What the...
"Greater consumption of oily fish, and elevated blood levels of the long chain omega-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are associated with a reduced incidence of heart attacks, arrhythmias, strokes, depression, cognitive decline and Alzheimer’s disease1–5. Diets low in seafood omega-3 fatty acids have recently been ranked as the sixth most important dietary risk factor—1.5 million deaths and 33 million disability-adjusted life-years worldwide are attributable to this deficiency6. Because of the strong epidemiological evidence of the benefits of seafood derived omega-3-PUFAs, most national and international guidelines recommend that adults eat at least one serving per week of oily fish (≥ 250 mg/day of EPA and DHA)7,8. However, uptake of these recommendations is poor, with many people not consuming any seafood at all. It has been estimated that less than 20% of the world’s population consume the recommended 250 mg of EPA and DHA daily9. Consequently, average omega-3-PUFA levels in most countries and regions of the world are sub-optimal10. The current main dietary source of EPA and DHA is oily fish. However, globally wild fish stocks are falling, and are insufficient to provide even one portion per week for the world’s population11. Aquaculture has steadily grown in recent years, but most farmed fish are dependent on dietary fish oil supplementation from the wild fish catch. This has become a scarce and expensive resource. As a consequence, levels of EPA and DHA in farmed fish have fallen considerably since 2006, such that at least two servings/week of farmed salmon are now required to deliver 250 mg/day of EPA and DHA12. T he most recent meta-analyses of randomized controlled trials (RCTs) testing marine omega-3-PUFA supplementation have confirmed protection against cardiovascular morbidity and mortality13,14. It is noteworthy that the benefits appear to be most pronounced at very high doses, up to 4,000 mg of long chain omega-3-PUFAs daily13–15. Possible explanations for the difference in beneficial dosages of the RCTs compared to the epidemiological studies, include; participant differences—mainly high risk populations, taking multiple cardiovascular medications, were studied in the RCTs, whereas normal populations were in large part studied in the epidemiological studies; poor long-term adherence to supplements; oxidant damage, lessor bioavailability and efficacy of the long-chain polyunsaturated fatty acids when provided as a concentrated fatty acid supplement rather than as a cell membrane phospholipid within a whole food matrix16. T he beneficial effects of EPA and DHA in humans are believed to result from their presence in cell membranes. From this location, they influence a myriad of molecular pathways including membrane structure, ion channel properties, genetic regulation, fatty acid metabolism (in hepatocytes), eicosanoid and inflammatory mediator synthesis17. It appears likely that some of the beneficial effects of omega-3-PUFAs on cardiovascular health are mediated through downstream effects on blood pressure (BP) and heart rhythm18,19. Hence, in this double-blind, controlled, randomized study, we aimed to quantify the impacts of regular consumption of recently developed alternatives to oily fish, namely chicken-meat and eggs naturally enriched with algae-sourced omega-3-PUFAs, on plasma and tissue (erythrocyte or red cell membrane) levels of DHA and EPA. Furthermore, we tested the hypothesis that the increased blood omega-3-PUFA levels, resulting from regular consumption omega-3-PUFA enriched foods, would have beneficial effects on ambulatory BP levels and heart rate."
I have quoted the introduction of your very own source:
1) It agrees that most people have a low consumption of Omega 3 (and not vegans nor vegetarians in particular, but out of everyone). Thus, criticizing vegan diets for a lack of Omega 3 when most people have a low intake of Omega 3 is unfair.
2) It mentions you need a very high dose to have the most pronounced benefits. (Up to 4000 mg)
3) You have not show WHY two servings of fish is recommended. You most certainly did show this diet, specifically, is recommended but not why. Your quoted study merely supports that such recommendation is made (and you had proven already that such recommendation is made), but not WHY.
In conclusion, I am going to take your source and use it to support my claim.