Comparison of the effects of two low fat diets with different alpha-linolenic:linoleic acid ratios on coagulation and fibrinolysis

Methodology for altering omega-3 EPA+DHA and omega-6 linoleic acid as controlled variables in a dietary trial

BACKGROUND & AIMS

Increasing dietary intake of n-3 EPA+DHA and lowering dietary n-6 LA is under investigation as a therapeutic diet for improving chronic pain syndromes as well as other health outcomes. Herein we describe the diet methodology used to modulate intake of n-3 and n-6 PUFA in a free living migraine headache population and report on nutrient intake, BMI and diet acceptability achieved at week 16 of the intensive diet intervention and week 22 follow-up time-point.

METHODS

A total of 178 participants were randomized and began one of three diet interventions: 1) a high n-3 PUFA, average n-6 PUFA (H3) diet targeting 1500 mg EPA+DHA/day and 7% of energy (en%) from n-6 linoleic acid (LA), 2) a high-n-3 PUFA, low-n-6 PUFA (H3L6) targeting 1500 mg EPA+DHA/day and <1.8 en% n-6 LA or 3) a Control diet with typical American intakes of both EPA+DHA (<150 mg/day) and 7 en% from n-6 LA. Methods used to achieve diet change to week 16 include diet education, diet counseling, supply of specially prepared foods, self-monitoring and access to online diet materials. Only study oils and website materials were provided for the follow-up week 16 to week 22 periods. Diet adherence was assessed by multiple 24 h recalls administered throughout the trial. Diet acceptability was assessed in a subset of participants at 4 time points by questionnaire.

RESULTS

At week 16 H3 and H3L6 diet groups significantly increased median n-3 EPA+DHA intake from 48 mg/2000 kcals at baseline to 1484 mg/2000 kcals (p < 0.0001) and from 44 mg/2000 kcals to 1341 mg/2000 kcals (p < 0.0001), respectively. In the Control group, EPA+DHA intake remained below the typical American intake with baseline median at 60 mg/2000 kcals and 80 mg/2000 kcals (p = 0.6) at week 16. As desired, LA intake was maintained in the H3 and Control group with baseline median of 6.5 en% to 7.1 en% (p = 0.4) at week 16 and from 6.5 en% to 6.8 en% (p = 1.0) at week 16, respectively. In the H3L6 group, n-6 LA decreased from 6.3 en% at baseline to 3.2 en% (p < 0.0001) at week 16. There were no significant changes in BMI or diet acceptability throughout the trial or between diet groups.

CONCLUSIONS

We find this diet method to be acceptable to research participants and successful in altering dietary n-3 EPA+DHA with and without concurrent decreases in n-6 LA. If n-6 LA of less than 3 en% is desired, additional techniques to limit LA may need to be employed.

Effects of plant oils with different fatty acid composition on cardiovascular risk factors in moderately hypercholesteremic Chinese adults: a randomized, double-blinded, parallel-designed trial

OBJECTIVES

Plant oil for cooking typically provides 40% to 50% of dietary fat, 65% of linoleic acid, 44% of α-linolenic acid and 41% of oleic acid in the Chinese diet. However, the comparative effects of fatty acids derived from plant oil on cardiovascular risk factors in Chinese are still inconclusive. Hence, the aim of this study is to investigate whether cardiovascular risk factors are altered depending on various types of plant oils such as peanut oil rich in oleic acid, corn oil rich in linoleic acid, and blend oil fortified by α-linolenic acid.

DESIGN

A randomized, double-blinded, parallel-designed trial.

SETTING

The First and the Second Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.

PARTICIPANTS

A total of 251 volunteers with fasting blood total cholesterol between 5.13 and 8.00 mmol L^-1 were enrolled.

INTERVENTION

Volunteers received peanut oil, corn oil or blend oil to use for cooking for one year.

