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"July 9, 2008 | Michael O'Riordan Boston, MA - The consumption of a diet containing vegetable oils rich in alpha-linolenic acid (ALA) is associated with significant reductions in the risk of nonfatal MI, a new study has shown [1]. Investigators say the protective effect of ALA is evident among individuals with low intakes, suggesting the greatest benefit might be in developing countries, where fatty-acid consumption is limited. "The potential for benefit is great when the baseline intake is low," said lead investigator Dr Hannia Campos (Harvard Medical School, Boston, MA). "In countries where people eat very little fish-and some of these countries have almost no sources of omega-3 fatty acids because they cook with corn or sunflower oils-the consumption of vegetable oils with ALA could have a major impact on heart disease." In an editorial accompanying the published study [2], Dr William Harris (University of South Dakota, Sioux Falls) said that the data are suggestive and would be good news for individuals who will not or cannot eat fish, but more studies are still needed. "If ALA were able to do the same 'heavy lifting' that [eicosapentaenoic acid] EPA and [docosahexaenoic acid] DHA do, this would be welcomed news, because the capacity to produce ALA is essentially limitless, whereas there are only so many fish in the sea," he writes. "

n-3 fatty acid dietary recommendations and food sources to achieve essentiality and cardiovascular benefits. Gebauer SK, Psota TL, Harris WS, Kris-Etherton PM. Am J Clin Nutr. 2006 Jun;83(6 Suppl):1526S-1535S. Review. PMID: 16841863 Dietary recommendations have been made for n-3 fatty acids, including {alpha}-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) to achieve nutrient adequacy and to prevent and treat cardiovascular disease. These recommendations are based on a large body of evidence from epidemiologic and controlled clinical studies. The n-3 fatty acid recommendation to achieve nutritional adequacy, defined as the amount necessary to prevent deficiency symptoms, is 0.6-1.2% of energy for ALA; up to 10% of this can be provided by EPA or DHA. To achieve recommended ALA intakes, food sources including flaxseed and flaxseed oil, walnuts and walnut oil, and canola oil are recommended. The evidence base supports a dietary recommendation of {approx}500 mg/d of EPA and DHA for cardiovascular disease risk reduction. For treatment of existing cardiovascular disease, 1 g/d is recommended. These recommendations have been embraced by many health agencies worldwide. A dietary strategy for achieving the 500-mg/d recommendation is to consume 2 fish meals per week (preferably fatty fish). Foods enriched with EPA and DHA or fish oil supplements are a suitable alternate to achieve recommended intakes and may be necessary to achieve intakes of 1 g/d.

n-3 fatty acids and cardiovascular disease. Breslow JL. Am J Clin Nutr. 2006 Jun;83(6 Suppl):1477S-1482S. Review. PMID: 16841857 The results of prospective cohort studies indicate that consuming fish or fish oil containing the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is associated with decreased cardiovascular death, whereas consumption of the vegetable oil-derived n-3 fatty acid {alpha}-linolenic acid is not as effective. Randomized control trials (RCTs) in the context of secondary prevention also indicate that the consumption of EPA plus DHA is protective at doses 3 g/d, EPA plus DHA can improve cardiovascular disease risk factors, including decreasing plasma triacylglycerols, blood pressure, platelet aggregation, and inflammation, while improving vascular reactivity. Mainly on the basis of the results of RCTs, the American Heart Association recommends that everyone eat oily fish twice per week and that those with coronary heart disease eat 1 g/d of EPA plus DHA from oily fish or supplements. Directions for future research include 1) RCTs to confirm the initial trials showing that EPA plus DHA decreases cardiovascular death and additional studies to determine whether this effect is due to EPA, DHA, or the combination; the dosage of the effective components; and whether the mechanism of action in humans is prevention of fatal arrhythmias. 2) Clinical studies to determine whether the reduction in cardiovascular disease risk factors is due to EPA, DHA, or the combination and the dosage of the effective components. 3) Clinical studies to determine whether vegetable oil-derived {alpha}-linolenic acid added to a diet enriched in n-6 fatty acids can effectively substitute for fish oil-derived EPA plus DHA.

Relationship of dietary linoleic acid to blood pressure. The International Study of Macro-Micronutrients and Blood Pressure Study [corrected] Miura K, Stamler J, Nakagawa H, Elliott P, Ueshima H, Chan Q, Brown IJ, Tzoulaki I, Saitoh S, Dyer AR, Daviglus ML, Kesteloot H, Okayama A, Curb JD, Rodriguez BL, Elmer PJ, Steffen LM, Robertson C, Zhao L; International Study of Macro-Micronutrients and Blood Pressure Research Group. Hypertension. 2008 Aug;52(2):408-14. Epub 2008 Jul 7. Erratum in: Hypertension. 2008 Sep;52(3):e29. PMID: 18606902 doi: 10.1161/HYPERTENSIONAHA.108.112383 Dietary linoleic acid intake may contribute to prevention and control of adverse blood pressure levels in general populations

AHA Science Advisory: Lyon Diet Heart Study. Benefits of a Mediterranean-style, National Cholesterol Education Program/American Heart Association Step I Dietary Pattern on Cardiovascular Disease.\nKris-Etherton P, Eckel RH, Howard BV, St Jeor S, Bazzarre TL; Nutrition Committee Population Science Committee and Clinical Science Committee of the American Heart Association.\nCirculation. 2001 Apr 3;103(13):1823-5. \nPMID: 11282918

Dietary linolenic acid is inversely associated with calcified atherosclerotic plaque in the coronary arteries: the National Heart, Lung, and Blood Institute Family Heart Study. Djoussé L, Arnett DK, Carr JJ, Eckfeldt JH, Hopkins PN, Province MA, Ellison RC; Investigators of the NHLBI FHS. Circulation. 2005 Jun 7;111(22):2921-6. Epub 2005 May 31. PMID: 15927976 doi: 10.1161/CIRCULATIONAHA.104.489534

Wang C, Harris WS, Chung M, Lichtenstein AH, Balk EM, Kupelnick B, Jordan HS, Lau J. \nn-3 Fatty acids from fish or fish-oil supplements, but not \nalpha-linolenic acid, benefit cardiovascular disease outcomes in \nprimary- and secondary-prevention studies: a systematic review. \nAm J Clin Nutr. 2006 Jul;84(1):5-17. Review. \nPMID: 16825676

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. Erratum in: Circulation. 2008 Sep 16;118(12):e492. PMID: 18606916 doi: 10.1161/CIRCULATIONAHA.107.762419 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.

Cardiovascular risk and alpha-linolenic acid: can Costa Rica clarify? Harris WS. Circulation. 2008 Jul 22;118(4):323-4. Epub 2008 Jul 7. Review. PMID: 18606912 doi: 10.1161/CIRCULATIONAHA.108.791467

Types of dietary fat and risk of coronary heart disease: a critical review. Hu FB, Manson JE, Willett WC. J Am Coll Nutr. 2001 Feb;20(1):5-19. Review. PMID: 11293467