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.     

Supplementing lactating women with flaxseed oil does not increase docosahexaenoic acid in their milk

BACKGROUND: Flaxseed oil is a rich source of 18:3n-3 (alpha-linolenic acid, or ALA), which is ultimately converted to 22:6n-3 (docosahexaenoic acid, or DHA), a fatty acid important for the development of the infant brain and retina. OBJECTIVE: The objective of this study was to determine the effect of flaxseed oil supplementation on the breast-milk, plasma, and erythrocyte contents of DHA and other n-3 fatty acids in lactating women. DESIGN: Seven women took 20 g flaxseed oil (10.7 g ALA) daily for 4 wk. Breast-milk and blood samples were collected weekly before, during, and after supplementation and were analyzed for fatty acid composition. RESULTS: Breast milk, plasma, and erythrocyte ALA increased significantly over time (P < 0.001) and after 2 and 4 wk of supplementation (P < 0.05). Over time, 20:5n-3 (eicosapentaenoic acid, or EPA) increased significantly in breast milk (P = 0.004) and in plasma (P < 0.001). In addition, plasma EPA increased significantly (P < 0.05) after 2 and 4 wk of supplementation. There were significant increases over time in breast-milk 22:5n-3 (docosapentaenoic acid, or DPA) (P < 0.02), plasma DPA (P < 0.001), and erythrocyte DPA (P < 0.01). No significant changes were observed in breast-milk, plasma, or erythrocyte DHA contents after flaxseed oil supplementation. CONCLUSIONS: Dietary flaxseed oil increased the breast-milk, plasma, and erythrocyte contents of the n-3 fatty acids ALA, EPA, and DPA but had no effect on breast-milk, plasma, or erythrocyte DHA contents.     

Effects of docosahexaenoic acid-rich n-3 fatty acid supplementation on cytokine release from blood mononuclear leukocytes: the OmegAD study

BACKGROUND: Dietary fish or fish oil rich in n-3 fatty acids (n-3 FAs), eg, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), ameliorate inflammatory reactions by various mechanisms. Whereas most studies have explored the effects of predominantly EPA-based n-3 FAs preparations, few have addressed the effects of n-3 FAs preparations with DHA as the main FA. OBJECTIVE: The objective was to determine the effects of 6 mo of dietary supplementation with an n-3 FAs preparation rich in DHA on release of cytokines and growth factors from peripheral blood mononuclear cells (PBMCs). DESIGN: In a randomized, double-blind, placebo-controlled trial, 174 Alzheimer disease (AD) patients received daily either 1.7 g DHA and 0.6 g EPA (n-3 FAs group) or placebo for 6 mo. In the present study blood samples were obtained from the 23 first randomized patients, and PBMCs were isolated before and after 6 mo of treatment. RESULTS: Plasma concentrations of DHA and EPA were significantly increased at 6 mo in the n-3 FAs group. This group also showed significant decreases of interleukin (IL)-6, IL-1beta, and granulocyte colony-stimulating factor secretion after stimulation of PBMCs with lipopolysaccharide. Changes in the DHA and EPA concentrations were negatively associated with changes in IL-1beta and IL-6 release for all subjects. Reductions of IL-1beta and IL-6 were also significantly correlated with each other. In contrast, this n-3 FA treatment for 6 mo did not decrease tumor necrosis factor-alpha, IotaL-8, IL-10, and granulocyte-macrophage colony-stimulating factor secretion. CONCLUSION: AD patients treated with DHA-rich n-3 FAs supplementation increased their plasma concentrations of DHA (and EPA), which were associated with reduced release of IL-1beta, IL-6, and granulocyte colony-stimulating factor from PBMCs. This trial was registered at clinicaltrials.gov as NCT00211159.     

