Fish oil and plasma fibrinogen

Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease

BACKGROUND

Omega-3 polyunsaturated fatty acids from oily fish (long-chain omega-3 (LCn3)), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), as well as from plants (alpha-linolenic acid (ALA)) may benefit cardiovascular health. Guidelines recommend increasing omega-3-rich foods, and sometimes supplementation, but recent trials have not confirmed this.

OBJECTIVES

To assess the effects of increased intake of fish- and plant-based omega-3 fats for all-cause mortality, cardiovascular events, adiposity and lipids.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase to February 2019, plus ClinicalTrials.gov and World Health Organization International Clinical Trials Registry to August 2019, with no language restrictions. We handsearched systematic review references and bibliographies and contacted trial authors.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that lasted at least 12 months and compared supplementation or advice to increase LCn3 or ALA intake, or both, versus usual or lower intake.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted data and assessed validity. We performed separate random-effects meta-analysis for ALA and LCn3 interventions, and assessed dose-response relationships through meta-regression.

MAIN RESULTS

We included 86 RCTs (162,796 participants) in this review update and found that 28 were at low summary risk of bias. Trials were of 12 to 88 months' duration and included adults at varying cardiovascular risk, mainly in high-income countries. Most trials assessed LCn3 supplementation with capsules, but some used LCn3- or ALA-rich or enriched foods or dietary advice compared to placebo or usual diet. LCn3 doses ranged from 0.5 g a day to more than 5 g a day (19 RCTs gave at least 3 g LCn3 daily). Meta-analysis and sensitivity analyses suggested little or no effect of increasing LCn3 on all-cause mortality (risk ratio (RR) 0.97, 95% confidence interval (CI) 0.93 to 1.01; 143,693 participants; 11,297 deaths in 45 RCTs; high-certainty evidence), cardiovascular mortality (RR 0.92, 95% CI 0.86 to 0.99; 117,837 participants; 5658 deaths in 29 RCTs; moderate-certainty evidence), cardiovascular events (RR 0.96, 95% CI 0.92 to 1.01; 140,482 participants; 17,619 people experienced events in 43 RCTs; high-certainty evidence), stroke (RR 1.02, 95% CI 0.94 to 1.12; 138,888 participants; 2850 strokes in 31 RCTs; moderate-certainty evidence) or arrhythmia (RR 0.99, 95% CI 0.92 to 1.06; 77,990 participants; 4586 people experienced arrhythmia in 30 RCTs; low-certainty evidence). Increasing LCn3 may slightly reduce coronary heart disease mortality (number needed to treat for an additional beneficial outcome (NNTB) 334, RR 0.90, 95% CI 0.81 to 1.00; 127,378 participants; 3598 coronary heart disease deaths in 24 RCTs, low-certainty evidence) and coronary heart disease events (NNTB 167, RR 0.91, 95% CI 0.85 to 0.97; 134,116 participants; 8791 people experienced coronary heart disease events in 32 RCTs, low-certainty evidence). Overall, effects did not differ by trial duration or LCn3 dose in pre-planned subgrouping or meta-regression. There is little evidence of effects of eating fish. Increasing ALA intake probably makes little or no difference to all-cause mortality (RR 1.01, 95% CI 0.84 to 1.20; 19,327 participants; 459 deaths in 5 RCTs, moderate-certainty evidence),cardiovascular mortality (RR 0.96, 95% CI 0.74 to 1.25; 18,619 participants; 219 cardiovascular deaths in 4 RCTs; moderate-certainty evidence), coronary heart disease mortality (RR 0.95, 95% CI 0.72 to 1.26; 18,353 participants; 193 coronary heart disease deaths in 3 RCTs; moderate-certainty evidence) and coronary heart disease events (RR 1.00, 95% CI 0.82 to 1.22; 19,061 participants; 397 coronary heart disease events in 4 RCTs; low-certainty evidence). However, increased ALA may slightly reduce risk of cardiovascular disease events (NNTB 500, RR 0.95, 95% CI 0.83 to 1.07; but RR 0.91, 95% CI 0.79 to 1.04 in RCTs at low summary risk of bias; 19,327 participants; 884 cardiovascular disease events in 5 RCTs; low-certainty evidence), and probably slightly reduces risk of arrhythmia (NNTB 91, RR 0.73, 95% CI 0.55 to 0.97; 4912 participants; 173 events in 2 RCTs; moderate-certainty evidence). Effects on stroke are unclear. Increasing LCn3 and ALA had little or no effect on serious adverse events, adiposity, lipids and blood pressure, except increasing LCn3 reduced triglycerides by ˜15% in a dose-dependent way (high-certainty evidence).

