21 September 2007
Almost all long-term epidemiological (population) studies averaging approximately 12 years in duration overall have indicated that consuming fish as source of DHA plus EPA appears to be protective against cardiac-related mortality. In general, most fish contain moderately higher levels of DHA relative to EPA. The so-called randomized control trials which have supported beneficial effects of fish oil-derived omega-3 fatty acids for reducing mortality from cardiovascular disease (including sudden cardiac death) have used supplemental sources which contain a mixture of DHA plus EPA (sometimes with higher levels of EPA as compared to DHA).
Since no long-term studies have ever been reported on omega-3 fatty acid intakes (intervention trials) where there has been a direct comparison of DHA alone versus EPA alone versus a mixture of DHA/EPA on cardiac mortality reduction, it would therefore appear reasonable to employ a daily source of DHA plus EPA (a mixture of the two so as to be consistent with the vast majority of the published literature wherein mixtures of these two fatty acids have been consumed).
The 1999 Workshop held in Bethesda (convened by ISSFAL) based on the input from the numerous international experts gathered there advised an intake for healthy adults of 650 mg of DHA/EPA (combined) per day such that at least 1/3 of the mixture would be represented by either DHA (at least 220 mg/day) and EPA (at least 220 mg/day). The American Heart Association has recommended an intake from fish or supplementation of 900 mg of DHA/EPA (combined) per day but make no specific indication that a certain portion of the mixture should be consumed as DHA or EPA. It may be reasonable, in keeping with the 1999 Workshop, to suggest that a mixture of both DHA plus EPA rather than only DHA or EPA is desirable based on current knowledge.