Omega-3 information sources
Evidence base for recommended intake of EPA and DHA
Evidence for a role of omega-3 fatty acids in primary prevention of cardiovascular diseases (CVD) comes mainly from epidemiological evidence (Albert et al. 2002; Ascherio et al. 1995; Dolecek 1992; Hu et al. 2002; Mozaffarian et al. 2003; Siscovick et al. 1995) in which the intakes of long chain polyunsaturated fatty acids (LC n-3 PUFA) among healthy adults were estimated and relative risk of death from CHD determined. Systematic reviews support these findings but conclude that evidence for benefits of increased fish or fish oil consumption in prevention of primary CVD is not strong. (Hooper et al. 2004; Wang et al. 2006). Whilst there is no evidence to suggest people should not take rich sources of omega 3 fats, high quality trials are needed to confirm suggestions of a protective effect of omega 3 fats on cardiovascular health. Until recently there has been a lack of data from randomised controlled trials (RCT) informing benefits for primary prevention of CVD. Two reports have found no benefit of supplementation either with EPA & DHA combined (Sanders et al. 2011) or DHA alone (Singhal et al. 2011), however the evidence for omega-3 fatty acids in prevention of CVD through a reduction of inflammatory vascular processes and that omega-3 may be cardioprotective is inceasing (Lorente-Cebrain S et al. 2013).
Evidence for secondary prevention of CVD, e.g. reduction in risk of sudden death following myocardial infarction (MI) comes from large randomised controlled trials (RCT) where subjects with existing CVD have been supplemented either with dietary fish or fish oil supplements at a range of intakes (Burr et al. 1989; Marchioli et al. 2002, Kromhout D and De Goede J 2014). The present fact sheet does not consider recommendations for people with pre-existing CVD.
The current UK guidelines for population fish consumption are based on a review of evidence carried out since publication of the COMA (1994) report into nutritional considerations of cardiovascular disease (Department of Health 1994). Revised recommendations were made by the Scientific Advisory Committee on Nutrition (SACN) in 2004 and endorsed a population recommendation of at least two portions of fish per week, one of which should be oily (Scientific Advisory Committee on Nutrition 2004). This level of dietary intake should provide approximately 0.45g/d LC n-3 PUFA/day.
Cognitive impairment and depression in adults
There is currently tentative evidence to support a role for n-3 supplementation, andparticularly in the omega-6/omega-3 ratio, in risk reduction of cognitive impairment or dementia in adults (Loef Mand Walach H 2013) and also in the treatment of depression in adults (Giles GE et al 2013).
Behavioural and learning difficulties in children
There is some evidence that n-3 fatty acids may benefit some children with attention deficit hyperactive disorder (ADHD) and related disorders. Observational studies suggest a link between inadequate dietary intake of n-3 fatty acids and disorders of fatty acid metabolism and behavioural difficulties in affected children (Richardson and Ross 2000). Supplementation studies among children with these disorders suggest there may be some benefit in increased n-3 fatty acid intake (Richardso and Puri 2002; Richardson and Montgomery 2005). However, omega-3 is not supported by current evidence as a primary treatment for ADHD or related conditions.
Foetal and infant development
In pregnancy and during lactation demands for LC n-3 PUFA are high due to foetal neuro-developmental requirements. DHA in particular, is important for the development of the brain and retina and there are a number of supplementation studies, both of mothers and infants, investigating the effects of DHA on foetal and infant development. Although no adverse effect of supplementation has been reported in infants, with respect to health benefits, clinical studies have reported conflicting results (Cheatham et al. 2006). No adverse effects have been seen for maternal LC n=3 PUFA supplementation (Helland et al. 2003; Helland et al. 2006).
There have been a number of clinical trials assessing the benefits of dietary supplementation with fish oils in several inflammatory and autoimmune diseases in humans, including rheumatoid arthritis, Crohn's disease, ulcerative colitis, psoriasis, lupus erythematous, multiple sclerosis and migraine headaches. Many of the placebo-controlled trials of fish oil in chronic inflammatory diseases reveal significant benefit, including decreased disease activity and a lowered use of anti-inflammatory drugs (Simopoulos 2002). However, the intake required to achieve these effects is usually outside of the recommended dietary range. For example benefits have been reported at intakes of 3-10g/d (Kremer et al. 1987; Kremer et al. 1995; van der et al. 1990).
Cancer aetiology and treatment
There is much interest in the role omega-3 fatty acids may have in both the development of specific cancer tumor cells and also in the treatment of cancer. Recent evidence shows a positive association in marine omega -3 fatty acids and reduced risk for developing breast cancer (Zheng JS et al 2013), and also that supplementation with marine omega-3 may enhance sensitivity and efficacy of cancer drugs whilst preserving non tumour tissues ( Hajjaji N and Bougnoux P 2013). This is an emerging area of research and no doubt will increase in near future.