AUTHORS' CONCLUSIONS

This is the most extensive systematic assessment of effects of omega-3 fats on cardiovascular health to date. Moderate- and low-certainty evidence suggests that increasing LCn3 slightly reduces risk of coronary heart disease mortality and events, and reduces serum triglycerides (evidence mainly from supplement trials). Increasing ALA slightly reduces risk of cardiovascular events and arrhythmia.

Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease

BACKGROUND

Researchers have suggested that omega-3 polyunsaturated fatty acids from oily fish (long-chain omega-3 (LCn3), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), as well as from plants (alpha-linolenic acid (ALA)) benefit cardiovascular health. Guidelines recommend increasing omega-3-rich foods, and sometimes supplementation, but recent trials have not confirmed this.

OBJECTIVES

To assess effects of increased intake of fish- and plant-based omega-3 for all-cause mortality, cardiovascular (CVD) events, adiposity and lipids.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase to April 2017, plus ClinicalTrials.gov and World Health Organization International Clinical Trials Registry to September 2016, with no language restrictions. We handsearched systematic review references and bibliographies and contacted authors.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that lasted at least 12 months and compared supplementation and/or advice to increase LCn3 or ALA intake versus usual or lower intake.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data and assessed validity. We performed separate random-effects meta-analysis for ALA and LCn3 interventions, and assessed dose-response relationships through meta-regression.

MAIN RESULTS

We included 79 RCTs (112,059 participants) in this review update and found that 25 were at low summary risk of bias. Trials were of 12 to 72 months' duration and included adults at varying cardiovascular risk, mainly in high-income countries. Most studies assessed LCn3 supplementation with capsules, but some used LCn3- or ALA-rich or enriched foods or dietary advice compared to placebo or usual diet. LCn3 doses ranged from 0.5g/d LCn3 to > 5 g/d (16 RCTs gave at least 3g/d LCn3).Meta-analysis and sensitivity analyses suggested little or no effect of increasing LCn3 on all-cause mortality (RR 0.98, 95% CI 0.90 to 1.03, 92,653 participants; 8189 deaths in 39 trials, high-quality evidence), cardiovascular mortality (RR 0.95, 95% CI 0.87 to 1.03, 67,772 participants; 4544 CVD deaths in 25 RCTs), cardiovascular events (RR 0.99, 95% CI 0.94 to 1.04, 90,378 participants; 14,737 people experienced events in 38 trials, high-quality evidence), coronary heart disease (CHD) mortality (RR 0.93, 95% CI 0.79 to 1.09, 73,491 participants; 1596 CHD deaths in 21 RCTs), stroke (RR 1.06, 95% CI 0.96 to 1.16, 89,358 participants; 1822 strokes in 28 trials) or arrhythmia (RR 0.97, 95% CI 0.90 to 1.05, 53,796 participants; 3788 people experienced arrhythmia in 28 RCTs). There was a suggestion that LCn3 reduced CHD events (RR 0.93, 95% CI 0.88 to 0.97, 84,301 participants; 5469 people experienced CHD events in 28 RCTs); however, this was not maintained in sensitivity analyses - LCn3 probably makes little or no difference to CHD event risk. All evidence was of moderate GRADE quality, except as noted.Increasing ALA intake probably makes little or no difference to all-cause mortality (RR 1.01, 95% CI 0.84 to 1.20, 19,327 participants; 459 deaths, 5 RCTs),cardiovascular mortality (RR 0.96, 95% CI 0.74 to 1.25, 18,619 participants; 219 cardiovascular deaths, 4 RCTs), and CHD mortality (1.1% to 1.0%, RR 0.95, 95% CI 0.72 to 1.26, 18,353 participants; 193 CHD deaths, 3 RCTs) and ALA may make little or no difference to CHD events (RR 1.00, 95% CI 0.80 to 1.22, 19,061 participants, 397 CHD events, 4 RCTs, low-quality evidence). However, increased ALA may slightly reduce risk of cardiovascular events (from 4.8% to 4.7%, RR 0.95, 95% CI 0.83 to 1.07, 19,327 participants; 884 CVD events, 5 RCTs, low-quality evidence with greater effects in trials at low summary risk of bias), and probably reduces risk of arrhythmia (3.3% to 2.6%, RR 0.79, 95% CI 0.57 to 1.10, 4,837 participants; 141 events, 1 RCT). Effects on stroke are unclear.Sensitivity analysis retaining only trials at low summary risk of bias moved effect sizes towards the null (RR 1.0) for all LCn3 primary outcomes except arrhythmias, but for most ALA outcomes, effect sizes moved to suggest protection. LCn3 funnel plots suggested that adding in missing studies/results would move effect sizes towards null for most primary outcomes. There were no dose or duration effects in subgrouping or meta-regression.There was no evidence that increasing LCn3 or ALA altered serious adverse events, adiposity or lipids, except LCn3 reduced triglycerides by ˜15% in a dose-dependant way (high-quality evidence).

