Dietary intake of alpha-linolenic acid and risk of fatal ischemic heart disease among women

BACKGROUND: Experimental studies in laboratory animals and humans suggest that alpha-linolenic acid (18:3n-3) may reduce the risk of arrhythmia. OBJECTIVE: The objective was to examine the association between dietary intake of alpha-linolenic acid and risk of fatal ischemic heart disease (IHD). DESIGN: This was a prospective cohort study. The intake of alpha-linolenic acid was derived from a 116-item food-frequency questionnaire completed in 1984 by 76283 women without previously diagnosed cancer or cardiovascular disease. RESULTS: During 10 y of follow-up, we documented 232 cases of fatal IHD and 597 cases of nonfatal myocardial infarction. After adjustment for age, standard coronary risk factors, and dietary intake of linoleic acid and other nutrients, a higher intake of alpha-linolenic acid was associated with a lower relative risk (RR) of fatal IHD; the RRs from the lowest to highest quintiles were 1.0, 0.99, 0.90, 0.67, and 0.55 (95% CI: 0.32, 0.94; P for trend = 0.01). For nonfatal myocardial infarction there was only a modest, nonsignificant trend toward a reduced risk when extreme quintiles were compared (RR: 0.85; 95% CI: 0.61, 1.19; P for trend = 0.50). A higher intake of oil and vinegar salad dressing, an important source of alpha-linolenic acid, was associated with reduced risk of fatal IHD when women who consumed this food > or =5-6 times/wk were compared with those who rarely consumed this food (RR: 0.46; 95% CI: 0.27, 0.76; P for trend = 0.001). CONCLUSIONS: This study supports the hypothesis that a higher intake of alpha-linolenic acid is protective against fatal IHD. Higher consumption of foods such as oil-based salad dressing that provide polyunsaturated fats, including alpha-linolenic acid, may reduce the risk of fatal IHD.     

Effect of varying the ratio of n-6 to n-3 fatty acids by increasing the dietary intake of alpha-linolenic acid, eicosapentaenoic and docosahexaenoic acid, or both on fibrinogen and clotting factors VII and XII in persons aged 45-70 y: the OPTILIP study

BACKGROUND: Elevated fibrinogen, activated factor XII (FXIIa), and factor VII coagulant activity (FVIIc) are associated with higher risk of fatal ischemic heart disease. This study tested the hypothesis that lowering the dietary ratio of n-6 to n-3 polyunsaturated fatty acids (n-6:n-3) would modify these risk factors in older men and women. OBJECTIVE: The objective of the study was to measure fasting hemostatic risk factors and postprandial changes in activated FVII (FVIIa) concentrations after a 6-mo alteration in dietary n-6:n-3. DESIGN: In a randomized, parallel design in 258 subjects aged 45-70 y, we compared 4 diets providing 6% of energy as polyunsaturated fatty acids at an n-6:n-3 between 5:1 and 3:1 with a control diet that had an n-6:n-3 of 10:1. The diets were enriched in alpha-linolenic acid, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid, or both. RESULTS: Fasting and 3-h plasma triacylglycerol concentrations were 11.1% and 7.2% lower with the diet that had an n-6:n-3 of approximately 3:1 and that was enriched with EPA and DHA than with the other diets. Fasting fibrinogen, FXIIa, FVIIc, FVIIa, and FVII antigen and postprandial FVIIa were not influenced by the diets. Avoiding foods high in fat the day before measurement decreased FVIIc and FVIIa by 8% and 19.2%, respectively. A test meal containing 50 g fat resulted in a mean 47% (95% CI: 42%, 52%) increase in FVIIa 6 h later, but the response did not differ by n-6:n-3. CONCLUSION: Decreasing the n-6:n-3 to approximately 3:1 by increasing the intake of EPA and DHA lowers fasting and postprandial plasma triacylglycerol concentrations in older persons but does not influence hemostatic risk factors.     

