Setting the Record Straight – 5 Misconceptions about Omega-3s and Heart Health

Lucy Jones, RD

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Published on

14 March 2017

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The link between omega-3 fatty acids and heart health is now pretty well known and widely accepted within the medical and health community with European approved claims for EPA and DHA omega-3s reducing blood pressure1, reducing triglycerides (a type of blood fat)1, and for overall heart function2. But that doesn’t mean we have all the facts straight. In fact, many of my clients and indeed the wider community still get some the facts wrong.

There are five misconceptions that I regularly come across in my practice.

No. 1:  They don’t make a big difference / The evidence doesn’t really support them.

Confusing headlines can mean that people underestimate the importance of omega-3s for their heart health. While not all studies have managed to find a benefit of omega-3 supplements on cardiovascular disease3, the overall findings from both observational studies and clinical trials indicate that consumption of fish or fish oil significantly reduces heart disease deaths including heart attacks4, 5, 6. Replacing saturated fat with unsaturated fats from oily fish, plant oils, nuts and seeds may lower LDL cholesterol and decrease cardiovascular disease risk4.

No. 2:  Canned tuna counts.

Lots of people count their canned tuna as their weekly oily fish portion without realizing that the beneficial oils are removed during the canning process. This is unique to tuna as canned sardines, mackerel and salmon all keep their omega-3 content when canned, making them easy and affordable ways to increase intakes.

No. 3:  Nuts and flax seed are rich sources.

It is widely misunderstood that plant based omega-3 oils from nuts, seeds, plant oils and dark green leafy vegetables can provide all the long chain omega-3 fatty acids (EPA and DHA) you need. In fact, plant sources only provide a type of omega-3 called ALA, which has to be converted by your body into EPA and DHA. Unfortunately, our body isn’t very good at it; studies have shown that young men can only convert 0-4 percent of dietary ALA into DHA7 and young women can convert up to 9 percent8, meaning relying on plant sources can place you at risk of low levels.

No. 4:  A portion a week is enough for everyone.

While a portion of oily fish a week is the recommendation for most adults (200-250mg/day)9, some people should consider topping this up further.

  • The European Food and Safety Authority (EFSA) recommends that pregnant and lactating women consume an additional 100-200 mg of omega-3 DHA on top of the 250 mg/day EPA plus DHA recommended for healthy adults9.
  • When it comes to heart health, The International Society for the Study of Fatty Acids and Lipids (ISSFAL) recommends a minimum of 500 mg/day of EPA plus DHA for cardiovascular health10.
  • The American Heart Association recommends that people without heart disease eat a variety of fish (preferably oily) at least twice weekly; providing approximately 500 mg of EPA plus DHA11. Those with heart disease are advised to consume approximately 1 g/day of EPA plus DHA preferably from oily fish, or to consider EPA and DHA supplements in consultation with a physician. Patients who need to lower serum triglycerides may take 2-4 g/day of EPA plus DHA supplements under a physician's care12; echoed by the World Health Organisation13.

No. 5:  The harm of pollutants outweighs the benefit.

While some types of fish may contain high levels of mercury, PCBs (polychlorinated biphenyls), dioxins and other environmental contaminants, the benefits of fish consumption far outweigh the potential risks as long as recommendations about quantity are followed; especially for middle-aged and older adults12. The UK SACN committee has reviewed the evidence and found that even eating four portions of oily fish per week does not exceed the guideline level for contaminants for a 60kg adult14. Levels of these substances are generally highest in older, larger, predatory fish and marine mammals14. Pregnant women and children should avoid fish that typically have higher levels of methylmercury such as shark, swordfish, marlin and white albacore tuna. Fish containing higher concentrations of dioxins, such as herring, should be consumed less frequently than fish with lower amounts, such as trout, salmon, tilapia and shrimp. You can minimize any potentially adverse effects due to environmental pollutants by eating a variety of fish12 or taking a vegetarian algal-based supplement, like the life’sDHA brand.