AUTHORS' CONCLUSIONS

This is the most extensive systematic assessment of effects of omega-3 fats on cardiovascular health to date. Moderate- and high-quality evidence suggests that increasing EPA and DHA has little or no effect on mortality or cardiovascular health (evidence mainly from supplement trials). Previous suggestions of benefits from EPA and DHA supplements appear to spring from trials with higher risk of bias. Low-quality evidence suggests ALA may slightly reduce CVD event and arrhythmia risk.

Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease

BACKGROUND

Researchers have suggested that omega-3 polyunsaturated fatty acids from oily fish (long-chain omega-3 (LCn3), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), as well as from plants (alpha-linolenic acid (ALA)) benefit cardiovascular health. Guidelines recommend increasing omega-3-rich foods, and sometimes supplementation, but recent trials have not confirmed this.

OBJECTIVES

To assess effects of increased intake of fish- and plant-based omega-3 for all-cause mortality, cardiovascular (CVD) events, adiposity and lipids.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase to April 2017, plus ClinicalTrials.gov and World Health Organization International Clinical Trials Registry to September 2016, with no language restrictions. We handsearched systematic review references and bibliographies and contacted authors.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that lasted at least 12 months and compared supplementation and/or advice to increase LCn3 or ALA intake versus usual or lower intake.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data and assessed validity. We performed separate random-effects meta-analysis for ALA and LCn3 interventions, and assessed dose-response relationships through meta-regression.

