume. This article provides an overview of the current national health and nutrition monitoring activities for HM-fed children, HM composition (HMC) and volume data used for exposure assessment, categories of potential measures in HM, and associated variability factors. In this Perspective, we advocate for a framework for collection and reporting of HMC data for national health and nutrition monitoring and programmatic needs, including a shared vision for a publicly available Human Milk Composition Data Repository (HMCD-R) to include essential metadata associated with HMC. HMCD-R can provide a central, integrated platform for researchers and public health officials for compiling, evaluating, and sharing HMC data. The compiled compositional and metadata in HMCD-R would provide pertinent measures of central tendency and variability and allow use of modeling techniques to approximate compositional profiles for subgroups, providing more accurate exposure assessments for purposes of monitoring and surveillance. HMC and related metadata could facilitate understanding the complexity and variability of HM composition, provide crucial data for assessment of infant and maternal nutritional needs, and inform public health policies, food and nutrition programs, and clinical practice guidelines.

Docosahexaenoic acid and arachidonic acid levels are correlated in human milk: Implications for new European infant formula regulations.

From February 2022, all infant formula sold in the European Union must contain docosahexaenoic acid (DHA) at ~0.33%-1.14% of total fat with no minimum requirement for arachidonic acid (ARA). This work examines the association between DHA and ARA levels in human milk, the gold standard for infant feeding. Human milk (n = 470) was collected over 12-weeks postpartum from lactating mothers (n = 100) of infants born weighing <1250 g (NCT02137473). Fatty acids were analyzed by gas chromatography. ARA and DHA concentrations were associated in human milk (ß = 0.47 [95% confidence interval 0.38-0.56] mol%), including transitional and mature milk, but not colostrum. This remained significant upon adjustment for percentages of other saturated, monounsaturated, n-3, or n-6 fatty acids, day of sample collection, or maternal characteristics (body mass index, ethnicity, education, and income). Infant formulas containing relatively high concentrations of DHA without ARA, as permitted by the new regulations, would not reflect the balance of these fatty acids in human milk.

Social-emotional functioning and dietary intake among children born with a very low birth weight.

Very low birth weight (VLBW, <1500 g)  infants are at an elevated risk of neurodevelopmental disorders, later obesity and cardiometabolic disease; if and how neurodevelopmental disorders impact chronic disease risk is poorly understood. The most common neurodevelopmental disorders experienced by VLBW children are those of social-emotional functioning. We compared dietary patterns and body composition between VLBW children with poor vs. typical social-emotional functioning using linear mixed models adjusted for sex, gestational age, cognitive impairment, parental education, and body mass index (BMI). VLBW children (n=158) attending the Donor Milk for Improved Neurodevelopmental Outcomes trial with 5.5-year follow-up participated. Poor social-emotional functioning was based on standardized parent-rated questionnaires and/or parent-reported physician diagnosis of autism spectrum or attention-deficit/hyperactivity disorders. Most children had diets categorized as "needs improvement" (67%) or "poor" (27%) and 29% of children exhibited poor social-emotional functioning. Poor social-emotional functioning was positively associated with 100% fruit juice (ß=0.3 cup equivalents/day; 95% CI 0.1, 0.5) and energy intake (ß=118.1 kcal/day; 95% CI 0.9, 235.2). Children with poor social-emotional functioning were more likely to have a limited food repertoire (p=0.02), but less likely to exceed dietary fat recommendations (p=0.04). No differences in overall diet quality or body composition were observed. Diet counselling and research are essential to improving the nutrition of VLBW children to mitigate chronic disease risk. Trial registration - Optimizing Mothers' Milk for Preterm Infants Program of Research: Study 1 - Impact of Donor Milk at Kindergarten, NCT02759809, https://clinicaltrials.gov/ct2/show/NCT02759809. Novelty: Overall diet quality and body composition did not differ between VLBW children with poor vs. typical social-emotional functioning. Most had diets "needing improvement" or "poor" according to the Healthy Eating Index-2010. Diet counselling may help mitigate chronic disease risk in this vulnerable population.