Long-chain n-3 polyunsaturated fatty acids in plasma in British meat-eating, vegetarian, and vegan men

BACKGROUND: Plasma concentrations of long-chain n-3 polyunsaturated fatty acids are lower in vegetarians and in vegans than in omnivores. No data are available on whether these concentrations differ between long- and short-term vegetarians and vegans. OBJECTIVES: We compared plasma fatty acid composition in meat-eaters, vegetarians, and vegans and examined whether the proportions of eicosapentaenoic acid (20:5n-3; EPA), docosapentaenoic acid (22:5n-3; DPA), and docosahexaenoic acid (22:6n-3; DHA) were related to the subjects' duration of adherence to their diets or to the proportions of plasma linoleic acid (18:2n-6; LA) and alpha-linolenic acid (18:3n-3; ALA). DESIGN: The present cross-sectional study included 196 meat-eating, 231 vegetarian, and 232 vegan men in the United Kingdom. Information on anthropometry, diet, and smoking habits was obtained through a questionnaire. Total fatty acid composition in plasma was measured. RESULTS: The proportions of plasma EPA and DHA were lower in the vegetarians and in the vegans than in the meat-eaters, whereas only small differences were seen for DPA. Plasma EPA, DPA, and DHA proportions were not significantly associated with the duration of time since the subjects became vegetarian or vegan, which ranged from <1 y to >20 y. In the vegetarians and the vegans, plasma DHA was inversely correlated with plasma LA. CONCLUSIONS: The proportions of plasma long-chain n-3 fatty acids were not significantly affected by the duration of adherence to a vegetarian or vegan diet. This finding suggests that when animal foods are wholly excluded from the diet, the endogenous production of EPA and DHA results in low but stable plasma concentrations of these fatty acids.     

Diet (n-3) polyunsaturated fatty acid content and parity interact to alter maternal rat brain phospholipid fatty acid composition

Low tissue levels of (n-3) polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid [DHA, 22:6(n-3)], are implicated in postpartum depression. The effects of 1-4 sequential reproductive cycles on maternal brain phospholipid fatty acid composition were determined in female rats fed diets containing alpha-linolenic acid (ALA), containing ALA and pre-formed DHA (ALA+DHA), or lacking ALA (low-ALA). Virgin females, fed the diets for commensurate durations served as a control for reproduction. Whole-brain total phospholipid composition was determined at weaning by TLC/GC. A single reproductive cycle on the low-ALA diet decreased brain DHA content by 18% compared to ALA primiparas (P < 0.05), accompanied by incorporation of docosapentaenoic acid ((n-6) DPA, 22:5(n-6)) to 280% of ALA primiparas (P < 0.05). DHA was not further decreased after subsequent cycles; however, there was an additional increase in (n-6) DPA after the second cycle (P < 0.05). Brain DHA of virgin females fed the low-ALA diet for 27 wk decreased 15% (P < 0.05), but was accompanied by a more modest increase in (n-6) DPA than in parous low-ALA dams (P < 0.05). Virgin females and parous dams fed the diet containing ALA+DHA exhibited only minor changes in brain fatty acid composition. These observations demonstrate that brain DHA content of adult animals is vulnerable to depletion under dietary conditions that supply inadequate (n-3) PUFAs, that this effect is augmented by the physiological demands of pregnancy and lactation, and that maternal diet and parity interact to affect maternal brain PUFA status.     

Effects of olive oil and its fractions on oxidative stress and the liver's fatty acid composition in 2,4-Dichlorophenoxyacetic acid-treated rats

Background

Dietary long-chain polyunsaturated fatty acids (LC-PUFA) are of crucial importance for the development of neural tissues. The aim of this study was to evaluate the impact of a dietary supplementation in n-3 fatty acids in female rats during gestation and lactation on fatty acid pattern in brain glial cells phosphatidylethanolamine (PE) and phosphatidylserine (PS) in the neonates.

Methods

Sprague-Dawley rats were fed during the whole gestation and lactation period with a diet containing either docosahexaenoic acid (DHA, 0.55%) and eicosapentaenoic acid (EPA, 0.75% of total fatty acids) or α-linolenic acid (ALA, 2.90%). At two weeks of age, gastric content and brain glial cell PE and PS of rat neonates were analyzed for their fatty acid and dimethylacetal (DMA) profile. Data were analyzed by bivariate and multivariate statistics.

Results

In the neonates from the group fed with n-3 LC-PUFA, the DHA level in gastric content (+65%, P < 0.0001) and brain glial cell PE (+18%, P = 0.0001) and PS (+15%, P = 0.0009) were significantly increased compared to the ALA group. The filtered correlation analysis (P < 0.05) underlined that levels of dihomo-γ-linolenic acid (DGLA), DHA and n-3 docosapentaenoic acid (DPA) were negatively correlated with arachidonic acid (ARA) and n-6 DPA in PE of brain glial cells. No significant correlation between n-3 and n-6 LC-PUFA were found in the PS dataset. DMA level in PE was negatively correlated with n-6 DPA. DMA were found to occur in brain glial cell PS fraction; in this class DMA level was correlated negatively with DHA and positively with ARA.

