Dietary n-3 polyunsaturated fatty acids alter the number, fatty acid profile and coagulatory activity of circulating and platelet-derived extracellular vesicles: a randomized, controlled crossover trial.

BACKGROUND: Extracellular vesicles (EVs) are proposed to play a role in the development of cardiovascular diseases (CVDs) and are considered emerging markers of CVDs. n-3 PUFAs are abundant in oily fish and fish oil and are reported to reduce CVD risk, but there has been little research to date examining the effects of n-3 PUFAs on the generation and function of EVs. OBJECTIVES: We aimed to investigate the effects of fish oil supplementation on the number, generation, and function of EVs in subjects with moderate risk of CVDs. METHODS: A total of 40 participants with moderate risk of CVDs were supplemented with capsules containing either fish oil (1.9 g/d n-3 PUFAs) or control oil (high-oleic safflower oil) for 12 wk in a randomized, double-blind, placebo-controlled crossover intervention study. The effects of fish oil supplementation on conventional CVD and thrombogenic risk markers were measured, along with the number and fatty acid composition of circulating and platelet-derived EVs (PDEVs). PDEV proteome profiles were evaluated, and their impact on coagulation was assessed using assays including fibrin clot formation, thrombin generation, fibrinolysis, and ex vivo thrombus formation. RESULTS: n-3 PUFAs decreased the numbers of circulating EVs by 27%, doubled their n-3 PUFA content, and reduced their capacity to support thrombin generation by >20% in subjects at moderate risk of CVDs. EVs derived from n-3 PUFA-enriched platelets in vitro also resulted in lower thrombin generation, but did not alter thrombus formation in a whole blood ex vivo assay. CONCLUSIONS: Dietary n-3 PUFAs alter the number, composition, and function of EVs, reducing their coagulatory activity. This study provides clear evidence that EVs support thrombin generation and that this EV-dependent thrombin generation is reduced by n-3 PUFAs, which has implications for prevention and treatment of thrombosis. CLINICAL TRIAL REGISTRY: This trial was registered at clinicaltrials.gov as NCT03203512.

Impact of a (poly)phenol-rich extract from the brown algae Ascophyllum nodosum on DNA damage and antioxidant activity in an overweight or obese population: a randomized controlled trial.

Background: Epidemiologic evidence suggests that a diet rich in (poly)phenols has beneficial effects on many chronic diseases. Brown seaweed is a rich source of (poly)phenols. Objective: The aim of this study was to investigate the bioavailability and effect of a brown seaweed (Ascophyllum nodosum) (poly)phenol extract on DNA damage, oxidative stress, and inflammation in vivo. Design: A randomized, double-blind, placebo-controlled crossover trial was conducted in 80 participants aged 30-65 y with a body mass index (in kg/m2) ≥25. The participants consumed either a 400-mg capsule containing 100 mg seaweed (poly)phenol and 300 mg maltodextrin or a 400-mg maltodextrin placebo control capsule daily for an 8-wk period. Bioactivity was assessed with a panel of blood-based markers including lymphocyte DNA damage, plasma oxidant capacity, C-reactive protein (CRP), and inflammatory cytokines. To explore the bioavailability of seaweed phenolics, an untargeted metabolomics analysis of urine and plasma samples after seaweed consumption was determined by ultra-high-performance liquid chromatography-high-resolution mass spectrometry. Results: Consumption of the seaweed (poly)phenols resulted in a modest decrease in DNA damage but only in a subset of the total population who were obese. There were no significant changes in CRP, antioxidant status, or inflammatory cytokines. We identified phlorotannin metabolites that are considered potential biomarkers of seaweed consumption including pyrogallol/phloroglucinol-sulfate, hydroxytrifurahol A-glucuronide, dioxinodehydroeckol-glucuronide, diphlorethol sulfates, C-O-C dimer of phloroglucinol sulfate, and C-O-C dimer of phloroglucinol. Conclusions: To the best of our knowledge, this work represents the first comprehensive study investigating the bioactivity and bioavailability of seaweed (poly)phenolics in human participants. We identified several potential biomarkers of seaweed consumption. Intriguingly, the modest improvements in DNA damage were observed only in the obese subset of the total population. The subgroup analysis should be considered exploratory because it was not preplanned; therefore, it was not powered adequately. Elucidation of the biology underpinning this observation will require participant stratification according to weight in future studies. This trial was registered at clinicaltrials.gov as NCT02295878.