Determinants of fatty acid content and composition of human milk fed to infants born weighing <1250 g.

BACKGROUND: Infants born at very low birth weight (VLBW) are vulnerable to deficits in fatty acids (FAs) but little is known of factors that influence the intakes or composition of their human milk feeds. OBJECTIVES: We aimed to identify sources of variability in the fat composition of human milk fed to VLBW infants and examine the impact of milk source (mother's own or donor) on fat and FA intakes. METHODS: Serial samples of mother's milk (n = 476) and donor milk (n = 53) fed to infants born weighing <1250 g (n = 114 infants from 100 mothers) were collected [Optimizing Mothers' Milk for Preterm Infants (OptiMoM) randomized clinical trial]. Fat and FA were analyzed using a mid-infrared human milk analyzer and GC with flame ionization detection. RESULTS: At full enteral feeding, donor milk is estimated to provide 1.3 g · kg-1 · d-1 less total fat than mature mother's milk (recommended intake: 4.8 g · kg-1 · d-1), and 5-9 mg · kg-1 · d-1 less DHA (22:6n-3) and arachidonic acid (20:4n-6) (estimated average requirement: 55-60 and 35-45 mg · kg-1 · d-1, respectively) than colostrum or transitional milk. Similar deficits were observed in measured intakes of a subset of OptiMoM infants. In multivariable-adjusted models, maternal ethnicity had medium to large [≥0.5 SD score (SDS)] effects on DHA, SFAs, and MUFAs. Mothers with prepregnancy BMI in overweight and obese categories had higher milk total fat (ß: 0.35; 95% CI: 0.10, 0.61 and ß: 0.46; 95% CI: 0.16, 0.77 SDS, respectively). Those with BMI ≥30 in addition had higher proportions of SFAs (ß: 0.61; 95% CI: 0.33, 0.89 SDS) and lower DHA (ß: -0.54; 95% CI: -0.89, -0.20 SDS). Other factors, such as gestational age and income, were also associated with FA composition. CONCLUSIONS: The fat and FA content of human milk fed to VLBW infants is variable. Care must be taken to ensure fat and FA intakes meet recommendations, particularly when feeding a high proportion of donor milk.This trial was registered at clinicaltrials.gov as NCT02137473.

Oxylipin concentration, but not fatty acid composition, is altered in human donor milk pasteurised using both thermal and non-thermal techniques.

Human donor milk (DM) is Holder pasteurised (62·5°C, 30 min) to ensure its microbiological safety for infant consumption. In low-resource settings, flash heating is used to pasteurise milk. Although there is considerable interest in non-thermal alternatives (high hydrostatic pressure processing (HHP) and UVC irradiation) for pasteurisation, their effect on the fatty acid composition is not well understood. Of particular interest is the effect of pasteurisation on the generation of oxylipins. DM from eight mothers containing bacteria >5 × 107 colony-forming units/l was used. In a paired design, each pool of milk underwent four pasteurisation techniques: Holder; flash heating; UVC (250 nm, 25 min) and HHP (500 MPa, 8 min). Fatty acids were quantified by GC-flame ionisation detection and oxylipins derived from arachidonic acid; 18-carbon PUFA (α-linolenic acid, linoleic acid and γ-linolenic acid) and EPA/DHA were measured by liquid chromatography-tandem MS in aliquots of raw and processed milk. There were no significant changes to the composition of fatty acids following all pasteurisation techniques compared with raw milk. The n-6:n-3 ratio remained constant ranging from 6·4 to 6·6. Several arachidonic acid-derived oxylipins were highest post-UVC and elevated post-HHP compared with raw milk. Several oxylipins derived from 18-carbon PUFA (linoleic and α-linolenic acids) were elevated in UVC-treated milk. EPA/DHA-derived oxylipins were on average, unaffected by pasteurisation. Although some PUFA-derived oxylipins were increased following UVC and HHP, no method affected the fatty acid composition of human DM. Further research is needed to determine if varying levels of oxylipins in human DM as a result of processing can potentially mediate cellular signalling; proliferation and apoptosis, especially important for preterm infant development.