MAIN OUTCOME MEASURES

The erythrocyte membrane fatty acid composition, fasting plasma lipids, glucose and insulin concentrations and high sensitivity C-reactive protein (hsCRP) levels were measured before, during and after the intervention. The level of α-linolenic acid in erythrocyte membranes was significantly increased in the blend oil group after the intervention (P < 0.001). The level of other fatty acids did not show any statistically significant differences between the three groups. No significant differences were observed in the concentrations of fasting plasma lipids, hsCRP, glucose, and insulin among the three groups using different types of plant oils.

CONCLUSIONS

The results suggest that although ingesting cooking oil with different fatty acid composition for one year could change erythrocyte membrane fatty acid compositions, it did not significantly modify cardiovascular risk factors in moderately hypercholesteremic people.

Dietary linoleic acid intake and blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

The aim of the present study was to investigate the effect of increasing dietary linoleic acid (LA) intake on the blood concentrations of inflammatory markers including cytokines, acute phase reactants and adhesion molecules in adults.

METHODS

We comprehensively searched PubMed, Embase and Cochrane Library for eligible studies. Overall, 30 randomized controlled studies involving 1377 subjects were included for meta-analysis.

RESULTS

No significant effect of higher LA intake was observed for cytokines: tumor necrosis factor (SMD: -0.01; 95% CI: -0.19 to 0.17), interleukin-6 (SMD: 0.11, 95% CI: -0.07 to 0.29), adiponectin (SMD: 0.17, 95% CI: -0.17 to 0.50) and monocyte chemoattractant protein 1 (SMD: 0.14, 95% CI: -0.33 to 0.60). Pooled effect size from 16 studies showed that the C-reactive protein (CRP) concentration was not significantly affected by increasing LA intake (SMD = 0.09, 95% CI: -0.05 to 0.24). However, subgroup and meta-regression analysis suggested that in subjects with a more profound increase of dietary LA intake, LA might increase the blood CRP level. Other acute phase reactants including fibrinogen and plasminogen activator inhibitor-1 and adhesion molecules were not significantly changed when LA was increased in diet. No significant heterogeneity or publication bias was observed, although only a limited number of eligible studies were included for some markers.

CONCLUSION

Our meta-analysis suggested that increasing dietary LA intake does not have a significant effect on the blood concentrations of inflammatory markers. However, the extent of change in dietary LA intake might affect the effect of LA supplementation on CRP.

Omega 6 fatty acids for the primary prevention of cardiovascular disease

BACKGROUND

Omega 6 plays a vital role in many physiological functions but there is controversy concerning its effect on cardiovascular disease (CVD) risk. There is conflicting evidence whether increasing or decreasing omega 6 intake results in beneficial effects.

OBJECTIVES

The two primary objectives of this Cochrane review were to determine the effectiveness of:1. Increasing omega 6 (Linoleic acid (LA), Gamma-linolenic acid (GLA), Dihomo-gamma-linolenic acid (DGLA), Arachidonic acid (AA), or any combination) intake in place of saturated or monounsaturated fats or carbohydrates for the primary prevention of CVD.2. Decreasing omega 6 (LA, GLA, DGLA, AA, or any combination) intake in place of carbohydrates or protein (or both) for the primary prevention of CVD.

SEARCH METHODS

We searched the following electronic databases up to 23 September 2014: the Cochrane Central Register of Controlled Trials (CENTRAL) on the Cochrane Library (Issue 8 of 12, 2014); MEDLINE (Ovid) (1946 to September week 2, 2014); EMBASE Classic and EMBASE (Ovid) (1947 to September 2014); Web of Science Core Collection (Thomson Reuters) (1990 to September 2014); Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment Database, and Health Economics Evaluations Database on the Cochrane Library (Issue 3 of 4, 2014). We searched trial registers and reference lists of reviews for further studies. We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions stating an intention to increase or decrease omega 6 fatty acids, lasting at least six months, and including healthy adults or adults at high risk of CVD. The comparison group was given no advice, no supplementation, a placebo, a control diet, or continued with their usual diet. The outcomes of interest were CVD clinical events (all-cause mortality, cardiovascular mortality, non-fatal end points) and CVD risk factors (changes in blood pressure, changes in blood lipids, occurrence of type 2 diabetes). We excluded trials involving exercise or multifactorial interventions to avoid confounding.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, extracted the data, and assessed the risk of bias in the included trials.

