Conversion Of Alpha-linolenic Acid Research Articles

Assessment of omega-3 and omega-6 fatty acid profiles and ratio of omega-6/omega-3 of white eggs produced by laying hens fed diets enriched with omega-3 rich vegetable oil

Abstract The aim of this study was to evaluate the levels of omega-3 (n-3) and omega-6 (n-6) fatty acids in egg and the ratio of n-6/n-3 of white eggs produced by laying hens (Hy-Line white) fed diets enriched with n-3 fats. In this study, alpha-linolenic acid (ALA) levels of the dietary treatments ranged from 0.3 to 6% energy. Grain-based diets containing a low linoleic acid (LA) content were selected to prepare a basal diet to optimize the conversion of ALA into n-3 long chain polyunsaturated fatty acids (LCPUFA). The results showed that the level of all n-3 LCPUFA in eggs improved (P < 0.01) by increasing the levels of dietary ALA. Importantly, eggs produced from laying hens fed diets containing 6%en ALA significantly increased (P < 0.01) the total of n-3 fats by approximately nine-fold. Diets enriched with ALA significantly reduced (P < 0.01) the ratio of n-6/n-3 of the eggs. The n-6/n-3 ratio of eggs decreased from 7.17% in the 0.3%en ALA diet to 1.29% in the 6%en ALA diet. In conclusion, white laying hens fed ALA-enriched diets produced eggs higher in n-3 fatty acids and lower n-6/n-3 ratio, which provides an alternative n-3 rich food for consumers and have beneficial health effects.

Patterns of alpha-linolenic acid incorporation into phospholipids in H4IIE cells

Alpha linolenic acid (ALA) is an 18-carbon essential fatty acid found in plant-based foods and oils. While much attention has been placed on conversion of ALA to long chain polyunsaturated fatty acids, alternative routes of ALA metabolism exist and may lead to formation of other bioactive metabolites of ALA. The current study employed a non-targeted metabolomics approach to profile ALA metabolites that are significantly upregulated by ALA treatment. H4IIE hepatoma cells (n=3 samples per time point) were treated with 60 μM ALA or vehicle for 0, 0.25, 0.5, 1, 2, 3, 4, 6, 8, and 12 h. Samples were then extracted with methanol and analyzed using high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. We observed selective changes in ALA incorporation into phospholipid classes and subclasses over the 12 h following ALA treatment. While levels of specific molecular species of ALA-containing phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and lysophospholipids were elevated with ALA treatment, others were not affected. Of the phospholipids that were increased, some (e.g., PC[18:3/18:1], PC[18:3/18:4], PE[18:3/18:2], PE[18:3/18:3]) were elevated almost immediately after exposure to ALA, while others [e.g., PE[18:1/18:3] PA[18:3/22:6], and PA[18:3/18:2]) were not elevated until several hours after ALA treatment. Overall, these results suggest that ALA incorporation into phospholipids is selective and support a metabolic hierarchy for ALA incorporation into specific phospholipids. Given the functionality of phospholipids based on their fatty acid composition, future studies will need to investigate the implications of ALA incorporation into specific phospholipids on cell function.

Alpha-Linolenic and Linoleic Fatty Acids in the Vegan Diet: Do They Require Dietary Reference Intake/Adequate Intake Special Consideration?

Good sources of the long-chain n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) include cold-water fish and seafood; however, vegan diets (VGNs) do not include animal-origin foods. Typically, US omnivores obtain enough dietary EPA and DHA, but unless VGNs consume algal n-3 supplements, they rely on endogenous production of long-chain fatty acids. VGN diets have several possible concerns: (1) VGNs have high intakes of linoleic acid (LA) as compared to omnivore/non-vegetarian diets. (2) High intakes of LA competitively interfere with the endogenous conversion of alpha-linolenic acid (ALA) to EPA and DHA. (3) High somatic levels of LA/low ALA indicate a decreased ALA conversion to EPA and DHA. (4) Some, not all VGNs meet the Dietary Reference Intake Adequate Intake (DRI-AI) for dietary ALA and (5) VGN diets are high in fiber, which possibly interferes with fat absorption. Consequently, health professionals and Registered Dietitians/Registered Dietitian Nutritionists working with VGNs need specific essential fatty acid diet guidelines. The purpose of this review was: (1) to suggest that VGNs have a DRI-AI Special Consideration requirement for ALA and LA based on VGN dietary and biochemical indicators of status and (2) to provide suggestions to ensure that VGNs receive adequate intakes of LA and ALA.

