Impact of foods enriched withn-3 long-chain polyunsaturated fatty acids on erythrocyten-3 levels and cardiovascular risk factors

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.

A restricted cubic spline approach to assess the association between high fat fish intake and red blood cell EPA + DHA content

BACKGROUND AND AIMS

Fish, especially fatty fish, are the main contributor to eicosapentaenoic (EPA) and docosahexaenoic (DHA) intake. EPA and DHA concentrations in red blood cells (RBC) has been proposed as a cardiovascular risk factor, with <4% and >8% associated with the lowest and greatest protection, respectively. The relationship between high fat fish (HFF) intake and RBC EPA + DHA content has been little investigated on a wide range of fish intake, and may be non-linear. We aimed to study the shape of this relationship among high seafood consumers.

METHODS AND RESULTS

Seafood consumption records and blood were collected from 384 French heavy seafood consumers and EPA and DHA were measured in RBC. A multivariate linear regression was performed using restricted cubic splines to consider potential non-linear associations. Thirty-six percent of subjects had an RBC EPA + DHA content lower than 4% and only 5% exceeded 8%. HFF consumption was significantly associated with RBC EPA + DHA content (P [overall association] = 0.021) adjusted for sex, tobacco status, study area, socioeconomic status, age, alcohol, other seafood, meat, and meat product intakes. This relationship was non-linear: for intakes higher than 200 g/wk, EPA + DHA content tended to stagnate. Tobacco status and fish contaminants were negatively associated with RBC EPA + DHA content.

CONCLUSION

Because of the saturation for high intakes, and accounting for the concern with exposure to trace element contaminants, intake not exceeding 200 g should be considered.

Are we consuming enough long chain omega-3 polyunsaturated fatty acids for optimal health?

The health benefits attributed to the consumption of long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) are enormous but are we consuming enough for optimal health? Cardiovascular disease rates are much lower in countries like Japan compared with the Western world. Western countries' LC n-3 PUFA intakes are up to 5 fold lower than Japanese intakes. Various professional bodies and government organisations recommend 500mg LC n-3 PUFA per day. The actual reported intake of LC n-3 PUFA from Australia and various other countries are compared to these recommended intakes. Not surprisingly, the actual intakes of LC n-3 PUFA in Western countries fall short of the recommended intakes. Consumption of fish and seafood is the easiest way to achieve the recommended intakes but increased consumption of foods enriched with LC n-3 PUFA will also contribute to achieving the recommended intakes. Most people are not consuming enough LC n-3 PUFA for optimal health.

Relative validity of adolescent dietary patterns: a comparison of a FFQ and 3 d food record

Interest in empirically derived dietary patterns has increased over the past decade. However, relatively few studies have evaluated dietary patterns using different dietary methods, or in young populations. We quantitatively compared dietary patterns from a FFQ with those from a 3 d food record (FR) in a cohort of adolescents. Subjects from the Western Australian Pregnancy Cohort (Raine) Study completed a semi-quantitative FFQ and a 3 d FR at 14 years of age (n 783). Major dietary patterns were identified using exploratory factor analysis on thirty-eight food groups. Dietary pattern z-scores were compared using 95 % limits of agreement (LOA) and Spearman's r. Two major dietary patterns were identified in the FFQ and FR: a 'Healthy' pattern, which was high in fresh fruit, vegetables, whole grains and grilled or canned fish, and a 'Western' pattern, which was high in take-away foods, confectionery, soft drinks, crisps and fried potato. The nutrient profiles of these dietary patterns were similar when estimated by the FFQ and FR. The LOA between dietary pattern scores from the FFQ and FR were - 1·69 to 1·75 ('Healthy') and - 1·89 to 1·82 ('Western'). Minor differences in agreement were observed when boys and girls were analysed separately. Spearman's correlation coefficients between the FFQ and the FR were r 0·45 ('Healthy') and r 0·36 ('Western'). Comparable dietary patterns may be obtained from the FFQ and FR using exploratory factor analysis. This supports the use of major dietary patterns identified using the FFQ in this adolescent cohort.

Effect of marine n-3 fatty acids on circulating inflammatory markers in healthy subjects and subjects with cardiovascular risk factors

Objective

The aim of the present paper was to review the literature in order to summarize the effects of marine n-3 fatty acids on circulating inflammatory markers among healthy subjects, subjects with high risk of developing cardiovascular disease (CVD) and in patients with CVD in human intervention studies.