MAIN RESULTS

We included four RCTs (five papers) that randomised 660 participants. No ongoing trials were identified. All included trials had at least one domain with an unclear risk of bias. There were no RCTs of omega 6 intake reporting CVD clinical events. Three trials investigated the effect of increased omega 6 intake on lipid levels (total cholesterol, low density lipoprotein (LDL-cholesterol), and high density lipoprotein (HDL-cholesterol)), two trials reported triglycerides, and two trials reported blood pressure (diastolic and systolic blood pressure). Two trials, one with two relevant intervention arms, investigated the effect of decreased omega 6 intake on blood pressure parameters and lipid levels (total cholesterol, LDL-cholesterol, and HDL-cholesterol) and one trial reported triglycerides. Our analyses found no statistically significant effects of either increased or decreased omega 6 intake on CVD risk factors.Two studies were supported by funding from the UK Food Standards Agency and Medical Research Council. One study was supported by Lipid Nutrition, a commercial company in the Netherlands and the Dutch Ministry of Economic Affairs. The final study was supported by grants from the Finnish Food Research Foundation, Finnish Heart Research Foundation, Aarne and Aili Turnen Foundation, and the Research Council for Health, Academy of Finland.

AUTHORS' CONCLUSIONS

We found no studies examining the effects of either increased or decreased omega 6 on our primary outcome CVD clinical endpoints and insufficient evidence to show an effect of increased or decreased omega 6 intake on CVD risk factors such as blood lipids and blood pressure. Very few trials were identified with a relatively small number of participants randomised. There is a need for larger well conducted RCTs assessing cardiovascular events as well as cardiovascular risk factors.

Dietary α-linolenic acid and health-related outcomes: a metabolic perspective

α-Linolenic acid (αLNA; 18: 3n-3) is essential in the human diet, probably because it is the substrate for the synthesis of longer-chain, more unsaturatedn-3 fatty acids, principally EPA (20: 5n-3) and DHA (22: 6n-3), which confer important biophysical properties on cell membranes and so are required for tissue function. The extent to which this molecular transformation occurs in man is controversial. The present paper reviews the recent literature on the metabolism of αLNA in man, including the use of dietary αLNA in β-oxidation, recycling of carbon by fatty acid synthesisde novoand conversion to longer-chain PUFA. Sex differences in αLNA metabolism and the possible biological consequences are discussed. Increased consumption of EPA and DHA in fish oil has a number of well-characterised beneficial effects on health. The present paper also reviews the efficacy of increased αLNA consumption in increasing the concentrations of EPA and DHA in blood and cell lipid pools, and the extent to which such dietary interventions might be protective against CVD and inflammation. Although the effects on CVD risk factors and inflammatory markers are variable, where beneficial effects have been reported these are weaker than have been achieved from increasing consumption of EPA+DHA or linoleic acid. Overall, the limited capacity for conversion to longer-chainn-3 fatty acids, and the lack of efficacy in ameliorating CVD risk factors and inflammatory markers in man suggests that increased consumption of αLNA may be of little benefit in altering EPA+DHA status or in improving health outcomes compared with other dietary interventions.