Conclusion

The present study confirms that early supplementation of maternal diet with n-3 fatty acids supplied as LC-PUFA is more efficient in increasing n-3 in brain glial cell PE and PS in the neonate than ALA. Negative correlation between n-6 DPA, a conventional marker of DHA deficiency, and DMA in PE suggests n-6 DPA that potentially be considered as a marker of tissue ethanolamine plasmalogen status. The combination of multivariate and bivariate statistics allowed to underline that the accretion pattern of n-3 LC-PUFA in PE and PS differ.     

Validation of a food frequency questionnaire to assess intake of n-3 polyunsaturated fatty acids in subjects with and without major depressive disorder

The role of n-3 polyunsaturated fatty acids (PUFAs) in psychiatric illness is a topic of public health importance. This report describes development and biomarker validation of a 21-item, self-report food frequency questionnaire (FFQ) intended for use in psychiatric research to assess intake of α-linolenic acid (18:3n-3 [ALA]), docosahexaenoic acid (22:6n-3 [DHA]), and eicosapentaenoic acid (20:5n-3 [EPA]). In a cross-sectional study conducted from September 2006 to September 2008, sixty-one ethnically diverse adult participants with (n=34) and without (n=27) major depressive disorder completed this n-3 PUFA FFQ and provided a plasma sample. Plasma levels of n-3 PUFAs EPA and DHA, and n-6 PUFA arachidonic acid (20:4n-6 [AA]) were quantified by gas chromatography. Using Spearman's ρ, FFQ-estimated intake correlated with plasma levels of DHA (r=0.50; P<0.0001) and EPA (r=0.38; P=0.002), but not with ALA levels (r=0.22; P=0.086). Participants were classified into quartiles by FFQ-estimated intake and plasma PUFA concentrations. Efficacy of the FFQ to rank individuals into same or adjacent plasma quartiles was 83% for DHA, 78.1% for EPA, and 70.6% for ALA; misclassification into extreme quartiles was 4.9% for DHA, 6.5% for EPA, and 8.2% for ALA. FFQ-estimated EPA intake and plasma EPA were superior to plasma AA levels as predictors of the plasma AA to EPA ratio. This brief FFQ can provide researchers and clinicians with valuable information concerning dietary intake of DHA and EPA.     

Are all n-3 polyunsaturated fatty acids created equal?

N-3 Polyunsaturated fatty acids have been shown to have potential beneficial effects for chronic diseases including cancer, insulin resistance and cardiovascular disease. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in particular have been studied extensively, whereas substantive evidence for a biological role for the precursor, alpha-linolenic acid (ALA), is lacking. It is not enough to assume that ALA exerts effects through conversion to EPA and DHA, as the process is highly inefficient in humans. Thus, clarification of ALA's involvement in health and disease is essential, as it is the principle n-3 polyunsaturated fatty acid consumed in the North American diet and intakes of EPA and DHA are typically very low. There is evidence suggesting that ALA, EPA and DHA have specific and potentially independent effects on chronic disease. Therefore, this review will assess our current understanding of the differential effects of ALA, EPA and DHA on cancer, insulin resistance, and cardiovascular disease. Potential mechanisms of action will also be reviewed. Overall, a better understanding of the individual role for ALA, EPA and DHA is needed in order to make appropriate dietary recommendations regarding n-3 polyunsaturated fatty acid consumption.     

Blood concentrations of individual long-chain n-3 fatty acids and risk of nonfatal myocardial infarction

