What Makes the Heart Beat: Omega-3s

Julia Bird

February 8, 2018

People have been honoring Valentine’s Day for centuries, expressing love by giving a card, flowers or a gift to that special someone who makes their heart beat faster. At the top of the list of popular presents are chocolates: around half of people who celebrate give candy for Valentine’s day [1]. But while chocolates might be sweet, they are not exactly recommended for a healthy heart. Instead, reach for some omega-3s, recommended to maintain a healthy heart by expert scientific organizations and authoritative bodies internationally [2].

The omega-3s are scientifically known as long chain omega-3 polyunsaturated fatty acids (PUFAs). Three omega-3s have a similar structure, and receive the most attention from the nutrition science community:

  • ALA (alpha-linolenic acid) from vegetable oils, nuts and green leafy vegetables
  • EPA (eicosapentaenoic acid) from oily fish and seafood
  • DHA (docosahexaenoic acid), also from oily fish and seafood

The omega-3s are a normal part of the diet. Because the omega-3s are all fatty acids, the foods that they are normally found often have a high fat content. ALA is found in high amounts in foods such as walnuts, flaxseed and spinach. EPA and DHA are normally found together in fatty fish like salmon, tuna, mackerel, and herring, and organ meats also provide modest amounts. The body can actually convert between the three types, although conversion rates from ALA through to EPA and DHA are low [3].

There is some variation in recommendations between the various international organizations responsible for setting dietary guidelines and providing nutrition advice, but two servings per week of preferably fatty fish for general health is a good rule of thumb, to provide 250 to 500 mg of EPA+DHA per day [2]. People at risk of cardiovascular disease are advised to increase their intakes of EPA and DHA above the recommendations for general health.

How do omega-3 fatty acids help the heart?

A well-established way that omega-3s contribute to heart health is by reducing levels of triglycerides, which are a risk factor for cardiovascular disease [3]. For this reason, high doses of omega-3s can be prescribed as medication to reduce triglyceride levels. Omega-3 fatty acids make up part of the walls of the cells that make up the body, including cells in the heart [3]. This improves the ability of specialized messaging proteins to communicate through the cell walls. In the heart in particular, when omega-3s are part of the cell wall, heart cells are less excitable and there is a reduction in large fluctuations in the flow of charged molecules between heart cells, which is thought to contribute to a reduction in irregular heartrates [3].

Omega-3s are also considered to be anti-inflammatory [3]. Both omega-3 and omega-6 PUFAs are used as a basis for messaging molecules that make up part of the immune system, called eicosanoids. Studies in the laboratory show that eicosanoids produced from omega-3s are less inflammatory than those from omega-6 PUFAs [3]. As greater levels of inflammation are associated with cardiovascular disease risk, this suggests that higher intakes of omega-3s could benefit the heart by reducing inflammation [3]. These mechanisms may explain why there is evidence of cardiovascular disease reduction, particularly for reductions in heart failure and stroke, from many population studies conducted over the last 40 years [4].

Getting enough omega-3s for the heart

It sounds easy enough for some people: eat about two servings of fatty fish per week to provide 250 to 500 mg omega-3s daily. However, very few people around the world meet current recommendations. Globally, around two thirds of the population has intakes of DHA less than 200 mg per day, primarily from fish and seafood [5]. High income countries have the highest DHA intakes [5], although national surveys show that even in these countries, intakes are less than ideal. For example, in the U.S., median intake of EPA+DHA omega-3s is only 86 mg per day, and 90% of the population has intakes less than 162 mg per day [6]. This is due to low intakes of fatty fish. Other international studies find that omega-3 intakes are low in many other countries [7]. Although dietary supplements containing omega-3s can help to meet nutrient needs when fish intake is not adequate, they are not used often enough to make up the gap [6].

The challenge is clear: healthy hearts need omega-3s, yet few people meet recommendations. There are several strategies that could be used to help people meet their omega-3 intake needs [8]. However, why not start on the one day of the year that we think most of our heart? This Valentine’s Day, say it with fish, not flowers!

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References

  1. National Retail Federation. NRF says consumers will spend $18.2 billion on Valentine's day; 2017; https://nrf.com/media/press-releases/nrf-says-consumers-will-spend-182-billion-valentines-day.
  2. Global Organization for EPA and DHA Omega-3s (GOED). Global Recommendations for EPA and DHA Intake (Rev 3 April 2017); 2017; https://drive.google.com/file/d/0B9qT6KspMkCJdEpUNlp4V2VOTG8/view.
  3. Mozaffarian, D.; Wu, J.H. Omega-3 fatty acids and cardiovascular disease: effects on risk factors, molecular pathways, and clinical events. J Am Coll Cardiol 2011, 58, 2047-2067. 10.1016/j.jacc.2011.06.063.
  4. Mori, T.A. Marine OMEGA-3 fatty acids in the prevention of cardiovascular disease. Fitoterapia 2017, 123, 51-58. 10.1016/j.fitote.2017.09.015.
  5. Forsyth, S.; Gautier, S.; Salem, N., Jr. Global Estimates of Dietary Intake of Docosahexaenoic Acid and Arachidonic Acid in Developing and Developed Countries. Ann Nutr Metab 2016, 68, 258-267. 10.1159/000446855.
  6. Papanikolaou, Y.; Brooks, J.; Reider, C.; Fulgoni, V.L., 3rd. U.S. adults are not meeting recommended levels for fish and omega-3 fatty acid intake: results of an analysis using observational data from NHANES 2003-2008. Nutr J 2014, 13, 31. 10.1186/1475-2891-13-31.
  7. Mozaffarian, D.; Dashti, H.S.; Wojczynski, M.K.; Chu, A.Y.; Nettleton, J.A.; Mannisto, S.; Kristiansson, K.; Reedik, M.; Lahti, J.; Houston, D.K., et al. Genome-wide association meta-analysis of fish and EPA+DHA consumption in 17 US and European cohorts. PLoS One 2017, 12, e0186456. 10.1371/journal.pone.0186456.
  8. Raatz, S.K.; Silverstein, J.T.; Jahns, L.; Picklo, M.J. Issues of fish consumption for cardiovascular disease risk reduction. Nutrients 2013, 5, 1081-1097. 10.3390/nu5041081.