Blood concentrations of individual long-chain n-3 fatty acids and risk of nonfatal myocardial infarction

BACKGROUND: Whereas dietary intake of long-chain n-3 fatty acids has been associated with risk of nonfatal myocardial infarction (MI), few studies have examined the relation for blood concentrations. OBJECTIVE: We aimed to investigate the effect of long-chain n-3 fatty acids in blood on the risk of nonfatal MI. DESIGN: Baseline blood samples were collected from 32 826 participants of the Nurses' Health Study in 1989-1990, among whom 146 incident cases of nonfatal MI were ascertained during 6 y of follow-up and matched with 288 controls. RESULTS: After multivariate adjustment, the relative risks (95% CI) comparing the highest with the lowest quartiles in plasma were 0.23 (0.09, 0.55; P for trend = 0.001) for eicosapentaenoic acid (EPA), 0.40 (0.20, 0.82; P for trend = 0.004) for docosapentaenoic acid (DPA), and 0.46 (0.18, 1.16; P for trend = 0.07) for docosahexaenoic acid (DHA). The associations for these fatty acids in erythrocytes were generally weaker and nonsignificant. In contrast to EPA and DHA, blood concentrations of DPA were not correlated with dietary consumption of n-3 fatty acids. Higher plasma concentrations of EPA, DPA, and DHA were associated with higher plasma concentrations of HDL cholesterol and lower concentrations of triacylglycerol and inflammatory markers. CONCLUSIONS: Higher plasma concentrations of EPA and DPA are associated with a lower risk of nonfatal MI among women. These findings may partly reflect dietary consumption but, particularly for DPA, may indicate important risk differences based on metabolism of long-chain n-3 fatty acids.     

Fish and shellfish consumption in relation to death from myocardial infarction among men in Shanghai, China.

Between 1986 and 1989, 18,244 men aged 45-64 years in Shanghai, China, participated in a prospective study of diet and cancer. All participants completed an in-person, structured interview and provided blood and urine samples. As of September 1, 1998, 113 deaths from acute myocardial infarction were identified. After analyses were adjusted for age, total energy intake, and known cardiovascular disease risk factors, men who consumed >or=200 g of fish/shellfish per week had a relative risk of 0.41 (95% confidence interval: 0.22, 0.78) for fatal acute myocardial infarction compared with men consuming <50 g per week. Similarly, dietary intake of n-3 fatty acids derived from seafood also was significantly associated with reduced mortality from myocardial infarction. Neither dietary seafood nor n-3 fatty acid intake was associated with a reduced risk of death from stroke or ischemic heart disease other than acute myocardial infarction. However, approximately a 20% reduction in total mortality associated with weekly fish/shellfish intake was observed in the study population (relative risk = 0.79, 95% confidence interval: 0.69, 0.91). These prospective data suggest that eating fish and shellfish weekly reduces the risk of fatal myocardial infarction in middle-aged and older men in Shanghai, China.     

Historical overview of n-3 fatty acids and coronary heart disease

The first evidence that fish oil fatty acids might have a beneficial effect on coronary heart disease came from the discovery that Greenland Eskimos, who have a diet high in n-3 fatty acids, have a lower mortality from coronary heart disease than do Danes and Americans. Long-chain polyunsaturated fatty acids are essential in our diets and can be classified in 2 groups: n-6 fatty acids found in plant seeds and n-3 fatty acids found in marine vertebrates. Further evidence of n-3 benefits to human health include a 1989 study demonstrating a 29% reduction in fatal cardiac arrhythmias among subjects with a recent myocardial infarction who had been advised to consume fish oil. The GISSI-Prevenzione Trial found a significant reduction in relative reduction of death, cardiac death, nonfatal myocardial infarction, and stroke in subjects consuming n-3 fatty acids. In a recent study, subjects with implanted cardiac defibrillators (ICDs) at high risk for fatal ventricular arrhythmias were randomly assigned to four 1-g capsules of either an ethyl ester concentrate of n-3 fatty acids or olive oil daily for 12 mo. Subjects receiving n-3 who thus had significantly higher levels of eicosapentaenoic acid and docosahexaenoic acid in their red blood cell membranes showed a longer time to first ICD events and had a significantly lower relative risk of having an ICD event or probable event (P = 0.033). These studies demonstrate that fish oil fatty acids have beneficial effects on coronary heart disease.     