BACKGROUND: Whereas dietary intake of long-chain n-3 fatty acids has been associated with risk of nonfatal myocardial infarction (MI), few studies have examined the relation for blood concentrations. OBJECTIVE: We aimed to investigate the effect of long-chain n-3 fatty acids in blood on the risk of nonfatal MI. DESIGN: Baseline blood samples were collected from 32 826 participants of the Nurses' Health Study in 1989-1990, among whom 146 incident cases of nonfatal MI were ascertained during 6 y of follow-up and matched with 288 controls. RESULTS: After multivariate adjustment, the relative risks (95% CI) comparing the highest with the lowest quartiles in plasma were 0.23 (0.09, 0.55; P for trend = 0.001) for eicosapentaenoic acid (EPA), 0.40 (0.20, 0.82; P for trend = 0.004) for docosapentaenoic acid (DPA), and 0.46 (0.18, 1.16; P for trend = 0.07) for docosahexaenoic acid (DHA). The associations for these fatty acids in erythrocytes were generally weaker and nonsignificant. In contrast to EPA and DHA, blood concentrations of DPA were not correlated with dietary consumption of n-3 fatty acids. Higher plasma concentrations of EPA, DPA, and DHA were associated with higher plasma concentrations of HDL cholesterol and lower concentrations of triacylglycerol and inflammatory markers. CONCLUSIONS: Higher plasma concentrations of EPA and DPA are associated with a lower risk of nonfatal MI among women. These findings may partly reflect dietary consumption but, particularly for DPA, may indicate important risk differences based on metabolism of long-chain n-3 fatty acids.     

Decreasing linoleic acid with constant alpha-linolenic acid in dietary fats increases (n-3) eicosapentaenoic acid in plasma phospholipids in healthy men

High linoleic acid (LA) intakes have been suggested to reduce alpha-linolenic acid [ALA, 18:3(n-3)] metabolism to eicosapentaenoic acid [EPA, 20:5(n-3)] and docosahexaenoic acid [DHA, 22:6(n-3)], and favor high arachidonic acid [ARA, 20:4(n-6)]. We used a randomized cross-over study with men (n = 22) to compare the effect of replacing vegetable oils high in LA with oils low in LA in foods, while maintaining constant ALA, for 4 wk each, on plasma (n-3) fatty acids. Nonvegetable sources of fat, except fish and seafoods, were unrestricted. We determined plasma phospholipid fatty acids at wk 0, 2, 4, 6, and 8, and triglycerides, cholesterol, serum CRP, and IL-6, and platelet aggregation at wk 0, 4, and 8. LA and ALA intakes were 3.8 +/- 0.12% and 1.0 +/- 0.05%, and 10.5 +/- 0.53% and 1.1 +/- 0.06% energy with LA:ALA ratios of 4:0 and 10:1 during the low and high LA diets, respectively. The plasma phospholipid LA was higher and EPA was lower during the high than during the low LA diet period (P < 0.001), but DHA declined over the 8-wk period (r = -0.425, P < 0.001). The plasma phospholipid ARA:EPA ratios were (mean +/- SEM) 20.7 +/- 1.52 and 12.9 +/- 1.01 after 4 wk consuming the high or low LA diets, respectively (P < 0.001); LA was inversely associated with EPA (r = -0.729, P < 0.001) but positively associated with ARA:EPA (r = 0.432, P < 0.001). LA intake did not influence ALA, ARA, DPA, DHA, or total, LDL or HDL cholesterol, CRP or IL-6, or platelet aggregation. In conclusion, high LA intakes decrease plasma phospholipid EPA and increase the ARA:EPA ratio, but do not favor higher ARA.     

(n-3) fatty acids and cardiovascular health: are effects of EPA and DHA shared or complementary?

Considerable research supports cardiovascular benefits of consuming omega-3 PUFA, also known as (n-3) PUFA, from fish or fish oil. Whether individual long-chain (n-3) PUFA have shared or complementary effects is not well established. We reviewed evidence for dietary and endogenous sources and cardiovascular effects on biologic pathways, physiologic risk factors, and clinical endpoints of EPA [20:5(n-3)], docosapentaenoic acid [DPA, 22:5(n-3)], and DHA [22:6(n-3)]. DHA requires direct dietary consumption, with little synthesis from or retroconversion to DPA or EPA. Whereas EPA is also largely derived from direct consumption, EPA can also be synthesized in small amounts from plant (n-3) precursors, especially stearidonic acid. In contrast, DPA appears principally derived from endogenous elongation from EPA, and DPA can also undergo retroconversion back to EPA. In experimental and animal models, both EPA and DHA modulate several relevant biologic pathways, with evidence for some differential benefits. In humans, both fatty acids lower TG levels and, based on more limited studies, favorably affect cardiac diastolic filling, arterial compliance, and some metrics of inflammation and oxidative stress. All three (n-3) PUFA reduce ex vivo platelet aggregation and DHA also modestly increases LDL and HDL particle size; the clinical relevance of such findings is uncertain. Combined EPA+DHA or DPA+DHA levels are associated with lower risk of fatal cardiac events and DHA with lower risk of atrial fibrillation, suggesting direct or indirect benefits of DHA for cardiac arrhythmias (although not excluding similar benefits of EPA or DPA). Conversely, EPA and DPA, but not DHA, are associated with lower risk of nonfatal cardiovascular endpoints in some studies, and purified EPA reduced risk of nonfatal coronary syndromes in one large clinical trial. Overall, for many cardiovascular pathways and outcomes, identified studies of individual (n-3) PUFA were relatively limited, especially for DPA. Nonetheless, the present evidence suggests that EPA and DHA have both shared and complementary benefits. Based on current evidence, increasing consumption of either would be advantageous compared to little or no consumption. Focusing on their combined consumption remains most prudent given the potential for complementary effects and the existing more robust literature on cardiovascular benefits of their combined consumption as fish or fish oil for cardiovascular benefits.     