There is no evidence to inform paediatric recommendations. Therefore guidelines in this fact sheet are based on extrapolation from adult requirements.
Albert, C.M., Campos, H., Stampfer, M.J., Ridker, P.M., Manson, J.E., Willett, W.C., & Ma, J. 2002. Blood levels of long-chain n-3 fatty acids and the risk of sudden death. New England Journal of Medicine, 346, (15) 1113-1118 available from: PM:11948270
Ascherio, A., Rimm, E.B., Stampfer, M.J., Giovannucci, E.L., & Willett, W.C. 1995. Dietary intake of marine n-3 fatty acids, fish intake, and the risk of coronary disease among men. New England Journal of Medicine, 332, (15) 977-982 available from: PM:7885425
Burr, M.L., Fehily, A.M., Gilbert, J.F., Rogers, S., Holliday, R.M., Sweetnam, P.M., Elwood, P.C., & Deadman, N.M. 1989. Effects of changes in fat, fish, and fibre intakes on death and myocardial reinfarction: diet and reinfarction trial (DART). Lancet, 2, (8666) 757-761 available from: PM:2571009
Cheatham, C.L., Colombo, J., & Carlson, S.E. 2006. N-3 fatty acids and cognitive and visual acuity development: methodologic and conceptual considerations. American Journal of Clinical Nutrition, 83, (6 Suppl) 1458S-1466S available from: PM:16841855
Department of Health 1994. Nutritional aspects of dardiovascular disease. Report of the Cardiovascular Review Group of the Committee on Medical Aspects of Food Policy. HMSO, London.
Dolecek, T.A. 1992. Epidemiological evidence of relationships between dietary polyunsaturated fatty acids and mortality in the multiple risk factor intervention trial. Proceedings of the Society for Experimental Biology and Medicine, 200, (2) 177-182 available from: PM:1579579
Giles GE; Mahoney CR; Kanarek RB. 2013 Omega-3 fatty acids influence in mood in healthy and depressed individuals. Nutrition Reviews (71) 727-741
Hajjaji N; Bougnoux P 2013 Selective sensitization of tumors to chemotherapy by marine-derived lipids: A review. Cancer Treatment Review (39) 473-488
Helland, I.B., Saugstad, O.D., Saarem, K., van Houwelingen, A.C., Nylander, G., & Drevon, C.A. 2006. Supplementation of n-3 fatty acids during pregnancy and lactation reduces maternal plasma lipid levels and provides DHA to the infants. J.Matern.Fetal Neonatal Med., 19, (7) 397-406 available from: PM:16923694
Helland, I.B., Smith, L., Saarem, K., Saugstad, O.D., & Drevon, C.A. 2003. Maternal supplementation with very-long-chain n-3 fatty acids during pregnancy and lactation augments children's IQ at 4 years of age. Pediatrics, 111, (1) e39-e44 available from: PM:12509593
Hooper, L., Thompson, R.L., Harrison, R.A., Summerbell, C.D., Moore, H., Worthington, H.V., Durrington, P.N., Ness, A.R., Capps, N.E., Davey, S.G., Riemersma, R.A., & Ebrahim, S.B. 2004. Omega 3 fatty acids for prevention and treatment of cardiovascular disease.Cochrane.Database.Syst.Rev. (4) CD003177 available from: PM:15495044
Hu, F.B., Bronner, L., Willett, W.C., Stampfer, M.J., Rexrode, K.M., Albert, C.M., Hunter, D., & Manson, J.E. 2002. Fish and omega-3 fatty acid intake and risk of coronary heart disease in women. JAMA, 287, (14) 1815-1821 available from: PM:11939867
Kremer, J.M., Jubiz, W., Michalek, A., Rynes, R.I., Bartholomew, L.E., Bigaouette, J., Timchalk, M., Beeler, D., & Lininger, L. 1987. Fish-oil fatty acid supplementation in active rheumatoid arthritis. A double-blinded, controlled, crossover study. Ann.Intern.Med., 106, (4) 497-503 available from: PM:3030173
Kremer, J.M., Lawrence, D.A., Petrillo, G.F., Litts, L.L., Mullaly, P.M., Rynes, R.I., Stocker, R.P., Parhami, N., Greenstein, N.S., Fuchs, B.R., & . 1995. Effects of high-dose fish oil on rheumatoid arthritis after stopping nonsteroidal antiinflammatory drugs. Clinical and immune correlates. Arthritis and Rheumatism, 38, (8) 1107-1114 available from: PM:7639807
Kromhout D; De Goede J 2014 Update on cardiometabolic health effects of n-3 fatty acids. Current Opinion in Lipidology (25) 85-90
Loef M; Walach H 2013 The Omega-6/Omega-3 Ratio nad Dementia or Cognitive Decline. A Systemic Review on Human Studies and Biological Evidence. J of Nutrition in Gerontology and Geriatrics (32) 1-23