Effect of 1- and 2-Month High-Dose Alpha-Linolenic Acid Treatment on 13 C-Labeled Alpha-Linolenic Acid Incorporation and Conversion in Healthy Subjects.

ScopeThe study aims at identifying 1) the most sensitive compartment among plasma phospholipids, erythrocytes, and LDL for studying alpha‐linolenic acid (ALA) conversion, and 2) whether ALA incorporation and conversion is saturable after administration of 13C‐labeled ALA‐rich linseed oil (LO). The effect of a daily intake of 7 g nonlabeled LO (>43% w/w ALA) for 1 month after bolus administration of 7 g 13C‐labeled LO on day 1, and for 2 months after bolus administration of 7 g 13C‐labeled LO on day 1 and day 29 on 13C‐ALA incorporation and conversion into its higher homologs is investigated in healthy volunteers.Methods and resultsIncorporation and conversion of LO‐derived 13C‐labeled ALA is quantified by applying compartmental modeling. After bolus administration, a fractional conversion of approximately 30% from 13C‐ALA to 13C‐DHA is calculated as reflected by the LDL compartment. Treatment with LO for 8 weeks induces a mean reduction of 13C‐ALA conversion to 13C‐DHA by 48% as reflected by the LDL compartment, and a mean reduction of the 13C‐ALA incorporation into LDL by 46%.ConclusionA 2‐month dietary intake of a high dose of LO is sufficient to reach saturation of ALA incorporation into LDL particles, which are responsible for ALA distribution in the body.

Supplemental flaxseed modulates ovarian functions of weanling gilts via the action of selected fatty acids

The aim of this study was to examine the influence of dietary flaxseed on the endocrine and ovarian functions of weanling gilts challenged with E. coli and Coronavirus infections treated with dietary probiotic cheeses and to understand the possible mechanisms of its effects on ovarian function. Probiotics were used as a natural substitution for antibiotics and 10% dietary flaxseed is an effective prebiotic which supports the action of probiotics and has other beneficial effects on the organism. Probiotics with or without flaxseed were fed to weanling gilts starting 10 days before and lasting up until 14 days after weaning. The ovaries were measured and histologically analysed. The blood samples for the levels of steroid hormones and insulin-like growth factor I (IGF-I) were assessed using immunoassays and the levels of fatty acids were assessed using gas chromatography. All samples were collected on the day of weaning and 14 days after weaning. On the day of weaning, increased levels of linoleic acid and IGF-I was associated with higher body weight. The steroid hormones were not affected by the diet. The conversion of alpha-linolenic acid (ALA) to timodonic (EPA) and cervonic (DHA) acids were lower compared to controls, and together with high levels of myristic, palmitic and palmitoleic acids was associated with the higher proliferation and lower apoptosis in the primordial, primary and secondary follicles; although the inhibition of the cell cycle was observed in relation to the low level of eicosadienoic acid. The high levels of ALA, EPA and DHA and the low levels of myristic, palmitic and palmitoleic acids may have been the effect of flaxseed feeding 14 days post-weaning and may have had a reverse effect on the proliferation and apoptosis of ovarian follicles. These data suggest that flaxseed may suppress the follicle development in weanlings via the stimulation of apoptosis and the inhibition of proliferation via the modulation of the metabolism of selected fatty acids.