Low plasma eicosapentaenoic acid and depressive symptomatology are independent predictors of dementia risk

BACKGROUND: The potential preventive role of polyunsaturated fatty acids (PUFAs) in Alzheimer disease has aroused increasing interest. Plasma n-3 PUFAs have been shown to be inversely related to the risk of dementia and to depression, which is frequently associated with dementia. OBJECTIVE: The objective was to ascertain whether plasma PUFAs predict the risk of incident dementia in a cohort of older persons, independently of their depressive status. DESIGN: Of 1214 nondemented participants in the Three-City Study from Bordeaux (France) who were followed up for 4 y, 65 developed dementia. The association between the proportion of plasma fatty acids at baseline and the risk of incident dementia was assessed by multivariate proportional hazard models, taking into account depressive status assessed on the basis of the Center for Epidemiologic Studies Depression scale. RESULTS: A higher plasma eicosapentaenoic acid (EPA) concentration was associated with a lower incidence of dementia [hazard ratio (HR) for 1 SD = 0.69; 95% CI: 0.48, 0.98], independently of depressive status and after adjustment for age, education, apolipoprotein E epsilon4 allele, diabetes, and baseline plasma vitamin E and triacylglycerol. The relations between docosahexaenoic acid (DHA), total n-3 PUFAs, and incident dementia did not remain significant in multivariate models. Higher ratios of arachidonic acid (AA) to DHA and of n-6 to n-3 fatty acids were related to an increased risk of dementia, particularly in depressive subjects (n = 90): ratio of AA to DHA (HR: 2.65; 95% CI: 1.07, 6.56) and ratio of n-6 to n-3 (HR: 1.61; 95% CI: 1.04, 2.47). CONCLUSIONS: A high plasma EPA concentration may decrease the risk of dementia, whereas high ratios of n-6 to n-3 fatty acids and of AA to DHA may increase the risk of dementia, especially in depressed older persons. The role of EPA in dementia warrants further research.     

Dietary supplementation with eicosapentaenoic acid, but not with other long-chain n-3 or n-6 polyunsaturated fatty acids, decreases natural killer cell activity in healthy subjects aged >55 y

BACKGROUND: Animal studies showed that dietary flaxseed oil [rich in the n-3 polyunsaturated fatty acid alpha-linolenic acid (ALA)], evening primrose oil [rich in the n-6 polyunsaturated fatty acid gamma-linolenic acid (GLA)], and fish oil [rich in the long-chain n-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] can decrease natural killer (NK) cell activity. There have been no studies of the effect on NK cell activity of adding these oils to the diet of humans. OBJECTIVE: Our objective was to determine the effect of dietary supplementation with oil blends rich in ALA, GLA, arachidonic acid (AA), DHA, or EPA plus DHA (fish oil) on the NK cell activity of human peripheral blood mononuclear cells. DESIGN: A randomized, placebo-controlled, double-blind, parallel study was conducted. Healthy subjects aged 55-75 y consumed 9 capsules/d for 12 wk; the capsules contained placebo oil (an 80:20 mix of palm and sunflower seed oils) or blends of placebo oil and oils rich in ALA, GLA, AA, DHA, or EPA plus DHA. Subjects in these groups consumed 2 g ALA, 770 mg GLA, 680 mg AA, 720 mg DHA, or 1 g EPA plus DHA (720 mg EPA + 280 mg DHA) daily, respectively. Total fat intake from the capsules was 4 g/d. RESULTS: The fatty acid composition of plasma phospholipids changed significantly in the GLA, AA, DHA, and fish oil groups. NK cell activity was not significantly affected by the placebo, ALA, GLA, AA, or DHA treatment. Fish oil caused a significant reduction (mean decline: 48%) in NK cell activity that was fully reversed by 4 wk after supplementation had ceased. CONCLUSION: A moderate amount of EPA but not of other n-6 or n-3 polyunsaturated fatty acids can decrease NK cell activity in healthy subjects.     