MAIN RESULTS

We included 79 RCTs (112,059 participants) in this review update and found that 25 were at low summary risk of bias. Trials were of 12 to 72 months' duration and included adults at varying cardiovascular risk, mainly in high-income countries. Most studies assessed LCn3 supplementation with capsules, but some used LCn3- or ALA-rich or enriched foods or dietary advice compared to placebo or usual diet.Meta-analysis and sensitivity analyses suggested little or no effect of increasing LCn3 on all-cause mortality (RR 0.98, 95% CI 0.90 to 1.03, 92,653 participants; 8189 deaths in 39 trials, high-quality evidence), cardiovascular mortality (RR 0.95, 95% CI 0.87 to 1.03, 67,772 participants; 4544 CVD deaths in 25 RCTs), cardiovascular events (RR 0.99, 95% CI 0.94 to 1.04, 90,378 participants; 14,737 people experienced events in 38 trials, high-quality evidence), coronary heart disease (CHD) mortality (RR 0.93, 95% CI 0.79 to 1.09, 73,491 participants; 1596 CHD deaths in 21 RCTs), stroke (RR 1.06, 95% CI 0.96 to 1.16, 89,358 participants; 1822 strokes in 28 trials) or arrhythmia (RR 0.97, 95% CI 0.90 to 1.05, 53,796 participants; 3788 people experienced arrhythmia in 28 RCTs). There was a suggestion that LCn3 reduced CHD events (RR 0.93, 95% CI 0.88 to 0.97, 84,301 participants; 5469 people experienced CHD events in 28 RCTs); however, this was not maintained in sensitivity analyses - LCn3 probably makes little or no difference to CHD event risk. All evidence was of moderate GRADE quality, except as noted.Increasing ALA intake probably makes little or no difference to all-cause mortality (RR 1.01, 95% CI 0.84 to 1.20, 19,327 participants; 459 deaths, 5 RCTs),cardiovascular mortality (RR 0.96, 95% CI 0.74 to 1.25, 18,619 participants; 219 cardiovascular deaths, 4 RCTs), and it may make little or no difference to CHD events (RR 1.00, 95% CI 0.80 to 1.22, 19,061 participants, 397 CHD events, 4 RCTs, low-quality evidence). However, increased ALA may slightly reduce risk of cardiovascular events (from 4.8% to 4.7%, RR 0.95, 95% CI 0.83 to 1.07, 19,327 participants; 884 CVD events, 5 RCTs, low-quality evidence), and probably reduces risk of CHD mortality (1.1% to 1.0%, RR 0.95, 95% CI 0.72 to 1.26, 18,353 participants; 193 CHD deaths, 3 RCTs), and arrhythmia (3.3% to 2.6%, RR 0.79, 95% CI 0.57 to 1.10, 4,837 participants; 141 events, 1 RCT). Effects on stroke are unclear.Sensitivity analysis retaining only trials at low summary risk of bias moved effect sizes towards the null (RR 1.0) for all LCn3 primary outcomes except arrhythmias, but for most ALA outcomes, effect sizes moved to suggest protection. LCn3 funnel plots suggested that adding in missing studies/results would move effect sizes towards null for most primary outcomes. There were no dose or duration effects in subgrouping or meta-regression.There was no evidence that increasing LCn3 or ALA altered serious adverse events, adiposity or lipids, although LCn3 slightly reduced triglycerides and increased HDL. ALA probably reduces HDL (high- or moderate-quality evidence).

AUTHORS' CONCLUSIONS

This is the most extensive systematic assessment of effects of omega-3 fats on cardiovascular health to date. Moderate- and high-quality evidence suggests that increasing EPA and DHA has little or no effect on mortality or cardiovascular health (evidence mainly from supplement trials). Previous suggestions of benefits from EPA and DHA supplements appear to spring from trials with higher risk of bias. Low-quality evidence suggests ALA may slightly reduce CVD event risk, CHD mortality and arrhythmia.

Omega 3 fatty acids for prevention and treatment of cardiovascular disease

BACKGROUND

It has been suggested that omega 3 (W3, n-3 or omega-3) fats from oily fish and plants are beneficial to health.

OBJECTIVES

To assess whether dietary or supplemental omega 3 fatty acids alter total mortality, cardiovascular events or cancers using both RCT and cohort studies.

SEARCH STRATEGY

Five databases including CENTRAL, MEDLINE and EMBASE were searched to February 2002. No language restrictions were applied. Bibliographies were checked and authors contacted.

SELECTION CRITERIA

RCTs were included where omega 3 intake or advice was randomly allocated and unconfounded, and study duration was at least six months. Cohorts were included where a cohort was followed up for at least six months and omega 3 intake estimated.

DATA COLLECTION AND ANALYSIS

Studies were assessed for inclusion, data extracted and quality assessed independently in duplicate. Random effects meta-analysis was performed separately for RCT and cohort data.