Omega-3 fatty acids and leukocyte-endothelium adhesion: Novel anti-atherosclerotic actions.

Endothelial cells (ECs) play a role in the optimal function of blood vessels. When endothelial function becomes dysregulated, the risk of developing atherosclerosis increases. Specifically, upregulation of adhesion molecule expression on ECs promotes the movement of leukocytes, particularly monocytes, into the vessel wall. Here, monocytes differentiate into macrophages and may become foam cells, contributing to the initiation and progression of an atherosclerotic plaque. The ability of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) to influence the expression of adhesion molecules by ECs and to modulate leukocyte-endothelial adhesion has been studied in cell culture using various types of ECs, in animal feeding studies and in human trials; the latter have tended to evaluate soluble forms of adhesion molecules that circulate in the bloodstream. These studies indicate that n-3 PUFAs (both eicosapentaenoic acid and docosahexaenoic acid) can decrease the expression of key adhesion molecules, such as vascular cell adhesion molecule 1, by ECs and that this results in decreased adhesive interactions between leukocytes and ECs. These findings suggest that n-3 PUFAs may lower leukocyte infiltration into the vascular wall, which could contribute to reduced atherosclerosis and lowered risk of cardiovascular disease.

Replacement of dietary saturated fat with unsaturated fats increases numbers of circulating endothelial progenitor cells and decreases numbers of microparticles: findings from the randomized, controlled Dietary Intervention and VAScular function (DIVAS) study.

Background: Endothelial progenitor cells (EPCs) and microparticles are emerging as novel markers of cardiovascular disease (CVD) risk, which could potentially be modified by dietary fat. We have previously shown that replacing dietary saturated fatty acids (SFAs) with monounsaturated or n-6 (ω-6) polyunsaturated fatty acids (MUFAs or PUFAs, respectively) improved lipid biomarkers, blood pressure, and markers of endothelial activation, but their effects on circulating EPCs and microparticles are unclear. Objective: The Dietary Intervention and VAScular function (DIVAS) Study investigated the replacement of 9.5-9.6% of total energy (%TE) contributed by SFAs with MUFAs or n-6 PUFAs for 16 wk on EPC and microparticle numbers in United Kingdom adults with moderate CVD risk. Design: In this randomized, controlled, single-blind, parallel-group dietary intervention, men and women aged 21-60 y (n = 190) with moderate CVD risk (≥50% above the population mean) consumed 1 of three 16-wk isoenergetic diets. Target compositions for total fat, SFAs, MUFAs, and n-6 PUFAs (%TE) were as follows: SFA-rich diet (36:17:11:4; n = 64), MUFA-rich diet (36:9:19:4; n = 62), and n-6 PUFA-rich diet (36:9:13:10; n = 66). Circulating EPC, endothelial microparticle (EMP), and platelet microparticle (PMP) numbers were analyzed by flow cytometry. Dietary intake, vascular function, and other cardiometabolic risk factors were determined at baseline. Results: Relative to the SFA-rich diet, MUFA- and n-6 PUFA-rich diets decreased EMP (-47.3%, -44.9%) respectively and PMP (-36.8%, -39.1%) numbers (overall diet effects, P < 0.01). The MUFA-rich diet increased EPC numbers (+28.4%; P = 0.023). Additional analyses that used stepwise regression models identified the augmentation index (measuring arterial stiffness determined by pulse-wave analysis) as an independent predictor of baseline EPC and microparticle numbers. Conclusions: Replacement of 9.5-9.6%TE dietary SFAs with MUFAs increased EPC numbers, and replacement with either MUFAs or n-6 PUFAs decreased microparticle numbers, suggesting beneficial effects on endothelial repair and maintenance. Further studies are warranted to determine the mechanisms underlying the favorable effects on EPC and microparticle numbers after SFA replacement. This trial was registered at www.clinicaltrials.gov as NCT01478958.

Pelargonidin-3-O-glucoside and its metabolites have modest anti-inflammatory effects in human whole blood cultures.

