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.     

The (n-3) fatty acid dose, independent of the (n-6) to (n-3) fatty acid ratio, affects the plasma fatty acid profile of normal dogs

The purpose of this study was to determine whether the dose of (n-3) fatty acids (FA) administered, independent of the relative ratio of (n-6) to (n-3) FA in the food, influences plasma FA composition in dogs. Healthy female, geriatric beagles (7-10 y old) were fed foods containing (n-6) to (n-3) FA ratios of either 40.0:1 or 1.4:1 for 12 wk (study 1) or 36 wk (study 2). In study 3, beagles were fed food with the same 1:1 ratio of (n-6) to (n-3) FA, but with increasing concentrations of (n-6) and (n-3) FA. Plasma FA concentrations were measured after completing the feeding studies. In studies 1 and 2, dogs fed fish oil-enriched food with a high (n-3) FA concentration had higher plasma total (n-3) FA, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) concentrations and lower plasma total (n-6) FA, linoleic acid, and arachidonic acid concentrations than dogs fed corn oil-enriched food with a low (n-3) FA concentration (P < 0.001). Both inclusion of fish oil (P < 0.001) and increased food intake independent of treatment effects increased the plasma DHA (P = 0.05) concentration. Furthermore, constancy of the dose of (n-3) FA administered over long periods of time was necessary to maintain plasma levels of total (n-3) FA, EPA, and DHA. In study 3, up to certain dietary concentrations (6.3 g total (n-3) FA/kg food for DHA and 9.8 g total (n-3) FA/kg food for EPA), the dose of (n-3) FA administered, independent of the (n-6) to (n-3) FA ratio, determined the plasma (n-3) FA composition. Results from our studies indicate that approximately 175 mg DHA/(kg body weight . d) is required to attain maximum plasma levels of DHA.     

Habitual fish consumption, plasma phospholipid fatty acids, and serum lipids: the Troms? study.

We examined the cross-sectional relationships between the frequency of habitual fish consumption, plasma phospholipid fatty acids, and serum lipids and lipoproteins in 152 men and women. There was a significant association between fish consumption starting from 1 dish/wk and plasma n-3, n-6, and n-9 fatty acids. Plasma eicosapentaenoic acid (EPA; 20: 5n-3) reflected fish consumption to a greater extent than did docosahexaenoic acid (DHA;22:6n-3). Triglycerides decreased (P less than 0.05) with fish consumption. In multivariate analysis in which anthropometric and lifestyle factors were controlled for, EPA correlated inversely with triglycerides (P less than 0.05) and positively with high-density-lipoprotein (HDL) cholesterol and apolipoprotein A-I (both P less than 0.001). In contrast, DHA did not correlate with triglycerides and showed negative associations to HDL cholesterol and apolipoprotein A-I (both P less than 0.001). Platelet phospholipid EPA, but not DHA, was associated with lower triglyceride and higher HDL-cholesterol concentrations (both P less than 0.05). This study suggests that long-term intake of small amounts of fish has biological effects, and that EPA and DHA have divergent relations with lipoprotein metabolism.     

Fish intake and serum fatty acid profiles from freshwater fish

BACKGROUND: Although high mercury concentrations in fish diets raise an alarm, fish can also be a healthy choice because it is the primary source of n-3 fatty acids (FAs). However, little information is available on the contribution of freshwater fish to serum FA concentrations. OBJECTIVE: This study examined the FA pathway from fish to serum in 243 moderate consumers of freshwater fish. DESIGN: A food-frequency questionnaire was used to determine the intakes of freshwater fish caught locally and not sold in markets and of fish purchased in markets (x +/- SD: 58 +/- 63 g/d). Locally caught freshwater fish accounted for an average of 45% of total fish intake. Fish were categorized as lean or fatty on the basis of the eicosapentaenoic acid + docosahexaenoic acid content estimated from published data. Serum FA concentrations were determined by gas chromatography. RESULTS: The results showed no relation between total fish intake or estimated n-3 FA intake from all fish and serum n-3 FA concentrations. Only fatty fish intake, particularly salmonid, and estimated EPA + DHA intake from fatty fish were significantly associated with serum EPA + DHA (R2 = 0.41 and 0.40, respectively). No relation was observed between the quantity of locally caught fish (g/d) consumed or the estimated FA intake from locally caught fish and serum n-3 FAs. Age, sex, and lipid metabolism medication were associated with serum n-3 FA concentrations. Neither blood selenium nor blood mercury was associated with serum FAs. CONCLUSION: The relation between fatty fish consumption and serum n-3 FAs cannot be generalized to all fish intakes.     