Dietary fish oil, and to a lesser extent the fat-1 transgene, increases astrocyte activation in response to intracerebroventricular amyloid-ß 1-40 in mice.

OBJECTIVES: Increases in astrocytes and one of their markers, glial fibrillary acidic protein (GFAP) have been reported in the brains of patients with Alzheimer's disease (AD). N-3 polyunsaturated fatty acids (PUFA) modulate neuroinflammation in animal models; however, their effect on astrocytes is unclear. METHODS: Fat-1 mice and their wildtype littermates were fed either a fish oil diet or a safflower oil diet deprived of n-3 PUFA. At 12 weeks, mice underwent intracerebroventricular infusion of amyloid-ß 1-40. Astrocyte phenotype in the hippocampus was assessed at baseline and 10 days post-surgery using immunohistochemistry with various microscopy and image analysis techniques. RESULTS: GFAP increased in all groups in response to amyloid-ß, with a greater increase in fish oil-fed mice than either fat-1 or wildtype safflower oil-fed mice. Astrocytes in this group were also more hypertrophic, suggesting increased activation. Both fat-1- and fish oil-fed mice had greater increases in branch number and length in response to amyloid-ß infusion than wildtype safflower animals. CONCLUSION: Fish oil feeding, and to a lesser extent the fat-1 transgene, enhances the astrocyte activation phenotype in response to amyloid-ß 1-40. Astrocytes in mice fed fish oil were more activated in response to amyloid-ß than in fat-1 mice despite similar levels of hippocampal n-3 PUFA, which suggests that other fatty acids or dietary factors contribute to this effect.

Nutrient Enrichment of Human Milk with Human and Bovine Milk-Based Fortifiers for Infants Born <1250 g: 18-Month Neurodevelopment Follow-Up of a Randomized Clinical Trial.

BACKGROUND: Bovine milk-based fortifiers (BMBF) have been standard of care for nutrient fortification of feeds for very low birth weight (VLBW) infants, however, there is increasing use of human milk-based fortifiers (HMBF) in neonatal care despite additional costs and limited supporting data. No randomized clinical trial has followed infants fed these fortifiers after initial hospitalization. OBJECTIVE: To compare neurodevelopment in infants born weighing <1250 g fed maternal milk with supplemental donor milk and either a HMBF or BMBF. METHODS: This is a follow-up of a completed pragmatic, triple-blind, parallel group randomized clinical trial conducted in Southern Ontario between August 2014 and March 2016 (NCT02137473) with feeding tolerance as the primary outcome. Infants weighing <1250 g at birth were block randomized by an online third-party service to receive either HMBF (n = 64) or BMBF (n = 63) added to maternal milk with supplemental donor milk during hospitalization. Neurodevelopment was assessed at 18-mo corrected age using the Bayley Scales of Infant and Toddler Development, Third Edition. Follow-up was completed in October 2017. RESULTS: Of the 127 infants randomized, 109 returned for neurodevelopmental assessment. No statistically significant differences between fortifiers were identified for cognitive composite scores [adjusted mean scores 94.7 in the HMBF group and 95.9 in the BMBF group; fully adjusted mean difference, -1.1 (95% CI: -6.5 to 4.4)], language composite scores [adjusted scores 92.4 in the HMBF group and 93.1 in the BMBF; fully adjusted mean difference, -1.2 (-7.5 to 5.1)], or motor composite scores [adjusted scores 95.6 in the HMBF group and 97.7 in the BMBF; fully adjusted mean difference, -1.1 (-6.3 to 4.2)]. There was no difference in the proportion of participants that died or had neurodevelopmental impairment or disability between groups. CONCLUSIONS: Providing HMBF compared with BMBF does not improve neurodevelopmental scores at 18-mo corrected age in infants born <1250 g otherwise fed a human milk diet. This trial was registered at clinicaltrials.gov as NCT02137473.