This study hypothesized that the predominant strawberry anthocyanin, pelargonidin-3-O-glucoside (Pg-3-glc), and 3 of its plasma metabolites (4-hydroxybenzoic acid, protocatechuic acid, and phloroglucinaldehyde [PGA]) would affect phagocytosis, oxidative burst, and the production of selected pro- and anti-inflammatory cytokines in a whole blood culture model. For the assessment of phagocytosis and oxidative burst activity of monocytes and neutrophils, whole blood was preincubated in the presence or absence of the test compounds at concentrations up to 5 µmol/L, followed by analysis of phagocytic and oxidative burst activity using commercially available test kits. For the cytokine analysis, diluted whole blood was stimulated with lipopolysaccharide in the presence or absence of the test compounds at concentrations up to 5 µmol/L. Concentrations of selected cytokines (tumor necrosis factor-α, interleukin [IL]-1ß, IL-6, IL-8, and IL-10) were determined using a cytometric bead array kit. There were no effects of any of the test compounds on phagocytosis of opsonized or nonopsonized Escherichia coli or on oxidative burst activity. Pg-3-glc and PGA at 0.08 µmol/L increased the concentration of IL-10 (P<.01 and P<.001, respectively), but there was no effect on tumor necrosis factor-α, IL-1ß, IL-6, and IL-8, and there were no effects of the other compounds. In conclusion, this study demonstrated a lack of effect of these compounds on the opsonization, engulfment, and subsequent destruction of bacteria. Pg-3-glc and PGA, at physiologically relevant concentrations, had anti-inflammatory properties; however, effects were modest, only observed at the lowest dose tested and limited to IL-10.

Effect of simulated gastrointestinal digestion and fermentation on polyphenolic content and bioactivity of brown seaweed phlorotannin-rich extracts.

SCOPE: Unlike other classes of polyphenols, there is a lack of knowledge regarding brown seaweed phlorotannins and their bioactivity. We investigated the impact of in vitro gastrointestinal digestion and colonic fermentation on the bioactivity of a seaweed phlorotannin extract from Ascophyllum nodosum and its high molecular weight (HMW) and low molecular weight (LMW) fractions. METHODS AND RESULTS: The highest phlorotannin and total polyphenol (TP) concentration was observed in the HMW fraction. Antioxidant capacity broadly followed phlorotannin and TP levels, with HMW having the highest activity. Both gastrointestinal digestion (GID) and colonic fermentation (CF) significantly affected phlorotannin and TP levels, and antioxidant capacity of the extract and fractions. Despite this, in HT-29 cells, all GID extracts significantly inhibit cell growth, whereas CF extracts effectively counteracted H2 O2 induced DNA damage. CONCLUSION: Although phlorotannins, TP levels and antioxidant power of the extracts were strongly reduced after in vitro digestion and fermentation, their anti-genotoxic activity and cell growth inhibitory effect in colon HT-29 cells was maintained and enhanced. HMW was the most effective fraction, indicating that the high molecular weight phlorotannins potentially exert a stronger beneficial effect in the colon.

Ageing alters the impact of nutrition on immune function.

Immunosenescence during ageing is a major challenge which weakens the ability of older individuals to respond to infection or vaccination. There has been much interest in dietary strategies to improve immunity in older people, but there is an assumption that modulation of the immune response in older people will be based on the same principles as for younger adults. Recent evidence suggests that ageing fundamentally alters the impact of nutrition on immune function. As a result, interpretation of data from studies investigating the impact of diet on immune function is highly dependent on subject age. Study design is critically important when investigating the efficacy of dietary components, and most studies involving older people include rigorous inclusion/exclusion criteria based on medical history, laboratory tests, general health status and often nutritional status. However, immunological status is rarely accounted for, but can vary significantly, even amongst healthy older people. There are several clear examples of age-related changes in immune cell composition, phenotype and/or function, which can directly alter the outcome of an intervention. This review uses two case studies to illustrate how the effects of n-3 PUFA and probiotics differ markedly in young v. older subjects. Evidence from both suggests that baseline differences in immunosenescence influence the outcome of an intervention, highlighting the need for detailed immunological characterisation of subjects prior to interventions. Finally, future work elucidating alterations in metabolic regulation within cells of the immune system as a result of ageing may be important in understanding the impact of diet on immune function in older people.

Impact of phenolic-rich olive leaf extract on blood pressure, plasma lipids and inflammatory markers: a randomised controlled trial.