Single measurement of serum phospholipid fatty acid as a biomarker of specific fatty acid intake in middle-aged Japanese men

OBJECTIVE: To assess the utility of serum phospholipid fatty acid (FA) levels as a biochemical indicator of habitual dietary fatty acid intake in Japanese, whose diet is characterized by low fat intake and high intake of n-3 polyunsaturated fatty acids (PUFA) of marine origin. SUBJECTS AND METHODS: Eighty-seven male volunteers from four public health center districts that were part of the Japan Public Health Center based Prospective Study (JPHC Study) cohort I, were included in this study. Habitual intake of fatty acid was obtained by 7 day weighed dietary records four times (in one area only twice) in 1994--1995. Blood was collected twice, in February and August of the same year, and the composition of FA in serum phospholipid was analyzed by gas chromatography. The correlation coefficient between serum phospholipid FA levels and fatty acid intake was calculated. RESULTS: High correlations were observed for eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA), which are marine origin n-3 PUFA (r=0.75, 0.49, 0.50, respectively). No significant correlation was observed for saturated fatty acid (SFA), although the monounsaturated fatty acid (MUFA), palmitoleic acid and oleic acid intake were moderately correlated (r=0.22, 0.35, respectively). The correlations for EPA, DPA and DHA were similar in both samples collected in February and August. CONCLUSIONS: These data suggest that in populations with a high and stable over time intake of n-3 PUFA of marine origin, a single measurement of serum phospholipids reflects the ranking of habitual intake of marine origin n-3 PUFA.     

n-3 Polyunsaturated fatty acids,fatal ischemic heart disease,and nonfatal myocardial infarction in older adults: the Cardiovascular Health Study

BACKGROUND: Little is known about the relation of the dietary intake of n-3 polyunsaturated fatty acids, ie, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) from fatty fish and alpha-linolenic acid from vegetable oils, with ischemic heart disease among older adults. OBJECTIVE: We investigated the associations of plasma phospholipid concentrations of DHA, EPA, and alpha-linolenic acid as biomarkers of intake with the risk of incident fatal ischemic heart disease and incident nonfatal myocardial infarction in older adults. DESIGN: We conducted a case-control study nested in the Cardiovascular Health Study, a cohort study of adults aged > or = 65 y. Cases experienced incident fatal myocardial infarction and other ischemic heart disease death (n = 54) and incident nonfatal myocardial infarction (n = 125). Matched controls were randomly selected (n = 179). We measured plasma phospholipid concentrations of n-3 polyunsaturated fatty acids in blood samples drawn approximately 2 y before the event. RESULTS: A higher concentration of combined DHA and EPA was associated with a lower risk of fatal ischemic heart disease, and a higher concentration of alpha-linolenic acid with a tendency to lower risk, after adjustment for risk factors [odds ratio: 0.32 (95% CI: 0.13, 0.78; P = 0.01) and 0.52 (0.24, 1.15; P = 0.1), respectively]. In contrast, n-3 polyunsaturated fatty acids were not associated with nonfatal myocardial infarction. CONCLUSIONS: Higher combined dietary intake of DHA and EPA, and possibly alpha-linolenic acid, may lower the risk of fatal ischemic heart disease in older adults. The association of n-3 polyunsaturated fatty acids with fatal ischemic heart disease, but not with nonfatal myocardial infarction, is consistent with possible antiarrhythmic effects of these fatty acids.     

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.     