The Influence of Probiotic Lactobacilli and Flaxseed on the Health of Weaned Piglets and Metabolism of Polyunsaturated Fatty Acids (PUFAs)

Abstract This study investigated for 14 days post-weaning, the influence of dietary supplementation of synbiotics in the form of probiotic cheeses containing cultures of L. plantarum and L. fermentum and crushed flaxseed (source of ω-3 polyunsaturated fatty acids — PUFAs and fibre) on 36 commercial piglets originating from an infected herd (Coronavirus and E. coli) during the critical period of weaning. We focused on the health and metabolism of PUFAs in this critical period of a piglet’s life. The dietary supplementation positively affected: the overall health state of weaners, reduced diarrhoea by 29 % by 14 days post-weaning and significantly increased the counts of lactic acid bacteria, bifidobacteria and the production of volatile fatty acids. The PUFA concentrations in the m. biceps femoris of the piglets were analysed by gas chromatography. High levels of ω-3 alpha-linolenic acid (ALA) in flaxseed increased significantly the level of ALA, eicosapentaenic acid (EPA) and docosahexaenic acid (DHA) in the pig muscles on days 7 and 14 post-weaning. The levels of ω-6 linolenic acid (LA) were less affected by the diet, but were increased on day 14 post-weaning, while the conversion products of LA, and arachidonic acid (AA), were decreased on days 7 and 14. The increased level of dietary ALA favoured the activity of Δ-6-desaturase for the conversion of ALA to EPA and DHA, at the expense of AA synthesis from LA. The ability of synbiotics to incorporate high levels of DHA in the pig muscles appear prospective for improving the nutritional properties of pork and reducing the occurrence of civilization diseases in consumers of this product of animal origin.

Increasing Levels of Dietary Hempseed Products Leads to Differential Responses in the Fatty Acid Profiles of Egg Yolk, Liver and Plasma of Laying Hens.

The limited efficiency with which dietary alpha-linolenic acid (ALA) is converted by hens into docosahexaenoic acid (DHA) for egg deposition is not clearly understood. In this study, dietary ALA levels were increased via the inclusion of hempseed (HS) and hempseed oil (HO) in hen diets, with the goal of assessing the effects on the fatty acid (FA) profiles of total lipids and lipid classes in yolk, liver and plasma. Forty-eight hens were individually caged and fed one of six diets containing either HS:10, 20 or 30, HO:4.5 or 9.0 (%, diet) or a control (containing corn oil), providing a range (0.1-1.28%, diet) of ALA. Fatty acid methyl esters of total lipids and lipid classes, including phosphatidyl choline (PtdCho) and ethanolamine (PtdEtn) in yolk, plasma and liver were then determined. Levels of n-3 FAs in both total lipids and lipid classes increased in all tissues. ALA and eicosapentaenoic acid (EPA) increased linearly, while docosapentaenoic acid and DHA increased quadratically. The FA profiles of yolk closely reflected levels in both plasma and liver. While ALA was highly concentrated in the triacylglycerol, it was low but equally distributed between PtdCho and PtdEtn in all tissues; however, the net accumulation was lower (P<0.0001) in liver compared to yolk and plasma. Levels of EPA and ALA in yolk-PtdEtn were linearly (P<0.0001; R (2)=0.93) associated, and reflected those in liver-PtdEtn (P<0.0001; R (2)=0.90). In the liver, a strong inverse correlation (P<0.0001; r=-0.94) between PL-DHA and ALA-to-EPA ratio in PtdEtn supports theories of low substrate availability, possibly limiting the conversion of ALA into DHA for egg enrichment.

FADS2 genotype influences whole-body resting fat oxidation in young adult men.

Considerable evidence supports an association between fatty acid desaturase 2 (FADS2) polymorphisms and the efficiency of converting alpha-linolenic acid (ALA) into eicosapentaenoic acid (EPA) via the desaturation-elongation pathway. However, ALA conversion into EPA represents only 1 of the metabolic fates for this essential fatty acid, as ALA is also highly oxidized. This study demonstrates for the first time that genetic variation in FADS2 (rs174576) is not only associated with the activity of the desaturation-elongation pathway, but also whole-body fat oxidation.

