Dokumentation zu Leinöl und Alpha-Linolensäure
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Alpha-linolenic acid: an omega-3 fatty acid with neuroprotective properties-ready for use in the stroke clinic?
Blondeau N1, Lipsky RH2, Bourourou M1, Duncan MW3, Gorelick PB4, Marini AM5. Biomed Res Int. 2015;2015:519830.
Alpha-linolenic acid (ALA) is plant-based essential omega-3 polyunsaturated fatty acids that must be obtained through the diet. This could explain in part why the severe deficiency in omega-3 intake pointed by numerous epidemiologic studies may increase the brain’s vulnerability representing an important risk factor in the development and/or deterioration of certain cardio- and neuropathologies. The roles of ALA in neurological disorders remain unclear, especially in stroke that is a leading cause of death. We and others have identified ALA as a potential nutraceutical to protect the brain from stroke, characterized by its pleiotropic effects in neuroprotection, vasodilation of brain arteries, and neuroplasticity. This review highlights how chronic administration of ALA protects against rodent models of hypoxic-ischemic injury and exerts an anti-depressant-like activity, effects that likely involve multiple mechanisms in brain, and may be applied in stroke prevention. One major effect may be through an increase in mature brain-derived neurotrophic factor (BDNF), a widely expressed protein in brain that plays critical roles in neuronal maintenance, and learning and memory. Understanding the precise roles of ALA in neurological disorders will provide the underpinnings for the development of new therapies for patients and families who could be devastated by these disorders.
α-Linolenic acid: nutraceutical, pharmacological and toxicological evaluation.
Kim KB1, Nam YA2, Kim HS2, Hayes AW3, Lee BM4. Food Chem Toxicol. 2014 Aug;70:163-78.
α-Linolenic acid (ALA), a carboxylic acid with 18 carbons and three cis double bonds, is an essential fatty acid needed for human health and can be acquired via regular dietary intake of foods that contain ALA or dietary supplementation of foods high in ALA, for example flaxseed. ALA has been reported to have cardiovascular-protective, anti-cancer, neuro-protective, anti-osteoporotic, anti-inflammatory, and antioxidative effects. ALA is the precursor of longer chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), but its beneficial effects on risk factors for cardiovascular diseases are still inconclusive. The recommended intake of ALA for cardiovascular health is reported to be 1.1-2.2g/day. Although there are limited toxicological data for ALA, no serious adverse effects have been reported. The evidence on an increased prostate cancer risk in association with dietary ALA is not conclusive. Based on the limited data currently available, it may be concluded that ALA may be beneficial as a nutraceutical/pharmaceutical candidate and is safe for use as a food ingredient.
Meta-analysis of the effects of flaxseed interventions on blood lipids.
Pan A, Yu D, Demark-Wahnefried W, Franco OH, Lin X. Am J Clin Nutr. 2009 Aug;90(2):288-97. Epub 2009 Jun 10.
BACKGROUND: Several clinical trials have investigated the effects of flaxseed and flaxseed-derived products (flaxseed oil or lignans) on blood lipids; however, the findings have been inconsistent. OBJECTIVE: We aimed to identify and quantify the effectiveness of flaxseed and its derivatives on blood lipid profiles. DESIGN: A comprehensive literature search was performed on the basis of English reports of randomized controlled trials of flaxseed or its derivatives on lipid profiles in adults, which were published from January 1990 to October 2008. Attempts also were made to access unpublished data. Study quality was assessed by using the Jadad score, and a meta-analysis was conducted. RESULTS: Twenty-eight studies were included. Flaxseed interventions reduced total and LDL cholesterol by 0.10 mmol/L (95% CI: -0.20, 0.00 mmol/L) and 0.08 mmol/L (95% CI: -0.16, 0.00 mmol/L), respectively; significant reductions were observed with whole flaxseed (-0.21 and -0.16 mmol/L, respectively) and lignan (-0.28 and -0.16 mmol/L, respectively) supplements but not with flaxseed oil. The cholesterol-lowering effects were more apparent in females (particularly postmenopausal women), individuals with high initial cholesterol concentrations, and studies with higher Jadad scores. No significant changes were found in the concentrations of HDL cholesterol and triglycerides. CONCLUSIONS: Flaxseed significantly reduced circulating total and LDL-cholesterol concentrations, but the changes were dependent on the type of intervention, sex, and initial lipid profiles of the subjects. Further studies are needed to determine the efficiency of flaxseed on lipid profiles in men and premenopausal women and to explore its potential benefits on other cardiometabolic risk factors and prevention of cardiovascular disease.
Alpha-linolenic acid and risk of nonfatal acute myocardial infarction.
Campos H, Baylin A, Willett WC. Circulation. 2008 Jul 22;118(4):339-45. Epub 2008 Jul 7.