A method for assessing dietary intakes of n-3 long-chain polyunsaturated fatty acids and trans fatty acids in an Irish adult population

Abstract

The present study aimed to quantify dietary intakes of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and trans fatty acids (trans FA) in Irish adults using the North/South Ireland Food Consumption Survey (NSIFCS). To update the NSIFCS database, specific approaches were necessary to select accurate data. Published references were the main data source used to update for EPA and DHA (21.7%), while the UK Nutrient Databank was most frequently used to update for trans FA (46.7%). Total EPA and DHA mean daily intake was 275 mg/day whilst trans FA mean daily intake was 0.72% food energy. Younger adults had significantly lower intakes of EPA and DHA than older adults. The present study shows that dietary EPA and DHA intakes in the Irish adult population are below recommendations, especially among the younger population. Conversely, trans FA intakes are within the recommended value of < 2% food energy.     

Association of marine-origin N-3 polyunsaturated fatty acids consumption and functional mobility in the community-dwelling oldest old

Objective

To examine whether habitual dietary intake of marine-origin n-3 polyunsaturated fatty acids (MOPUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are associated with functional mobility in the community-dwelling oldest old, 85 years or older, who are at high risk for physical disability.

Design

A cross-sectional study.

Setting

A community-based survey conducted at university research center or home-based.

Participants

Four hundred seventeen (189 men, 228 women) out of 542 participants in the baseline examination of the Tokyo Oldest Old Survey on Total Health, a community-based ongoing longitudinal study among the oldest old living in the center of Japan.

Measurements

Habitual dietary intake of MOPUFA was assessed by the brief-type self-administered diet history questionnaire (BDHQ), and functional mobility was assessed by the Timed Up and Go test. Plasma inflammatory biomarkers (C-reactive protein, interleukin-6 and tumor necrosis factor-a) were measured. We evaluated the cross-sectional association between habitual intake of MOPUFA and functional mobility using multivariate logistic regression analysis — Prior to the analysis, validation of BDHQ in this study was confirmed among 190 participants (96 men, 94 women) based on the EPA and DHA concentrations in the erythrocyte membrane phospholipids as reference.

Results

Moderate correlation between estimated dietary intake of EPA/DHA and concentration of EPA/DHA in the erythrocyte membrane phospholipids was obtained (Spearman’s r=0.29–0.58, p<0.01). Multivariate logistic regression analysis revealed that a lower habitual intake of EPA+DHA was significantly associated with poor functional mobility in men but not in women (OR (95%CI) per 1 SD increase of EPA+DHA intake; 0.55 (0.33–0.91), 0.88 (0.59–1.32), men and women respectively).

Conclusions

Habitual intake of MOPUFA was associated with functional mobility in community-dwelling oldest old men.     

Fingertip Whole Blood as an Indicator of Omega-3 Long-Chain Polyunsaturated Fatty Acid Changes during Dose-Response Supplementation in Women: Comparison with Plasma and Erythrocyte Fatty Acids

The sensitivity of fingertip whole blood to reflect habitual dietary and dose-dependent supplemental omega-3 long-chain polyunsaturated fatty acid (n-3 LCPUFA) intake in premenopausal women was compared to that of venous erythrocytes and plasma fatty acids. Samples were obtained from women in a randomised, double-blind, placebo-controlled trial in which premenopausal women (n = 53) were supplemented with DHA-rich tuna oil capsules and/or placebo (Sunola oil) capsules (6 capsules per day) for 8 weeks to achieve doses of either 0, 0.35, 0.7 or 1.05 g/day n-3 LCPUFA. All blood biomarkers were very similar in their ability to reflect dietary n-3 LCPUFA intake (r = 0.38–0.46 for EPA and DHA intake), and in their dose-dependent increases in n-3 LCPUFA levels after supplementation (R² = 0.41–0.51 for dose effect on biomarker EPA and DHA levels (mol %)). Fingertip whole blood is an effective alternative to erythrocytes and plasma as a biomarker n-3 LCPUFA intake in premenopausal women.     

