Elsevier

Atherosclerosis

Volume 189, Issue 1, November 2006, Pages 19-30
Atherosclerosis

Review
Effects of omega-3 fatty acids on serum markers of cardiovascular disease risk: A systematic review

https://doi.org/10.1016/j.atherosclerosis.2006.02.012Get rights and content

Abstract

Greater fish oil consumption has been associated with reduced CVD risk, although the mechanisms are unclear. Plant-source oil omega-3 fatty acids (ALA) have also been studied regarding their cardiovascular effect. We conducted a systematic review of randomized controlled trials that evaluated the effect of consumption of fish oil and ALA on commonly measured serum CVD risk factors, performing meta-analyses when appropriate. Combining 21 trials evaluating lipid outcomes, fish oil consumption resulted in a summary net change in triglycerides of −27 (95% CI −33, −20) mg/dL, in HDL cholesterol of +1.6 (95% CI +0.8, +2.3) mg/dL, and in LDL cholesterol of +6 (95% CI +3, +8) mg/dL. There was no effect of fish oil on total cholesterol. Across studies, higher fish oil dose and higher baseline levels were associated with greater reductions in serum triglycerides. Overall, the 27 fish oil trials evaluating Hgb A1c or FBS found small non-significant net increases compared to control oils. Five studies of ALA were inconsistent in their effects on lipids, Hgb A1c or FBS. Four studies investigating the effects of omega-3 fatty acids on hs-CRP were also inconsistent and non-significant. The evidence supports a dose-dependent beneficial effect of fish oil on serum triglycerides, particularly among people with more elevated levels. Fish oil consumption also modestly improves HDL cholesterol, increases LDL cholesterol levels, but does not appear to adversely affect glucose homeostasis. The evidence regarding the effects of omega-3 fatty acids on hs-CRP is inconclusive, as are data on ALA.

Section snippets

Background

The relationship between dietary omega-3 fatty acids and risk of developing CVD began to emerge in the late 1970s [1], [2], [3]. Thereafter, a limited number of intervention trials reported lower rates of CVD mortality and sudden death, but not stroke, after supplementation with the long-chain omega-3 fatty acids EPA or DHA; however, the data on the shorter-chain omega-3 fatty acid ALA are far less certain [4]. Potential mechanisms for the cardioprotective effect of omega-3 fatty acids include

Literature search and eligibility criteria

Details of the systematic review and statistical methods have been reported [11]. Briefly, we conducted a systematic review of the English-language literature on omega-3 fatty acids and cardiovascular disease in Medline, Embase, Cochrane Central Register of Controlled Trials, Biological Abstracts, and Commonwealth Agricultural Bureau databases through April 2003. Search terms included the specific omega-3 fatty acids, fish and other marine oils, and omega-3 fatty acid-rich plant oils. We also

Results

The literature search for all studies of omega-3 fatty acids and cardiovascular disease related conditions yielded 7464 citations. We retrieved and reviewed 807 articles to analyze cardiovascular events, risk factors or intermediate markers. Of these we analyzed 123 articles that reported about 23 different cardiovascular disease risk factors and intermediate markers. Here, we discuss the 52 randomized controlled trials that reported data on the effect of omega-3 fatty acid consumption on the

Discussion

Although the relationship between dietary fish and fish oil and CVD risk has been known for some time, the relationship between omega-3 fatty acids and surrogate circulating markers of CVD risk has been less clear. This area is of interest in light of our previous observations that in randomized studies, compared to placebo, the summary risk ratio of coronary artery restenosis was in favor of fish oil is (0.87 [95% CI 0.73, 1.05]) [11]. However, the data from prospective and cross-sectional

Acknowledgements

This evidence report was prepared by the Tufts-New England Medical Center Evidence-based Practice Center under contract to the Agency for Healthcare Research and Quality (contract no. 290-02-0023), Rockville, MD. Funding was provided by the Office of Dietary Supplements, National Institutes of Health.

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