PURPOSE: Dietary polyphenols have been demonstrated to favourably modify a number of cardiovascular risk markers such as blood pressure (BP), endothelial function and plasma lipids. We conducted a randomised, double-blind, controlled, crossover trial to investigate the effects of a phenolic-rich olive leaf extract (OLE) on BP and a number of associated vascular and metabolic measures. METHODS: A total of 60 pre-hypertensive [systolic blood pressure (SBP): 121-140 mmHg; diastolic blood pressure (DBP): 81-90 mmHg] males [mean age 45 (±SD 12.7 years, BMI 26.7 (±3.21) kg/m2] consumed either OLE (136 mg oleuropein; 6 mg hydroxytyrosol) or a polyphenol-free control daily for 6 weeks before switching to the alternate arm after a 4-week washout. RESULTS: Daytime [-3.95 (±SD 11.48) mmHg, p = 0.027] and 24-h SBP [-3.33 (±SD 10.81) mmHg, p = 0.045] and daytime and 24-h DBP [-3.00 (±SD 8.54) mmHg, p = 0.025; -2.42 (±SD 7.61) mmHg, p = 0.039] were all significantly lower following OLE intake, relative to the control. Reductions in plasma total cholesterol [-0.32 (±SD 0.70) mmol/L, p = 0.002], LDL cholesterol [-0.19 (±SD 0.56) mmol/L, p = 0.017] and triglycerides [-0.18 (±SD 0.48), p = 0.008] were also induced by OLE compared to control, whilst a reduction in interleukin-8 [-0.63 (±SD 1.13) pg/ml; p = 0.026] was also detected. Other markers of inflammation, vascular function and glucose metabolism were not affected. CONCLUSION: Our data support previous research, suggesting that OLE intake engenders hypotensive and lipid-lowering effects in vivo.

Secoiridoids delivered as olive leaf extract induce acute improvements in human vascular function and reduction of an inflammatory cytokine: a randomised, double-blind, placebo-controlled, cross-over trial.

The leaves of the olive plant (Olea europaea) are rich in polyphenols, of which oleuropein and hydroxytyrosol (HT) are most characteristic. Such polyphenols have been demonstrated to favourably modify a variety of cardiovascular risk factors. The aim of the present intervention was to investigate the influence of olive leaf extract (OLE) on vascular function and inflammation in a postprandial setting and to link physiological outcomes with absorbed phenolics. A randomised, double-blind, placebo-controlled, cross-over, acute intervention trial was conducted with eighteen healthy volunteers (nine male, nine female), who consumed either OLE (51 mg oleuropein; 10 mg HT), or a matched control (separated by a 4-week wash out) on a single occasion. Vascular function was measured by digital volume pulse (DVP), while blood collected at baseline, 1, 3 and 6 h was cultured for 24 h in the presence of lipopolysaccharide in order to investigate effects on cytokine production. Urine was analysed for phenolic metabolites by HPLC. DVP-stiffness index and ex vivo IL-8 production were significantly reduced (P< 0.05) after consumption of OLE compared to the control. These effects were accompanied by the excretion of several phenolic metabolites, namely HT and oleuropein derivatives, which peaked in urine after 8-24 h. The present study provides the first evidence that OLE positively modulates vascular function and IL-8 production in vivo, adding to growing evidence that olive phenolics could be beneficial for health.

Replacement of saturated with unsaturated fats had no impact on vascular function but beneficial effects on lipid biomarkers, E-selectin, and blood pressure: results from the randomized, controlled Dietary Intervention and VAScular function (DIVAS) study.

BACKGROUND: Public health strategies to lower cardiovascular disease (CVD) risk involve reducing dietary saturated fatty acid (SFA) intake to ≤10% of total energy (%TE). However, the optimal type of replacement fat is unclear. OBJECTIVE: We investigated the substitution of 9.5-9.6%TE dietary SFAs with either monounsaturated fatty acids (MUFAs) or n-6 (ω-6) polyunsaturated fatty acids (PUFAs) on vascular function and other CVD risk factors. DESIGN: In a randomized, controlled, single-blind, parallel-group dietary intervention, 195 men and women aged 21-60 y from the United Kingdom with moderate CVD risk (≥50% above the population mean) followed one of three 16-wk isoenergetic diets (%TE target compositions, total fat:SFA:MUFA:n-6 PUFA) that were rich in SFAs (36:17:11:4, n = 65), MUFAs (36:9:19:4, n = 64), or n-6 PUFAs (36:9:13:10, n = 66). The primary outcome measure was flow-mediated dilatation; secondary outcome measures included fasting serum lipids, microvascular reactivity, arterial stiffness, ambulatory blood pressure, and markers of insulin resistance, inflammation, and endothelial activation. RESULTS: Replacing SFAs with MUFAs or n-6 PUFAs did not affect the percentage of flow-mediated dilatation (primary endpoint) or other measures of vascular reactivity. Of the secondary outcome measures, substitution of SFAs with MUFAs attenuated the increase in night systolic blood pressure (-4.9 mm Hg, P = 0.019) and reduced E-selectin (-7.8%, P = 0.012). Replacement with MUFAs or n-6 PUFAs lowered fasting serum total cholesterol (-8.4% and -9.2%, respectively), low-density lipoprotein cholesterol (-11.3% and -13.6%), and total cholesterol to high-density lipoprotein cholesterol ratio (-5.6% and -8.5%) (P ≤ 0.001). These changes in low-density lipoprotein cholesterol equate to an estimated 17-20% reduction in CVD mortality. CONCLUSIONS: Substitution of 9.5-9.6%TE dietary SFAs with either MUFAs or n-6 PUFAs did not significantly affect the percentage of flow-mediated dilatation or other measures of vascular function. However, the beneficial effects on serum lipid biomarkers, blood pressure, and E-selectin offer a potential public health strategy for CVD risk reduction. This trial was registered at www.clinicaltrials.gov as NCT01478958.