MAIN RESULTS

Forty eight randomised controlled trials (36,913 participants) and 41 cohort analyses were included. Pooled trial results did not show a reduction in the risk of total mortality or combined cardiovascular events in those taking additional omega 3 fats (with significant statistical heterogeneity). Sensitivity analysis, retaining only studies at low risk of bias, reduced heterogeneity and again suggested no significant effect of omega 3 fats. Restricting analysis to trials increasing fish-based omega 3 fats, or those increasing short chain omega 3s, did not suggest significant effects on mortality or cardiovascular events in either group. Subgroup analysis by dietary advice or supplementation, baseline risk of CVD or omega 3 dose suggested no clear effects of these factors on primary outcomes. Neither RCTs nor cohorts suggested increased relative risk of cancers with higher omega 3 intake but estimates were imprecise so a clinically important effect could not be excluded.

REVIEWERS' CONCLUSIONS

It is not clear that dietary or supplemental omega 3 fats alter total mortality, combined cardiovascular events or cancers in people with, or at high risk of, cardiovascular disease or in the general population. There is no evidence we should advise people to stop taking rich sources of omega 3 fats, but further high quality trials are needed to confirm suggestions of a protective effect of omega 3 fats on cardiovascular health. There is no clear evidence that omega 3 fats differ in effectiveness according to fish or plant sources, dietary or supplemental sources, dose or presence of placebo.

Influence of n-6 versus n-3 polyunsaturated fatty acids in diets low in saturated fatty acids on plasma lipoproteins and hemostatic factors

Modification of dietary fat composition may influence hemostatic variables, which are associated with increased risk of coronary heart disease (CHD). To address this question, we performed a controlled feeding study on 26 healthy male nonsmoking subjects with diets of differing fat composition. For the first 3 weeks, the subjects were given a diet calculated to supply 30% energy as total fat: 8% as monounsaturated, 4% as polyunsaturated, and 16% energy as saturated fatty acids, respectively (saturated diet). This was followed immediately by two diets taken in random order, each of 3-week duration and separated by an 8-week washout period on the subject's usual diet. Both diets were calculated to supply 30% of energy as fat: 14% monounsaturated, 6% as polyunsaturated, and 8% energy as saturated fatty acids. They both provided 5 g (approximately 1.7% energy) more of polyunsaturated fatty acids than the saturated fat diet; in one diet as long-chain n-3 fatty acids (n-3 diet) and in the other as linoleic acid (n-6 diet). Fasting plasma lipids, lipoproteins, and hemostatic factors were measured on the final 3 days of each dietary period. In a subset of 9 subjects the postprandial responses to a test meal were studied on the penultimate day of each period, each meal having the fat composition of its parent diet. On the n-3 diet compared with the n-6 diet, plasma triglyceride, HDL3 cholesterol, apoprotein AII, and fibrinogen concentrations were lower and HDL2 cholesterol concentration was higher (P = .0001, P = .003, P = .0001, P = .004, and P = .001, respectively). On both the n-3 and n-6 diets compared with the saturated diet, fasting plasma total and LDL cholesterol, apoprotein B, beta-thromboglobulin concentrations, and platelet counts were lower (P < .0001, P < .0001, P < .001, P < .01, and P < .05 respectively) and plasma Lp(a) and von Willebrand factor concentrations were higher (P = .02 and P < .01, respectively). Fasting factor VII coagulant activity (VIIc) was increased and apoprotein AI concentration reduced following the n-3 diet (P = .004 and P = .01, respectively) compared with the saturated diet. Plasma fibrinogen concentration was significantly greater following the n-6 diet than on the saturated diet (P = .02). Postprandially, plasma triglyceridemia was greater on the n-6 diet and lowest on the n-3 diet (P < .001) with the saturated diet being intermediate. Plasma VIIc was increased at 4 hours following the standardized test meals on the n-3 and n-6 diets (both P < .05) but not on the saturated diet. An increased intake of long chain n-3 fatty acids decreases fasting plasma triglyceride and apoprotein AII concentrations and increases HDL2 cholesterol concentrations and results in less postprandial lipemia but leads to an increase in VIIc. An increased intake of linoleic acid may raise plasma fibrinogen concentration. Decreasing the intake of saturated fatty acids reduces plasma LDL cholesterol and apoprotein B without affecting HDL cholesterol concentration independent of the type of polyunsaturated fatty acids in the diet. When advice is given to reduce saturated fat intake, it is important to ensure an appropriate ratio of n-3/n-6 fatty acids in the diet.