Effect of altered dietary n-3 fatty acid intake upon plasma lipid fatty acid composition,conversion of [13C]alpha-linolenic acid to longer-chain fatty acids and partitioning towards beta-oxidation in older men

The effect of increased dietary intakes of alpha-linolenic acid (ALNA) or eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for 2 months upon plasma lipid composition and capacity for conversion of ALNA to longer-chain metabolites was investigated in healthy men (52 (SD 12) years). After a 4-week baseline period when the subjects substituted a control spread, a test meal containing [U-(13)C]ALNA (700 mg) was consumed to measure conversion to EPA, docosapentaenoic acid (DPA) and DHA over 48 h. Subjects were then randomised to one of three groups for 8 weeks before repeating the tracer study: (1) continued on same intake (control, n 5); (2) increased ALNA intake (10 g/d, n 4); (3) increased EPA+DHA intake (1.5 g/d, n 5). At baseline, apparent fractional conversion of labelled ALNA was: EPA 2.80, DPA 1.20 and DHA 0.04 %. After 8 weeks on the control diet, plasma lipid composition and [(13)C]ALNA conversion remained unchanged compared with baseline. The high-ALNA diet resulted in raised plasma triacylglycerol-EPA and -DPA concentrations and phosphatidylcholine-EPA concentration, whilst [(13)C]ALNA conversion was similar to baseline. The high-(EPA+DHA) diet raised plasma phosphatidylcholine-EPA and -DHA concentrations, decreased [(13)C]ALNA conversion to EPA (2-fold) and DPA (4-fold), whilst [(13)C]ALNA conversion to DHA was unchanged. The dietary interventions did not alter partitioning of ALNA towards beta-oxidation. The present results indicate ALNA conversion was down-regulated by increased product (EPA+DHA) availability, but was not up-regulated by increased substrate (ALNA) consumption. This suggests regulation of ALNA conversion may limit the influence of variations in dietary n-3 fatty acid intake on plasma lipid compositions.     

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.     

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.     

Inhibition of tumour necrosis factor-alpha and interleukin 6 production by mononuclear cells following dietary fish-oil supplementation in healthy men and response to antioxidant co-supplementation

Increased dietary consumption of the n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (20 : 5n-3; EPA) and docosahexaenoic acid (22 : 6n-6; DHA) is associated with their incorporation into circulating phospholipid and increased production of lipid peroxide metabolites. The relationship between peripheral blood mononuclear cell (PBMC) function, n-3 PUFA intake and antioxidant co-supplementation is poorly defined. We therefore investigated tumour necrosis factor (TNF)-alpha and interleukin (IL) 6 production by PBMC and phospholipid fatty acid composition in plasma and erythrocytes of healthy male subjects (n 16) receiving supplemental intakes of 0.3, 1.0 and 2.0 g EPA+DHA/d, as consecutive 4-week courses. All subjects were randomised in a double-blind manner to receive a concurrent antioxidant supplement (200 microg Se, 3 mg Mn, 30 mg D-alpha-tocopheryl succinate, 90 mg ascorbic acid, 450 microg vitamin A (beta-carotene and retinol)) or placebo. There was a positive dose-dependent relationship between dietary n-3 PUFA intake and EPA and DHA incorporation into plasma phosphatidylcholine and erythrocyte phosphatidylethanolamine, with a tendency towards a plateau at higher levels of intake. Production of TNF-alpha and IL-6 by PBMC decreased with increasing n-3 PUFA intake but tended towards a 'U-shaped' dose response. Both responses appeared to be augmented by antioxidant co-supplementation at intermediate supplementary n-3 PUFA intakes. Thus, increased dietary n-3 PUFA consumption resulted in defined but contrasting patterns of modulation of phospholipid fatty acid composition and PBMC function, which were further influenced by antioxidant intake.     