Fish-oil supplementation alters numbers of circulating endothelial progenitor cells and microparticles independently of eNOS genotype.

BACKGROUND: Emerging cellular markers of endothelial damage and repair include endothelial microparticles (EMPs) and endothelial progenitor cells (EPCs), respectively. Effects of long-chain (LC) n-3 (omega-3) polyunsaturated fatty acids (PUFAs) and the influence of genetic background on these markers are not known. OBJECTIVE: We investigated effects of fish-oil supplementation on both classical and novel markers of endothelial function in subjects prospectively genotyped for the Asp298 endothelial nitric oxide synthase (eNOS) polymorphism and at moderate risk of cardiovascular disease (CVD). DESIGN: A total of 84 subjects with moderate risk of CVD (GG: n = 40; GT/TT: n = 44) completed a randomized, double-blind, placebo-controlled, 8-wk crossover trial of fish-oil supplementation that provided 1.5 g LC n-3 PUFAs/d. Effects of genotype and fish-oil supplementation on the blood lipid profile, inflammatory markers, vascular function (by using peripheral artery tonometry), and numbers of circulating EPCs and EMPs (by using flow cytometry) were assessed. RESULTS: There was no significant effect of fish-oil supplementation on blood pressure, plasma lipids, or plasma glucose, although there was a trend (P = 0.069) toward a decrease in the plasma triglyceride concentration after fish-oil supplementation compared with placebo treatment. GT/TT subjects tended to have higher concentrations of total cholesterol and low-density lipoprotein cholesterol, but vascular function was not affected by either treatment or eNOS genotype. Biochemical markers of endothelial function were also unaffected by treatment and eNOS genotype. In contrast, there was a significant effect of fish-oil supplementation on cellular markers of endothelial function. Fish-oil supplementation increased numbers of EPCs and reduced numbers of EMPs relative to those with placebo treatment, which potentially favored the maintenance of endothelial integrity. There was no influence of genotype for any cellular markers of endothelial function, which indicated that effects of fish-oil supplementation were independent of eNOS genotype. CONCLUSION: Emerging cellular markers of endothelial damage, integrity, and repair appear to be sensitive to potentially beneficial modification by dietary n-3 PUFAs. This trial was registered at www.controlled-trials.com/isrctn as ISRCTN76272133.

Development of a food-exchange model to replace saturated fat with MUFAs and n-6 PUFAs in adults at moderate cardiovascular risk.