Methods

A systematic literature search in PubMed was performed. Intervention studies describing the effects of marine n-3 fatty acids on circulating inflammatory markers in healthy subjects, subjects with high risk of CVD and patients with CVD were included. The following exclusion criteria were used: (1) interventions assessing inflammatory markers with ex vivo methods (2) interventions with children (3) articles describing animal or cell culture studies. Twenty-two articles were included. Additionally, 13 papers from their literature lists were included based on the same inclusion and exclusion criteria as the literature search.

Results and conclusion

Intervention studies with marine n-3 fatty acids administered from either fish or fish oil demonstrate different results on inflammatory markers. No firm conclusion can be drawn about the effect of marine n-3 fatty acids on circulating inflammatory markers in healthy individuals, individuals with high risk of developing CVD or individuals with CVD related diseases.

The effect of farmed trout on cardiovascular risk markers in healthy men

Increased intake of marine long-chain n-3 PUFA (n-3 LCPUFA) may decrease the risk of CVD and reduce mortality by lowering serum TAG and blood pressure (BP). Furthermore, n-3 LCPUFA may affect novel CVD risk markers related to inflammation and vascular function. The objective of the present study was to examine the effect of farmed trout on novel and traditional CVD risk markers in healthy men, and to evaluate whether this was affected by the aquacultural feed regime. We performed a parallel, 8-week intervention study in which sixty-eight healthy male volunteers were randomised to consume either a daily meal with 150 g farmed trout raised on either marine or vegetable-based feed, or a reference meal containing 150 g chicken. Twenty-four hour BP, pulse wave velocity, augmentation index, fatty acid composition of erythrocyte (RBC), and concentrations of TAG, HDL-cholesterol, LDL-cholesterol, glucose, insulin, C-reactive protein (CRP) and other markers of inflammation were measured at weeks 0 and 8. RBC content of total n-3 LCPUFA, both EPA and DHA, was significantly higher among men consuming trout raised on marine feed compared with men consuming the vegetable-fed trout or chicken. The three intervention groups did not differ significantly with respect to any of the other outcome variables, although there were trends towards associations between the changes in RBC n-3 LCPUFA and those in BP and CRP. In the present study, we conclude that we could not confirm the fish oil-induced reduction in CVD risk markers after daily consumption of trout with high or low n-3 LCPUFA content. However, trout raised on vegetable-based feed had less pronounced impact on RBC n-3 LCPUFA status.

Long-chain omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid dose-dependently reduce fasting serum triglycerides

The objectives of this review were to determine whether the long-chain omega-3 fatty acids eicosapentaenoic acid and/or docosahexaenoic acid dose-dependently reduce fasting serum triglycerides (TG) and, if so, to create a mathematical model that may be used to predict potential percent reductions in fasting serum TG levels at the recommended intakes of 200-500 mg/day. The assessment included 15 randomized controlled trials that met pre-defined inclusion and exclusion criteria. Across these 15 studies, the dose-response was modeled using a first-order elimination curve. The response variable was defined as percent change from baseline in fasting serum TG, adjusted for the placebo effect. A weighting factor equal to the product of each study's sample size and quality score was used. Using the equation of the dose-response curve, predicted reductions in fasting serum TG levels at the recommended long-chain omega-3 fatty acid intakes of 200-500 mg/day are 3.1 to 7.2%.

The effect of modifying dietary protein and carbohydrate in weight loss on arterial compliance and postprandial lipidemia in overweight women with polycystic ovary syndrome

In overweight women with polycystic ovary syndrome, weight loss improves arterial compliance and postprandial lipidemia. Modifying dietary carbohydrate or protein in weight loss provided similar improvements in arterial compliance and postprandial lipidemia.

Associations of very high intakes of eicosapentaenoic and docosahexaenoic acids with biomarkers of chronic disease risk among Yup'ik Eskimos

BACKGROUND

Few studies have examined the associations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with biomarkers of chronic disease risk in populations with high intakes.

OBJECTIVE

We examined the associations of red blood cell (RBC) EPA and DHA, as percentages of total fatty acids, with biomarkers of chronic disease risk across a wide range of EPA and DHA intakes.

DESIGN

In a cross-sectional study of 357 Yup'ik Eskimos, generalized additive models were used to plot covariate-adjusted associations of EPA and DHA with chronic disease biomarkers. Linear regression models were used to test for the statistical significance of these associations.