The application of probiotics and flaxseed promotes metabolism of n-3 polyunsaturated fatty acids in pigs

ABSTRACTThe effect of combining probiotics (Lactobacillus plantarum and Lactobacillus fermentum) with flaxseed (a source of n-3 PUFAs) on the lipid metabolism and long-chain fatty acid profile of conventional piglets after weaning was studied. The levels of total lipids and high-density lipoproteins cholesterol decreased from Day 7 post-weaning, whereas levels of low-density lipoproteins cholesterol, total cholesterol and triglycerides did not change significantly in piglets with supplemented diet. The levels of alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increased seven days post-weaning; however, the levels of dihomogamma-linolenic acid and arachidonic acid (AA) were lower and linoleic acid (LA) higher in synbioticsfed piglets compared with controls. This study demonstrates the efficacy of conversion of ALA to EPA and DHA, where delta-6-desaturase was predominantly used for n-3 polyunsaturated fatty acid synthesis from ALA at the expense of n-6 PUFAs from LA, which caused rapid increase in EPA/AA ratio on Day 14 after weaning. Combination of probiotic cheese and flaxseed is a good dietary supplement for piglets before weaning, helping them to adapt to change in diet more easily by regulating changes in lipid metabolism and vitality, and reducing the likelihood of chronic diseases.

Long-chain polyunsaturated fatty acid (LCPUFA) requirement for brain development: A personal view

Dietary docosahexaenoic acid (DHA) is known to accumulate in the infant brain and clinical trials have established that dietary DHA is associated with improvements in visual and neural function in preterm infants. Thus, an elevated DHA status is considered to be important throughout infancy for brain development. While DHA can be added directly to infant foods, there have been important studies to show that infants can partially meet their own DHA requirements by consuming adequate levels of omega 3 alpha linolenic acid (ALA). A key requirement to allow for the conversion of ALA to DHA and to maximise its incorporation into tissues is a diet that is also low in omega 6 linoleic acid (LA). Such diets are hard to find commercially because dietary guidelines dictate that ~3% energy of infant diets should be in the form of LA. These estimates were based on early animal experiments in which basal diets were devoid of both LA and ALA. However, recent animal experiments have indicated that the level of LA required to avoid essential fatty acid deficiency is much lower when ALA is also present in the diet. When a wide range diets are evaluated in animal systems, it is possible to see that the level of DHA found in the blood of animals fed diets containing only LA and ALA can reach levels similar to that of animals fed diets rich in fish oil, but only when the ALA:LA ratio is high and the total amount of dietary polyunsaturated fatty acids (PUFA) is low. Diets that are rich in either monounsaturates or saturates meet these requirements. Importantly, there are human infant studies that have tested such diets and demonstrated that human infants accumulate greater amounts of DHA than when diets are high in LA. It might be time to reconsider the dietary requirement of the two essential fatty acids LA and ALA in human infants in terms of their ability to enhance endogenous synthesis of DHA rather than more adult biomarkers like cholesterol levels.

Providing male rats deficient in iron and n-3 fatty acids with iron and alpha-linolenic acid alone affects brain serotonin and cognition differently from combined provision.