The recommendation to reduce saturated fatty acid (SFA) consumption to ≤10% of total energy (%TE) is a key public health target aimed at lowering cardiovascular disease (CVD) risk. Replacement of SFA with unsaturated fats may provide greater benefit than replacement with carbohydrates, yet the optimal type of fat is unclear. The aim of the DIVAS (Dietary Intervention and Vascular Function) study was to develop a flexible food-exchange model to investigate the effects of substituting SFAs with monounsaturated fatty acids (MUFAs) or n-6 (ω-6) polyunsaturated fatty acids (PUFAs) on CVD risk factors. In this parallel study, UK adults aged 21-60 y with moderate CVD risk (50% greater than the population mean) were identified using a risk assessment tool (n = 195; 56% females). Three 16-wk isoenergetic diets of specific fatty acid (FA) composition (%TE SFA:%TE MUFA:%TE n-6 PUFA) were designed using spreads, oils, dairy products, and snacks as follows: 1) SFA-rich diet (17:11:4; n = 65); 2) MUFA-rich diet (9:19:4; n = 64); and 3) n-6 PUFA-rich diet (9:13:10; n = 66). Each diet provided 36%TE total fat. Dietary targets were broadly met for all intervention groups, reaching 17.6 ± 0.4%TE SFA, 18.5 ± 0.3%TE MUFA, and 10.4 ± 0.3%TE n-6 PUFA in the respective diets, with significant overall diet effects for the changes in SFAs, MUFAs, and n-6 PUFAs between groups (P < 0.001). There were no differences in the changes of total fat, protein, carbohydrate, and alcohol intake or anthropometric measures between groups. Plasma phospholipid FA composition showed changes from baseline in the proportions of total SFAs, MUFAs, and n-6 PUFAs for each diet group, with the changes in SFAs and MUFAs differing between the groups (P < 0.001). In conclusion, successful implementation of the food-exchange model broadly achieved the dietary target intakes for the exchange of SFAs with MUFAs or n-6 PUFAs with minimal disruption to the overall diet in a free-living population. This trial was registered at clinicaltrials.gov as NCT01478958.

Effect of salmon consumption during pregnancy on maternal and infant faecal microbiota, secretory IgA and calprotectin.

The gut microbiota plays an important role in the development of the immune and gastrointestinal systems of infants. In the present study, we investigated whether increased salmon consumption during pregnancy, maternal weight gain during pregnancy or mode of infant feeding alter the markers of gut immune defence and inflammation. Women (n 123) who rarely ate oily fish were randomly assigned to continue consuming their habitual diet or to consume two 150 g portions of farmed salmon per week from 20 weeks of pregnancy to delivery. Faecal samples were collected from the mothers (n 75) at 38 weeks of gestation and from their infants (n 38) on days 7, 14, 28 and 84 post-partum. Fluorescence in situ hybridisation was used to determine faecal microbiota composition and ELISA to measure faecal secretory IgA (sIgA) and calprotectin concentrations. There was no effect of salmon consumption on maternal faecal microbiota or on maternal or infant faecal sIgA and calprotectin concentrations. The degree of weight gain influenced maternal faecal microbiota, and the mode of infant feeding influenced infant faecal microbiota. Faecal samples collected from infants in the salmon group tended to have lower bacterial counts of the Atopobium cluster compared with those collected from infants in the control group (P=0·097). This difference was significant in the formula-fed infants (P< 0·05), but not in the exclusively breast-fed infants. In conclusion, the impact of oily fish consumption during pregnancy on maternal and infant gut microbiota composition is limited, but significant differences are associated with maternal weight gain during pregnancy and mode of infant feeding.

Salmon consumption during pregnancy alters fatty acid composition and secretory IgA concentration in human breast milk.

Fish oil supplementation during pregnancy alters breast milk composition, but there is little information about the impact of oily fish consumption. We determined whether increased salmon consumption during pregnancy alters breast milk fatty acid composition and immune factors. Women (n = 123) who rarely ate oily fish were randomly assigned to consume their habitual diet or to consume 2 portions of farmed salmon per week from 20 wk of pregnancy until delivery. The salmon provided 3.45 g long-chain (LC) (n-3) PUFA/wk. Breast milk fatty acid composition and immune factors [soluble CD14, transforming growth factor-ß (TGFß)1, TGFß2, and secretory IgA] were analyzed at 1, 5, 14, and 28 d postpartum (PP). Breast milk from the salmon group had higher proportions of EPA (80%), docosapentaenoic acid (30%), and DHA (90%) on d 5 PP compared with controls (P < 0.01). The LC (n-6) PUFA:LC (n-3) PUFA ratio was lower for the salmon group on all days of PP sampling (P ≤ 0.004), although individual (n-6) PUFA proportions, including arachidonic acid, did not differ. All breast milk immune factors decreased between d 1 and 28 PP (P < 0.001). Breast milk secretory IgA (sIgA) was lower in the salmon group (d 1-28 PP; P = 0.006). Salmon consumption during pregnancy, at the current recommended intakes, increases the LC (n-3) PUFA concentration of breast milk in early lactation, thus improving the supply of these important fatty acids to the breast-fed neonate. The consequence of the lower breast milk concentration of sIgA in the salmon group is not clear.

Marine omega-3 fatty acids and coronary heart disease.