Fish intake may limit the increase in risk of coronary heart disease morbidity and mortality among heavy smokers. The Honolulu Heart Program

BACKGROUND

Research has shown that fish consumption limits damage to the lungs caused by cigarette smoking, possibly by the effects of fish on arachidonic acid metabolism. We explored this fish-smoking interaction using coronary heart disease (CHD) incidence and mortality as the outcome.

METHODS AND RESULTS

The Honolulu Heart Program began in 1965 to follow a cohort of 8006 Japanese-American men aged 45 to 65 years who lived on Oahu, Hawaii, in 1965. Fish intake was measured at baseline by use of a questionnaire. For current smokers at baseline (n = 3310) who reported low fish intake (< 2 times/wk), age-adjusted 23-year CHD mortality rates increased with the number of cigarettes smoked per day (2.3, 3.1, and 6.9 per 1000 person-years for men who smoked < 20, 20 to 30, and > 30 cigarettes/d, respectively; trend test P < .0001). Among current smokers whose fish intake was high (> or = 2 times/wk), CHD mortality rates showed no relation with cigarettes/d (3.7, 3.2, and 3.7 per 1000 person-years for the corresponding levels of smoking). A Cox proportional hazards model based on current smokers, adjusted for age, years in Japan, calories/d, alcohol intake, physical activity index, years smoked, hypertension, and serum cholesterol, blood glucose, and uric acid levels, was examined. In the high-smoking group, the risk factor-adjusted relative risk (RR) for CHD mortality among those with high fish intake was half that of those with low fish consumption (RR = 0.5, 95% confidence interval = 0.28 to 0.91). A Cox model that adjusted for similar risk factors confirmed a significant interaction of cigarettes/d and fish intake (P < .01) on CHD mortality. Analyses for CHD incidence showed similar results.

CONCLUSIONS

Despite the findings of this investigation, the public health message for smokers continues to be to stop smoking. However, an interaction between fish intake and cigarette smoking is biologically plausible and deserves further investigation. The study of this phenomenon may shed light on the biological mechanisms by which cigarette smoking leads to CHD.

Effects of various fatty acids alone or combined with vitamin E on cell growth and fibrinogen concentration in the medium of HepG2 cells

Dietary intake of fish oils, rich in the polyunsaturated fatty acids (PUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), has given inconsistent results as to their influence on the plasma fibrinogen level (1, 2, 3, 4, 5, 6). In the present study we have examined the effects of various fatty acids, the PUFAs and the saturated fatty acid palmitic acid (PA), alone or combined with the antioxidant vitamin E (Vit.E), on the fibrinogen concentration in the growth medium of human hepatoma (HepG2) cells. Vit.E alone decreased the amount of fibrinogen in the medium in a dose dependent fashion, where fibrinogen was measured as Fibrinopeptide A (FPA) releasable by thrombin. EPA and Vit.E decreased the amount of fibrinogen additively. PUFAs alone increased the fibrinogen concentration in a dose dependent manner. PUFAs combined with a fixed dose of Vit.E decreased the fibrinogen concentration, also dose dependently. OA and PA had an inhibitory effect, both alone and combined with Vit.E. These results indicate that Vit.E may be necessary for PUFAs to have a fibrinogen lowering effect, whereas both OA and PA apparently may decrease the fibrinogen concentration in the cell medium of HepG2 cells, both alone and combined with Vit.E. Possibly, peroxidation of the PUFAs may increase the fibrinogen production, that may be counteracted and reversed by the simultaneous presence of Vit.E.