RESULTS

Means (5th-95th percentiles) for RBC EPA and DHA were 2.8% (0.5-5.9%) and 6.8% (3.3-9.0%), respectively. Associations of EPA and DHA were inverse and linear for triglycerides (beta +/- SE = -0.10 +/- 0.01 and -0.05 +/- 0.01, respectively) and positive and linear for HDL cholesterol (beta +/- SE = 2.0 +/- 0.5 and 0.9 +/- 0.6, respectively) and apolipoprotein A-I (beta +/- SE = 2.6 +/- 0.8 and 1.7 +/- 0.8, respectively). Positive linear associations of DHA with LDL and total cholesterol (beta +/- SE = 7.5 +/- 1.4 and 6.80 +/- 1.57, respectively) were observed; for EPA, these associations were nonlinear and restricted to concentrations approximately <5% of total fatty acids. Associations of EPA and DHA with C-reactive protein were inverse and nonlinear: for EPA, the association appeared stronger at concentrations approximately >3% of total fatty acids; for DHA, it was observed only at concentrations approximately >7% of total fatty acids.

CONCLUSION

Increasing EPA and DHA intakes to amounts well above those consumed by the general US population may have strong beneficial effects on chronic disease risk.

Do pregnant women and those at risk of developing post-natal depression consume lower amounts of long chain omega-3 polyunsaturated fatty acids?

The aims were to compare intakes of long chain omega-3 polyunsaturated fatty acid (LC n-3 PUFA) in pregnant and non-pregnant women in Australia and to compare these intakes to the Australian National Nutrition Survey of 1995 (NNS95) [1] and to determine if the LC n-3 PUFA intakes differed in women who may be ‘at risk’ compared with women ‘not at risk’ of developing post-natal depression (PND). A validated LC n-3 PUFA food frequency questionnaire and pregnant women’s Edinburgh Postnatal Depression Scale (EPDS) scores were used. LC n-3 PUFA intakes were comparable to the NNS95 but did not differ due to pregnancy or whether or not a woman is at risk of developing PND.

No effect of fish oil supplementation on serum inflammatory markers and their interrelationships: a randomized controlled trial in healthy, middle-aged individuals

BACKGROUND

A high intake of n-3 polyunsaturated fatty acids (PUFAs), mainly present in fish, may be associated with decreased inflammation. Previous intervention studies on fish PUFA and inflammatory markers in healthy individuals did not analyze a broad spectrum of inflammatory cytokines, chemokines and cell adhesion molecules, or their interrelationships. Therefore, we determined the effects of fish oil supplementation on 19 serum inflammatory markers and their interrelationships in healthy, middle-aged individuals.

METHODS

Individuals (n=77) aged 50-70 years completed a randomized, double-blind placebo-controlled intervention study. Participants received 3.5 g/day fish oil (1.5 g/day total n-3 PUFA) (n=39) or placebo (high oleic sunflower oil) (n=38) for 12 weeks. Serum concentrations of 19 inflammatory markers were determined using a multiplex immunoassay before and after intervention. Changes in concentrations were analyzed using analysis of covariance and differences in patterns in inflammatory markers between the fish oil and placebo group were analyzed by principal component analysis.

RESULTS

Fish oil supplementation did not significantly affect serum concentrations of cytokines, chemokines or cell adhesion molecules as compared with placebo. However, there was a trend for all inflammatory markers to increase after fish oil supplementation. PCA did not result in markedly distinctive patterns of inflammatory markers for the fish oil and placebo group.

CONCLUSION

In conclusion, this 12-week randomized, double-blind placebo-controlled intervention trial did not show that 1.5 g/day n-3 PUFA significantly affected the serum inflammatory response in healthy individuals, nor did patterns of inflammatory markers. Thus, a healthy middle-aged population may not benefit from fish oil as an anti-inflammatory agent.

Fish oil supplementation lowers C-reactive protein levels independent of triglyceride reduction in patients with end-stage renal disease

BACKGROUND

Inflammation has been identified as a marker for cardiovascular disease. The purpose of this study is to examine the effects of fish oil fatty acid supplementation on C-reactive protein (CRP) levels.

METHODS

The study uses a double-blind, permuted-randomized, and placebo-controlled experimental protocol. Patients are randomly placed into a fish oil group or a control group. Thirty-three patients in the experimental and control groups ingest 2 soft-gel pills (1 g each) of fish oil supplements containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) or placebo at each meal. Patients follow the supplementation protocol for 6 months. Analysis of variance (ANOVA) is used to measure pretest and posttest differences in the variable of interest. A Kolmogorov-Smirnov test for normality is used to test whether CRP levels are normally distributed.