PURPOSE OF REVIEW: To provide an overview of the key earlier intervention studies with marine omega-3 fatty acids and to review and comment on recent studies reporting on mortality outcomes and on selected underlying mechanisms of action. RECENT FINDINGS: Studies relating marine omega-3 fatty acid status to current or future outcomes continue to indicate benefits, for example, on incident heart failure, congestive heart failure, acute coronary syndrome, and all-cause mortality. New mechanistic insights into the actions of marine omega-3 fatty acids have been gained. Three fairly large secondary prevention trials have not confirmed the previously reported benefit of marine omega-3 fatty acids towards mortality in survivors of myocardial infarction. Studies of marine omega-3 fatty acids in atrial fibrillation and in cardiac surgery-induced atrial fibrillation have produced inconsistent findings and meta-analyses demonstrate no benefit. A study confirmed that marine omega-3 fatty acids reduce the inflammatory burden with advanced atherosclerotic plaques, so inducing greater stability. SUMMARY: Recent studies of marine omega-3 fatty acids on morbidity of, and mortality from, coronary and cardiovascular disease have produced mixed findings. These studies raise new issues to be addressed in future research.

The nutritional and clinical significance of lipid rafts.

PURPOSE OF REVIEW: Lipid rafts are potentially modifiable by diet, particularly (but not exclusively) by dietary fatty acids. This review examines the potential for dietary modification of raft structure and function in the immune system, brain and retinal tissue, the gut, and in cancer cells. RECENT FINDINGS: In-vitro and ex-vivo studies suggest that dietary n-3 polyunsaturated fatty acids (PUFAs) may exert immunosuppressive and anticancer effects through changes in lipid raft organization. In addition, gangliosides and cholesterol may modulate lipid raft organization in a number of tissues, and recent work has highlighted sphingolipids in membrane microdomains as potential targets for inhibition of tumor growth. The roles of fatty acids and gangliosides, especially in relation to lipid rafts, in cognitive development, age-related cognitive decline, psychiatric disorders, and Alzheimer's disease are poorly understood and require further investigation. The roles of lipid rafts in cancer, in microbial pathogenesis, and in insulin resistance are starting to emerge, and indicate compelling evidence for the growing importance of membrane microdomains in health and disease. SUMMARY: In-vitro and animal studies show that n-3 PUFAs, cholesterol, and gangliosides modulate the structure and composition of lipid rafts, potentially influencing a wide range of biological processes, including immune function, neuronal signaling, cancer cell growth, entry of pathogens through the gut barrier, and insulin resistance in metabolic disorders. The physiological, clinical, and nutritional relevance of these observations remains to be determined.

Understanding omega-3 polyunsaturated fatty acids.

Current intakes of very long-chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are low in most individuals living in Western countries. A good natural source of these fatty acids is seafood, especially oily fish. Fish oil capsules contain these fatty acids also. Very long-chain omega-3 fatty acids are readily incorporated from capsules into transport (blood lipids), functional (cell and tissue), and storage (adipose) pools. This incorporation is dose-dependent and follows a kinetic pattern that is characteristic for each pool. At sufficient levels of incorporation, EPA and DHA influence the physical nature of cell membranes and membrane protein-mediated responses, lipid-mediator generation, cell signaling, and gene expression in many different cell types. Through these mechanisms, EPA and DHA influence cell and tissue physiology and the way cells and tissues respond to external signals. In most cases the effects seen are compatible with improvements in disease biomarker profiles or health-related outcomes. As a result, very long-chain omega-3 fatty acids play a role in achieving optimal health and in protection against disease. Long-chain omega-3 fatty acids not only protect against cardiovascular morbidity but also against mortality. In some conditions, for example rheumatoid arthritis, they may be beneficial as therapeutic agents. On the basis of the recognized health improvements brought about by long-chain omega-3 fatty acids, recommendations have been made to increase their intake. The plant omega-3 fatty acid, alpha-linolenic acid (ALA), can be converted to EPA, but conversion to DHA appears to be poor in humans. Effects of ALA on human health-related outcomes appear to be due to conversion to EPA, and since this is limited, moderately increased consumption of ALA may be of little benefit in improving health outcomes compared with increased intake of preformed EPA + DHA.

Omega-3 polyunsaturated fatty acids and human health outcomes.