Supplementation of conventional therapy with the novel grain Salba (Salvia hispanica L.) improves major and emerging cardiovascular risk factors in type 2 diabetes: results of a randomized controlled trial

OBJECTIVE

To determine whether addition of Salba (Salvia hispanica L.), a novel whole grain that is rich in fiber, alpha-linolenic acid (ALA), and minerals to conventional treatment is associated with improvement in major and emerging cardiovascular risk factors in individuals with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Using a single-blind cross-over design, subjects were randomly assigned to receive either 37 +/- 4 g/day of Salba or wheat bran for 12 weeks while maintaining their conventional diabetes therapies. Twenty well-controlled subjects with type 2 diabetes (11 men and 9 women, aged 64 +/- 8 years, BMI 28 +/- 4 kg/m2, and A1C 6.8 +/- 0.9%) completed the study. This study was set in the outpatient clinic of the Risk Factor Modification Center, St. Michael's Hospital, Toronto, Canada.

RESULTS

Compared with the control treatment, Salba reduced systolic blood pressure (SBP) by 6.3 +/- 4 mmHg (P < 0.001), high-sensitivity C-reactive protein (hs-CRP) (mg/l) by 40 +/- 1.6% (P = 0.04), and vonWillebrand factor (vWF) by 21 +/- 0.3% (P = 0.03), with significant decreases in A1C and fibrinogen in relation to the Salba baseline but not with the control treatment. There were no changes in safety parameters including liver, kidney and hemostatic function, or body weight. Both plasma ALA and eicosapentaenoic polyunsaturated fatty acid levels were increased twofold (P < 0.05) while consuming Salba.

CONCLUSIONS

Long-term supplementation with Salba attenuated a major cardiovascular risk factor (SBP) and emerging factors (hs-CRP and vWF) safely beyond conventional therapy, while maintaining good glycemic and lipid control in people with well-controlled type 2 diabetes.

Long-chain n-3 fatty acid supplementation in men increases resistance to activated protein C

It has recently and controversially been demonstrated that fish oil supplementation may not be beneficial for everyone, but to date there have been no biological explanations. We suggest that resistance to the anticoagulant, activated protein C (APC), be considered as a potential mechanism, because it has been demonstrated that the type of fatty acids on phospholipids modulates function of the APC pathway. The APC ratio in plasma was decreased by 7% after fish oil supplementation in healthy men (P<.005; n=35). The decrease in APC ratio equates to an increase in APC resistance. Fish oil lowered the APC ratio by (1) increasing low-density lipoprotein (LDL) cholesterol (P<.01) and apolipoprotein B (P<.05) and (2) increasing platelet microparticles (P<.05). In vitro, purified LDL decreased the APC ratio and increased microparticle formation. These changes affecting the anticoagulant APC could contribute toward a prothrombotic state, potentially explaining the recent observation that fish oil supplementation may not always be of benefit. These findings will need to be repeated in different disease states.

Hemostasis and aging

Many changes in the vasculature, hemostasis and endothelium, including alterations of platelets, coagulation and fibrinolytic factors, occur during aging. While the increasing hypercoagulability observed with aging may account for the higher incidence of thrombotic cardiovascular disorders in the elderly, the lack of genetic protective factors against thrombosis in healthy centenarians suggests that little is yet known about the age-associated changes of hemostasis. The complex inter-relationships between inherited and acquired factors influencing the hemostatic system during aging are discussed in this review.

Effects of alpha-linolenic acid versus those of EPA/DHA on cardiovascular risk markers in healthy elderly subjects

OBJECTIVE

To compare the effects of alpha-linolenic acid (ALA, C18:3n-3) to those of eicosapentaenoic acid (EPA, C20:5n-3) plus docosahexaenoic acid (DHA, C22:6n-3) on cardiovascular risk markers in healthy elderly subjects.

DESIGN

A randomized double-blind nutritional intervention study.

SETTING

Department of Human Biology, Maastricht University, the Netherlands.

SUBJECTS

Thirty-seven mildly hypercholesterolemic subjects, 14 men and 23 women aged between 60 and 78 years.

INTERVENTIONS

During a run-in period of 3 weeks, subjects consumed an oleic acid-rich diet. The following 6 weeks, 10 subjects remained on the control diet, 13 subjects consumed an ALA-rich diet (6.8 g/day) and 14 subjects an EPA/DHA-rich diet (1.05 g EPA/day + 0.55 g DHA/day).