BackgroundWe recently showed that a combined deficiency of iron (ID) and n-3 fatty acids (n-3 FAD) in rats disrupts brain monoamine metabolism and produces greater memory deficits than ID or n-3 FAD alone. Providing these double-deficient rats with either iron (Fe) or preformed docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) alone affected brain monoamine pathways differently from combined repletion and even exacerbated cognitive deficits associated with double-deficiency. Iron is a co-factor of the enzymes responsible for the conversion of alpha-linolenic acid (ALA) to EPA and DHA, thus, the provision of ALA with Fe might be more effective in restoring brain EPA and DHA and improving cognition in double-deficient rats than ALA alone.MethodsIn this study we examined whether providing double-deficient rats with ALA and Fe, alone or in combination, can correct deficits in monoamine metabolism and cognition associated with double-deficiency. Using a 2 × 2 design, male rats with concurrent ID and n-3 FAD were fed an Fe + ALA, Fe + n-3 FAD, ID + ALA, or ID + n-3 FAD diet for 5 weeks (postnatal day 56–91). Biochemical measures, and spatial working and reference memory (using the Morris water maze) were compared to age-matched controls.ResultsIn the hippocampus, we found a significant Fe × ALA interaction on DHA: Compared to the group receiving ALA alone, DHA was significantly higher in the Fe + ALA group. In the brain, we found significant antagonistic Fe × ALA interactions on serotonin concentrations. Provision of ALA alone impaired working memory compared with age-matched controls, while in the reference memory task ALA provided with Fe significantly improved performance.ConclusionThese results indicate that providing either iron or ALA alone to double-deficient rats affects serotonin pathways and cognitive performance differently from combined provision. This may be partly explained by the enhancing effect of Fe on the conversion of ALA to EPA and DHA.

Fats and Factors: Lipid Profiles Associate with Personality Factors and Suicidal History in Bipolar Subjects

Polyunsaturated fatty acids (PUFA) have shown efficacy in the treatment of bipolar disorder, however their specific role in treating the illness is unclear. Serum PUFA and dietary intakes of PUFA associate with suicidal behavior in epidemiological studies. The objective of this study was to assess serum n-3 and n-6 PUFA levels in bipolar subjects and determine possible associations with suicidal risk, including suicidal history and relevant personality factors that have been associated with suicidality. We studied 27 bipolar subjects using the NEO-PI to assess the big five personality factors, structured interviews to verify diagnosis and assess suicidal history, and lipomics to quantify n-3 and n-6 PUFA in serum. We found positive associations between personality factors and ratios of n-3 PUFA, suggesting that conversion of short chain to long chain n-3s and the activity of enzymes in this pathway may associate with measures of personality. Thus, ratios of docosahexaenoic acid (DHA) to alpha linolenic acid (ALA) and the activity of fatty acid desaturase 2 (FADS2) involved in the conversion of ALA to DHA were positively associated with openness factor scores. Ratios of eicosapentaenoic acid (EPA) to ALA and ratios of EPA to DHA were positively associated with agreeableness factor scores. Finally, serum concentrations of the n-6, arachidonic acid (AA), were significantly lower in subjects with a history of suicide attempt compared to non-attempters. The data suggest that specific lipid profiles, which are controlled by an interaction between diet and genetics, correlate with suicidal history and personality factors related to suicidal risk. This study provides preliminary data for future studies to determine whether manipulation of PUFA profiles (through diet or supplementation) can affect personality measures and disease outcome in bipolar subjects and supports the need for further investigations into individualized specific modulations of lipid profiles to add adjunctive value to treatment paradigms.

Influence of duration of supplementation with ruminally protected linseed oil on the fatty acid composition of feedlot lambs

