By: Dr. Wei-guo Zhang, Director of Nutrition Science & Advocacy at DSM China
Elevated heart rate is a significant risk factor for cardiovascular disease. There is emerging evidence to suggest that the omega-3s, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have a heart rate-slowing effect on individuals, particularly those with a risk of sudden cardiac death (SCD), like coronary artery disease patients. A new meta-analysis was conducted by DSM and Soochow University in China to investigate the efficacy of EPA and DHA on heart rate reduction, when taken both together and alone.2
The omega-3s, EPA and DHA, are well documented in several studies for their potential heart health benefits, such as lowering blood pressure, plasma triglycerides and inflammation. However, their role in slowing elevated heart rate, and particularly SCD prevention, is still an emerging area. For instance, a prospective study of male physicians without a history of pre-existing cardiovascular disease (CVD) found that those who consumed fish at least once a week had a lower risk of SCD.
Although the exact mechanisms behind the preventative effects of EPA and DHA on SCD remain unclear, it is suggested that it is because of their ability to reduce heart rate. Elevated heart rate is a potential risk factor for cardiovascular morbidity and mortality, and particularly SCD. Therefore, any agent that has heart rate-reducing properties, with no side effects, could be pivotal in preventing SCD in the future.
Given the evidence behind the protective effects of EPA and DHA on the body against SCD, a new meta-analysis was conducted by DSM and SooChow University in China to assess their efficacy in lowering elevated heart rates, either taken alone or together.
Most of the randomized controlled trials (RCTs) to date have indicated heart rate reduction with EPA and DHA supplementation when taken together. This study is the most recent meta-analysis conducted since 2005. Altogether, 51 RCTs were eligible for the meta-analysis, with approximately 3,000 participants between 1988 and 2016 – an increase from the previous meta-analysis, with 30 RCTs and 1,678 subjects. Although several studies have separately investigated the effects of EPA and DHA, the difference between the two in heart rate reduction has never been examined before.
The results were noteworthy; compared to the placebo, omega-3 supplementation resulted in a mild, yet significant, reduction in heart rate. While a modest heart rate reduction was noted in trials supplemented with DHA, no statistically significant effect was observed with EPA supplementation. Overall, omega-3 supplementation reduced heart rate by 2.23 beats per minute (bpm), while DHA reduced heart rate by 2.47 bpm.
The findings from the meta-analysis could have significant public health implications, with it estimated that a heart rate reduction of 3.2 bpm corresponds to a 7.5% lower risk of SCD.3 However, as all existing meta-analyses have shown a greater reduction trend in those with a higher baseline heart rate, future clinical trials comparing the effect of omega-3 supplementation on different levels of baseline heart rate would be beneficial, particularly in those with tachycardia (a resting heart rate of more than 100 bpm) or high-normal.
Implementing omega-3 supplementation into public health strategies as part of a lifestyle modification could help to reduce all-cause mortality among general populations, as well as lower the risk of SCD, especially in those who do not have a diet high in omega-3 fatty acids. However, according to recent research, adults in most regions of the world have a low to very low status of omega-3s, particularly EPA and DHA.4 The problem is further highlighted by a new study that found that, within a group of US family physicians, most were unaware of their own omega-3 status, and only 5% had the recommended omega-3 levels in their blood.5
1. K. Hidayat et al., ‘Effect of omega-3 long-chain polyunsaturated fatty acid supplementation on heart rate: a meta-analysis of randomized controlled trials’, European Journal of Clinical Nutrition, 2017. https://doi.org/10.1038/s41430-017-0052-3
3. D. Mozaffarian et al., ‘Dietary ﬁsh and n-3 fatty acid intake and cardiac electrocardiographic parameters in humans’ J Am Coll Cardiol., vol. 47, no. 3, 2006, p. 478-84.
4. K. Stark et al., ‘Global survey of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid in the blood stream of healthy adults’, Progress in Lipid Research, vol. 63, 2016, p.132-152.
5. N.V. Matusheski et al., ‘US family physicians overestimate personal omega-3 fatty acid biomarker status: Associations with fatty fish and omega-3 supplement intake,’ Current Developments in Nutrition, 2017, vol. 1, issue 12.