RESULTS

Both n-3 fatty acid diets did not change concentrations of total-cholesterol, LDL-cholesterol, HDL-cholesterol, triacylglycerol and apoA-1 when compared with the oleic acid-rich diet. However, after the EPA/DHA-rich diet, LDL-cholesterol increased by 0.39 mmol/l (P = 0.0323, 95% CI (0.030, 0.780 mmol/l)) when compared with the ALA-rich diet. Intake of EPA/DHA also increased apoB concentrations by 14 mg/dl (P = 0.0031, 95% CI (4, 23 mg/dl)) and 12 mg/dl (P = 0.005, 95% CI (3, 21 mg/dl)) versus the oleic acid and ALA-rich diet, respectively. Except for an EPA/DHA-induced increase in tissue factor pathway inhibitor (TFPI) of 14.6% (P = 0.0184 versus ALA diet, 95% CI (1.5, 18.3%)), changes in markers of hemostasis and endothelial integrity did not reach statistical significance following consumption of the two n-3 fatty acid diets.

CONCLUSIONS

In healthy elderly subjects, ALA might affect concentrations of LDL-cholesterol and apoB more favorably than EPA/DHA, whereas EPA/DHA seems to affect TFPI more beneficially.

Influence of alpha-linolenic acid and fish-oil on markers of cardiovascular risk in subjects with an atherogenic lipoprotein phenotype

We tested the hypothesis that dietary alpha-linolenic acid (ALA) can exert effects on markers of cardiovascular risk similar to that produced by its longer chain counterparts in fish-oil. A dietary intervention study was undertaken to examine the effects of an ALA-enriched diet in 57 men expressing an atherogenic lipoprotein phenotype (ALP). Subjects were randomly assigned to one of three diets enriched either with flaxseed oil (FXO: high ALA, n = 21), sunflower oil (SO: high linoleic acid, n = 17), or SO with fish-oil (SOF n = 19) for 12 weeks, resulting in dietary intake ratios of n-6:n-3 PUFA of 0.5, 27.9 and 5.2, respectively. The relative abundance of ALA and EPA in erythrocyte membranes increased on the FXO diet (p < 0.001), whereas both EPA and DHA increased after fish-oil (p < 0.001). There were significant decreases in total plasma cholesterol within (FXO -12.3%, p = 0.001; SOF -7.6%, p = 0.014; SO -7.3%, p = 0.033) and between diets (p = 0.019), and decreases within diets after 12 weeks for HDL cholesterol on flaxseed oil (FXO -10%, p=0.009), plasma TG (-23%, p < 0.001) and small, dense LDL (-22% p = 0.003) in fish-oil. Membrane DHA levels were inversely associated with the changes in plasma TG ( p= 0.001) and small, dense LDL (p<0.05) after fish-oil. In conclusion, fish-oil produced predictable changes in plasma lipids and small, dense LDL (sdLDL) that were not reproduced by the ALA-enriched diet. Membrane DHA levels appeared to be an important determinant of these fish-oil-induced effects.

Effects of omega-3 polyunsaturated fatty acids on plasma indices of thrombogenesis and inflammation in patients post-myocardial infarction

OBJECTIVE

To determine the effects of n-3 PUFAs supplementation on plasma indices of coagulation (fibrinogen), fibrin D-Dimer (an index of thrombogenesis and fibrin turnover), endothelial damage/dysfunction (von Willebrand factor (vWf)), platelet activation (soluble P-selectin (sP-sel)) and inflammation (interleukin-6, IL-6) in patients following acute myocardial infarction.

METHODS

Open-labelled randomised controlled trial. Seventy-seven post-myocardial infarction (MI) patients stabilized on standard secondary prevention therapy were randomised either to 3 months' treatment with Omacor 1 g/day (n=37) or 'usual care' control (n=40). Plasma levels of fibrinogen, D-Dimer, vWf, sP-sel, IL-6 and plasma viscosity at baseline and after 3 months were determined.