Comparison between plasma and erythrocyte fatty acid content as biomarkers of fatty acid intake in US women

BACKGROUND: Erythrocyte fatty acids may be superior to plasma fatty acids for reflecting long-term fatty acid intake because of less sensitivity to recent intake and a slower turnover rate. OBJECTIVE: The objective was to compare the fatty acid content of erythrocytes with that of plasma with respect to their abilities to reflect usual fatty acid intake. DESIGN: Fatty acids in plasma and erythrocytes were measured by capillary gas-liquid chromatography in 306 US women aged 43-69 y. Fatty acid intake was assessed with a food-frequency questionnaire, which was validated for measuring intakes of various fatty acids. RESULTS: Docosahexaenoic acid (DHA, 22:6n-3) in erythrocytes and plasma provided the strongest correlations with its intake, but erythrocyte DHA concentrations [Spearman's partial correlation coefficient (r(s))=0.56] were better than plasma DHA concentrations (r(s)=0.48) as a biomarker. Total trans fatty acids (r(s)=0.43) and total 18:1 trans isomers (r(s)=0.42) in erythrocytes were also more strongly correlated with intake than were those in plasma (r(s)=0.30 and r(s)=0.29, respectively). Moderate correlations were observed for linoleic acid (18:2n-6; erythrocytes, r(s)=0.24; plasma, r(s)=0.25), alpha-linolenic acid (18:3n-3; erythrocytes, r(s)=0.18; plasma, r(s)=0.23), and eicosapentaenoic acid (20:5 n-3; erythrocytes, r(s)=0.38; plasma, r(s)=0.21). For polyunsaturated and trans fatty acids, correlations between intakes and biomarkers improved moderately when average intakes over previous years were used. CONCLUSION: Erythrocyte n-3 fatty acids of marine origin and trans fatty acid content are suitable biomarkers for long-term intake.     

Dietary methods and biomarkers of omega 3 fatty acids: a systematic review

The aims of the present study were to review the validity of dietary methods used to measure the usual long chain (LC) omega-3 polyunsaturated fatty acid (n-3 PUFA) intake of a population and to assess the usefulness of different biomarkers of n-3 PUFA in healthy humans. Two systematic literature searches were conducted until May 2011 to update previous systematic reviews. The first literature search aimed to find studies validating the methodology used for measuring the dietary intake of n-3 PUFA. The second search aimed to find human intervention studies in which n-3 PUFA status changed after 2 weeks of n-3 PUFA supplementation. Sixteen studies were identified for inclusion in the first review. Correlation coefficients between fatty acids in subcutaneous fat or blood lipids and dietary intake of n-3 PUFA from different questionnaires were similar. Subcutaneous fat has been reported as the best reference method for some authors, and these studies showed moderate correlation coefficients with no dietary intake method being superior to any other. As for the evaluation of biomarkers of docosahexaenoic acid (DHA, 22 : 6 n-3) and eicosapentaenoic acid (EPA, 20 : 5n-3) status in response to supplementation, the new search reaffirmed and reinforced the evidence supporting that plasma phospholipid DHA, erythrocyte DHA, and platelet DHA were all effective and robust biomarkers of DHA status. Our findings only confirmed earlier studies and did not provide evidence for reaching new conclusions.     

Moderate fish-oil supplementation reverses low-platelet, long-chain n-3 polyunsaturated fatty acid status and reduces plasma triacylglycerol concentrations in British Indo-Asians

BACKGROUND: The mechanisms involved in the increased mortality from coronary artery disease in British Indo-Asians are not well understood. OBJECTIVES: This study aimed to investigate whether British Indo-Asian Sikhs have higher plasma triacylglycerol concentrations, lower platelet phospholipid levels, and lower dietary intakes of long-chain n-3 polyunsaturated fatty acids (PUFAs) than do age- and weight-matched Europeans and whether moderate dietary fish-oil intake can reverse these differences. DESIGN: A randomized, double-blind, placebo-controlled, parallel, fish-oil intervention study was performed. After a 2-wk run-in period, 44 Europeans and 40 Indo-Asian Sikhs were randomly assigned to receive either 4.0 g fish oil [1.5 g eicosapentaenoic acid (EPA) and 1.0 g docosahexaenoic acid (DHA)] or 4.0 g olive oil (control) daily for 12 wk. RESULTS: At baseline, the Indo-Asians had significantly higher plasma triacylglycerol, small dense LDL, apolipoprotein B, and dietary and platelet phospholipid n-6 PUFA values and significantly lower long-chain n-3 PUFAs (EPA and DHA) than did the Europeans. A significant decrease in plasma triacylglycerol, plasma apolipoprotein B-48, and platelet phospholipid arachidonic acid concentrations and a significant increase in plasma HDL concentrations and platelet phospholipid EPA and DHA levels were observed after fish-oil supplementation. No significant effect of ethnicity on the responses to fish-oil supplementation was observed. CONCLUSIONS: Moderate fish-oil supplementation contributes to a reversal of lipid abnormalities and low n-3 PUFA levels in Indo-Asians and should be considered as an important, yet simple, dietary manipulation to reduce CAD risk in Indo-Asians with an atherogenic lipoprotein phenotype.     