A feeding experiment was conducted to determine if the duration of supplementation of lambs with protected linseed oil (PLO) affected the apparent conversion of alpha linolenic acid (ALA) into the longer chain n-3 polyunsaturated fatty acids PUFA (n-3 PUFA): eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Forty-eight 4-month-old Merino lambs with mean initial live weights of 29.5 ± 0.27 kg were divided into four groups of 12 and randomly assigned to 0PLO, 3PLO, 6PLO or 9PLO treatments corresponding to 0, 3, 6 and 9 weeks of PLO supplementation, respectively. At slaughter, all groups had similar live weight (37–40 kg), hot carcass weight (15–16 kg) and ultimate pH (5.76–5.85). The intramuscular fat content was lower ( P<0.01) in 0PLO (2.26 g) than the supplemented group (2.94–3.12 g/100 g muscle); there was no difference among supplemented groups. Increases in ALA and total n-3 PUFA content in the intramuscular fat of the Longissimus dorsi muscle were greatest in the first three weeks. PLO increased ( P<0.05) the concentrations of ALA, docosapentaenoic acid (DPA) and DHA in L. dorsi; changes in EPA were not significant. The total n-3 (mg/100 g muscle) content was higher in the supplemented group ( P<0.01) than in 0PLO; but did not differ among the supplemented groups. The treatment means were 46, 75, 91 and 94 mg/100 g for 0PLO, 3PLO, 6PLO and 9PLO, respectively. The sum of EPA and DHA, which forms the criterion for health claim, was 17 mg for 0PLO, which was lower ( P<0.05) than that for 3PLO (21 mg), 6PLO (27 mg) and 9PLO (31 mg/100 g muscle). Only the 9PLO value met the 30 mg cut-off point for “source” claim under Australian guidelines. Consumer panel ratings were not different ( P>0.05) between treatments. The PLO supplement was effective in significantly enriching lamb meat with n-3 PUFA in three weeks, but longer periods were required to increase the levels of the longer chain PUFAs that are required for “source claim” and product differentiation.

Quantitation of alpha-linolenic acid elongation to eicosapentaenoic and docosahexaenoic acid as affected by the ratio of n6/n3 fatty acids

BackgroundConversion of linoleic acid (LA) and alpha-linolenic acid (ALA) to their higher chain homologues in humans depends on the ratio of ingested n6 and n3 fatty acids.Design and methodsIn order to determine the most effective ratio with regard to the conversion of ALA to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), human hepatoma cells were incubated with varying ratios of [13C] labeled linoleic acid ([13C]LA)- and alpha-linolenic acid ([13C]ALA)-methylesters. Regulative cellular signal transduction pathways involved were studied by determinations of transcript levels of the genes encoding delta-5 desaturase (D5D) and delta-6 desaturase (D6D), peroxisome proliferator-activated receptor alpha (PPARα) and sterol regulatory element binding protein 1c (SREBP-1c). Mitogen-activated protein kinase kinase 1 (MEK1) and mitogen-activated protein kinase kinase kinase 1 (MEKK1) were also examined.ResultsMaximum conversion was observed in cells incubated with the mixture of [13C]LA/[13C]ALA at a ratio of 1:1, where 0.7% and 17% of the recovered [13C]ALA was converted to DHA and EPA, respectively. Furthermore, differential regulation of enzymes involved in the conversion at the transcript level, dependent on the ratio of administered n6 to n3 fatty acids in human hepatocytes was demonstrated.ConclusionFormation of EPA and DHA was highest at an administered LA/ALA ratio of 1:1, although gene expression of PPARα, SREBP-1c and D5D involved in ALA elongation were higher in the presence of ALA solely. Also, our findings suggest that a diet-induced enhancement of the cell membrane content of highly unsaturated fatty acids is only possible up to a certain level.

Confusion over different types of n‐3 polyunsaturated fatty acids

AbstractThere are two kinds of n‐3 polyunsaturated fatty acid (PUFA). Alpha‐linolenic acid (ALA) is the parent n‐3 PUFA; it cannot be synthesized by the human body and as a result is an essential fatty acid. The two long chain n‐3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can in principle be synthesized from ALA or obtained from the diet. While the cardioprotective effects of long chain n‐3 PUFA are well established the effects of ALA on the cardiovascular system are more controversial. The Lyon Diet Heart Study which it is claimed provides evidence for beneficial effects of ALA on the cardiovascular system is flawed. The argument that ALA conversion into EPA and DHA provides significant quantities of the two long chain n‐3 PUFA is unsustainable as rates of conversion are too low. To avoid confusion a distinction needs to be drawn between ALA and the long chain n‐3 PUFA. Health claims for foods rich in EPA and DHA cannot be extended to foods rich in ALA nor is ALA a substitute for EPA and DHA in vegetarian diets.