Dietary intakes of arachidonic acid and alpha-linolenic acid are associated with reduced risk of hip fracture in older adults

PUFA are hypothesized to influence bone health, but longitudinal studies on hip fracture risk are lacking. We examined associations between intakes of PUFA and fish, and hip fracture risk among older adults (n = 904) in the Framingham Osteoporosis Study. Participants (mean age ~75 y at baseline) were followed for incident hip fracture from the time they completed the baseline exam (1988-1989) until December 31, 2005. HR and 95% CI were estimated for energy-adjusted dietary fatty acid exposure variables [(n-3) fatty acids: α-linolenic acid (ALA), EPA, DHA, EPA+DHA; (n-6) fatty acids: linoleic acid, arachidonic acid (AA); and the (n-6):(n-3) ratio] and fish intake categories, adjusting for potential confounders and covariates. Protective associations were observed between intakes of ALA (P-trend = 0.02) and hip fracture risk in a combined sample of women and men and between intakes of AA (P-trend = 0.05) and hip fracture risk in men only. Participants in the highest quartile of ALA intake had a 54% lower risk of hip fracture than those in the lowest quartile (Q4 vs. Q1: HR = 0.46; 95% CI = 0.26-0.83). Men in the highest quartile of AA intake had an 80% lower risk of hip fracture than those in the lowest quartile (Q4 vs. Q1: HR = 0.20; 95% CI = 0.04-0.96). No significant associations were observed among intakes of EPA, DHA, EPA+DHA, or fish. These findings suggest dietary ALA may reduce hip fracture risk in women and men and dietary AA may reduce hip fracture risk in men.     

Effects of fish-oil supplementation on myocardial fatty acids in humans

BACKGROUND: Increased fish or fish-oil consumption is associated with reduced risk of cardiac mortality, especially sudden death. This benefit putatively arises from the incorporation of the long-chain n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into cardiomyocyte phospholipids. OBJECTIVE: The study examined the kinetics of incorporation of n-3 fatty acids into human myocardial membrane phospholipids during supplementation with fish oil and alpha-linolenic acid-rich flaxseed oil. DESIGN: Patients with low self-reported fish intake (<1 fish meal/wk and no oil supplements) accepted for elective cardiac surgery involving cardiopulmonary bypass were randomly allocated to 1 of 6 groups: no supplement; fish oil (6 g EPA+DHA/d) for either 7, 14, or 21 d before surgery; flaxseed oil; or olive oil (both 10 mL/d for 21 d before surgery). Right atrial appendage tissue removed during surgery and blood collected at enrollment and before surgery were analyzed for phospholipid fatty acids. RESULTS: Surgery rescheduling resulted in a range of treatment times from 7 to 118 d. In the fish-oil-treated subjects, accumulation of EPA and DHA in the right atrium was curvilinear with time and reached a maximum at approximately 30 d of treatment and displaced mainly arachidonic acid. Flaxseed oil supplementation yielded a small increase in atrial EPA but not DHA, whereas olive oil did not significantly change atrial n-3 fatty acids. CONCLUSION: The results of the present study show that dietary n-3 fatty acids are rapidly incorporated into human myocardial phospholipids at the expense of arachidonic acid during high-dose fish-oil supplementation.     

Intake of n-6 and n-3 fatty acids and fish and risk of community-acquired pneumonia in US men

BACKGROUND: Essential fatty acids modulate inflammation and glucose metabolism and may alter infection risk. OBJECTIVE: We examined the association between intakes of n-6 and n-3 fatty acids and fish and the risk of community-acquired pneumonia. DESIGN: We prospectively evaluated 38,378 male US health professionals aged 44-79 y at the outset. We updated medical and lifestyle information biennially through questionnaires and diet every 4 y with the use of a validated food-frequency questionnaire. We excluded men who reported pneumonia, myocardial infarction, stroke, other heart disease, arterial surgery, cancer, or asthma before 1990 or those with incomplete dietary data. Community-acquired pneumonia was determined by blinded medical record review of chest radiographs. RESULTS: During 10 y of follow-up, there were 441 new cases of nonfatal community-acquired pneumonia. Pneumonia risk was lower in men in the highest energy-adjusted quintiles of intake than in men in the lowest quintiles of intake of linoleic acid [multivariate relative risk (RR): 0.70; 95% CI: 0.51, 0.96; P for trend = 0.01] and alpha-linolenic acid (multivariate RR: 0.68; 95% CI: 0.50, 0.93; P for trend = 0.01). Pneumonia risk decreased 4% for every 1-g/d increase in linoleic acid intake (multivariate RR: 0.96; 95% CI: 0.93, 0.99). Pneumonia risk was reduced by 31% for every 1-g/d increase in alpha-linolenic acid intake (multivariate RR: 0.69; 95% CI: 0.51, 0.93). Intakes of eicosapentaenoic acid and docosahexaenoic acid were not significantly related to pneumonia risk. CONCLUSION: Higher intakes of alpha-linolenic and linoleic acids and possibly of fish may reduce the risk of pneumonia.     