Discrepancies in dietary intakes and plasma concentrations of fatty acids according to age among Japanese female dietitians

OBJECTIVE: To clarify the influences of age on dietary intakes and plasma concentrations of fatty acids (FAs) in Japanese female dietitians. SUBJECTS AND METHODS: In autumn 1996, we estimated dietary FA intakes based on 7 day weighed diet records and analyzed plasma FA concentrations in 79 healthy Japanese female dietitians, and investigated their relationships with age, dividing into three age groups (young (32-42 y), middle-aged (43-50 y) and elderly (51-66 y)). RESULTS: Dietary intakes of total FA, saturated FAs, monounsaturated FAs, n-3 polyunsaturated FAs (PUFAs) and alpha-linolenic acid (18:3n-3) were significantly highest in the middle-aged group, and lowest in the elderly. Similar trends were observed for dietary intakes of n-6 PUFAs and linoleic acid (18:2n-6), but there were no differences with regard to eicosapentaenoic acid (EPA; 20:5n-3), docosahexaenoic acid (DHA; 22:6n-3) and n-3 highly unsaturated FAs (HUFAs=EPA+22:5n-3+DHA). On the other hand, plasma concentrations of all FAs except for arachidonic acid (20:4n-6) demonstrated positive correlations with age. Moreover, plasma concentrations of EPA in all age groups, DHA in the elderly and n-3 HUFAs in the middle-aged and the elderly were all positively correlated with dietary intakes. CONCLUSIONS: We should take into account the influence of age on dietary habit and lipid metabolism when interpreting associations between dietary FA intakes and plasma FA concentrations.     

Flaxseed oil and fish-oil capsule consumption alters human red blood cell n-3 fatty acid composition: a multiple-dosing trial comparing 2 sources of n-3 fatty acid

BACKGROUND: An increase in plasma n-3 fatty acid content, particularly eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA), is observed after consumption of fish oil-enriched supplements. Because alpha-linolenic acid (18:3n-3; ALA) is the direct precursor of EPA and DHA, ALA-enriched supplements such as flax may have a similar effect, although this hypothesis has been challenged because of reported low conversion of ALA into DHA. OBJECTIVE: To address this question, we designed a clinical trial in which flax oil, fish-oil, and sunflower oil (placebo group) capsules were given to firefighters (n = 62), a group traditionally exposed to cardiovascular disease risk factors. DESIGN: Firefighters were randomly divided into 6 experimental groups receiving 1.2, 2.4, or 3.6 g flax oil/d; 0.6 or 1.2 g fish oil/d; or 1 g sunflower oil/d for 12 wk. Blood was drawn every 2 wk, and the total phospholipid fatty acid composition of red blood cells was determined. RESULTS: As expected, fish oil produced a rapid increase in erythrocyte DHA and total n-3 fatty acids. The consumption of either 2.4 or 3.6 g flax oil/d (in capsules) was sufficient to significantly increase erythrocyte total phospholipid ALA, EPA, and docosapentaenoic acid (22:5n-3) fatty acid content. There were no differences among groups in plasma inflammatory markers or lipid profile. CONCLUSIONS: The consumption of ALA-enriched supplements for 12 wk was sufficient to elevate erythrocyte EPA and docosapentaenoic acid content, which shows the effectiveness of ALA conversion and accretion into erythrocytes. The amounts of ALA required to obtain these effects are amounts that are easily achieved in the general population by dietary modification.     