RESULTS

The Kolmogorov-Smirnov test for CRP finds a P value of .273 (KS = .997), revealing that the distribution is normal. ANOVA reveals no statistically significant difference between groups at baseline for CRP (F = 4.118, P = .053). ANOVA reveals a significant main effect (F = 4.29, P = .048) for CRP, with the EPA/DHA group having a significant change in values from pretest (16 mg/dL, standard deviation [SD] = 13.80) to posttest (10.22 mg/dL, SD = 7.87). The placebo group's CRP levels do not change significantly from pretest (13.37, standard deviation [SD] = 7.94) to posttest (13.67, SD = 7.07). An observed power calculation using Cohen's D with a computed alpha of .05 is .588.

CONCLUSIONS

The study demonstrates that consuming 960 mg/d of EPA and 600 mg/d of DHA can lower CRP.

Docosahexaenoic acid (DHA) supplementation of orange juice increases plasma phospholipid DHA content of children

The major dietary source of docosahexaenoic acid (DHA) is fish, which is not widely consumed by children. There is concern, therefore, that children may not receive adequate DHA and so might benefit from dietary supplementation. The aim of the present study was to evaluate the effects of providing a supplement of microencapsulated algal DHA in juice. We assessed the effects of two levels of DHA supplementation on the plasma phospholipid DHA content of healthy 4- to 6-year-old and 7- to 12-year-old children who were randomly assigned to consume 180 mL juice containing either 50 mg (lower dose) or 100 mg (higher dose) DHA daily for 6 weeks. Plasma phospholipid DHA content (mole % of total fatty acids) was measured before and after 6 weeks of daily juice consumption. Because there are no data for plasma phospholipid DHA content in healthy children, data were compared to that of breastfed infants. At baseline, plasma phospholipid DHA content was lower in both age groups and dose groups than observed in breastfed infants. It increased significantly in both dose groups, but more so in the higher dose group of both age groups (P<0.05, overall mean+/-standard deviation: 3.72+/-0.66 vs 4.64+/-0.77); reaching levels similar to or greater than content of breastfed infants. Thus, DHA supplementation of juice at either 50 mg/day or 100 mg/day for 6 weeks was effective in increasing plasma phospholipid DHA contents of children.

Fish, docosahexaenoic acid and Alzheimer's disease

Cognitive decline in the elderly, particularly Alzheimer's disease (AD), is a major socio-economic and healthcare concern. We review here the literature on one specific aspect of diet affecting AD, that of the omega3 fatty acids, particularly the brain's principle omega3 fatty acid - docosahexaenoic acid (DHA). DHA has deservedly received wide attention as a nutrient supporting both optimal brain development and for cardiovascular health. Our aim here is to critically assess the quality of the present literature as well as the potential of omega3 fatty acids to treat or delay the onset of AD. We start with a brief description of cognitive decline in the elderly, followed by an overview of well recognized biological functions of DHA. We then turn to epidemiological studies, which are largely supportive of protective effects of fish and DHA against risk of AD. However, biological studies, including blood and brain DHA analyses need careful interpretation and further investigation, without which the success of clinical trials with DHA may continue to struggle. We draw attention to some of the methodological issues that need resolution as well as an emerging mechanism that may explain how DHA could be linked to protecting brain function in the elderly.

Towards establishing dietary reference intakes for eicosapentaenoic and docosahexaenoic acids

There is considerable interest in the impact of (n-3) long-chain PUFA in mitigating the morbidity and mortality caused by chronic diseases. In 2002, the Institute of Medicine concluded that insufficient data were available to define Dietary Reference Intakes (DRI) for eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), noting only that EPA and DHA could contribute up to 10% toward meeting the Adequate Intake for alpha-linolenic acid. Since then, substantial new evidence has emerged supporting the need to reassess this recommendation. Therefore, the Technical Committee on Dietary Lipids of the International Life Sciences Institute North America sponsored a workshop on 4-5 June 2008 to consider whether the body of evidence specific to the major chronic diseases in the United States--coronary heart disease (CHD), cancer, and cognitive decline--had evolved sufficiently to justify reconsideration of DRI for EPA+DHA. The workshop participants arrived at these conclusions: 1) consistent evidence from multiple research paradigms demonstrates a clear, inverse relation between EPA+DHA intake and risk of fatal (and possibly nonfatal) CHD, providing evidence that supports a nutritionally achievable DRI for EPA+DHA between 250 and 500 mg/d; 2) because of the demonstrated low conversion from dietary ALA, protective tissue levels of EPA+DHA can be achieved only through direct consumption of these fatty acids; 3) evidence of beneficial effects of EPA+DHA on cognitive decline are emerging but are not yet sufficient to support an intake level different from that needed to achieve CHD risk reduction; 4) EPA+DHA do not appear to reduce risk for cancer; and 5) there is no evidence that intakes of EPA+DHA in these recommended ranges are harmful.