References

1. EFSA Panel on Dietetic Products, Nutrition and Allergies (2009) Scientific Opinion on the substantiation of health claims related to EPA, DHA, DPA and maintenance of normal blood pressure (ID 502), maintenance of normal HDL-cholesterol concentrations (ID 515), maintenance of normal (fasting) blood concentrations of triglycerides (ID 517), maintenance of normal LDL-cholesterol concentrations (ID 528, 698) and maintenance of joints (ID 503, 505, 507, 511, 518, 524, 526, 535, 537) pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Journal vol 7(9):1263 [26 pp.].

2. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) (2010)  Scientific Opinion on the substantiation of health claims related to eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA) and maintenance of normal cardiac function (ID 504, 506, 516, 527, 538, 703, 1128, 1317, 1324, 1325), maintenance of normal blood glucose concentrations (ID 566), maintenance of normal blood pressure (ID 506, 516, 703, 1317, 1324), maintenance of normal blood HDL-cholesterol concentrations (ID 506), maintenance of normal (fasting) blood concentrations of triglycerides (ID 506, 527, 538, 1317, 1324, 1325), maintenance of normal blood LDL-cholesterol concentrations (ID 527, 538, 1317, 1325, 4689), protection of the skin from photo-oxidative (UV-induced) damage (ID 530), improved absorption of EPA and DHA (ID 522, 523), contribution to the normal function of the immune system by decreasing the levels of eicosanoids, arachidonic acid-derived mediators and pro-inflammatory cytokines (ID 520, 2914), and “immunomodulating agent” (4690) pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Journal vol 8(10):1796. [32 pp.].

3.  Rizos EC, Ntzani EE, Bika E, Kostapanos MS, Elisaf MS. Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: a systematic review and meta-analysis. JAMA. 2012;308(10):1024-1033. 

4. Mozaffarian D, Wu JH. Omega-3 fatty acids and cardiovascular disease: effects on risk factors, molecular pathways, and clinical events. J Am Coll Cardiol. 2011;58(20):2047-2067. 

5.  Kromhout D. Omega-3 fatty acids and coronary heart disease. The final verdict? Curr Opin Lipidol. 2012;23(6):554-559.

6. Mente A, de Koning L, Shannon HS, Anand SS. A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch Intern Med. 2009;169(7):659-669. 

7. Burdge GC, Jones AE, Wootton SA. Eicosapentaenoic and docosapentaenoic acids are the principal products of α-linolenic acid metabolism in young men*. Br J Nutr. 2002;88(4):355-364. 

8. Burdge GC, Wootton SA. Conversion of α-linolenic acid to eicosapentaenoic, docosapentaenoic and docosahexaenoic acids in young women. Br J Nutr. 2002;88(4):411-420.

9. European Food Safety Authority Panel on Dietetic Products, Nutrition, and Allergies (NDA) Scientific Opinion on Dietary Reference Values for fats, including saturated fatty acids, polyunsaturated fatty acids, monounsaturated fatty acids, trans fatty acids, and cholesterol. EFSA J. 2010;8(3):107. Available at: http://www.efsa.europa.eu

10. International Society for the Study of Fatty Acids and Lipids. Recommendations for Intake of Polyunsaturated Fatty Acids in Healthy Adults. Available at: http://www.issfal.org/statements/pufa-recommendations. Accessed 8/2/17.

11. American Heart Association. The American Heart Association's Diet and Lifestyle Recommendations. http://www.heart.org/HEARTORG/HealthyLiving/HealthyEating/Nutrition/The-American-Heart-Associations-Diet-and-Lifestyle-Recommendations_UCM_305855_Article.jsp#.WJsLS_mLTIU . Accessed 8/2/17.

12. American Heart Association. Fish and omega 3 fatty acids. http://www.heart.org/HEARTORG/HealthyLiving/HealthyEating/Nutrition/Fish-and-Omega-3-Fatty-Acids_UCM_303248_Article.jsp#.WJsLr_mLTIU Accessed 8/2/17

13. FAO/WHO. Interim Summary of Conclusions and Dietary Recommendations on Total Fat & Fatty Acids. Joint FAO/WHO Expert Consultation on Fats and Fatty Acids in Human Nutrition. Geneva: WHO; 2008:1-14.

14. SACN (2004) Advice on fish consumption: Benefits and risks. Accessed from https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/338801/SACN_Advice_on_Fish_Consumption.pdf Accessed 8/2/17

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