Since 1990 in Canada and 2002 in the United States, a specific recommendation for minimal intakes of omega-3 fatty acid as alpha-linolenic acid (LNA) from plant food sources (eg., canola oil, flaxseed, English walnuts, others) has existed with a recommended intake of 0.6% of total daily energy as LNA. This translates into approximately 1500 mg per day for an adults consuming 2300 kcal daily. In 2002, the Food and Nutrition Board (Institute of Medicine) in the U.S. advised that up to 10% of the total omega-3 as LNA may be consumed as DHA/EPA. In the aforementioned case, this would amount to a suggested intake of DHA/EPA of approximately 150 mg/day (as an optional but not mandatory intake). In contrast, other countries have specific minimal recommended intakes for DHA/EPA omega-3 fatty acids in addition to recommended intakes of LNA omega-3. For example, Australia and New Zealand have recommended (as acceptable intakes) 160 and 90 mg/day of DHA/EPA (combined) for adult men and women, respectively, with suggested dietary targets (FDT) values for men and women of 610 and 430 mg/day, respectively for reducing chronic disease risk. In your message, you also asked if DHA and EPA always come as a pair. With respect to fish/seafood, these always contain both DHA+EPA in varying amounts and ratios depending upon the source. A commercially-available algal oil contains DHA but lacks in EPA. Much of the human evidence suggests that LNA mediates its beneficial effects via conversion to DHA/EPA (which can accumulate in body tissues and the circulation) although there is some mounting evidence that LNA may impart beneficial effects independent of conversion to DHA+EPA. Of course, the conversion efficiency of dietary LNA to DHA/EPA is very limited.