DHA supplementation decreases serum C-reactive protein and other markers of inflammation in hypertriglyceridemic men

Dietary (n-3) PUFA reduce inflammation, an independent risk factor for cardiovascular disease. The antiinflammatory effects of docosahexaenoic acid (DHA) in hypertriglyceridemic men have not been previously reported, to our knowledge, and were the focus of this study. Hypertriglyceridemic men (n = 17 per group) aged 39-66 y, participated in a double-blind, randomized, placebo-controlled parallel study. They received no supplements for the first 8 d and then received either 7.5 g/d DHA oil (3 g DHA/d) or olive oil (placebo) for the last 90 d. Blood samples were collected from fasting men on study days -7, 0, 45, 84, and 91. DHA supplementation for 45 and 91 d decreased the number of circulating neutrophils by 11.7 and 10.5%, respectively (P < 0.05). It did not alter the circulating concentrations of other inflammatory markers tested within 45 d, but at 91 d it reduced (P < 0.05) concentrations of C-reactive protein (CRP) by 15%, interleukin-6 by 23%, and granulocyte monocyte-colony stimulating factor by 21% and DHA increased the concentration of antiinflammatory matrix metalloproteinase-2 by 7%. The number of circulating neutrophils was positively associated with the weight percent (wt %) of 20:4(n-6) in RBC lipids, and negatively to the wt % of 20:5(n-3) and 22:6(n-3). Concentrations of CRP and serum amyloid A were positively associated with the sum of SFA and negatively with the wt % of 18:1(n-9) and 17:0 in RBC lipids; CRP was also positively associated with the wt % of 20:2(n-6). The mean size of VLDL particles was positively associated with plasma concentrations of neutrophils and CRP. In conclusion, DHA may lessen the inflammatory response by altering blood lipids and their fatty acid composition.

Fatty acids and postprandial inflammation

PURPOSE OF REVIEW

Postprandial inflammation is an independent factor in evaluating food quality in addition to the well known parameters of nutritional value, caloric content and amount of carbohydrates, fats, proteins, minerals and vitamins. Among the latter, the quality and quantity of fatty acids in a meal is a major determinant of the magnitude of postprandial inflammation. Purpose of this review is to describe this exciting new area of research and its repercussions in the way we, the consumers, and the food industry evaluate the type and quantity of fat in food.

RECENT FINDINGS

A number of, by now classical, epidemiologic studies have documented a strong association between the type of fatty acids consumed and the incidence of cardiovascular diseases. Recently published reports suggest that the adverse effect of dietary fatty acids on cardiovascular health depends on their postprandial modification of innate immunity ending in the so-called 'postprandial metabolic inflammation'.

SUMMARY

The quantity of fat and its qualitative characteristics such as the percentage of saturated fatty acids and the ratio of n-3 to n-6 polyunsaturated fatty acids (PUFAs) in a meal have emerged as major determinants of the magnitude of postprandial inflammatory response. In this review, we will summarize all experimental evidence suggesting that the two families of PUFA appear to have antagonistic effects on postprandial inflammation, n-3 PUFA being anti-inflammatory while n-6 PUFA proinflammatory.