Are all n-3 polyunsaturated fatty acids created equal?

N-3 Polyunsaturated fatty acids have been shown to have potential beneficial effects for chronic diseases including cancer, insulin resistance and cardiovascular disease. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in particular have been studied extensively, whereas substantive evidence for a biological role for the precursor, alpha-linolenic acid (ALA), is lacking. It is not enough to assume that ALA exerts effects through conversion to EPA and DHA, as the process is highly inefficient in humans. Thus, clarification of ALA's involvement in health and disease is essential, as it is the principle n-3 polyunsaturated fatty acid consumed in the North American diet and intakes of EPA and DHA are typically very low. There is evidence suggesting that ALA, EPA and DHA have specific and potentially independent effects on chronic disease. Therefore, this review will assess our current understanding of the differential effects of ALA, EPA and DHA on cancer, insulin resistance, and cardiovascular disease. Potential mechanisms of action will also be reviewed. Overall, a better understanding of the individual role for ALA, EPA and DHA is needed in order to make appropriate dietary recommendations regarding n-3 polyunsaturated fatty acid consumption.     

Adipose tissue n-6 fatty acids and acute myocardial infarction in a population consuming a diet high in polyunsaturated fatty acids

BACKGROUND: The Jewish population of Israel consumes a diet rich in n-6 polyunsaturated fatty acids (PUFAs), principally linoleic acid. The consequences of this diet for ischemic heart disease (IHD) remain unclear. OBJECTIVE: We assessed the association of adipose tissue n-6 fatty acids, which are derived entirely from the diet, with acute myocardial infarction (AMI). DESIGN: A total of 180 cases and 492 IHD-free controls aged 25-64 were included in a population-based case-control study of Jerusalem residents hospitalized with a first AMI. Diet was assessed by the use of a food-frequency questionnaire and adipose tissue fatty acids by gas chromatography of biopsy samples taken from subcutaneous gluteal tissue. The data were analyzed by multivariate logistic regression. RESULTS: Dietary PUFAs (: 10.1% of energy) correlated (r = 0.43, P < 0.001) with adipose tissue linoleic acid, which constituted 25.6% of storage fatty acids. High intakes of linoleic acid were not associated with excess risk of AMI (age- and sex-adjusted odds ratio for the third versus the first tertile: 0.96; 95% CI: 0.62, 1.48; NS). In contrast, arachidonic acid, the long chain n-6 derivative of linoleic acid, was positively associated with AMI (age- and sex-adjusted odds ratio: 2.12; 95% CI: 1.33, 3.36; P = 0.004). With multivariate adjustment, there was no evidence for an adverse association of linoleic acid with AMI, whereas the risk associated with arachidonic acid persisted, albeit attenuated. CONCLUSIONS: A very high linoleic acid intake does not appear to confer increased risk of nonfatal AMI. Nonetheless, the increased risk associated with arachidonic acid, a finding that requires confirmation, tempers an inference that diets rich in n-6 fatty acids are safe vis-à-vis coronary health.     

Relations between n-3 fatty acid status and cardiovascular disease risk factors among Quebecers.