Dietary fatty acids augment tissue levels of n-acylethanolamines in n-acylphosphatidylethanolamine phospholipase D (NAPE-PLD) knockout mice.

N-acylethanolamines (NAEs) are lipid signaling mediators, which can be synthesized from dietary fatty acids via n-acylphosphatidylethanolamine-phospholipase D (NAPE-PLD) and in turn influence physiological outcomes; however, the roles of NAPE-PLD upon dietary fatty acid modulation are not fully understood. Presently, we examine if NAPE-PLD is necessary to increase NAEs in response to dietary fatty acid manipulation. Post-weaning male wild-type (C57Bl/6), NAPE-PLD (-/+) and NAPE-PLD (-/-) mice received isocaloric fat diets containing either beef tallow, corn oil, canola oil or fish oil (10% wt/wt from fat) for 9 weeks. Brain docosahexaenoic acid (DHA) levels were higher (P<.01) in NAPE-PLD (-/+) (10.01±0.31 µmol/g) and NAPE-PLD (-/-) (10.89±0.61 µmol/g) than wild-type (7.72±0.61 µmol/g) consuming fish oil. In NAPE-PLD (-/-) mice, brain docosahexaenoylethanolamide (DHEA) levels were higher (P<.01) after fish oil feeding suggesting that NAPE-PLD was not necessary for DHEA synthesis. Liver and jejunum arachidonoylethanolamide, 1,2-arachidonoylglycerol and DHEA levels reflected their corresponding fatty acid precursors suggesting that alternate pathways are involved in NAE synthesis. NAPE-PLD (-/-) mice had lower oleoylethanolamide levels in the jejunum and a leaner phenotype compared to wild-type mice. Overall, these results demonstrate that dietary fatty acid can augment tissue NAEs in the absence of NAPE-PLD.

Applying stable carbon isotopic analysis at the natural abundance level to determine the origin of docosahexaenoic acid in the brain of the fat-1 mouse.

A key factor limiting the study of the origin and metabolism of brain fatty acids is the lack of cost-efficient methods available to trace fatty acids. Here, through the application of compound-specific isotope analysis (CSIA), a novel, cost-efficient method, we successfully differentiated between brain DHA originating directly from dietary omega (n)-3 polyunsaturated fatty acids (PUFA), and brain DHA biochemically synthesized to determine the origin of brain DHA in fat-1 mice. Fat-1 mice and their wild-type littermates were either weaned onto n-6 PUFA rich, n-3 PUFA deficient diets or diets rich in both n-3 and n-6 PUFA. Isotopic analysis of fatty acid methyl esters from brain and liver tissue was conducted via gas chromatography- isotope ratio mass spectrometry. Our data demonstrates that in the presence of n-3 and n-6 PUFA, fat-1 mice obtain their brain DHA solely from n-3 PUFA sources. This study reflects the first application of CSIA to a complex multivariate model to determine the origin of brain fatty acids.

Two weeks of docosahexaenoic acid (DHA) supplementation increases synthesis-secretion kinetics of n-3 polyunsaturated fatty acids compared to 8 weeks of DHA supplementation.