Using a fingertip whole blood sample for rapid fatty acid measurement: method validation and correlation with erythrocyte polar lipid compositions in UK subjects

It is well accepted that n-3 long-chain PUFA intake is positively associated with a range of health benefits. However, while benefits have been clearly shown, especially for CVD, the mechanisms for prevention/benefit are less understood. Analysis of plasma and erythrocyte phospholipids (PL) have been used to measure the status of the highly unsaturated fatty acids (HUFA), especially EPA (20 : 5n-3) and DHA (22 : 6n-3), although the time and complexity of the process places limitations on the sample numbers analysed. An assay has been developed using whole blood, collected by finger prick, and stored on absorbant paper, subjected to direct methylation and fatty acids quantified by automated GC. Tests on fatty acid stability show that blood samples are stable when stored at - 20°C for 1 month although some loss of HUFA was seen at 4°C. A total of fifty-one patients, including twenty-seven who consumed no fatty acid supplements, provided a blood sample for analysis. Concentrations of all major fatty acids were measured in erythrocyte PL and whole blood. The major HUFA, including EPA, DHA and arachidonic acid (ARA; 20 : 4n-6), as well as the ARA:EPA ratio and the percentage n-3 HUFA/total HUFA all showed good correlations, between erythrocyte PL and whole blood. Values of r2 ranged from 0.48 for ARA to 0.95 for the percentage of n-3 HUFA/total HUFA. This assay provides a non-invasive, rapid and reliable method of HUFA quantification with the percentage of n-3 HUFA value providing a potential blood biomarker for large-scale nutritional trials.     

Depressive symptoms during pregnancy in relation to fish consumption and intake of n-3 polyunsaturated fatty acids

An inverse association between depression and the n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), primarily obtained from fish consumption, is observed in both observational and experimental research and is biologically plausible. Study objectives were to examine whether prenatal depressive symptoms were associated with lower intakes of fish or EPA+DHA. Pregnant women (n = 2394) completed a telephone interview between 10 and 22 weeks' gestation in London, Ontario, 2002-05. Depressive symptoms were measured using the Center for Epidemiologic Studies - Depression Scale (CES-D). Intakes of fish and EPA+DHA were measured using a validated food-frequency questionnaire. Sequential multiple regression was used to examine associations of depressive symptoms with intake of fish and EPA+DHA, respectively, while controlling for sociodemographic, health and lifestyle variables. The mean CES-D score was 9.9 (SD 8.0). Intake of EPA+DHA was dichotomised at the median value of 85 mg/day. Fish consumption and intake of EPA+DHA were not associated with prenatal depressive symptoms after adjustment for confounders; however, depressive symptoms were significantly higher for lower intakes of EPA+DHA among current smokers and women of single/separated/divorced marital status. The adjusted difference in CES-D scores between intake categories of EPA+DHA was -2.4 [95% CI -4.2, -0.4] for current smokers and -2.8 [95% CI -5.2, -0.4] for women of single marital status. Although pregnant women may be at risk for low concentrations of EPA and DHA, an association between low intakes of EPA+DHA and increased depressive symptoms was only observed among current smokers and women of single marital status.     

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.