BACKGROUND: Epidemiologic evidence shows an inverse relation between fish consumption and death from ischemic heart disease. This beneficial effect is attributed to n-3 fatty acids. OBJECTIVES: The purpose of this study was to examine the association between plasma phospholipid concentrations of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and various cardiovascular disease risk factors among Quebecers. DESIGN: The study population consisted of 1460 subjects aged 18-74 y who participated in the 1990 Quebec Heart Health and Nutrition Survey. Data were obtained through home interviews and clinic visits. RESULTS: Expressed as the percentage of total fatty acids in plasma phospholipids, the geometric means of EPA, DHA, and their combination were 0.47%, 1.19%, and 1.70%, respectively. Concentrations of n-3 fatty acids were positively associated with fish intake. We found positive associations between EPA and total cholesterol, LDL cholesterol, HDL cholesterol, plasma glucose, and systolic and diastolic blood pressure. We found positive associations between DHA and total cholesterol, the ratio of total to HDL cholesterol, triacylglycerols, systolic blood pressure, and plasma glucose and insulin. We also found positive associations between the ratio of EPA to arachidonic acid and total cholesterol, HDL cholesterol, and systolic blood pressure and a negative association with the ratio of total to HDL cholesterol. CONCLUSIONS: Our results indicate that concentrations of EPA and DHA in plasma phospholipids reflected Quebecer fish consumption. Results also show that EPA and the ratio of EPA to arachidonic acid can positively influence HDL-cholesterol concentrations.     

n-3 Fatty acids and cardiovascular disease risk factors among the Inuit of Nunavik

BACKGROUND: Inuit traditionally consume large amounts of marine foods rich in n-3 fatty acids. Evidence exists that n-3 fatty acids have beneficial effects on key risk factors for cardiovascular disease. OBJECTIVE: Our goal was to verify the relation between plasma phospholipid concentrations of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and various cardiovascular disease risk factors among the Inuit of Nunavik, Canada. DESIGN: The study population consisted of 426 Inuit aged 18-74 y who participated in a 1992 health survey. Data were obtained through home interviews and clinical visits. Plasma samples were analyzed for phospholipid fatty acid composition. RESULTS: Expressed as the percentage of total fatty acids, geometric mean concentrations of EPA, DHA, and their combination in plasma phospholipids were 1.99%, 4.52%, and 6.83%, respectively. n-3 Fatty acids were positively associated with HDL-cholesterol concentrations and inversely associated with triacylglycerol concentrations and the ratio of total to HDL cholesterol. In contrast, concentrations of total cholesterol, LDL cholesterol, and plasma glucose increased as n-3 fatty acid concentrations increased. There were no significant associations between n-3 fatty acids and diastolic and systolic blood pressure and plasma insulin. CONCLUSIONS: Consumption of marine products, the main source of EPA and DHA, appears to beneficially affect some cardiovascular disease risk factors. The traditional Inuit diet, which is rich in n-3 fatty acids, is probably responsible for the low mortality rate from ischemic heart disease in this population.     

Omega-3 and omega-6 fatty acid intakes and endometrial cancer risk in a population-based case–control study

Purpose

Animal and laboratory studies suggest that long-chain omega-3 (n-3) fatty acids, a type of polyunsaturated fat found in fatty fish, may protect against carcinogenesis, but human studies on dietary intake of polyunsaturated fats and fish with endometrial cancer risk show mixed results.

Methods

We evaluated the associations between endometrial cancer risk and intake of fatty acids and fish in a population-based sample of 556 incident cancer cases and 533 age-matched controls using multivariate unconditional logistic regression methods.

Results

Although total n-3 fatty acid intake was not associated with endometrial cancer risk, higher intakes of eicosapentaenoic (EPA 20:5) and docosahexaenoic (DHA 22:6) fatty acids were significantly associated with lower risks (OR = 0.57, 95 % CI: 0.39–0.84; OR = 0.64, 95 % CI: 0.44–0.94; respectively) comparing extreme quartiles. The ratio of n-3:n-6 fatty acids was inversely associated with risk only on a continuous scale (OR = 0.84, 95 % CI: 0.71–0.99), while total fish intake was not associated with risk. Fish oil supplement use was significantly associated with reduced risk of endometrial cancer: OR = 0.63 (95 % CI: 0.45–0.88).

Conclusions

Our results suggest that dietary intake of the long-chain polyunsaturated fatty acids EPA and DHA in foods and supplements may have protective associations against the development of endometrial cancer.     