The effect of age and gender on current and potential intakes of very long chain n-3 polyunsaturated fatty acids from oil-rich fish and animal derived foods in the UK

The health benefits of consuming sufficient very long chain n-3 polyunsaturated fatty acids (VLC n-3 PUFA) such as EPA (C20:5) and DHA (C22:6) are well established. A key supplier of these fatty acids is oil-rich fish, however a recent study relating to UK adults indicated that only 27% of the population consume oil-rich fish and current intakes of VLC n-3 PUFA are substantially sub-optimal (Givens and Gibbs, 2006). There is also evidence to indicate that in vivo conversion of alpha linolenic acid (C18:3 n-3) to EPA and DHA is limited and highlights the need for an increased supply of preformed EPA and DHA in the diet. The role of animal-derived foods in the supply of VLC n-3 PUFA has been identified and emphasis has been placed on the need to enrich foods such as poultry meat which are widely consumed in order to make a valuable contribution to the supply of EPA and DHA to those with low or zero oil-rich fish consumption. However the effect of age and gender on intakes remained unclear. The objective of this study was to investigate the effect of age and gender on oil-rich fish consumption.

Dietary fish intake and plasma phospholipid n–3 polyunsaturated fatty acid concentrations in men and women in the European Prospective Investigation into Cancer–Norfolk United Kingdom cohort

The n-3 polyunsaturated fatty acids (n-3 PUFAs) docosahexaenoic acid and eicosapentaenoic acid, found in fish and fish-oil supplements and also formed by conversion of alpha-linolenic acid in soy and rapeseed (canola) oils, are thought to have cardioprotective effects. Because the relative feasibility and measurement error of dietary methods varies, this study compared fish and fish-oil intakes obtained from 4 dietary methods with plasma n-3 PUFAs in men and women in a general population. The study participants were 4949 men and women aged 40-79 y from the European Prospective Investigation into Cancer-Norfolk United Kingdom cohort. Measurements of plasma phospholipid n-3 PUFA concentrations and fish intakes were made with the use of 4 dietary methods (food-frequency questionnaire, health and lifestyle questionnaire, 7-d diary, and first-day recall from the 7-d diary). Amounts of fish consumed and relations with plasma phospholipid n-3 PUFAs were not substantially different between the 4 dietary methods. Plasma n-3 PUFA concentrations were significantly higher in women than in men, were 20% higher in fish-oil consumers than in non-fish-oil consumers, and were twice as high in fatty fish consumers as in total fish consumers. Only approximately 25% of the variation in plasma n-3 PUFA was explained by fish and fish-oil consumption. This large study found no substantial differences between dietary methods and observed clear sex differences in plasma n-3 PUFAs. Because variation in n-3 PUFA was only partially determined by fish and fish-oil consumption, this could explain the inconsistent results of observational and intervention studies on coronary artery disease protection.

Omega 6 to omega 3 fatty acid imbalance early in life leads to persistent reductions in DHA levels in glycerophospholipids in rat hypothalamus even after long-term omega 3 fatty acid repletion

Failure to provide omega 3 fatty acids in the perinatal period results in alterations in nerve growth factor levels, dopamine production and permanent elevations in blood pressure. The present study investigated whether changes in brain (i.e., hypothalamus) glycerophospholipid fatty acid profiles induced by a diet rich in omega 6 fatty acids and very low in alpha-linolenic acid (ALA) during pregnancy and the perinatal period could be reversed by subsequent feeding of a diet containing ALA. Female rats (6 per group) were mated and fed either a low ALA diet or a control diet containing ALA throughout pregnancy and until weaning of the pups at 3 weeks. At weaning, the pups (20 per group) remained on the diet of their mothers until 9 weeks, when half the pups were switched onto the other diet, thus generating four groups of animals. At 33 weeks, pups were killed, the hypothalamus dissected from the male rats and analysed for glycerophospholipid fatty acids. In the animals fed the diet with very little ALA and then re-fed the control diet containing high levels of ALA for 24 weeks, the DHA levels were still significantly less than the control values in PE, PS and PI fractions, by 9%, 18% and 34%, respectively. In this group, but not in the other dietary groups, ALA was detected in all glycerophospholipid classes at 0.2–1.7% of the total fatty acids. The results suggest that omega 6–3 PUFA imbalance early in life leads to irreversible changes in hypothalamic composition. The increased ALA and reduced DHA proportions in the animals re-fed ALA in later life are consistent with a dysfunction or down-regulation of the conversion of ALA to 18:4n-3 by the delta-6 desaturase.

