Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease

Abdelhamid, Asmaa S; Brown, Tracey J; Brainard, Julii S; Biswas, Priti; Thorpe, Gabrielle C; Moore, Helen J; Deane, Katherine HO; AlAbdulghafoor, Fai K; Summerbell, Carolyn D; Worthington, Helen V; Song, Fujian; Hooper, Lee

Abstract

Review question We reviewed randomised trials (where participants have an equal chance of being assigned to either treatment) examining effects of increasing fish- and plant-based omega-3 fats on heart and circulatory disease (called cardiovascular diseases, CVD, which include heart attacks and stroke), fatness and blood fats (lipids, including cholesterol, triglycerides, high-density lipoprotein (HDL - ’good’ cholesterol) and low-density lipoprotein (LDL - ’bad’ cholesterol)). Background: Omega-3 fats are essential - to stay healthy we must obtain some from food. The main types of omega-3 fats are alpha-linolenic acid (ALA), a fat found in plant foods, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both found in fish. There is a common belief that eating more fish or taking omega-3 supplements reduces our risk of heart disease, stroke and death. Study characteristics: The evidence is current to April 2017. The review included 79 trials involving over 112,000 people. These studies assessed effects of greater omega-3 intake versus lower or no omega-3 intake for heart and circulatory disease. Twenty-five studies were very trustworthy (well-designed so as not to give biased results). Participants were adults, some with existing illness and some healthy, living in North America, Europe, Australia and Asia. Participants increased omega-3 fats, or maintained their usual fats for at least a year. Most EPA and DHA trials provided capsules, few gave oily fish. Key results Increasing EPA and DHA has little or no effect on all-cause deaths and cardiovascular events (high-quality evidence) and probably makes little or no difference to cardiovascular death, coronary deaths or events, stroke, or heart irregularities (moderate-quality evidence, coronary events are illnesses of the arteries which supply the heart). EPA and DHA slightly reduce serum triglycerides and raise HDL (high-quality evidence). Eating more ALA (for example, by increasing walnuts or enriched margarine) probably makes little or no difference to all-cause or cardiovascular deaths or coronary events but probably slightly reduce cardiovascular events, coronary mortality and heart irregularities (moderate/low-quality evidence). Effects of ALA on stroke are unclear as the evidence was of very low quality. There is evidence that taking omega-3 capsules does not reduce heart disease, stroke or death. There is little evidence of effects of eating fish. Although EPA and DHA reduce triglycerides, supplementary omega-3 fats are probably not useful for preventing or treating heart and circulatory diseases. However, increasing plant-based ALA may be slightly protective for some heart and circulatory diseases.

Citation

Abdelhamid, A. S., Brown, T. J., Brainard, J. S., Biswas, P., Thorpe, G. C., Moore, H. J., Deane, K. H., AlAbdulghafoor, F. K., Summerbell, C. D., Worthington, H. V., Song, F., & Hooper, L. (2018). Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews, 2018(7), Article CD003177. https://doi.org/10.1002/14651858.cd003177.pub3

• Journal Article Type: Article
• Online Publication Date: Jul 18, 2018
• Publication Date: Jul 18, 2018
• Deposit Date: Aug 7, 2018
• Publicly Available Date: Jul 18, 2019
• Journal: The Cochrane library
• Publisher: Cochrane Collaboration
• Peer Reviewed: Peer Reviewed
• Volume: 2018
• Issue: 7
• Article Number: CD003177
• DOI: https://doi.org/10.1002/14651858.cd003177.pub3
• Public URL: https://durham-repository.worktribe.com/output/1318380