Long-chain n-3 polyunsaturated fatty acids in plasma in British meat-eating, vegetarian, and vegan men

BACKGROUND: Plasma concentrations of long-chain n-3 polyunsaturated fatty acids are lower in vegetarians and in vegans than in omnivores. No data are available on whether these concentrations differ between long- and short-term vegetarians and vegans. OBJECTIVES: We compared plasma fatty acid composition in meat-eaters, vegetarians, and vegans and examined whether the proportions of eicosapentaenoic acid (20:5n-3; EPA), docosapentaenoic acid (22:5n-3; DPA), and docosahexaenoic acid (22:6n-3; DHA) were related to the subjects' duration of adherence to their diets or to the proportions of plasma linoleic acid (18:2n-6; LA) and alpha-linolenic acid (18:3n-3; ALA). DESIGN: The present cross-sectional study included 196 meat-eating, 231 vegetarian, and 232 vegan men in the United Kingdom. Information on anthropometry, diet, and smoking habits was obtained through a questionnaire. Total fatty acid composition in plasma was measured. RESULTS: The proportions of plasma EPA and DHA were lower in the vegetarians and in the vegans than in the meat-eaters, whereas only small differences were seen for DPA. Plasma EPA, DPA, and DHA proportions were not significantly associated with the duration of time since the subjects became vegetarian or vegan, which ranged from <1 y to >20 y. In the vegetarians and the vegans, plasma DHA was inversely correlated with plasma LA. CONCLUSIONS: The proportions of plasma long-chain n-3 fatty acids were not significantly affected by the duration of adherence to a vegetarian or vegan diet. This finding suggests that when animal foods are wholly excluded from the diet, the endogenous production of EPA and DHA results in low but stable plasma concentrations of these fatty acids.     

Current intakes of EPA and DHA in European populations and the potential of animal-derived foods to increase them

The beneficial effects of long-chain (C chain >or=20) n-3 PUFA are well documented and, overall, increased intake reduces risk of CVD. Recent evidence also points to a role in reducing age-related decline in cognitive function. The two key fatty acids are EPA (20:5) and DHA (22:6), with current UK recommendation for adults being 450 mg EPA+DHA/d. Whilst some EPA and DHA can be synthesised in vivo from alpha-linolenic acid, recent data indicate this source to be very limited, suggesting that EPA and DHA should be classified as dietary essentials. In many parts of Europe the daily intake of EPA+DHA by adults and especially young adults (18-24 years) is <100 mg/d, since many never eat oily fish. Poultry meat contributes small but worthwhile amounts of EPA+DHA. Studies to enrich the EPA+DHA content of animal-derived foods mainly use fish oil in the diet of the animal. Recent work has shown that such enrichment has the potential to provide to the UK adult diet a daily intake of EPA+DHA of about 230 mg, with poultry meat providing the largest amount (74 mg). There are, however, concerns that the continued and possibly increased use of fish oils in animals' diets is not sustainable and alternative approaches are being examined, including the genetic modification of certain plants to allow them to synthesise EPA and DHA from shorter-chain precursors.     

Eicosapentaenoic Acid Is Associated with Decreased Incidence of Alzheimer’s Dementia in the Oldest Old

Background. Omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs) may have different effects on cognitive health due to their anti- or pro-inflammatory properties. Methods. We aimed to prospectively examine the relationships between n-3 and n-6 PUFA contents in serum phospholipids with incident all-cause dementia and Alzheimer’s disease dementia (AD). We included 1264 non-demented participants aged 84 ± 3 years from the German Study on Ageing, Cognition, and Dementia in Primary Care Patients (AgeCoDe) multicenter-cohort study. We investigated whether fatty acid concentrations in serum phospholipids, especially eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), alpha-linolenic acid (ALA), linoleic acid (LA), dihomo-γ-linolenic acid (DGLA), and arachidonic acid (AA), were associated with risk of incident all-cause dementia and AD. Results. During the follow-up window of seven years, 233 participants developed dementia. Higher concentrations of EPA were associated with a lower incidence of AD (hazard ratio (HR) 0.76 (95% CI 0.63; 0.93)). We also observed that higher concentrations of EPA were associated with a decreased risk for all-cause dementia (HR 0.76 (95% CI 0.61; 0.94)) and AD (HR 0.66 (95% CI 0.51; 0.85)) among apolipoprotein E ε4 (APOE ε4) non-carriers but not among APOE ε4 carriers. No other fatty acids were significantly associated with AD or dementia. Conclusions. Higher concentrations of EPA were associated with a lower risk of incident AD. This further supports a beneficial role of n-3 PUFAs for cognitive health in old age.     