RESULTS

At baseline, there were no significant differences between the groups in all research indices, except vWf levels were higher in patients allocated to Omacor supplementation. After 3 months, there were no significant changes in the levels of any research indices in either the Omacor supplemented or the 'usual care' control patients when compared to baseline. Patients who received Omacor experienced a fall in total cholesterol (p=0.019), total/HDL-cholesterol ratio (p=0.009) and LDL-cholesterol (p=0.023). However, the relative changes in plasma lipids and lipoproteins did not differ between the two groups.

CONCLUSIONS

Three-month supplementation of Omacor at 1 g per day in post-MI patients is not associated with an improvement in the levels of peripheral indices of coagulation potential, endothelial function, platelet reactivity and inflammation.

A Diet Rich in High-Oleic-Acid Sunflower Oil Favorably Alters Low-Density Lipoprotein Cholesterol, Triglycerides, and Factor VII Coagulant Activity

OBJECTIVE

To compare concentrations of factor VII coagulant activity (factor VIIc), fibrinogen, plasminogen activator inhibitor-1, and blood lipids on a saturated fat-rich diet with one rich in monounsaturated fat.

DESIGN

Subjects were randomly allocated to two groups. The study design was an ABB/BAA extra-period crossover. One group consumed a diet rich in saturated fatty acid (SFA) with fat making up 20.8% of total energy, for 5 weeks and then one rich in monounsaturated fatty acid (MUFA), with fat making up 20.3% of total energy for 10 weeks. The other group consumed the MUFA diet for 5 weeks followed by the SFA diet for 10 weeks.

SUBJECTS/SETTING

Men and women aged 35 to 69 years who were nonsmokers with no chronic illness and not on any medication were recruited to participate. Eighteen subjects were recruited and 15 (5 men, 10 women) completed the community-based study.

INTERVENTION

Blood was sampled at the beginning and end point of each 5-week diet period for analysis of coagulation and fibrinolysis factors and blood lipids. Subjects kept 3-day food diaries twice during each of the three diet periods and were weighed on each visit for blood collection. Analysis of plasma fatty acids was used to indicate dietary compliance.

MAIN OUTCOME MEASURES

Differences in fasting factor VIIc, fibrinogen, plasminogen activator inhibitor-1, insulin, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, apolipoproteins A-1 and B, and plasma oleic acid levels while receiving the SFA diet vs MUFA diet.

STATISTICAL ANALYSIS

A general linear model allowing for the ABB/BAA extra-period crossover, was used for each of the outcome measures.

RESULTS

Factor VIIc was lower on the MUFA diet ( P <.05) but fibrinogen and insulin concentrations and plasminogen activator inhibitor-1 activity did not differ between diets. Low-density lipoprotein cholesterol ( P <.001) and triglyceride ( P <.01) levels were lower on the MUFA diet compared with the SFA diet. A significant increase in both plasma phospholipid and neutral lipid oleic acid (P <.0001) occurred on the MUFA diet.

CONCLUSIONS

Substitution of foods rich in saturated fat with foods rich in high-oleic-acid sunflower oil and margarine has favorable outcomes on blood lipids and factor VIIc. This oil presents another useful source of MUFA for diets aimed at prevention of heart disease.