Docosahexaenoic acid (DHA, 22:6n-3) must be consumed in the diet or synthesized from n-3 polyunsaturated fatty acid (PUFA) precursors. However, the effect of dietary DHA on the metabolic pathway is not fully understood. Presently, 21-day-old Long Evans rats were weaned onto one of four dietary protocols: 1) 8 weeks of 2% ALA (ALA), 2) 6 weeks ALA followed by 2 weeks of 2% ALA + 2% DHA (DHA), 3) 4 weeks ALA followed by 4 weeks DHA and 4) 8 weeks of DHA. After the feeding period, 2H5-ALA and 13C20-eicosapentaenoic acid (EPA, 20:5n-3) were co-infused and blood was collected over 3 h for determination of whole-body synthesis-secretion kinetics. The synthesis-secretion coefficient (ml/min, means ± SEM) for EPA (0.238±0.104 vs. 0.021±0.001) and DPAn-3 (0.194±0.060 vs. 0.020±0.008) synthesis from plasma unesterified ALA, and DPAn-3 from plasma unesterified EPA (2.04±0.89 vs. 0.163±0.025) were higher (P<.05) after 2 weeks compared to 8 weeks of DHA feeding. The daily synthesis-secretion rate (nmol/d) of DHA from EPA was highest after 4 weeks of DHA feeding (843±409) compared to no DHA (70±22). Liver gene expression of ELOVL2 and FADS2 were lower (P<.05) after 4 vs. 8 weeks of DHA. Higher synthesis-secretion kinetics after 2 and 4 weeks of DHA feeding suggests an increased throughput of the PUFA metabolic pathway. Furthermore, these findings may lead to novel dietary strategies to maximize DHA levels while minimizing dietary requirements.

Increased brain docosahexaenoic acid has no effect on the resolution of neuroinflammation following intracerebroventricular lipopolysaccharide injection.

Resolution of inflammation in the periphery was once thought to be a passive process, but new research now suggests it is an active process mediated by specialized pro-resolving lipid mediators (SPM) derived from omega-3 polyunsaturated fatty acids (n-3 PUFA). However, this has yet to be illustrated in neuroinflammation. The purpose of this study was to measure resolution of neuroinflammation and to test whether increasing brain docosahexaenoic acid (DHA) affects the resolution of neuroinflammation. C57Bl/6 mice, fat-1 mice and their wildtype littermates, fed either fish oil or safflower oil, received lipopolysaccharide (LPS) in the left lateral ventricle. Animals were then euthanized at various time points for immunohistochemistry, gene expression, and lipidomic analyses. Peak microglial activation was observed at 5 days post-surgery and the resolution index was 10 days. Of the approximately 350 genes significantly changed over the 28 days post LPS injection, 130 were uniquely changed at 3 days post injection. No changes were observed in the bioactive mediator pools. However, a few lysophospholipid species were decreased at 24hr post surgery. When brain DHA is increased, microglial cell density did not resolve faster and did not alter gene expression. In conclusion, resolution of neuroinflammation appears to be independent of SPM. Increasing brain DHA had no effect in this model.

Complete assessment of whole-body n-3 and n-6 PUFA synthesis-secretion kinetics and DHA turnover in a rodent model.

Previous assessments of the PUFA biosynthesis pathway have focused on DHA and arachidonic acid synthesis. Here, we determined whole-body synthesis-secretion kinetics for all downstream products of PUFA metabolism, including direct measurements of DHA and n-6 docosapentaenoic acid (DPAn-6, 22:5n-6) turnover, and compared n-6 and n-3 homolog kinetics. We infused labeled α-linolenic acid (ALA, 18:3n-3), linoleic acid (LNA, 18:2n-6), DHA, and DPAn-6 as 2H5-ALA, 13C18-LNA, 13C22-DHA, and 13C22-DPAn-6. Eight 11-week-old Long Evans rats fed a 10% fat diet were infused with the labeled PUFAs over 3 h, and plasma enrichment of labeled products was measured every 30 min. The DHA synthesis-secretion rate (94 ± 34 nmol/day) did not differ from other PUFA products (range, 21.8 ± 4.3 nmol/day to 408 ± 116 nmol/day). Synthesis-secretion rates of n-6 and n-3 PUFA homologs were similar, except 22:4n-6 and DPAn-6 had lower synthesis rates. However, daily turnover from newly synthesized DHA (0.067 ± 0.023%) was 56-fold to 556-fold slower than all other PUFA turnover and was 130-fold slower than that determined directly from the total plasma unesterified DHA pool. In conclusion, n-6 and n-3 PUFA synthesis-secretion kinetics suggest that differences in turnover, not in synthesis-secretion rates, primarily determine PUFA plasma levels.

Fish oil feeding attenuates neuroinflammatory gene expression without concomitant changes in brain eicosanoids and docosanoids in a mouse model of Alzheimer's disease.