Regular consumption ofn-3 fatty acid-enriched pork modifies cardiovascular risk factors

The long-chain (LC)n-3 PUFA content of pork, particularly DHA, can be increased by including 15 % PorcOmega®(a fortified tuna fishmeal product) in pig finisher diets. The aim of the present study was to see whether this enriched pork could deliver cardiovascular health benefits to consumers. In a double-blind intervention trial, thirty-three healthy adult volunteers (sixteen female and seventeen male) were randomised to consume eithern-3-enriched or regular (control) pork (a selection of five fresh cuts totalling 1000 g/week) for 12 weeks. Fasting blood samples were collected every 4 weeks and analysed for serum lipids, maximally stimulated thromboxane production and erythrocyte fatty acid composition. Then-3-enriched pork provided subjects with 1·3 g LCn-3 PUFA per week. Erythrocyte DHA levels rose 15 % in then-3 group and fell 5 % in the control group over 12 weeks (P = 0·001). Compared with the control group, serum TAG decreased to a greater extent in then-3 group (P = 0·02) and serum thromboxane production increased to a lesser extent (P = 0·004). Changes in the latter were inversely associated with changes in incorporation of DHA into erythrocytes (r − 0·54;P < 0·05). Thus the modest increases in LCn-3 PUFA intake resulting from regular consumption of enriched pork can improve cardiovascular risk factors.

Leukocyte numbers and function in subjects eating n-3 enriched foods: selective depression of natural killer cell levels

Introduction

While consumption of omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) has been recommended for those at risk of inflammatory disease such as rheumatoid arthritis, the mechanism of their anti-inflammatory effect remains to be clearly defined, particularly in relation to the dose and type of n-3 LCPUFA. The objective of this study was to determine whether varying the levels of n-3 LCPUFA in erythrocyte membrane lipids, following dietary supplementation, is associated with altered numbers and function of circulating leukocytes conducive to protection against inflammation.

Methods

In a double-blind and placebo-controlled study, 44 healthy subjects aged 23 to 63 years consumed either standard or n-3 LCPUFA-enriched versions of typical processed foods, the latter allowing a target daily consumption of 1 gram n-3 LCPUFA. After six months, peripheral blood leukocyte and subpopulation proportions and numbers were assessed by flow cytometry. Leukocytes were also examined for lymphoproliferation and cytokine production, neutrophil chemotaxis, chemokinesis, bactericidal, adherence and iodination activity. Erythrocytes were analyzed for fatty-acid content.

Results

Erythrocyte n-3 LCPUFA levels were higher and absolute leukocyte and lymphocyte numbers were lower in subjects consuming n-3 enriched foods than in controls. There were no changes in the number of neutrophils, monocytes, T cells (CD3⁺), T-cell subsets (CD4⁺, CD8⁺) and B cells (CD19⁺). However, natural killer (NK) (CD3^-CD16⁺CD56⁺) cell numbers were lower in n-3 supplemented subjects than in controls and were inversely related to the amount of eicosapentaenoic acid or docosahexaenoic acid in erythrocytes. No significant correlations were found with respect to lymphocyte lymphoproliferation and production of IFN-γ and IL-2, but lymphotoxin production was higher with greater n-3 LCPUFA membrane content. Similarly, neutrophil chemotaxis, chemokinesis, bactericidal activity and adherence did not vary with changes in erythrocyte n-3 LCPUFA levels, but the iodination reaction was reduced with higher n-3 LCPUFA content.

Conclusion

The data show that regular long-term consumption of n-3 enriched foods leads to lower numbers of NK cells and neutrophil iodination activity but higher lymphotoxin production by lymphocytes. These changes are consistent with decreased inflammatory reaction and tissue damage seen in patients with inflammatory disorders receiving n-3 LCPUFA supplementation.

Dose-dependent effects of docosahexaenoic acid-rich fish oil on erythrocyte docosahexaenoic acid and blood lipid levels

Consumption of long-chainn-3 PUFA, particularly DHA, has been shown to improve cardiovascular risk factors but the intake required to achieve benefits is unclear. We sought to determine the relationship between DHA intake, increases in erythrocyte DHA content and changes in blood lipids. A total of sixty-seven subjects (thirty-six male, thirty-one female, mean age 53 years) with fasting serum TAG ≥ 1·1 mmol/l and BMI>25 kg/m2completed a 12-week, randomized, double-blind, placebo-controlled parallel intervention. Subjects consumed 2, 4 or 6 g/d of DHA-rich fish oil (26 % DHA, 6 % EPA) or a placebo (Sunola oil). Fasting blood lipid concentrations and fatty acid profiles in erythrocyte membranes were assessed at baseline and after 6 and 12 weeks. For every 1 g/d increase in DHA intake, there was a 23 % reduction in TAG (mean baseline concentration 1·9 (sem0·1) mmol/l), 4·4 % increase in HDL-cholesterol and 7·1 % increase in LDL-cholesterol. Erythrocyte DHA content increased in proportion to the dose of DHA consumed (r0·72,P < 0·001) and the increase after 12 weeks was linearly related to reductions in TAG (r− 0·38,P < 0·01) and increases in total cholesterol (r0·39,P < 0·01), LDL-cholesterol (r0·33,P < 0·01) and HDL-cholesterol (r0·30,P = 0·02). The close association between incorporation of DHA in erythrocytes and its effects on serum lipids highlights the importance of erythrocyte DHA as an indicator of cardiovascular health status.