Plant and marine derived (n-3) polyunsaturated fatty acids do not affect blood coagulation and fibrinolytic factors in moderately hyperlipidemic humans

Dietary alpha-linolenic acid (ALA) can be converted to long-chain (n-3) PUFA in humans and may potentially reproduce the beneficial effects of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids on risk factors for coronary heart disease (CHD). This study compared the effects of increased intakes of ALA with those of dietary EPA and DHA on blood coagulation and fibrinolytic factors in fasting subjects. A placebo-controlled, parallel study was conducted in 150 moderately hyperlipidemic subjects, age 25-72 y. Subjects were randomly assigned to one of five interventions and consumed a total intake of 0.8 or 1.7g/d EPA+DHA, 4.5 or 9.5g/d ALA or control (linoleic acid; LA) for 6 mo. Fatty acids were incorporated into 25 g of fat spread, which replaced the subject's normal spread and three capsules. Long-term supplementation with either dietary EPA+DHA or estimated biologically equivalent amounts of ALA did not affect factors VIIa, VIIc, VIIag, XIIa, XIIag, fibrinogen concentrations, plasminogen activator inhibitor-1 or tissue plasminogen activator activity compared with the control. (n-3) PUFA of plant or marine origin do not differ from one another or from LA in their effect on a range of blood coagulation and fibrinolytic factors.

Effect of an increased intake of alpha-linolenic acid and group nutritional education on cardiovascular risk factors: the Mediterranean Alpha-linolenic Enriched Groningen Dietary Intervention (MARGARIN) study

BACKGROUND

The effect of long-term increased intakes of alpha-linolenic acid (ALA; 18:3n-3) on cardiovascular risk factors is unknown.

OBJECTIVES

Our objectives were to assess the effect of increased ALA intakes on cardiovascular risk factors and the estimated risk of ischemic heart disease (IHD) at 2 y and the effect of nutritional education on dietary habits.

DESIGN

Subjects with multiple cardiovascular risk factors (124 men and 158 women) were randomly assigned in a double-blind fashion to consume a margarine rich in either ALA [46% linoleic acid (LA; 18:2n-6) and 15% ALA; n = 114] or LA (58% LA and 0.3% ALA; n = 168). An intervention group (n = 110; 50% ALA) obtained group nutritional education, and a control group (n = 172; 34% ALA) received a posted leaflet containing the standard Dutch dietary guidelines.

RESULTS

Average ALA intakes were 6.3 and 1.0 g/d in the ALA and LA groups, respectively. After 2 y, the ALA group had a higher ratio of total to HDL cholesterol (+0.34; 95% CI: 0.12, 0.56), lower HDL cholesterol (-0.05 mmol/L; -0.10, 0), higher serum triacylglycerol (+0.24 mmol/L; 0.02, 0.46), and lower plasma fibrinogen (-0.18 g/L; -0.31, -0.04; after 1 y) than did the LA group (adjusted for baseline values, sex, and lipid-lowering drugs). No significant difference existed in 10-y estimated IHD risk. After 2 y, the intervention group had lower saturated fat intakes and higher fish intakes than did the control group.

CONCLUSIONS

Increased ALA intakes decrease the estimated IHD risk to an extent similar to that found with increased LA intakes. Group nutritional education can effectively increase fish intake.

The effect of flaxseed supplementation in processed foods on serum fatty acids and enterolactone

OBJECTIVE

The purpose was to study the effects of flaxseed supplementation as a part of daily diet on serum lipids, fatty acids and plasma enterolactone.

DESIGN

Eighty volunteers participated in this clinical nutrition study which was carried out in a controlled, double-blind and cross-over manner. The subjects were randomized to diet sequences AB or BA. Diet A meals contained 1.3 g/100 g ground flaxseed and 5 g/100 g flaxseed oil. Also 3-4 g/100 of inulin and wheat fiber was added. AB diet with non-supplemented foods served as control. Test subjects were on both diets for 4 weeks separated by a 4-week wash-out period. Fifteen test subjects continued an open part of the study for 4 additional months.

INTERVENTIONS

The dietary intake, basic blood values, serum lipids, fatty acids and enterolactone were measured at baseline, after both intervention periods and during the open study, at baseline and after 2 and 4 months. Serum thiocyanate and blood cadmium were controlled after both intervention periods.

