Here's a great article:
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Not Enough Fish in the Sea
21 June 2006

We need omega-3 oils for our brains to function properly. But where will they come from?
By George Monbiot. Published in the Guardian 20th June 2006.

The more it is tested, the more compelling the hypothesis becomes. Dyslexia, ADHD, dyspraxia 
and other neurological problems seem to be associated with a deficiency of omega-3 fatty acids, 
especially in the womb (1,2,3,4). The evidence of a link with depression, chronic fatigue syndrome 
and dementia is less clear, but still suggestive (5,6,7). None of these conditions are caused 
exclusively by a lack of these chemicals, or can be entirely remedied by their application, but it’s 
becoming pretty obvious that some of our most persistent modern diseases are, at least in part, 
diseases of deficiency.
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The full article (and references) can be found at:

http://www.monbiot.com/archives/2006/06/21/not-enough-fish-in-the-sea/

There is one point where Monbiot is wrong. There are plenty of fish in the sea; there are just too 
many human beings on the land.

Keith