The Research Associations of Habitual Fish Oil Supplements with Cardiovascular Outcomes and All-round Mortality: Evidence from a large population-based cohort study examined whether regular use of fish oil supplements would lower the risk of cardiovascular problems such as heart attack and stroke.
Omega-3 fatty acids in fish oil are known to be useful in protecting people from cardiovascular disease by improving blood pressure, lowering inflammation, and helping heart blood flow.
Despite the widespread presence and awareness of the use of fish oil supplements, “significant gaps in knowledge” remain regarding the link between omega-3 fatty acids and the prevention of CVD incidents, the researchers said.
There is conflicting research. Data from laboratory studies, epidemiological studies, and randomized controlled trials suggest that omega-3 fatty acids play a role in the prevention of CVD. However, studies and meta-analyzes have shown that supplementing omega-3 fatty acids has no positive effect on CVD prevention.
With the relationship remaining uncertain, researchers at the UK Biobank believed that a large-scale cohort study could provide important information on the relationship between fish oil supplements and clinical outcomes.
The research team used population cohort data from a total of 427,678 male and female participants aged between 40 and 69 from 22 assessment centers in England, Scotland and Wales.
None of the participants had CVD or cancer at baseline. Participants took part in the survey between 2006 and 2010 and were then followed up through the end of 2018.
The study, published in the British Medical Journal, asked all participants to answer questions about their habitual uses of dietary supplements, including fish oil.
The participants completed a questionnaire and completed a personal interview. They also provided biological samples and a selection of physical measurements.
Compared to non-users of fish oil supplements, the study found that fish oil users were older and more likely to be female, not currently smoking, and physically active.
In addition, participants in fish oil supplements reported eating oily fish more often and had a higher incidence of high blood pressure and long-term illnesses, but a decreased prevalence of diabetes. Fish oil supplements were also more likely than non-users to take antihypertensive drugs, aspirin, vitamin supplements, and mineral and other dietary supplements.
The study suggests that habitual fish oil supplementation was linked to significantly lower all-cause mortality, as well as the incidence and mortality of CVD and myocardial infarction.
Specifically, the scientists found that fish oil supplements were found to have a 13% reduced risk of total death, a 16% lower risk of dying from cardiovascular disease, and a 7% lower risk of cardiovascular disease events such as heart attack or stroke.
As part of the observational study, the scientists found that the protective association of fish oil intake against CVD events was stronger in people with predominant hypertension. In addition, the study suggests that the association for CVD mortality appears to be stronger than for the incidence of CVD, suggesting that fish oils may have a greater impact in people with established CVD events.
There is currently no evidence as to which component of omega-3 fatty acids (docosahexaenoic acid, eicosapentaenoic acid, or docosahexaenoic acid and eicosapentaenoic acid) might be helpful in CVD outcomes or all-cause mortality.
Highlights from other research
The researchers commented on the benefits of the fish oil supplement, highlighting five key findings from previous studies:
1. Several previous studies have shown that omega-3 fatty acid supplementation has beneficial effects on blood pressure, plasma triglycerides, and heart rate. Indication of a protective effect against the development of CVD.
2. A number of studies have shown that omega-3 fatty acids can improve flow-mediated arterial dilation, which is a measure of endothelial function and health.
3. Omega-3 fatty acids have been found to have antiarrhythmic properties that could be clinically beneficial.
4. Studies have shown that fish oil can reduce thrombosis.
5. Studies have shown that the anti-inflammatory properties of fish oil may play a preventive role in the pathophysiology of CVD outcomes.
The research team noted that future studies are needed to assess the extent to which fish oil supplements affect the ability to produce a “clinically meaningful effect”.
2020; 368: m456 doi: https://doi.org/10.1136/bmj.m456
“Associations of Habitual Fish Oil Supplementation with Cardiovascular Outcomes and All Causes Mortality: Evidence from a Large Population-Based Cohort Study”
Authors: Z. Li et al.