University of Cambridge scientists found food and supplement intake of these fish oils corresponded to a 26% lower risk of coronary heart disease (CHD) mortality compared with non-supplement use.
“The associations observed at the low dose of supplemental Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in this cohort makes an antiarrhythmic function of Omega-3 polyunsaturated fatty acids (PUFA), a likely biological pathway,” the study stated.
“Recent use of Omega-3 PUFA supplements was associated with a lower hazard of CHD mortality in a population-based cohort with low fish consumption.
Although there is a wealth of evidence linking Omega-3 PUFA intake and CHD, the evidence for a protective association between supplement intake and CHD remains inconclusive.
Consumption of Omega-3 PUFA supplements is traditionally high in Northern European countries.
In Europe, the highest oily fish consumption is observed in Spain and Scandinavian countries, where a lower number of CHD hospitalisations is also noted.
Fish consumption in these countries is approximately 2–3 fold higher than fish intake in the UK.
The prospective cohort study, spanning over 22 years, enrolled 22 035 men and women from the general population, aged between 39–79 years.
Three questionnaires were first used to assess supplement use over this period. Next, participants were grouped into non-supplement users (NSU), Omega-3 PUFA supplement users (SU+n3) and non–Omega-3 PUFA supplement users (SU-n3).
Statistical analysis also took into account variables such as age, smoking, prevalent illnesses, body mass index, social class, education and dietary intake (7-day diet diary).
The team found that while supplement use at the beginning of the study was not associated with CHD mortality, baseline food and supplement intake of Omega-3 PUFA was inversely associated with CHD mortality after adjustment for fish consumption.
Further analysis found significant associations observed in the SU+n3 group but not for SU-n3 when compared to NSU.
Those who became SU+n3 over time or were consistent SU+n3 had a lower hazard of CHD mortality, compared to consistent NSU.
No association with CHD was observed in those who stopped using Omega-3 PUFA-containing supplements.
“We observed a protective association between Omega-3 PUFA supplement use and CHD mortality in this general population where fish consumption was low and the mean age was approximately 60 years at baseline,” the team said, led by Dr Marleen Lentjes, Department of Public Health and Primary Care art the University of Cambridge.
“When data from three dietary supplement assessments (DSA) were used, lower hazards of CHD mortality were observed for SU+n3 at all three DSA, which were strongest when the follow-up time was short; however, this analysis lacked statistical power.
“We also observed a 26% lower hazard of CHD mortality among SU+n3 compared with NSU.”
The study referred to a similar piece of Icelandic research conducted last year, where the majority of women consumed 2–4 fish portion per week (85% lean fish).
Here, researchers observed a lower risk of hospitalisation due to CHD when Omega-3 PUFA from cod liver oil (CLO) was below 5.9 g/week, whereas no association was observed with fish consumption.
”We did not observe any association with CHD hospitalisation; however, the Omega-3 PUFA dose in the Icelandic AGES study was much higher and therefore efficacy might have been through atherosclerotic pathways.”
The team added that fish oil supplements cannot contain all the nutrients that would be obtained when consuming fish, or indeed the other meal components consumed with it (eg, vegetables) or the red meat replacement that took place.
“However, Omega-3 PUFA supplements contain lower concentrations of contamination and provide essential fatty acids without any coating and/or frying oils which might supply trans-fatty acids which are positively associated with CHD.”
Commenting on the study’s findings Dr Harry Rice, VP of regulatory and scientific affairs for the Global Organisation for EPA and DHA Omega-3s (GOED) said, “Omega-3 PUFA supplement use’s association with a statistically significant lower hazard (somewhat akin to risk) of CHD mortality is particularly interesting, given the current efforts at the Codex level to establish a nutrient reference value non-communicable disease (NRV-NCD) for EPA+DHA.”
“Many country delegations are pushing back on the adoption of an NRV because they believe the supporting evidence is specific to fish consumption and there is an absence of data for supplement use. Results from this study stand in stark contrast to those erroneously held beliefs.
“The reality is that results from this study corroborate a wealth of data, RCT and observational alike, demonstrating a reduced risk of CHD mortality with EPA/DHA supplementation and thus supporting the adoption of an NRV for EPA+DHA.”
Source: BMJ Open
Published online ahead of print: doi.org/10.1136/bmjopen-2017-017471
“Longitudinal associations between marine omega-3 supplement users and coronary heart disease in a UK population-based cohort.”
Authors: Marleen Hentjes, Ruth H Keogh, Ailsa Welch, Angela Mulligan, Robert N Luben, Nicholas Wareham, Kay-Tee Khaw