Lack of effect of foods enriched with plant- or marine-derived n-3 fatty acids on human immune function

BACKGROUND: Greatly increasing dietary flaxseed oil [rich in the n-3 polyunsaturated fatty acid (PUFA) alpha-linolenic acid (ALA)] or fish oil [rich in the long-chain n-3 PUFAs eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids] can reduce markers of immune cell function. The effects of more modest doses are unclear, and it is not known whether ALA has the same effects as its long-chain derivatives. OBJECTIVE: The objective was to determine the effects of enriching the diet with ALA or EPA+DHA on immune outcomes representing key functions of human neutrophils, monocytes, and lymphocytes. DESIGN: In a placebo-controlled, double-blind, parallel study, 150 healthy men and women aged 25-72 y were randomly assigned to 1 of 5 interventions: placebo (no additional n-3 PUFAs), 4.5 or 9.5 g ALA/d, and 0.77 or 1.7 g EPA+DHA/d for 6 mo. The n-3 PUFAs were provided in 25 g fat spread plus 3 oil capsules. Blood samples were taken at 0, 3, and 6 mo. RESULTS: The fatty acid composition of peripheral blood mononuclear cell phospholipids was significantly different in the groups with higher intakes of ALA or EPA+DHA. The interventions did not alter the percentages of neutrophils or monocytes engaged in phagocytosis of Escherichia coli or in phagocytic activity, the percentages of neutrophils or monocytes undergoing oxidative burst in response to E. coli or phorbol ester, the proliferation of lymphocytes in response to a T cell mitogen, the production of numerous cytokines by monocytes and lymphocytes, or the in vivo delayed-type hypersensitivity response. CONCLUSION: An intake of 相似文献   

High α-linolenic acid and fish oil ingestion promotes ovulation to the same extent in rats

Prostaglandins (PG) have a regulatory influence on ovulation. α-Linolenic acid (ALA) vs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) differently influence PG biosynthesis. Whereas high EPA/DHA reduces PGE₂, enhancing ovulation, we hypothesized that ALA would not affect ovulation. Our objective was to determine the effect of low and high ALA intake vs EPA/DHA on ovarian phospholipids, ovulation, and PG synthesis in rats. Following 27 days on diet and ovulation induction, ovaries were isolated and analyzed in 22 pups per diet. Ovarian phospholipid (n-3) polyunsaturated fatty acid (PUFA) incorporation increased with EPA/DHA ingestion. With significant ovarian (n-3) PUFA or EPA (P < .05) enrichment in the high–n-3 PUFA diets, ova release increased. Although high ALA did not enrich total (n-3), it increased ova release and tissue EPA over low ALA or control. Dietary EPA/DHA more effectively reduced ovarian arachidonic acid levels than dietary ALA. Dietary ALA increased PGF and very high intake reduced PGE, whereas EPA/DHA did not alter PGE or PGF. Enhanced ova release with high (n-3) PUFA intake may be induced via multiple mechanisms including reduced ovarian arachidonic acid. Significant ovarian retention of EPA and DHA enhanced ovulation with unchanged total PGE and PGF. Lack of change in PGE may have resulted from reduced PGE₂ combined with increased PGE₃. When EPA alone was elevated, PGE was reduced, whereas PGF was increased. Results indicate that very high ALA intake enhances ovulation similar to very high EPA/DHA ingestion, an effect potentially mediated via similar patterns of PGF₂α and PGE₂ synthesis.     