Maternal fat intake during pregnancy and wheeze and eczema in Japanese infants: the Kyushu Okinawa Maternal and Child Health Study

PurposeThis cohort study examined the relationship between maternal intake of individual fatty acids, meat, and fish during pregnancy and the risk of wheeze and eczema in children aged 23–29 months because epidemiologic evidence on this topic is inconclusive.MethodsSubjects were 1354 Japanese mother-child pairs. Data on maternal intake during pregnancy were assessed with a validated diet history questionnaire. Data on symptoms of wheeze and eczema were based on criteria of the International Study of Asthma and Allergies in Childhood.ResultsSignificant inverse exposure-response relationships were observed between maternal intake of eicosapentaenoic acid (EPA) and EPA plus docosahexaenoic acid (DHA) during pregnancy and infantile wheeze although the adjusted odds ratios between extreme quartiles fell just short of the significance level. No such inverse relationships were detected for infantile eczema. Maternal intake of total fat, saturated fatty acids, monounsaturated fatty acids, total n-3 polyunsaturated fatty acids (PUFA), α-linolenic acid, DHA, total n-6 PUFA, linoleic acid, arachidonic acid, cholesterol, fish, and meat and the ratio of n-3 to n-6 PUFA consumption were not significantly related to infantile wheeze or eczema.ConclusionsHigher maternal intake of EPA and EPA plus DHA during pregnancy may reduce the risk of infantile wheeze.     

Adipose tissue fatty acids and risk of myocardial infarction--a case-control study

OBJECTIVES: To study the association between content in adipose tissue of very long-chain n-3 fatty acids, trans fatty acids, linoleic acid and alpha-linolenic acid and risk of a first myocardial infarction. DESIGN AND SUBJECTS: A case-control design among 100 patients and 98 population controls both men and postmenopausal women, age 45-75 y. Adipose tissue fatty acids were determined by gas-liquid chromatography. Intake data were obtained through interview using a validated food frequency questionnaire. RESULTS: Dietary intake and adipose tissue content of the fatty acids studied correlated significantly. Adipose tissue contents of eicosapentaenoic acid (20:5n-3), docosapentaenoic acid (22:5n-3) and docosahexaenoic acid (22:6n-3) were significantly lower while those of trans fatty acids, linoleic and alpha-linolenic acid were significantly higher in patients than in controls. Age and sex adjusted odds ratios (OR) were significantly reduced with increasing quintiles of very long-chain n-3 fatty acids, thus the OR in the fifth compared to the first quintile was 0.23 (95% CI 0.08-0.70). After further adjustment for waist-to-hip ratio, smoking, family history of CHD and content of trans fatty acids, the OR in the highest quintile was 0.17 (95% CI 0.04-0.76) and the P for trend 0. 016. Age and sex adjusted OR was increased in the fifth compared to the first quintile of trans fatty acids (OR 2.81, 95% CI 1.16-6.84), linoleic acid (OR 2.10, 95% CI 0.87-5.07) and alpha-linolenic acid (OR 1.96, 95% CI 0.83-4.61), and P for trend was 0.002, 0.005 and 0. 020, respectively. The trends remained significant after adjustment for waist-to-hip ratio, smoking, and family history of coronary heart disease. Trans fatty acids, linoleic acid and alpha-linolenic acid in adipose tissue were strongly correlated, indicating a common source, most likely margarine. When each of these fatty acid species were adjusted for the two others the trends were no longer significant. CONCLUSION: Intake of very long-chain n-3 fatty acids as reflected in adipose tissue content is inversely associated with risk of myocardial infarction. Trans fatty acids, linoleic and alpha-linolenic acid were intercorrelated and associated with increased risk. It is suggested that the increased risk may be connected to trans fatty acids or to some other factor associated with margarine consumption. European Journal of Clinical Nutrition 54, 618-625.