Lorente-Cebrian S; Costa AG; Navas-Carretero S; ZabalaM; Martinez JA; Moreno-Aliaga MJ. 2013 Role of Omega-3 fatty acids in obesity,metabolic syndrome, and cardiovascular diseases: A review of the evidence J Physio and Biochem (69) 633-651
Marchioli, R., Barzi, F., Bomba, E., Chieffo, C., Di Gregorio, D., Di Mascio, R., Franzosi, M.G., Geraci, E., Levantesi, G., Maggioni, A.P., Mantini, L., Marfisi, R.M., Mastrogiuseppe, G., Mininni, N., Nicolosi, G.L., Santini, M., Schweiger, C., Tavazzi, L., Tognoni, G., Tucci, C., & Valagussa, F. 2002. Early protection against sudden death by n-3 polyunsaturated fatty acids after myocardial infarction: time-course analysis of the results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-Prevenzione. Circulation, 105, (16) 1897-1903 available from: PM:11997274
Mozaffarian, D., Lemaitre, R.N., Kuller, L.H., Burke, G.L., Tracy, R.P., & Siscovick, D.S. 2003. Cardiac benefits of fish consumption may depend on the type of fish meal consumed: the Cardiovascular Health Study. Circulation, 107, (10) 1372-1377 available from: PM:12642356
Richardso, A.J. & Puri, B.K. 2002. A randomized double-blind, placebo-controlled study of the effects of supplementation with highly unsaturated fatty acids on ADHD-related symptoms in children with specific learning difficulties. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 26, (2) 233-239 available from: PM:11817499
Richardson, A.J. & Montgomery, P. 2005. The Oxford-Durham study: a randomized, controlled trial of dietary supplementation with fatty acids in children with developmental coordination disorder. Pediatrics, 115, (5) 1360-1366 available from: PM:15867048
Richardson, A.J. & Ross, M.A. 2000. Fatty acid metabolism in neurodevelopmental disorder: a new perspective on associations between attention-deficit/hyperactivity disorder, dyslexia, dyspraxia and the autistic spectrum. Prostaglandins Leukotrienes and Essential Fatty Acids, 63, (1-2) 1-9 available from: PM:10970706
Sanders, T.A., Hall, W.L., Maniou, Z., Lewis, F., Seed, P.T., & Chowienczyk, P.J. 2011. Effect of low doses of long-chain n-3 PUFAs on endothelial function and arterial stiffness: a randomized controlled trial. American Journal of Clinical Nutrition, 94, (4) 973-980 available from: PM:21865334
Scientific Advisory Committee on Nutrition 2004, Advice on Fish Consumption: Benefits and Risk.
Simopoulos, A.P. 2002. Omega-3 fatty acids in inflammation and autoimmune diseases.Journal of the American College of Nutrition, 21, (6) 495-505 available from: PM:12480795
Singhal, A., Lanigan, J., Low, S., Lucas, A., & Deanfield, J. E. The influence of docosaexaenoic acid supplementation on vascular function: a double-blind placebo-controlled randomised trial. Atheroscler.Suppl 12, 13-184. 2011.
Siscovick, D.S., Raghunathan, T.E., King, I., Weinmann, S., Wicklund, K.G., Albright, J., Bovbjerg, V., Arbogast, P., Smith, H., Kushi, L.H., & . 1995. Dietary intake and cell membrane levels of long-chain n-3 polyunsaturated fatty acids and the risk of primary cardiac arrest. JAMA, 274, (17) 1363-1367 available from: PM:7563561
van der, T.H., Tulleken, J.E., Limburg, P.C., Muskiet, F.A., & van Rijswijk, M.H. 1990. Effects of fish oil supplementation in rheumatoid arthritis. Annals of the Rheumatic Diseases, 49, (2) 76-80 available from: PM:2138449
Wang, C., Harris, W.S., Chung, M., Lichtenstein, A.H., Balk, E.M., Kupelnick, B., Jordan, H.S., & Lau, J. 2006. n-3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review. Am J Clin Nutr, 84, (1) 5-17 available from: PM:16825676
Zheng J.S; Hu X J; Zhao Y. M; Yang J; Li D 2013 Intake of fish and marine n-3 polyunsaturated fatty acids and risk of breast cancer: meta analysis of data from 21 independent prospective cohort studies BMJ (34) 1756-1833
Corresponds with the Omega-3 Food Fact Sheet written by Julie Lanigan, Dietitian. Reviewed by Katrina Brown, Dietitian. ©BDA September 2014. Review date September 2017. Version 4