Endocannabinoids and nutrition

The endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) are bioactive lipids derived from the n-6 family of polyunsaturated fatty acids that are essential fatty acids. Symptoms of essential fatty acid deficiency in rats - growth retardation, scaly skin, and increased transepidermal water loss - can mainly be attributed to lack of linoleic acid as a structural element of the epidermis. Arachidonic acid, however, also serve essential functions, particularly in cellular signalling via its precursor role for numerous oxygenated derivatives such as prostaglandins, leukotrienes, hepoxilins and other eicosanoids. Furthermore, arachidonic acid is also a structural part of endocannabinoids that have signalling functions in relation to modulation of neurotransmitter release, which might involve physiological and pathophysiological phenomena such as regulation of appetite, energy metabolism, pain perception, memory and learning. Furthermore, along with AEA formation other acylethanolamides are always formed - e.g., oleoylethanolamide (OEA), that can inhibit food intake, and palmitoylethanolamide, that is anti-inflammatory - possibly through activation of peroxisome proliferator activated receptor alpha (PPAR alpha) and/or GPR119. As all these unsaturated fatty acids are ingested daily in smaller or larger amounts, one can ask whether different dietary fats can affect the levels of these fatty acids in the tissues and thereby the quantitative formation of these bioactive signalling molecules. Generally, in vivo arachidonic-acid-derived eicosanoid production can be increased and decreased by prolonged feeding with pharmacological levels of arachidonic acid and long-chain (n-3) fatty acids (fish oil), respectively. Changes in levels of these two fatty acids within the traditional human diet hardly affects the eicosanoid production, however. Moreover, preliminary data suggest that dietary intake of arachidonic acid and fish oil also doesn't easily affect endocannabinoid formation; however, dietary fat in terms of saturated, polyunsaturated and monounsaturated seems to affect tissue levels of AEA, 2-AG and OEA.

Docosahexaenoic acid supplementation decreases remnant-like particle-cholesterol and increases the (n-3) index in hypertriglyceridemic men

Plasma remnant-like particle-cholesterol (RLP-C) and the RBC (n-3) index are novel risk factors for cardiovascular disease. Effects of docosahexaenoic acid (DHA) supplementation on these risk factors in hypertriglyceridemic men have not been studied. We determined effects of DHA supplementation on concentrations of plasma RLP-C, the RBC (n-3) index, and associations between concentrations of plasma RLP-C with those of plasma lipids and fatty acids. Hypertriglyceridemic men aged 39-66 y, participated in a randomized, placebo-controlled, parallel study. They received no supplements for 8 d and then received either 7.5 g/d DHA oil (3 g DHA/d) or olive oil (placebo) for the last 90 d. Fasting blood samples were collected on study d -7, 0 (baseline), 45 (mid-intervention), 84, and 91 (end-intervention). DHA supplementation for 45 d decreased (P < 0.05) fasting RLP-C (36%) and increased plasma eicosapentaenoic acid (EPA):arachidonic acid (AA) (100%) and the RBC (n-3) index (109%). Continued supplementation with DHA between d 45 and 91 further increased the RBC (n-3) index (162%) and plasma EPA:AA (137%) compared with baseline values. RLP-C concentration was positively associated (P < 0.01) with the plasma concentrations of triacylglycerols (Kendall's correlation coefficient or r = 0.46), triacylglycerol:HDL cholesterol (HDL-C) (r = 0.44), total cholesterol:HDL-C (r = 0.26), Apo B (r = 0.22), C III (r = 0.41), and E (r = 0.17), and 18:1(n-9) (r = 0.32); it was negatively associated (P < 0.05) with plasma concentrations of DHA (r = -0.32), EPA (r = -0.25), HDL-C (r = -0.21), LDL cholesterol:Apo B (r = -0.30), and HDL-C:Apo A (r = -0.25). Supplementation with placebo oil did not alter any of the response variables tested. Decreased atherogenic RLP-C and increased cardio-protective (n-3) index may improve cardio-vascular health.