BACKGROUND: Intake of long-chain n-3 fatty acids found in fish is low in many countries worldwide. alpha-Linolenic acid could be a viable cardioprotective alternative to these fatty acids in these countries. METHODS AND RESULTS: Cases (n=1819) with a first nonfatal acute myocardial infarction and population-based controls (n=1819) living in Costa Rica matched for age, sex, and area of residence were studied. Fatty acids were assessed by gas chromatography in adipose tissue samples and by a validated food frequency questionnaire specifically designed for this population. Odds ratios and 95% confidence intervals were calculated from multivariate conditional logistic regression models. alpha-Linolenic acid in adipose tissue ranged from 0.36% in the lowest decile to 1.04% in the highest decile. The corresponding median levels of intake were 0.42% and 0.86% energy. Greater alpha-linolenic acid (assessed either in adipose or by questionnaire) was associated with lower risk of myocardial infarction. The odds ratios for nonfatal myocardial infarction for the highest compared with the lowest deciles were 0.41 (95% confidence interval, 0.25 to 0.67) for alpha-linolenic acid in adipose tissue and 0.61 (95% confidence interval, 0.42 to 0.88) for dietary alpha-linolenic acid. The relationship between alpha-linolenic acid and myocardial infarction was nonlinear; risk did not decrease with intakes > approximately 0.65% energy (1.79 g/d). Fish or eicosapentaenoic acid and docosahexaenoic acid intake at the levels found in this population did not modify the observed association. CONCLUSIONS: Consumption of vegetable oils rich in alpha-linolenic acid could confer important cardiovascular protection. The apparent protective effect of alpha-linolenic acid is most evident among subjects with low intakes.
Antihypertensive Effect and Safety of Dietary alpha-Linolenic Acid in Subjects with High-Normal Blood Pressure and Mild Hypertension.
Takeuchi H, Sakurai C, Noda R, Sekine S, Murano Y, Wanaka K, Kasai M, Watanabe S, Aoyama T, Kondo K. J Oleo Sci. 2007;56(7):347-60.
We investigated the antihypertensive effect and safety of alpha-linolenic acid (ALA) in human subjects. In Experiment 1, subjects with high-normal blood pressure and mild hypertension ingested bread containing 14 g of common blended oil (control oil) or ALA-enriched oil for 12 weeks. The test oil contained 2.6g/14 g of ALA. The subjects ingested strictly controlled meals during the study period. Systolic blood pressure was significantly lower in the ALA group than in the control group after ingestion of the test diet for 4, 8 and 12 weeks. Diastolic blood pressure was significantly lower in the ALA group than in the control group after ingestion of the test diet for 12 weeks. In Experiment 2, we evaluated the safety of high intake of ALA (7.8g/d), particularly its effects on oxidation in the body and blood coagulation. Normotensive, high-normotensive and mildly hypertensive subjects ate bread that contained 42 g of the control oil or the test oil for 4 weeks. No significant difference was noted in the lipid peroxide level, high-sensitive C-reactive protein level, plasma prothrombin time or activated partial thromboplastin time between the two groups. No abnormal changes were noted after test diet ingestion on blood test or urinalysis, and no adverse event considered to have been induced by the test oil was observed in Experiment 1 and 2. These results suggest that ALA have an antihypertensive effect with no adverse effect in subjects with high-normal blood pressure and mild hypertension.
An increase in dietary n-3 fatty acids decreases a marker of bone resorption in humans.
Griel AE, Kris-Etherton PM, Hilpert KF, Zhao G, West SG, Corwin RL. Nutr J. 2007 Jan 16;6:2.
Human, animal, and in vitro research indicates a beneficial effect of appropriate amounts of omega-3 (n-3) polyunsaturated fatty acids (PUFA) on bone health. This is the first controlled feeding study in humans to evaluate the effect of dietary plant-derived n-3 PUFA on bone turnover, assessed by serum concentrations of N-telopeptides (NTx) and bone-specific alkaline phosphatase (BSAP). Subjects (n = 23) consumed each diet for 6 weeks in a randomized, 3-period crossover design: 1) Average American Diet (AAD; [34% total fat, 13% saturated fatty acids (SFA), 13% monounsaturated fatty acids (MUFA), 9% PUFA (7.7% LA, 0.8% ALA)]), 2) Linoleic Acid Diet (LA; [37% total fat, 9% SFA, 12% MUFA, 16% PUFA (12.6% LA, 3.6% ALA)]), and 3) alpha-Linolenic Acid Diet (ALA; [38% total fat, 8% SFA, 12% MUFA, 17% PUFA (10.5% LA, 6.5% ALA)]). Walnuts and flaxseed oil were the predominant sources of ALA. NTx levels were significantly lower following the ALA diet (13.20 +/- 1.21 nM BCE), relative to the AAD (15.59 +/- 1.21 nM BCE) (p < 0.05). Mean NTx level following the LA diet was 13.80 +/- 1.21 nM BCE. There was no change in levels of BSAP across the three diets. Concentrations of NTx were positively correlated with the pro-inflammatory cytokine TNFalpha for all three diets. The results indicate that plant sources of dietary n-3 PUFA may have a protective effect on bone metabolism via a decrease in bone resorption in the presence of consistent levels of bone formation.