When balanced for precursor fatty acid supply echium oil is not superior to linseed oil in enriching lamb tissues with long-chain n-3 PUFA

Vegetable oils containing stearidonic acid (SDA, 18 : 4n-3) are considered better precursors of long-chain n-3 PUFA (LC n-3 PUFA) than those with only α-linolenic acid (ALA, 18 : 3n-3). The present study re-examined this premise using treatments where added ALA from linseed oil was matched with ALA plus SDA from echium oil. Lambs (n 6) were abomasally infused with saline (control (C), 25 ml), echium oil low (EL, 25 ml), echium oil high (EH, 50 ml), linseed oil low (LL, 25 ml) or linseed oil high (LH, 50 ml) for 4 weeks. The basal ration used was identical across all treatments. EPA (20 : 5n-3) in meat increased from 6·5 mg in the C lambs to 16·8, 17·7, 13·5 and 11·7 (SEM 0·86) mg/100 g muscle in the EL, EH, LL and LH lambs, respectively. For muscle DPA (docosapentaenoic acid; 22 : 5n-3), the corresponding values were 14·3, 22·2, 18·6 18·2 and 19·4 (SEM 0·57) mg/100 g muscle. The DHA (22 : 6n-3) content of meat was 5·8 mg/100 g in the C lambs and ranged from 4·53 to 5·46 (SEM 0·27) mg/100 g muscle in the oil-infused groups. Total n-3 PUFA content of meat (including ALA and SDA) increased from 39 mg to 119, 129, 121 and 150 (SEM 12·3) mg/100 g muscle. We conclude that both oil types were effective in enhancing the EPA and DPA, but not DHA, content of meat. Furthermore, we conclude that, when balanced for precursor n-3 fatty acid supply, differences between linseed oil and echium oil in enriching meat with LC n-3 PUFA were of little, if any, nutritional significance.     

Correlation between changes in blood fatty acid composition and visual sustained attention performance in children with inattention: effect of dietary n-3 fatty acids containing phospholipids

BACKGROUND: Increasing evidence supports n-3 fatty acid (FA) supplementation for patients with psychiatric disorders, such as attention deficit hyperactivity disorder. However, the exact metabolic fate of dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on different glyceride carriers remains unclear. OBJECTIVE: We investigated whether conjugation of EPA and DHA to phospholipid (PL-n-3) or to triacylglycerol (fish oil; FO) affects their incorporation in blood compartments and influences executive functioning. DESIGN: Children aged 8-13 y with impaired visual sustained attention performance received placebo, 250 mg/d EPA + DHA esterified to PL-n-3 (300 mg/d phosphatidylserine), or FO for 3 mo in a randomized double-blind manner. Main outcome measures included plasma and erythrocyte FA profile and continuous performance test results (Test of Variables of Attention; TOVA). RESULTS: Sixty of the 83 children enrolled completed the interventions (n = 18-21 per group). There was an enrichment of EPA (1.5-2.2-fold), docosapentaenoic acid (DPA; 1.2-fold), and DHA (1.3-fold) in the PL fraction in the plasma of FO- and PL-n-3-fed children. In erythrocytes, only PL-n-3 resulted in a significant reduction (approximately 30%) of very-long-chain saturated FAs (C20-24) and in an increase (1.2- and 2.2-fold, respectively) in linoleic acid and DPA. Total TOVA scores increased in the PL-n-3 (mean +/- SD: 3.35 +/- 1.86) and FO (1.72 +/- 1.67) groups but not in the placebo group (-0.42 +/- 2.51) (PL-n-3 > FO > placebo; P < 0.001). A significant correlation between the alterations in FAs and increased TOVA scores mainly occurred in the PL-n-3 group. CONCLUSION: Consumption of EPA+DHA esterified to different carriers had different effects on the incorporation of these FAs in blood fractions and on the visual sustained attention performance in children. This trial was registered at clinicaltrials.gov as NCT00382616.     

Dietary supplementation with eicosapentaenoic acid, but not with other long-chain n-3 or n-6 polyunsaturated fatty acids, decreases natural killer cell activity in healthy subjects aged >55 y

