Study under review: Omega-3 polyunsaturated fatty acids supplementation and cardiovascular outcomes: do formulation, dosage, and baseline cardiovascular risk matter? An updated meta-analysis of randomized controlled trials
Cardiovascular disease (CVD) is the leading cause of mortality in the U.S., causing more than 850,000 deaths per year, according to the American Heart Association. Investigations have shown an inverse association between intake of omega-3 long-chain polyunsaturated fatty acids (n-3 PUFA) and CVD. There is evidence that intake of n-3 PUFA, particularly EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), may be involved in many physiological and biochemical processes that act to decrease the risk of cardiovascular-related diseases. Mechanistic studies have shown that n-3 PUFA may inhibit inflammatory signaling pathways, downregulate fatty acid synthesis gene expression, and upregulate gene expression involved in fatty acid oxidation, which could help explain their putative cardioprotective effects. These mechanisms may modulate cell membrane function and positively affect lipoprotein metabolism and pathways involved in atherosclerosis.
While the mechanistic and observational studies evaluating this relationship have produced promising results, randomized controlled trials have yielded conflicting results. Some trials have shown a benefit, while other trials have not. However, the scales have recently been tipped pretty strongly in favor of efficacy thanks to the REDUCE-IT study published in January 2019, which showed a 25% decrease in cardiovascular events and a 20% reduction of risk from cardiovascular death in a high cardiovascular disease risk population with elevated triglyceride levels upon administration of statins and four daily grams of icosapent ethyl (a highly purified and stable EPA ethyl ester). Since this trial differed from some of the others in a few key ways, it’s possible that the inconsistency between previous studies could be due to differences in disease risk, dose, and n-3 type.
Given the inconsistent results of the randomized controlled trials and the relatively recent publication of the REDUCE-IT trial, the authors of the study under review decided to meta-analyze the literature. Their goal was to examine the state of the evidence and determine which aspects of study design may be responsible for the inconsistency. They did this by focusing on the role of dose and type of n-3 PUFA administered and the effect of n-3 PUFA on populations with different baseline CV risk.
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Other Articles in Issue #72 (October 2020)
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NERD Mini: Predicting the route of the regain train
Here, we give the lowdown on a secondary analysis of a clinical trial exploring what factors can predict regaining weight.
Recovering from osteoarthritis surgery: a joint effort between amino acid supplementation and exercise
Adding amino acid supplementation to mixed-mode exercise may improve pain and preserve muscle compared to exercise alone. More data would be useful, though.