BACKGROUND: Neuroinflammation is a recognized hallmark of Alzheimer's disease, along with accumulation of amyloid-ß plaques, neurofibrillary tangles and synaptic loss. n-3 polyunsaturated fatty acids (PUFA) and molecules derived from them, including eicosapentaenoic acid-derived eicosanoids and docosahexaenoic acid-derived docosanoids, are known to have both anti-inflammatory and pro-resolving properties, while human observational data links consumption of these fatty acids to a decreased risk of Alzheimer's disease. Few studies have examined the neuroinflammation-modulating effects of n-3 PUFA feeding in an Alzheimer's disease-related model, and none have investigated whether these effects are mediated by changes in brain eicosanoids and docosanoids. Here, we use both a fat-1 transgenic mouse and a fish oil feeding model to study the impact of increasing tissue n-3 PUFA on neuroinflammation and the production of pro-inflammatory and pro-resolving lipid mediators. METHODS: Fat-1 mice, transgenic animals that can convert n-6 to n-3 PUFA, and their wildtype littermates were fed diets containing either fish oil (high n-3 PUFA) or safflower oil (negligible n-3 PUFA) from weaning to 12 weeks. Animals then underwent intracerebroventricular infusion of either amyloid-ß 1-40 or a control peptide. Hippocampi were collected from non-surgery and surgery animals 10 days after infusion. Microarray was used to measure enrichment of inflammation-associated gene categories and expression of genes involved in the synthesis of lipid mediators. Results were validated by real-time PCR in a separate cohort of animals. Lipid mediators were measured via liquid chromatography tandem mass spectrometry. RESULTS: Fat-1 and wildtype mice fed fish oil had higher total hippocampal DHA than wildtype mice fed the safflower oil diet. The safflower-fed mice, but not the fat-1 or fish oil-fed mice, had significantly increased expression in gene ontology categories associated with inflammation in response to amyloid-ß infusion. These effects were independent of changes in the expression of genes involved in the synthesis of eicosanoids or docosanoids in any group. Gene expression was replicated upon validation in the wildtype safflower and fish oil-fed, but not the fat-1 mice. Protectin, maresin and D and E series resolvins were not detected in any sample. There were no major differences in levels of other eicosanoids or docosanoids between any of the groups in response to amyloid-ß infusion. CONCLUSIONS: Fish oil feeding decreases neuroinflammatory gene expression in response to amyloid-ß. Neither amyloid-ß infusion or increasing brain DHA affects the brain concentrations of specialized pro-resolving mediators in this model, or the concentrations of most other eicosanoids and docosanoids.

Docosahexaenoic acid (DHA) accretion in the placenta but not the fetus is matched by plasma unesterified DHA uptake rates in pregnant Long Evans rats.

Maternal delivery of docosahexaenoic acid (DHA, 22:6n-3) to the developing fetus via the placenta is required for fetal neurodevelopment, and is the only mechanism by which DHA can be accreted in the fetus. The aim of the current study was to utilize a balance model of DHA accretion combined with kinetic measures of serum unesterified DHA uptake to better understand the mechanism by which maternal DHA is delivered to the fetus via the placenta. Female rats maintained on a 2% α-linolenic acid diet free of DHA for 56 days were mated, and for balance analysis, sacrificed at 18 days of pregnancy, and fetus, placenta and maternal carcass fatty acid concentration were determined. For tissue DHA uptake, pregnant dams (14-18 days) were infused for 5 min with radiolabeled 14C-DHA and kinetic modeling was used to determine fetal and placental serum unesterified DHA uptake rates. DHA accretion rates in the fetus were determined to be 38 ± 2 nmol/d/g, 859 ± 100 nmol/d/litter and 74 ± 3 nmol/d/pup, which are all higher (P < 0.05) than the fetal serum unesterified DHA uptake rates of 16 ± 6 nmol/d/g, 239 ± 145 nmol/d/litter and 14 ± 8 nmol/d/pup. No differences (p > 0.05) in placental DHA accretion rates versus serum unesterified DHA uptake rates were observed as values varied only 6-35% between studies. No differences in placental accretion and uptake rates suggests that serum unesterified DHA is a significant pool for the maternal-placental transfer of DHA, and lower fetal DHA uptake compared to accretion supports remodeling of placental DHA for delivery to the fetus.