BACKGROUND: Animal studies showed that dietary flaxseed oil [rich in the n-3 polyunsaturated fatty acid alpha-linolenic acid (ALA)], evening primrose oil [rich in the n-6 polyunsaturated fatty acid gamma-linolenic acid (GLA)], and fish oil [rich in the long-chain n-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] can decrease natural killer (NK) cell activity. There have been no studies of the effect on NK cell activity of adding these oils to the diet of humans. OBJECTIVE: Our objective was to determine the effect of dietary supplementation with oil blends rich in ALA, GLA, arachidonic acid (AA), DHA, or EPA plus DHA (fish oil) on the NK cell activity of human peripheral blood mononuclear cells. DESIGN: A randomized, placebo-controlled, double-blind, parallel study was conducted. Healthy subjects aged 55-75 y consumed 9 capsules/d for 12 wk; the capsules contained placebo oil (an 80:20 mix of palm and sunflower seed oils) or blends of placebo oil and oils rich in ALA, GLA, AA, DHA, or EPA plus DHA. Subjects in these groups consumed 2 g ALA, 770 mg GLA, 680 mg AA, 720 mg DHA, or 1 g EPA plus DHA (720 mg EPA + 280 mg DHA) daily, respectively. Total fat intake from the capsules was 4 g/d. RESULTS: The fatty acid composition of plasma phospholipids changed significantly in the GLA, AA, DHA, and fish oil groups. NK cell activity was not significantly affected by the placebo, ALA, GLA, AA, or DHA treatment. Fish oil caused a significant reduction (mean decline: 48%) in NK cell activity that was fully reversed by 4 wk after supplementation had ceased. CONCLUSION: A moderate amount of EPA but not of other n-6 or n-3 polyunsaturated fatty acids can decrease NK cell activity in healthy subjects.     

Plant- and marine-derived n-3 polyunsaturated fatty acids have differential effects on fasting and postprandial blood lipid concentrations and on the susceptibility of LDL to oxidative modification in moderately hyperlipidemic subjects

BACKGROUND: Dietary alpha-linolenic acid (ALA) can be converted to long-chain n-3 polyunsaturated fatty acids (PUFAs) in humans and may reproduce some of the beneficial effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on cardiovascular disease risk factors. OBJECTIVE: This study aimed to compare the effects of increased dietary intakes of ALA and EPA+DHA on a range of atherogenic risk factors. DESIGN: This was a placebo-controlled, parallel study involving 150 moderately hyperlipidemic subjects randomly assigned to 1 of 5 interventions: 0.8 or 1.7 g EPA+DHA/d, 4.5 or 9.5 g ALA/d, or an n-6 PUFA control for 6 mo. Fatty acids were incorporated into 25 g of fat spread and 3 capsules to be consumed daily. RESULTS: The change in fasting or postprandial lipid, glucose, or insulin concentrations or in blood pressure was not significantly different after any of the n-3 PUFA interventions compared with the n-6 PUFA control. The mean (+/- SEM) change in fasting triacylglycerols after the 1.7-g/d EPA+DHA intervention (-7.7 +/- 4.99%) was significantly (P < 0.05) different from the change after the 9.5-g/d ALA intervention (10.9 +/- 4.5%). The ex vivo susceptibility of LDL to oxidation was higher after the 1.7-g/d EPA+DHA intervention than after the control and ALA interventions (P < 0.05). There was no significant change in plasma alpha-tocopherol concentrations or in whole plasma antioxidant status in any of the groups. CONCLUSION: At estimated biologically equivalent intakes, dietary ALA and EPA+DHA have different physiologic effects.     

The Evidence for α-Linolenic Acid and Cardiovascular Disease Benefits: Comparisons with Eicosapentaenoic Acid and Docosahexaenoic Acid

Our understanding of the cardiovascular disease (CVD) benefits of α-linolenic acid (ALA, 18:3n–3) has advanced markedly during the past decade. It is now evident that ALA benefits CVD risk. The expansion of the ALA evidence base has occurred in parallel with ongoing research on eicosapentaenoic acid (EPA, 20:5n–3) and docosahexaenoic acid (DHA, 22:6n–3) and CVD. The available evidence enables comparisons to be made for ALA vs. EPA + DHA for CVD risk reduction. The epidemiologic evidence suggests comparable benefits of plant-based and marine-derived n–3 (omega-3) PUFAs. The clinical trial evidence for ALA is not as extensive; however, there have been CVD event benefits reported. Those that have been reported for EPA + DHA are stronger because only EPA + DHA differed between the treatment and control groups, whereas in the ALA studies there were diet differences beyond ALA between the treatment and control groups. Despite this, the evidence suggests many comparable CVD benefits of ALA vs. EPA + DHA. Thus, we believe that it is time to revisit what the contemporary dietary recommendation should be for ALA to decrease the risk of CVD. Our perspective is that increasing dietary ALA will decrease CVD risk; however, randomized controlled clinical trials are necessary to confirm this and to determine what the recommendation should be. With a stronger evidence base, the nutrition community will be better positioned to revise the dietary recommendation for ALA for CVD risk reduction.