A common deletion in the promoter of the delta‐6 desaturase gene is associated with high plasma triglycerides and low arachidonic acid and EPA in tissues

We studied 1384 population-based free-living Costa Ricans to examine a common deletion [T/-] in the promoter of the delta-6 desaturase gene (FADS2) that may affect the efficiency of conversion of linoleic and alpha-linolenic acid (ALA) into long-chain PUFA. Subjects completed a food-frequency questionnaire and donated blood and adipose tissue samples. PUFA from adipose tissue (N=1384) and plasma (N=200) were quantified by gas-liquid chromatography. Least square means from generalized linear models adjusted for potential confounders were used to estimate the association between FADS2 genotypes and plasma triglycerides, adipose tissue and plasma PUFA. The prevalence of the variant allele was 49.2%. Adipose tissue PUFA for homozygous for the wild type [TT], heterozygous [T −], and homozygous for the mutant [− −] were (% total FA): 0.52, 0.47, and 0.41 for arachidonic acid (p<0.0001), and 0.0389, 0.0386, and 0.0333 for EPA (p<0.0001). Similarly, in plasma they were 7.32, 6.03, and 4.46 for arachidonic acid (p<0.0001), and 0.49, 0.35, and 0.30 for EPA (N=63, p=0.06). On the other hand, adipose tissue and plasma 20:3n-3 and 20:2n-6 increased with the number of deletions (p-value <0.05 for all comparisons). Plasma triglycerides by genotype were 138 mg/dL, 147 mg/dL, and 155 mg/dL (p=0.036), after adjusting for intake of ALA, EPA, DHA, and other potential confounders. Our data suggest that the FADS2 deletion prevents the conversion of linoleic and ALA to long chain PUFA by decreasing the activity of delta-6 desaturase. The inverse association of FADS2 with 20:2n-6 and 20:3n-3 suggests an increased elongation of linoleic acid and ALA to these fatty acids, which represent dead-end products in the biosynthetic PUFA pathway. Because of its association with higher plasma triglycerides this common polymorphism may increase the risk of CHD.

Flaxseed Oil Increases the Plasma Concentrations of Cardioprotective (n-3) Fatty Acids in Humans

Alpha-linolenic acid (ALA) is a major dietary (n-3) fatty acid. ALA is converted to longer-chain (n-3) PUFA, such as eicosapentaenoic acid (EPA) and possibly docosahexaenoic acid (DHA). EPA and DHA are fish-based (n-3) fatty acids that have proven cardioprotective properties. We studied the effect of daily supplementation with 3 g of ALA on the plasma concentration of long-chain (n-3) fatty acids in a predominantly African-American population with chronic illness. In a randomized, double-blind trial, 56 participants were given 3 g ALA/d from flaxseed oil capsules (n = 31) or olive oil placebo capsules (n = 25). Plasma EPA levels at 12 wk in the flaxseed oil group increased by 60%, from 24.09 +/- 16.71 to 38.56 +/- 28.92 micromol/L (P = 0.004), whereas no change occurred in the olive oil group. Plasma docosapentaenoic acid (DPA) levels in the flaxseed oil group increased by 25% from 19.94 +/- 9.22 to 27.03 +/- 17.17 micromol/L (P = 0.03) with no change in the olive oil group. Plasma DHA levels did not change in either group. This study demonstrates the efficacy of the conversion of ALA to EPA and DPA in a minority population with chronic disease. ALA may be an alternative to fish oil; however, additional clinical trials with ALA are warranted.