Maternal liver docosahexaenoic acid (DHA) stores are increased via higher serum unesterified DHA uptake in pregnant long Evans rats.

Maternal docosahexaenoic acid (DHA, 22:6n-3) supplies the developing fetus during pregnancy; however, the mechanisms are unclear. We utilized pregnant rats to determine rates of DHA accretion, tissue unesterified DHA uptake and whole-body DHA synthesis-secretion. Female rats maintained on a DHA-free, 2% α-linolenic acid diet were either:1) sacrificed at 56 days for baseline measures, 2) mated and sacrificed at 14-18 days of pregnancy or 3) or sacrificed at 14-18 days as age-matched virgin controls. Maternal brain, adipose, liver and whole body fatty acid concentrations was determined for balance analysis, and kinetic modeling was used to determine brain and liver plasma unesterified DHA uptake and whole-body DHA synthesis-secretion rates. Total liver DHA was significantly higher in pregnant (95±5 µmol) versus non-pregnant (49±5) rats with no differences in whole-body DHA synthesis-secretion rates. However, liver uptake of plasma unesterified DHA was 3.8-fold higher in pregnant animals compared to non-pregnant controls, and periuterine adipose DHA was lower in pregnant (0.89±0.09 µmol/g) versus non-pregnant (1.26±0.06) rats. In conclusion, higher liver DHA accretion during pregnancy appears to be driven by higher unesterified DHA uptake, potentially via DHA mobilization from periuterine adipose for delivery to the fetus during the brain growth spurt.

Whole-Body Docosahexaenoic Acid Synthesis-Secretion Rates in Rats Are Constant across a Large Range of Dietary α-Linolenic Acid Intakes.

BACKGROUND: Docosahexaenoic acid (DHA) is an ω-3 (n-3) polyunsaturated fatty acid (PUFA) thought to be important for brain function. Although the main dietary source of DHA is fish, DHA can also be synthesized from α-linolenic acid (ALA), which is derived from plants. Enzymes involved in DHA synthesis are also active toward ω-6 (n-6) PUFAs to synthesize docosapentaenoic acid n-6 (DPAn-6). It is unclear whether DHA synthesis from ALA is sufficient to maintain brain DHA. OBJECTIVE: The objective of this study was to determine how different amounts of dietary ALA would affect whole-body DHA and DPAn-6 synthesis rates. METHODS: Male Long-Evans rats were fed an ALA-deficient diet (ALA-D), an ALA-adequate (ALA-A) diet, or a high-ALA (ALA-H) diet for 8 wk from weaning. Dietary ALA concentrations were 0.07%, 3%, and 10% of the fatty acids, and ALA was the only dietary PUFA that differed between the diets. After 8 wk, steady-state stable isotope infusion of labeled ALA and linoleic acid (LA) was performed to determine the in vivo synthesis-secretion rates of DHA and DPAn-6. RESULTS: Rats fed the ALA-A diet had an ∼2-fold greater capacity to synthesize DHA than did rats fed the ALA-H and ALA-D diets, and a DHA synthesis rate that was similar to that of rats fed the ALA-H diet. However, rats fed the ALA-D diet had a 750% lower DHA synthesis rate than rats fed the ALA-A and ALA-H diets. Despite enrichment into arachidonic acid, we did not detect any labeled LA appearing as DPAn-6. CONCLUSIONS: Increasing dietary ALA from 3% to 10% of fatty acids did not increase DHA synthesis rates, because of a decreased capacity to synthesize DHA in rats fed the ALA-H diet. Tissue concentrations of DPAn-6 may be explained at least in part by longer plasma half-lives.