The Nutrition Examination Research Digest (NERD) aims to provide rigorous, unbiased analysis of the latest and most important nutrition and supplementation studies. Click here to subscribe or login if already a subscriber .
Study under review: Associations of Omega-3 Fatty Acid Supplement Use With Cardiovascular Disease Risks: Meta-analysis of 10 Trials Involving 77 917 Individuals.
Introduction
In 2015[1], 17.9 million deaths were caused by cardiovascular diseases (CVDs), which include coronary heart disease, angina, heart attacks, strokes, and heart failure. The most common age group to suffer from CVD are older adults[2] over the age of 60.
The strongest risk factors for CVD include high blood pressure, high cholesterol, smoking, diabetes, lack of physical activity, obesity, and poor nutrition. Thus, many events that result from CVD are largely preventable[3] through lifestyle. When it comes to nutrition, government agencies and organizations have promoted the consumption of unrefined plants and discouraged excessive consumption of foods and drinks high in fats, sugars, salt, and alcohol.
Fish and fish oil consumption, in particular, has a long history linking it to CVD prevention, which is summarized in Figure 1. The story started, in part, due to observational evidence[4] suggesting that fish consumption was associated with a reduced risk of cardiovascular disease, which led to randomized trials investigating the effects of fish oil on CVD outcomes.
| 1970s | Researchers saw that a group of people[4] who ate fish had a lower incidence of CVD. |
| 1980s–1990s | Early studies[5][6] found associations between fish consumption and heart disease risk. |
| 1990s | Randomized trials[7][8] were conducted to see the effects of fish oil on CVD outcomes. |
| 2002 | The American Heart Association puts out a statement[9] explaining that fish oil supplementation was protective with regards to fatal outcomes. |
| 2002–2016 | More randomized trials[10][11] and systematic reviews produced inconsistent results. |
| 2016 | The American Heart Association forms a scientific advisory group[12] to synthesize and analyze all the available evidence and concludes that there was a small benefit from fish oil for people who had a history of CVD events. |
| 2018 | Large meta-analysis[13] published in JAMA with 77,000 + participants found no benefit from fish oil supplementation on real clinical endpoints. |
In 2002, the American Heart Association (AHA) put out a statement[14] discussing the available randomized controlled trials (RCTs) at the time and concluded that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplements significantly reduced fatal cardiac events.
Several RCTs[11] conducted after this statement found conflicting evidence of fish oil supplementation improving fatal or even nonfatal CVD outcomes. In 2016[12], the AHA formed an advisory group to perform another review of all the RCTs available at the time and concluded that despite there being controversial evidence, the AHA believed that fish oil supplementation was beneficial for people who recently experienced a cardiac event.
However, this review performed by the AHA was not a quantitative analysis of all the published data. The meta-analysis under review decided to look at the largest controlled trials published to objectively review the relationship between fish oil supplementation and CVD outcomes and to end the confusion around fish oil.
CVD is the leading cause of death worldwide and is sometimes preventable through lifestyle changes. Several researchers and organizations have been interested in the effects of fish oil on CVD outcomes but have found conflicting evidence. The meta-analysis under review re-evaluated some of the largest trials on the topic, and assessed the relationship between fish oil supplementation and CVD outcomes.
Who and what was studied
What were the findings?
What does the study really tell us?
The Big Picture
Frequently asked questions
What should I know?
Other Articles in Issue #42 (April 2018)
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Interview: Danny Lennon, MSc
We chat with the founder of Sigma Nutrition and combat sports nutritionist Danny Lennon about his background, the unique nutritional challenges faced by combat sports athletes, and two things he thinks everyone can do to improve their lives.
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Alpha-lipoic acid for carpal tunnel syndrome
Previous human studies examining ALA have either given it along with other supplements or only administered it post-surgery. This trial looks at ALA's effects on its own, both before and after surgery.
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Throwdown, round 3: plant vs. animal protein for bone health
We've previously covered plant vs. animal protein's effects on the metabolic syndrome and diabetes, and both rounds have ended in a draw for main outcomes. Will either come out on top this round?
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Protein gains: not just for the men
Women are underrepresented in many areas of research. This study focuses specifically on female physique athletes to see how high vs. low protein intake affects fat-free mass.
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From French Paradox to plaque regression
Observational data suggests that moderate wine consumption could be heart healthy. This follow-up to a study we covered in a previous NERD puts this hypothesis to the test.
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Can whole grains improve insulin resistance in obese adults?
What impact does replacing refined grains with whole grains in a macronutrient-matched diet have on weight loss and glucose regulation? This study aims to find out.
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Interview: Michael Crosier, PhD
In this interview, we chat with Dr. Crosier about the ins and outs of learning and teaching nutrition and dietetics, his research on vitamin K, and more.