Effects of alpha-linolenic acid versus those of EPA/DHA on cardiovascular risk markers in healthy elderly subjects.
Goyens PL, Mensink RP. Eur J Clin Nutr. 2006 Feb 15; [Epub ahead of print]
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.
Does alpha-linolenic acid intake reduce the risk of coronary heart disease? A review of the evidence.
Mozaffarian D. Altern Ther Health Med. 2005 May-Jun;11(3):24-30; quiz 31, 79.
Alpha-linolenic acid (ALA) is an n-3 polyunsaturated fatty acid found mainly in plant sources, including flaxseed oil, canola oil, and walnuts. Although substantial evidence indicates that consumption of long-chain n-3 polyunsaturated fatty acids from seafood reduces the risk of coronary heart disease (CHD), the effect of ALA intake on CHD risk is less well-established. ALA may reduce cardiovascular risk through a variety of biologic mechanisms, including platelet function, inflammation, endothelial cell function, arterial compliance, and arrhythmia. Although clinical benefits have not been seen consistently in all studies, most prospective observational studies suggest that ALA intake reduces the incidence of CHD, and two randomized trials have demonstrated that a dietary pattern that includes fruits, vegetables, whole grains, nuts or legumes, and ALA-rich foods substantially reduces the recurrence of CHD events. Additional observational and clinical studies will help establish the effects of ALA on CHD risk and determine whether such effects vary based on gender, duration of intake, background dietary intake of seafood, or other factors. Presently, the weight of the evidence favors recommendations for modest dietary consumption of ALA (2 to 3 g per day) for the primary and secondary prevention of CHD.
Dietary alpha-linolenic acid intake and risk of sudden cardiac death and coronary heart disease.
Albert CM, Oh K, Whang W, Manson JE, Chae CU, Stampfer MJ, Willett WC, Hu FB. Circulation. 2005 Nov 22;112(21):3232-8.
BACKGROUND: Alpha-linolenic acid, an intermediate-chain n-3 fatty acid found primarily in plants, may decrease the risk of fatal coronary heart disease (CHD) through a reduction in fatal ventricular arrhythmias and sudden cardiac death (SCD). METHODS AND RESULTS: We prospectively examined the association between dietary intake of alpha-linolenic acid assessed via updated food-frequency questionnaires and the risk of SCD, other fatal CHD, and nonfatal myocardial infarction (MI) among 76,763 women participating in the Nurses‘ Health Study who were free from cancer and completed a dietary questionnaire at baseline in 1984. During 18 years of follow-up, we identified 206 SCDs, 641 other CHD deaths, and 1604 nonfatal MIs. After controlling for coronary risk factors and other fatty acids, including long-chain n-3 fatty acids, the intake of alpha-linolenic acid was inversely associated with the risk of SCD (P for trend, 0.02) but not with the risk of other fatal CHD or nonfatal MI. Compared with women in the lowest quintile of alpha-linolenic acid intake, those in the highest 2 quintiles had a 38% to 40% lower SCD risk. This inverse relation with SCD risk was linear and remained significant even among women with high intakes of long-chain n-3 fatty acids. CONCLUSIONS: These prospective data suggest that increasing dietary intake of alpha-linolenic acid may reduce the risk of SCD but not other types of fatal CHD or nonfatal MI in women. The specificity of the association between alpha-linolenic acid and SCD supports the hypothesis that these n-3 fatty acids may have antiarrhythmic properties.
Alpha-linolenic acid and coronary heart disease.
de Lorgeril M, Salen P. Nutr Metab Cardiovasc Dis. 2004 Jun;14(3):162-9.
AIM: To summarize our present knowledge about vegetable omega-3 fatty acids. DATA SYNTHESIS: Alpha-linolenic acid (ALA) is one of the two essential fatty acids in humans. Epidemiological studies and dietary trials strongly suggest that this fatty acid is important in relation with the pathogenesis (and prevention) of coronary heart disease. Like other n-3 fatty acids from marine origin, it may prevent cardiac arrhythmias and sudden cardiac death. The optimal dietary intake of alpha-linolenic acid seems to be about 2 g per day or 0.6 to 1% of total energy intake. Obtaining an optimal ratio of the two essential fatty acids, linoleic and alpha-linolenic acids–ie a ratio of less than 4 to 1 in the diet–is a major issue. The main sources of alpha-linolenic acid for the European population should be canola oil (and canola-oil based margarine if available), nuts (English walnut), ground linseeds and green leafy vegetables such as purslane. CONCLUSIONS: Epidemiological studies and dietary trials in humans suggest that alpha-linolenic acid is a major cardio-protective nutritient.