The null conclusion of the Cochrane report rests entirely upon inclusion of one trial, DART 2 2. This was a randomized dietary trial with clinical endpoints testing the effects on total mortality of either giving advice to eat fish or providing fish oil capsules to men with angina. Surprisingly, while total mortality was not statistically different in the two groups, there was less sudden death in the control group than in the intervention group. Upon exclusion of DART 2 from the meta-analysis, the overall decrease in relative risk with omega-3 consumption became similar to that reported in a previous meta-analysis by Bucher et al: 0.83 (95% confidence interval, 0.75 to 0.91) 3
In our view, the weight of the evidence available in May of 2006 is sufficient to conclude, even in light of the Cochrane analysis, that EPA and DHA reduce risk for cardiovascular diseases. Not only do we feel so, but also the American Heart Association/American College of Cardiology 15 , the European Society for Cardiology 16 , a systematic review conducted for the Agency for Healthcare Research and Quality at the NIH 17 , the Harvard Center for Risk Analysis 18 , and a number of other national and international bodies 19-22
There are effectively no plant sources, except for algae.
25,000 years ago we consumed omega-3 and omega-6 precursors in a 1:1 ratio. Today, thanks to the widespread consumption of cereal grains and few sweetbread meats, that ratio is about 1:20. That has drastic implications for the production of essential lipids like EPA that the body cannot create on its own.
It is not clear that dietary or supplemental omega 3 fats alter total mortality, combined cardiovascular events or cancers in people with, or at high risk of, cardiovascular disease or in the general population. There is no evidence we should advise people to stop taking rich sources of omega 3 fats, but further high quality trials are needed to confirm suggestions of a protective effect of omega 3 fats on cardiovascular health.
There is no clear evidence that omega 3 fats differ in effectiveness according to fish or plant sources, dietary or supplemental sources, dose or presence of placebo.