I have at least 3 books on Omega 3 which point out the benefits for both
mental and physical health. How the benefits of it were learned was in
studies of the Inuit of Greenland - before they introduced Western foods.
The key is the ratio of Omega 6 to Omega 3 and the Inuit ingested a ratio of 1:1
and rarely had either heart disease or cancer (until they added Western
foods). They ate very little vegetable food and subsisted on seals, fish
and anything from the sea - and were very healthy. Fish oil is the
recommended source in each of the books I have and they have a ratio of 2:1
Omega 6 to 3. The SAD diet is a ratio of 20 to 50 to 1. Flax oil
capsules is 6:1 and are not recommended as an Omega 3 supplement. A
prescription fish oil has been developed which is completely toxin free, but it
is very expensive and deep sea fish oil capsules claim they are also toxin free.