We talk a lot about keeping a good ratio of omega 3 to 6. I have seen the epidemiological study that shows that people in countries with a better ratio are healthier. But I have not seen much other evidence. My concern is epidemiological studies cannot show causation. What could be happening is that low grain and grain oil intake is what is giving them better ratios and it is also the lack of grains that are the primary cause for health. The omega profile might be correlated but not be the actual cause.
Also, for any group with low fat intake, addition of some fats might have major health benefits. Or the benefits could be in simply keeping the omega 6s within reason and may have less to do with the exact ration of 3 to 6. Another concern is that both omega 3 and omega 6 are PUFAs and therefore unstable and easily going rancid. Maybe high intake of any PUFAs is just not that good for you in general, especially if the food is not fresh like it is in many fish eating coastal regions that have the higher omega 3 consumption.
I have heard some people worry that omega 3 is on its way to becoming like the next 'fiber' or 'whole grain' trend in that the overall theory sounds good but really has minimal research behind it and may well turn out to be in error over the long haul. There are many such theories that sound logical at first but later are found to be in error due to factors that were not yet known at the time. Meanwhile, companies make money marketing another pill. I have heard that some people felt ill after consuming a lot of fish oil pills and that also got me to thinking. How much strong evidence do we really have that fish oil and omega 3 is really so good for you that you should be eating a lot of them?