Associations of fish intake and dietary n-3 polyunsaturated fatty acids with a hypocoagulable profile. The Atherosclerosis Risk in Communities (ARIC) Study

Recent epidemiological evidence indicates that the hemostatic profile is an important predictor of cardiovascular disease, yet its dietary determinants are not well established. An important question is whether dietary fatty acid intake influences blood levels of coagulation proteins. We examined potential dietary determinants of six hemostatic factors--fibrinogen, factor VII, factor (vWF), protein C, and antithrombin III--in four population-based samples totaling over 15,000 participants, blacks and whites, in the Atherosclerosis Risk in Communities (ARIC) Study. Usual dietary intake was assessed by a food frequency questionnaire. Cross-sectional associations were explored using multiple linear regression analysis, adjusting for gender, race, age, body mass index, smoking status, alcohol use, diabetes, and field center. Dietary intake of n-3 polyunsaturated fatty acids (PUFAs) showed negative associations with fibrinogen, factor VIII, and vWF (blacks and whites) and a positive association with protein C (whites only). Fish intake, the major source of dietary n-3 PUFAs, was similarly related to the hemostatic profile: a 1 serving per day greater fish intake was associated with the following predicted differences (95% confidence interval): fibrinogen, -2.9 mg/dL (-6.3, 0.5); factor VIII, -3.3% (-5.4, -1.3); vWF, -2.7% (-5.2, -0.1) (blacks and whites); and protein C, +0.07 microgram/mL (0.03, 0.11) (whites only). Other nutrients or foods were variably associated with the hemostatic factors. These population-based associations, although cross-sectional, suggest that increases in n-3 PUFA intake from fish may modify the blood levels of several coagulation factors.

Long-term supplementation with n-3 fatty acids, I: Effect on blood lipids, haemostasis and blood pressure

The effect of dietary supplementation with 4 g of n-3 polyunsaturated fatty acids (PUFA) daily for 9 months on blood pressure, plasma lipids and lipoproteins, platelet function, coagulation and fibrinolysis was studied in 24 healthy volunteers. Each variable was determined before, after 6 weeks and 9 months of supplementation with n-3 PUFA, and 3 months after the supplementation period had ended. Systolic and diastolic blood pressure declined after intake of n-3 PUFAs. Plasma triglycerides were reduced, and there was a trend towards an increase in HDL-cholesterol after 9 months of supplementation, while total cholesterol, LDL-cholesterol and apolipoproteins A1 and B were unaltered. The bleeding time was increased, and plasma levels of von Willebrand factor decreased after 9 months supplementation with n-3 PUFA. Fibrinogen levels increased, while fibrinolysis was reduced after 9 months supplementation with n-3 PUFA. Overall, no clear benefit on lipid pattern and haemostasis was achieved with respect to development of coronary heart disease.

Coronary heart disease: seven dietary factors

The dietary factors believed to be linked with the incidence of coronary heart disease are reviewed in the light of evidence with regard to their functional role, either in protection or in promotion. Detailed analysis of the evidence shows that the relations are more complex than the current lipid hypothesis suggests. It is proposed that, in particular, the polyunsaturated/saturated ratio as a measure of the propensity of the diet to influence the incidence of coronary heart disease should be replaced by indices of atherogenicity and thrombogenicity.

n-3 fatty acids and acute-phase proteins

The aim of this study was to determine the effects of n-3 fatty acids on acute-phase proteins and response. Healthy male volunteers were submitted to standard bicycle ergometry once without supplementation and a second time after 3-weeks supplementation with highly purified n-3 fatty acids (1.75 g eicosapentaenoic acid and 1.05 g docosahexaenoic acid per day). Acute-phase proteins (immunoglobulin M, complement C4, haptoglobin, C-reactive protein, alpha 2-macroglobulin, coerulopasmin, fibrinogen, alpha 1-glycoprotein) were measured before, immediately after, 24 and 72 h after exercise. There were significantly lower values of immunoglobulin M (pre-exercise and at 72 h) and alpha 2-macroglobulin (pre-exercise) when cross-sectionally comparing the baseline data with and without n-3 supplementation. Longitudinal comparisons show that the ergometric test induced a discrete acute-phase reaction, which is evident with and without n-3 fatty acids. Yet the kinetics of the response seem to be altered by n-3 supplementation. The relative increase of most acute-phase proteins is numerically larger and the rise persists longer, which is particularly evident for fibrinogen and alpha 1-glycoprotein. The findings suggest that n-3 fatty acids lower acute-phase proteins at baseline and alter the pattern of change following acute exercise.