RESULTS

The percentage of flaxseed supplemented test food out of total dietary intake was 20% of energy. The test food contained significantly higher amounts of fiber, polyunsaturated fatty acids (PUFAs) and especially alpha-linolenic acid than the control food. No significant changes were observed in the basic laboratory values or in blood lipids. There was a significant increase in serum alpha-linolenic acid, eicosapentaenoic acid and docosapentaenoic acid. Serum enterolactone concentration was doubled during flaxseed supplementation. Serum thiocyanate and blood cadmium values did not exceed reference values and there was no difference between the diets.

CONCLUSIONS

In this study we were able to show that, by adding ground flaxseed and flaxseed oil to one or two daily meals, it is possible to obtain significant effects on serum levels of enterolactone and alpha-linolenic acid.

SPONSORSHIP

The study was sponsored by the National Technology Agency of Finland (Tekes).

Haemostasis in Relation to Dietary Fat as Estimated by Erythrocyte Fatty Acid Composition: The Prime Study

We investigated whether haemostatic variables were related with dietary fatty acid composition as estimated by the fatty acid content of erythrocytes. Subjects were a subsample (n=283) of the participants in the Prospective Epidemiological Study of Myocardial Infarction (PRIME) Study. Factor VII, fibrinogen, tissue-type plasminogen activator antigen (tPA-ag), plasminogen activator inhibitor type 1 (PAI-1), D-dimer and von Willebrand factor (vWf) were measured and the fatty acid composition was determined in the phospholipids of total erythrocytes by gas chromatography. Statistical analyses were performed using multiple linear regression analyses with adjustment for age, center and body mass index. tPA-ag was significantly related to the n-3 fatty acids derived from fish. This was reflected in an inverse association of all n-3 fatty acids combined with tPA-ag (beta=-0.37 ng/ml/%, 95% confidence intervals: -0.45, -0.29, P<.01). Positive and significant associations of D-dimer with arachidic and eicosamonoenoic acid were observed (P<.01). No relationships were found between fatty acids and fibrinogen, vWf, PAI-1 or factor VII. The results of this study suggest that consumption of n-3 fatty acids derived from fish may favourably influence tPA-ag.

Fats, lipids and blood coagulation

Saturated and n-3 fatty acids, postprandial lipaemia, and the combined effects of fatty acids and lipid-lowering drugs have been of principal interest in recent studies in the field of dietary fats, lipids and haemostasis. The sex-specific effect of individual saturated fatty acids on coagulation factor VII activity has been discovered, and the significant effect of factor VII R353Q polymorphism on the postprandial response has also been found. An increased intake of n-3 fatty acids or fat reduction when combined with intensive lifestyle interventions may lead to reduced thrombotic potential in type 2 diabetic patients and obese individuals. Furthermore, positive effects on haemostasis by combined treatment with long-chain n-3 fatty acids and simvastatin indicate that n-3 fatty acids may be of some relevance with lipid-lowering drugs. The possible unfavourable effect of n-3 fatty acids on plasminogen activator inhibitor-1 activity is still a matter of dispute, but recent studies suggest that n-3 fatty acids, including alpha-linolenic acid, may have antithrombotic effects by enhancing protein C activity.

Dietary treatment of thrombogenic disorders related to the metabolic syndrome

The increased risk of coronary heart disease associated with the metabolic syndrome may be partially explained by prothrombotic deviations of the haemostatic system. Individuals with insulin resistance, dyslipidaemia and obesity are characterized by elevated plasma fibrinogen and factor VII coagulant activity levels and raised concentrations of plasminogen-activator inhibitor, the main inhibitor of endogenous fibrinolysis. These haemostatic abnormalities may be corrected with dietary treatment of the underlying clinical disorder. Dietary trials of diseased and healthy volunteers suggest that the optimal antithrombotic diet is a low-fat diet with a high content of foods rich in complex carbohydrates and dietary fibre. The dietary fatty acid composition has a profound effect on blood lipids, but seems of minor importance for the haemostatic system.