Current intakes of very long chain omega-3 fatty acids, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are low in most individuals living in Western countries. A good natural source of these fatty acids is seafood, especially oily fish. Fish oil capsules contain these fatty acids too. Very long chain omega-3 fatty acids are readily incorporated from capsules into transport, functional, and storage pools. This incorporation is dose-dependent and follows a kinetic pattern that is characteristic for each pool. At sufficient levels of incorporation, EPA and DHA influence the physical nature of cell membranes and membrane protein-mediated responses, eicosanoid generation, cell signaling and gene expression in many different cell types. Through these mechanisms, EPA and DHA influence cell and tissue physiology, and the way cells and tissues respond to external signals. In most cases, the effects seen are compatible with improvements in disease biomarker profiles or in health-related outcomes. As a result, very long chain omega-3 fatty acids play a role in achieving optimal health and in protection against disease. Long chain omega-3 fatty acids protect against cardiovascular morbidity and mortality, and might be beneficial in rheumatoid arthritis, inflammatory bowel diseases, childhood learning, and behavior, and adult psychiatric and neurodegenerative illnesses. DHA has an important structural role in the eye and brain, and its supply early in life is known to be of vital importance. On the basis of the recognized health improvements brought about by long chain omega-3 fatty acids, recommendations have been made to increase their intake.

The nutritional significance of lipid rafts.

The structure, size, stability, and functionality of lipid rafts are still in debate, but recent techniques allowing direct visualization have characterized them in a wide range of cell types. Lipid rafts are potentially modifiable by diet, particularly (but not exclusively) by dietary fatty acids. However, it is not clear whether dietary polyunsaturated fatty acids (PUFAs) are incorporated into raft lipids or whether their low affinity to cholesterol disallows this and causes phase separation from rafts and displacement of raft proteins. This review examines the potential for dietary modification of raft structure and function in the immune system, brain and retinal tissue, the gut, and in cancer cells. Although there is increasing evidence to suggest that membrane microdomains, and their modulation, have an impact in health and disease, it is too early to judge whether modulation of lipid rafts is responsible for the immunomodulatory effects of n-3 PUFA. In addition to dietary fatty acids, gangliosides and cholesterol may also modulate microdomains in a number of tissues, and recent work has highlighted sphingolipids in membrane microdomains as potential targets for inhibition of tumor growth by n-3 PUFA. The roles of fatty acids and gangliosides in cognitive development, age-related cognitive decline, psychiatric disorders, and Alzheimer's disease are poorly understood and require clarification, particularly with respect to the contribution of lipid rafts. The roles of lipid rafts in cancer, in microbial pathogenesis, and in insulin resistance are only just emerging, but compelling evidence indicates the growing importance of membrane microdomains in health and disease.

Modulation of the fecal microflora profile and immune function by a novel trans-galactooligosaccharide mixture (B-GOS) in healthy elderly volunteers.

BACKGROUND: Aging is associated with reduced numbers of beneficial colonic bifidobacteria and impaired immunity. Galactooligosaccharides (GOSs) stimulate the growth of bifidobacteria in younger adults, but little is known about their effects in the elderly and their immunomodulatory capacity. OBJECTIVE: We assessed the effect of a prebiotic GOS mixture (B-GOS) on immune function and fecal microflora composition in healthy elderly subjects. DESIGN: In a double-blind, placebo-controlled, crossover study, 44 elderly subjects were randomly assigned to receive either a placebo or the B-GOS treatment (5.5 g/d). Subjects consumed the treatments for 10 wk, and then went through a 4-wk washout period, before switching to the other treatment for the final 10 wk. Blood and fecal samples were collected at the beginning, middle (5 wk), and end of the test period. Predominant bacterial groups were quantified, and phagocytosis, natural killer (NK) cell activity, cytokine production, plasma cholesterol, and HDL cholesterol were measured. RESULTS: B-GOS significantly increased the numbers of beneficial bacteria, especially bifidobacteria, at the expense of less beneficial groups compared with the baseline and placebo. Significant increases in phagocytosis, NK cell activity, and the production of antiinflammatory cytokine interleukin-10 (IL-10) and significant reduction in the production of proinflammatory cytokines (IL-6, IL-1beta, and tumor necrosis factor-alpha) were also observed. B-GOS exerted no effects on total cholesterol or HDL-cholesterol production, however. CONCLUSIONS: B-GOS administration to healthy elderly persons resulted in positive effects on both the microflora composition and the immune response. Therefore, B-GOS may be a useful dietary candidate for the enhancement of gastrointestinal health and immune function in elderly persons.